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January, 1892.J ENGINEERING
ENGINEERING MECHANICS.
Devoted to Civil, Electrical, Mechanical, and Mining Engineering.
PUBLISHED MONTHLY AT NO. 430, WALNUT STREET, PHILADELPHIA.
Entered at th* Post-opfi.ce in Philadelphia as Second- Class Mail Matter.
SUBSCRIPTION RATES.
Subscription, per year $2 oo
Subscription, per year, foreign countries 2 50 be opened by the driver when necessary for letting out'^h.e.^ „
ashes. The high-pressure valve motion is of the ordinary cuiv*e

.'•'.•'A , *. "*. [Copyrighted.]
DIACTpAitjS, FORM-OtAS AND TABLES FOR THE USE OF EN-
. " ."rGINEE-ffS, DRAUGHTSMEN AND ARCHITECTS.
On- Plate-XV/for — = 30, follow the vertical line until it cuts
d
tfee curvejbf•*"• I Then follow the horizontal through this
ENGINEERING MECHANICS. [Tanuary, 1892.
For Wrought Iron.
1 , Max s .
A'12 = 9000 1—i—-• -
* 1 Max S >
For Steel.
(9')
r , Max s x / „>.
Ra = C I ——, =. (92)
I Max S I
pointful 'it cuts the inclined line marked EE, then the ver- wh£re Q -s [Q bg ,letermined by the results of tests of full-sized
tieaHb'.ough this point down to the quantities designated "value members.
A'Acs.
;b"!,— —," where 0.47 is found, which is the value of —
For - Soooo Iron.
1
/'
In the shearing of rivetted connections:
1 + C
d
Bonscaren's Formulas for Alternating Stresses.
I 1 Max s \
HIGHWAY BRIDGES.
For Wrought Iron in Tension, Rolled Bars.
n 1 , Max s 1
R a = 12000 i J. " 1 ' — i J Max S i
Ra:
For Plates and Shapes.
< , Max s x
IOCOO 1—i '
I ' Max S i
PLATE XXIII.
For Steel in Tension.
r, ( 1 Max s I
/?« = 14000 { 1—.', \
I " Max S i
For Wrought Iron in Compression, when /— r

January, 1892.]
PLATE XXV.
PLATE XXVI.
MECHANICS. 3
PLATE XXVII.
PLATE XXVIII.

4
For Iron.
Ra, ( Max s
= 9000 -, 1 —
I " Max S I
Ra = C X 1
For Steel.
Max s
Max S
ENGINEERING MECHANICS. [January, 1892.
(99)
(100)
when C is to be determined from the results of tests of fullsized
members.
In shearing of rivetted connections
For Iron.
„ 1 , Max s x
tfa = 9oco{,_*___}
(101)
For Steel.
1
R
a = 10000 .
, Max s -1
1 —). — 5.
(102)
I " Max S I
In the above formulas Max s = the smaller maximum stress,
and Max S = the greater maximum stress. No attention is
paid to the signs of the stresses when using the formu'as.
A'j^jEMuiMa
T SlTE TTT
] 1 fuHilin tt J -tf j LLI IJ n Tl
: :: :
B L Trmffln tfflfJTJjtt'' i
iMri *i 1!! i 1 li i
Hi 1 JTri l' I ft Fr
IfifitE iiii 4-IIT111,1-
:gl|:|[|
'TTT'iTT FTli
MT T J T ""W ' ill'
JKXllirmiRtf
KAWHI it
fwM
-iM'"
T^r-iftfi-r
tijrj- - -ti*fcn~iti [-yi'f 1
^nflpnP' I^F1I1 :
¥ 111 /Im T 1
^ .''WH^TTI
1|||B|.|.||
iF+-1—rtitt --T-T-I
r^iiTm-iJIJ
±ttitijm:m:|J
rfflBIJM
11|[ |; f[f:
where R is the intensity that would be used were there no reversion
of stress, and adopting the greater of the two areas
thus found.
Formulas (86) to (103) inclusive have not been diagramed,
as so many lines on the same diagram would be confusing.
However, the formulas can be easily diagramed on Plate XXII
by using different colored inks, each formula requiring but one
straight line.
STIFFENERS FOR PLATE GIRDERS.
It is the practice of the Boston Bridge Works to use stiffeners
when the allowable shear per square inch is greater than the
value of R, obtained from the following formula :
R
2500
Where a has values from 9000 to 12000, and Q = d -j- t, d
being the unsupported depth in inches and I the thickness in
inches of the web of the girder.
From Plate XXX (a modification of a diagram sent to the
writer by R. H. Brown, Consulting Engineer of the Boston
3+ TAA rTTT'TTl II '
4*111 ra I' "a
fr f^t [ \g-£ ft - f*i fy ji -j-—li iHJ\}E*
Ml\Ml -I
5581111
3*5
ff##
t'Ps
ins
|gB|H:
("llli
||Hi|;i^ffi
g|g|j:;::|
gii-iii;i:|
^7-^rh;i^t3 -pjt*T^f : :;j 1 jj|
«|ggij|
PLATE XXIX. PLATE XXX.
#

January, 1S92.] ENGINEERING MECHANICS.
ELECTROTECHNICS.
A Compilation of Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
Permanent Magnet Ammeters have for a controlling field a
permanent steel magnet, which has been "aged," by subjection
to rough treatment, heating, etc. A coil through which the
current passes, deflects the magnet needle, which deflection is
resisted by the controlling magnet. Carpentier's and Ayrton &
Perry's ammeters belong to this class.
Electro-controlling magnet ammeters differ only from the
above in replacing the permanent magnet by an electro-magnet.
The core of the magnet should be laminated or subdivided, to
prevent persistent magnetism.
Gravity ammeters are those in which the force tending to deflect
the needle (either a magnet or a piece of soft iron) is counterbalanced
by the force of gravity.
Spring ammeters substitute the torsion (generally) of a spring
for the action of gravity.
Ammeters should be supplied with short circuiting switches.
;«). Calibration of Ammeters.
Standard ammeters are generally calibrated with a standard
cell, or by the electro-deposition method. Commercial ammeters
are generally calibrated by placing a number in series with
a standard ammeter, and altering the current strength by
means of rheostats in circuit or in shunt, and noting the deflections
of each instrument.
When voltameters are used, those of silver are chosen when
extreme accuracy is demanded. Copper voltameters, however,
are more practical.
Gray recommends an area of cathodes in copper voltameters
of 20 sq. cm. (3 sq. in.) per ampere. The cathodes, or gain plates,
should be of pure copper in thin sheets. The edges should be
rounded, and the surfaces thoroughly cleaned, by polishing,
washing and drying.
'

c is a constant of the condenser, obtained from a table pre­
pared as follows :
The deflection of the galvanometer for i Daniell = 1.068 volts
is plotted as an ordinate to the abscissa of the E. M. F., causing
it (1.06S), aud similarly for 2, 3, 4, etc., cells. The curve passing
through the points thus determined is the locus of all values
ofr.
b). Quadrant Electrometer Method.
The terminals whose potential difference is to be measured
are connected to the quadrant pairs, and the deflection noted
and compared with that given by a standard cell.
E = S X constant depending ou instrument.
Where E is potential difference in volts. Also with standard cell
£j=iiiX constant,
ri
whence I: = IA volts.
Thomson's electrometer, with scale at a distance of 1.6 meters,
gives a deflection of 400 mm. per volt. This instrument is not
extraordinarily accurate, and is somewhat inconveuient to use.
c). Method of Equal Deflections.
Let A",, E., be the E. M. F.'s of batteries to be compared.
Take deflection of E, in circuit with resistance Rlt and galvanometer,
and obtain same deflection with E2 and A',.
Let G = resistance of galvanometer, A 1 , and B., those of batteries.
E., = E, ~—-fAL-J. or approximately E..^=El —- volts.
«i+ *> + -°i ^1
When a galvanometer shunt s.. is used with larger batter)- E2:
R
G + s,
E2 = E, -A-
A,
- and if shunts are used in both measurements
G + s,
R,
E, = E, -ii—
i? G + A
-"-1
-u
In the above, Rx, R, are taken so large that resistance of batteries
and galvanometer ma}' be neglected.
d). Method of Equal Resistances.
If the resistances of the cells A, and E, are known,—1. Connect
E\ with galvanometer and resistance A\, aud note deflection
Sx. 2. Replace E^ by E2, and alter R1 to R., in order to
make total resistance of circuit as before, and take the deflection

January, 1892 ] ENGINEERING MECHANICS.
The plugs are inserted iu the resistances io, ioo aud iooo, and
(2) the plug between III and IV is taken out. Each cell to be
measured is compared with the standard cell E0. The E. M. F.'s
are in the ratio of the measurements which are made by turning
FIG. 37-
the contact arm on the wire A B until, on depressing the key,
no current passes through the galvanometer. The key is generally
placed between I and IV, II and V being connected
together. If ax and a., are the deflections,
150±«!
E, = 1 and, AAAAEO
150 ±CL,
a is taken as positive on A side,—negative on B.
The universal resistance box of Siemens & Halske is employed
in comparing E- M. F.'s as in Fig. 3S.
FIG. 38.
E0 is a standard cell (or cells), and E a cell to be measured.
The E. M. F. of the first should be the greater. Such a resist­
ance in the part A of the arrangement in Fig. is chosen, that
the galvanometer gives no deflection.
Where A, B, Cand D are the resistances indicated in the
Fig., and w0 the resistance of the standard cell, or cells.
j). Clark's Potentiometer.
A still better method is that of Clark's potentiometer, which
can be used with the universal galvanometer (Fig. 39).
El is a standard cell, E the element to be measured, and A°
an auxiliary battery.
First E0 and Ex are so connected and the resistance W so ad­
justed that no curreut passes through galvanometer G, on de­
pressing key T. The circuit through E is then closed and the
contact p is adjusted on
the wire until on the de- FlG. 39.
pression of T no deflec­
tion is noticed. Then,
E=E, 1AAA. on A side.
300
E = E, I H°A±- on Aside.
300
If A > A,, two standard
cells must be used and the
battery E0 strengthened.
These compensation methods, employing the universal gal­
vanometer, are not as adaptable as others given, but are never­
theless of importance.
k). Voltmeters.
Voltmeters are used in practical work for the measurement of
potential differences. They are in general designed on the same
lines as ammeters, and differ only in details of winding and pro­
portions.
The Deprez-Carpentier voltmeter consists of a needle of soft
iron, movable ou au axis in the interior of a coil of wire, whose
ends are connected to exterior binding posts. An aluminum
pointer is used, and the instrument is so balanced that it will
work in any position. It is direct reading and almost dead beat.
Resistance about 2000 ohms. Ammeters are made of the same
type. Both instruments may be supplied with resistances which
increase the range of measurement.
The Ayrton cV Perry Magnifying Spring Voltmeter. In this
instrument a phosphor-bronze spring, of the shape of a shaving,
or spiral curl is used. The top of this spring is fastened to a
brass pin, which is secured by a binding nut to the glass top.
The lower end of spring is fastened to a brass cap, which fits
the bottom of a thin charcoal irou tube, and which surrounds
the spring. The end of the cap is prolonged, and forms a guide
by passing through a hole in the base. To the upper part of the
iron tube is attached an aluminum pointer. Surrounding the
tube is wound a coil of high resistance whose terminals are
attached to binding posts. This form of spring has the property
of rotating one end through a large angle (the other being fixed)
when a slight increase in length is made, and the angle of rota­
tion is directly proportional to the axial extension.
The instrument is dead beat, direct reading, portable and,
having no permanent magnets, may be used around dynamos
without altering the readings. They are not calibrated below \
of their range, the saturation of the thin irou core not being
complete below this point.
Au ammeter of this type is also made.
The Hot wire voltmeter of the same inventors consists of a
horizontal tube in which is suspended a platinum wire. At the
centre is fastened a spiral spring made by winding a flat strip of
metal around a cylinder, and opposing the tension of this spring
is that of a flat spring behind the other. The end of the spiral
is attached to the glass cover as in the spring voltmeter, and to
the pointer are fastened fine hairs to produce damping without
solid friction. When a curreut passes, the wire is heated, and
expands ; the flat spring, being stronger, stretches the spiral and
produces a proportional deflection. The voltmeter is supplied
with an automatically inserted fuse in case the current becomes
too great for the wire. It is direct reading, calibrated throughout
scale, uninfluenced by magnetism, and may be used with
either direct or alternate currents.
A voltmeter called "inspectional" is constructed on the prin­
ciple of the current balances, by Sir Wm. Thomson, for small
ranges of E. M. F. The composite balance may also be used
to measure potential differences.

Cardeiv' s Voltmeter has been described iu paragraph j. It is
calibrated generally at 15 0 C, and for close accuracy a correction
of .03 per cent, per degree should be made (negative). The
diameter of fuse wire employed on 120 volt pattern instrument
= .0014 ; resistance cold 90 ohms per foot.
A line of instruments is made by Jas. W. Queen & Co., of
Philadelphia, in which the deflections are caused by the repul­
sion which takes place between a fixed and a movable strip of
soft iron when a current circulates in the coil which surrounds
them. The movable strip or ''vane " is mounted in agate bearings,
and practically frictiouless. The instruments are dead
beat, portable, unaffected by magnets, and carefully calibrated.
The Wirt Voltmeter is a portable application of the potentiometer
method of balancing the E. M, F. to be measured with
a known standard. Two Clark cells made to stand rough usage
are contained in each instrument, with means for comparing
them. The resistance is high—2500 ohms. Range of instrument
is from 1.5 to 250 volts, lower scale reading to T',r volt and
easily read to ,,,,, volt. This instrument has no moving parts
except the needle of detector, whose function is simply to determine
the passage of curreut.
tn) The Weston Voltmeter is extensively used by American
electricians and fully sustains its reputation as a highly accurate
instrument (Fig. 40).
A
It consists of a circular permanent magnet A (partiv cut
away in fig.) with the cylindrically bored pole pieces A B' which
embrace an iron core G supported by the brass pieces C and C
spanning the pole pieces. The bridges D and D' are fastened
over the ends of the bored cavity, and within is pivoted the
coil II, which moves with as little clearance as possible in construction.
II consists of a coil of insulated wire wound on a
rectangular spool of thin copper, the circumference being
covered by a frame of thicker copper, thereby enclosing the
winding in a metallic sheath to secure dead beat actiou. The
coil is fastened to the pivots by an insulated arrangement, and
these are held in jeweled bearings. The motion of the coil is
opposed by flat spiral springs shown in figure.
A high resistance coil is included in the circuit. The current
enters one binding post, then through high resistance coil to
bridge D, arm which holds end of spring, spring pivot, thence
through coil to pivot spring, spring arm, bridge D' to second
binding post. A third binding post is provided, which is connected
with a certain definite part of the high resistance coil,
and by which voltmeter may be calibrated with a standard cell
of known E. M. F. The construction described gives a very
strong uniform field, When no current traverses the coil it is
held in position shown in figure. When current is passed the
coil becomes a magnetic shell and the N pole of the magnet
will attract S pole of coil, also 5 pole of magnet the A r pole of
coil, turning the coil in direction of arrow until half its path 45 0
has been reached. The coil is then parallel to the brasses C and
CA The next movement brings iVpole of coil facing jYpole of
magnet, and similarly the S poles, and repulsion takes place,
continuing the deflection. The springs oppose the motion of the
coil and increase in resistance proportionately to the movement
of the coil. This allows the use of an evenly divided scale.
ENGINEERING MECHANICS. [January, 1S92.
These instruments are direct reading (beginning at zero), dead
beat, have no moving parts of iron, temperature corrections,
negligable ordinarily, and instrument may be kept in circuit
indefinitely. They should not, however (in common with any
permanent magnet instruments), be used in proximity to motors
or dynamos. These instruments range from o to 6000 volts in
different sizes. Ammeters are constructed on similar lines, the
high resistance coil, however, being omitted.
For measuring high potentials, say 500 to 3000 volts, with an
ordinary voltmeter of from o to 150 volts range, a number of
110 volt lamps of the same make may be arranged so that any
uuniber of them maybe connected in series across the points to
be measured. Enough are cut out until the remainder are at
normal brilliancy or less. A voltmeter shunted around one
lamp gives voltage for one lamp, which multiplied by the number
of lamps lighted gives the approximate total voltage. Or
more accurately, a point switch may be used and the sum of the
voltages of all the lamps used may be taken for total.
11) Calibration of Voltmeters.
Iu the figure the letters represent as follows :
/', the voltmeter under calibration.
SB, Storage batteries or other sources of current.
Ii,
FIG. 41.
R,i, Variable resistance to 100,000 ohms.
A, = 56.2 ohms.
A', = 143.S ohms.
A:1 = 9800 ohms.
Ri = Res. of arm of bridge.
A", A",, Bridge keys.
A3, Key closed only when reading is taken in order not to
heat A,, A, and R,y
S C= Standard Clark cell.
Ra is of German silver or platinoid ; Rlt R, and A3 should be
of platinum silver, so as to have equal and simultaneous temperature
variations. The above arrangement is for calibrating
at 100 volts.
Rl + R2 + R.t = 10,000 ohms or 100 ohms per volt.
., 143.S ohms
Also, —-— = 100 ohms per volt.
1.43S volts
r
-43S v. E. M. F. of
Clark cell.
Ra should theu be altered until Galv. G gives no deflection on
closing A"; and A,, or, in other words, on balancing.
The drop of potential is then 100 ohms per volt in A„ A2, R3,
and deflection of Vis for 100 volts. A\ is connected up with
Ri (iooo ohms or over), and should be used instead of A"2 until
deflection of galvanometer is very small, in order to prevent the
passage of a strong current through G aud the standard cell.
For any other voltage E, make A! + A2 + A3 = 100 E and
vary Ra as previously, until balance is obtained.
To check a voltmeter already calibrated, vary Ra until desired
deflection in voltmeter is given, then alter A3 until deflection of
G is null, wheu the correct reading is
A = *' + S * + **•
100
(To be continued?)
SC

January, 1892.] ENGINEERING MECHANICS. 9
[Copyrighted.]
THE MARINE ENGINE:
Its Construction, Mode of Action and Management.
BY CARL BUSLEY,
Piofessor at the Imperial Academy at Kiel.
From this we derive the follow ng relations :
Bet-ween -volume and pressure. Between vol. and temperature'
In order to eliminate I, dif­ To eliminate/, substitute its
ferentiating equation (17), value from (16)
Translated iy Assistant-Engineer EMIL JHF.ISS, U. S. A'.
16. The curve of pressures given by a gas expanding according
dT
= 5 (pdv+vdp).
to the law of Mariotte is called the isother-
Substituting this value for
then
7]
Curve ot Mariotte mat curve. It is a rectangular hyperbola
Cvd T+AR 7 dv
or the isothermal whose asymptotes are theaxesof co-ordinates.
curve. To construct it for a gas expanding from v to
:,, divide the length V, — V into any number
of equal or unequal parts, aud erect perpendiculars at the points
of division. Parallel to z\ — v, and at a distance from it equal
to/>, draw a straight line. Connect the points of intersection I,
2, 3, etc., of this parallel with the perpendiculars on z\ — v with
the origin O, and from the point? of intersection I, II, III, etc.,
of these radial lines with the initial ordinate/, draw parallels to
i\ — v; the intersections of these, ii, 2n, 3m, etc., with the perpendiculars
on z\— v will give points on the desired curve. The
proof of this construction is found in the similarity of triangles
O A I and I, II, I,.
17. Laws of Gay-Lussac and Mariotte cotn-
LawsofGay-Lus- bined : The external work performed by a
sac and Mariotte perfect gas healed 1° under constant pressure
combined. is constant.
this law. under atmospheric pressure. Under a pressure
of p atmospheres its volume will be by
«*—J-(i + «A
Similarly the volume l^of a pound of a perfect gas at t° and
a pressure pv will be
vt = A (1 + atx)
Pi
Hence h {E 4. A
V pfl + at) Pl \ a ^ I _py
«.- /(! + ««- ,(_!+,,) P 7 ~\
and y = ^ = A> = constant (.6)
1 pv = R T (17)
Explanation of 19. Equation (17) expressed in words
equation 17. means, that if a pouud of a perfect gas is
heated from absolute zero to T° under a constant
pressure of p pounds per sq. foot, it will perform external
work equal \.o p V ft. lbs.; for each degree rise in temperature,
p v
R=—r
According to Regnault, for
Nitrogen R = 54-9 1
Oxygen R = 4S.24
Hydrogen R = 770.08
Carbonic acid at 32 0 R = 34-88
Steam at atmospheric pressure .... A = 85.68
Qvdp+[ ( ^ + A)pdv=o. |
21. The volume of a perfect gas enclosed in According to (19)
Law of Poisson. a non-heat-conducting vessel is inversely proportional
to the nth {1.41th) root of the pressure
and to the (n —l)th (0.41th) root of its absolute temperature.
22. In a non-conducting vessel heat is
Hence,
Non-heat-conduct- neither imparted nor abstracted during
ing vessel. changes of volume or pressure.
A =
23. For a change of volume or pressure
Relations between under these conditions by (2),
pressure, volume, d Q = A (d W + d f + d L) = o
and temperature of *a
perfect gas ac- For a perfect gas df = o; according to (3),
cording to the law A d W= Cv d I, and from (18) d A =pdv ,of
Poisson. hence
d Q= Cvd T+ A p d v = 0.
Cv
we shall have,
According to (7) we may write
According to (5") we may write this
this,
Cv
B (•'+ «-pdv) = o.
A
Multiplying out by , we
Cvpv
get
G *„ [rf T+(,

IO ENGINEERING MECHANICS. [January, 1892.

January, 1892.] ENGINEERING MECHANICS. n
Non-reversible 2. A cycle becomes non-reversible, when it
cycle. comprises changes in the course of which
heat is transmitted directly, by radiation or
conduction, from a body of higher to one of lower temperature,
or in the course of which heat is produced by frictional resistance.
Carnot's cycle. 3. A cycle consisting of four changes only,
two of which are isothermal and two adiabatic
is known as a simple reversible cycle or Carnot cycle.
4. In Carnot's cycle (Plate 1, P^ig. 3) the
Changes involved following changes take place :
in Carnot's cycle. a. Isothermal expansion from volume v to
~\ ; the temperature remains constant, a
quantity of heat Q being imparted.
b. Adiabatic expansion from vx to v2; the temperature falls
from A to A,, heat being neither imparted nor abstracted.
e. Isothermal compression from ZJjtOWj ; the temperature Aremains
constant, a quantity of heat (J, being abstracted.
Q T
and finally A A = Q —-
Q •
lhis value of — is called by Zeuner the
thermal weight. The difference A— Tx is
called by the same authority the temperature
range.
10. If for the passage of a body from its
initial to its present condition we form the
* / ft
A'A
Thermal weight.
Temperature
range.
Transformation
value.
Entropy.
integral /—j^- (where //denotes the heat
d. Adiabatic compression from v., to the original volume v ;
the temperature rises from A, to A, heat being neither imparted
nor abstracted.
Diagram of Car- 5. The diagram representing the changes
not cycle. of pressure and volume of a Carnot cycle
shows that external work, measured by the
circumscribed area F, (J 6, 2) has been performed. This work
must be the equivalent of the excess of the heat imparted over
that abstracted, that is
AL=Q-ft
On performing the cycle in the inverse order an equal amount
of work is expended and an equal amount of heat generated.
6. The work performed by or upon a body
External work undergoing the changes of the Carnot cycle
from Carnot cycle, is calculated as follows : The heat absorbed
during isothermal expansiou is, by equation
'5.
Q = A R Aloge —
V
That abstracted during isothermal compression is
Ol = AR Aloge As
v3
Hence Q : Qx = Aloge — : A, loge —
v v,
Equation 19 gives the following relations between absolute
temperature and volume,
1 A\K — 1 1
^ = ( ^ ) K - 1 actually present in the body), then this integral is known, according
to Clausius, as the transformation value of the heat actually
present in the body when calculated from the given initial
condition. That is, wheu in any way whatever work is transformed
into heat, or heat into work, and the quantity of heat
present in the body is thereby altered, the increment or decrement
of this integral gives the equivalence-value of the transformations
that have taken place. This integral is also called
the transformation value of the thermal content. Similarly the
disgregatiou is the transformation value of the existing arrangement
of the particles of the body. Finally the sum of these two
is known as the transformational content or the entropy.
0 T Q
11. Equation -=- = -=: may be written ~ Other form of the
Qi I
and^=(^-)
vx \Txl v \ A,/
From this we have
—- = —; or — = — . Therefore also
Vx v v v3
Q T QT,
-, = T ], and £• = ---
r II. Law.
= As; ; and as Q is the applied or positive quantity of heat, and
' 1
Qx the abstracted or negative quantity, we may place
T -r (22)
T
Or, in other words : in any Carnot cycle the thermal weights
added are equal to those abstracted; i.e., their algebraic sum is
equal to zero.
12. Equation 21 has been expressed in External work
words by Zeuner, as follows : the heal eon- due to Carnot cycle
verted into external ivork in a Carnot cycle is is a maximum.
equal lo the thermal weight multiplied by
the temperature-range. He proves, besides, that of all similar
cycles the Carnot cycle gives the maximum of external work.
13. The external work performed increases
with the range of temperature. In many in- Fixed limits of
stances this has a definite value, because the temperature.
initial temperature Aand the final temperature
A, are found within certain circumscribed limits. Moreover,
as these temperatures are directly proportional to the
quantities of heat imparted and abstracted, Q and Qx, we derive
the following theorem, a very important one in the theory of the
steam engine, viz.:
14. The external -work due to a Carnot cycle Perfect cycle.
becomes a maximum, if all additions of heat
occur at the highest temperature, and all abstractions of heat
occur at the lowest. CHAPTER II.
A L = -^ (T— Tj) thermal units
5 8. Different Conditions of Steam.
L = -9—(T- A,) ft. lbs.
(21)
I. Steam occurs in two different conditions
as to temperature, namely, as saturated steam
and superheated steam.
Steam.
2. Saturated steam can exist only in con- Saturated steam.
Conclusions drawn 7. From the preceding we conclude that tact in with the water from which it was gener­
from Carnot's the Carnot cycle two transformations take ated, although the quantity of water present maybe very small.
cycle. place : one is the transformation of heat into Saturated steam of any pressure is at the lowest temperature,
work (or the reverse), the other that of heat and possesses the least specific volume and the greatest specific
at a higher iuto heat at a lower temperature. In other words : density consistent with that pressure. It is in such a condition
If a quantity of heat is to be converted into mechanical work, that the slightest decrease of temperature results in partial con­
another quantity must be brought from a higher to a lower densation. The temperature corresponding with that of satur­
temperature.
ated steam of any pressure is called the temperature of satura­
//. Law of the 8. Two transformations, which, without tion.
Mechanical Theory necessitating any other permanent change, 3. In practice distinction is made in the Different condi-
of Heat. can mutually replace one another, are called case of saturated steam between dry sleam, tions of saturated
equivalent.
moist sleam and wet steam. steam.
Equivalence- 9. The generation of a quantity of heat Q 4. Dry steam is steam just on the point of
yalues. at equivalence-value temperature / by -—, mechanical where work T=f(t), has the an condensation. It contains no entrained water. Dry steam.
transformation of a quantity of heat Q from a higher tempera-
Its production necessitates the use of a superheater,
and it is for the purpose of dryiug the steam, not of
, ture to I, a lower /,, has an equivalence-value Q ( = — -—).
superheating it, that superheaters find a place in modern practice.
In what follows, saturated steam is always understood to
mean dry saturated steam.
(To be continued.)
STEAM.

12
Translated by Henry Harrison Suplee.
\ 214.
GENERAL REMARKS ON THE FOREGOING METHODS.
THE CONSTRUCTOR.
Each of the preceding methods possesses its merits and disadvantages.
Epicycloidal Teeth. These possess the great advantage that
they will work together in any series with as few as seven teeth,
while for evolute teeth the lowest in series is 14 teeth, and in
no case fewer than II. The loss from tooth friction is a minimum
with this form, and the wear less injurious to the shape of
the tooth. The minor objections which have been raised are
that the double curve increases the difficulty of construction,
and that any variation of the distance between centre causes imperfect
action to follow.
Evolute 'Jeelh. The advantages of this form are that the
simple shape is readily made and that any variation of the distance
between centres does not affect the action.
Against these must be set the fact that for low numbered
pinions the flanks must be altered to avoid interference, or the
tops of the teeth must be taken off. The fact that the distance
between centres may vary is rather an objection in many cases,
as the arc of action is reduced, and in transmission of heavy
power the shocks upon the teeth are liable to be increased.
Evolute teeth are well suited for interchangeable gears, if lownumbered
pinions are not required (30 teeth being the minimum 1,
and where but small power is to be transmitted they are excellently
adapted. For wheels which run only in pairs, and hence
for bevel gears, this form is excellent, since it is so readily made.
See \ 222.
Pin tooth gearing and the mixed outlines are only used for
special work, such as in hoisting machinery and the like, and
in such cases the wheels are often made of wrought iron or steel.
Disc wheels have a very limited application, but in some special
forms of mechanism they are very useful, and will be discussed
further. See Chapter XVIII.
[January, 1892.
Translation Copyright, 1890.
The effect of this may frequently be observed in practice, If bevel gears are required to interchange (see {*• 200) they
where the smaller of a pair of evolute gear wheels will be no­ must not onl v be of the same pitch, but must also have the same
ticed to be worn into deep hollows below the pitch circle.
length of contact line, A S, Fig. 596. Since these conditions
The conclusions given above about the percentage of loss may are very infrequent, it follows that bevel gears are generally
also be determined geometrically in the following manner : only made to work in pairs. In practice it is found that a vari­
Take the two portions of the tooth prof les which work together ation of less than 5 per cent, iu the length of the contact line
and divide each by the chord of the corresponding portion of the may be neglected. Gears of the same pitch and same angle of
line of action, multiply each result by the ratio of the length of
its portion of the line of action to the entire length of the line
of action, and then multiply the sum of the two quotients by the
coefficient of friction.
The result will be the percentage of loss, pr. The chord referred
to becomes the line of action itself in the case of evolute
teeth. This method serves also for pin teeth, and is very useful
for the designer, as the data can all be taken off the drawing
with the dividers.
\ 2*5-
GENERAL CONSIDERATIONS.
B. CONICAL GEAR WHEELS.
In the case of conical gear wheels, or as they are generally
termed, Bevel Gears, the working circles of a pair of gears which
run together, lie on the surfaces of a pair of cones, the apex of
each cone being at the intersection of the axes of rotation. In
such case the pitch circles are taken at the/ base circles of the
respective cones, as SD, and SE, Fig. 596. The length of the
teeth is measured on the supplementary cone, to each base cone,
SB being the supplementary cone for SD, and .SCthat for S
E, B C being at right angles to .-/ S. The length of teeth is laid
off ou SB and S C, and the width of face on S A ; the tooth
thickness being spaced off on the pitch circle and all the teeth
converging to the point A.
The respective radii SD and SE of the two cones are found
by dividing the angle a of the axes, in such a manner that the
perpendiculars SD and SE let fall from .S' to the axes, bearthe
same ratio to each other as do the numbers of teeth, or inversely
as the number of revolutions : thus S D • S E = Z ; Zx =
n, : n. There are, therefore, two solutions possible, according
as the pitch line SA is taken within the angle ", or in its supplement
; or what is the same thing, according to which angle
is taken as the angle of the axes. The difference between the
two consists in the fact that for a constant direction of revolution
of the driving shaft the driven gear revolves in one direction
for the first solution and in the opposite direction for the
second solution. One of the solutions gives an internal gear,
when '/, : n < cos a.
FIG. 596.
axes, but with a small variation of contact line, are called
"bastard gears.'' A pair of right angled bevel gears of 80 and
45 teeth, might be altered in practice, if required, into bastard
gears of So (1 ±0.05), i. e., 84 to 76 teeth, which wduld work
with the other gear of 45 teeth.
? 216.
CONSTRUCTION CIRCLES FOR BEVEL GEARS.
The geometrical figures which are formed by one cone rollin
upon another, require that both cones should have a common
apex. The surface thus developed is called a spherical cycloid.
Of these there are five particular forms, as with the plane cycloids,
the latter being really those for a cone with an apex
angle of iSo°. The spherical cycloid is very similar in form to
the plane cycloid, as are also the corresponding evolutes ; the
branches of the curves assuming a zig-zag form.*
FIG. 597.
The use of the spherical cycloid for the formation of bevel gear
'teeth would involve many difficulties. In order to construct
such teeth, it is therefore common to use the method (first devised
by Tredgold) of auxiliary circles, based upon tbe supplementary
cones, and enabling the teeth to be laid out in a similar
manner to those of spur gears. The auxiliary circles for the
bevel gears R and A„ Fig. 597, are those of the spur gears having
the same pitch, their radii being respectively rand rx, the
elements A 5 and CSof the supplementary cones.
For any given angle a between the axes, the radius r, and
number of teeth 3, for the auxiliary circle can be determined
th^S^ricaTc 'cSd^ 111 "*' l8?6 ' PP ' 3 "' 449 ' Reuleaux ' Development of

January, 1892.] ENGINEERING MECHANICS. '3
from the radii Aand A',, and tooth numbers Z and Z,, by the
following formula :
r_ _ ^^±jf?il±_ 2 _ A lj /? i c °_
R R, + R cos a
Z
-vZl ±AlAyry^A.A°^
Z\-\- Z cos a
If the axes are at right angles, we have
r_ = s/R> + A,'-' £ _yzyZe
R R, z z,
AA)'
(I92)
Exampit-.-~,\ pair of bevel gears have 30 and 50 teeth, and an angle between
.xes a = 6o°, hence cos a — 1 tooth gear : 2 — 30
^ •»«'' —- > *— " -•'- -•—•- -* •-•-
V^JQ2 %, and we have for the auxiliary circle of the 30 = tan y2 = j
+ 50^ + 2
x/.
3
50 + 30 . 0.5
= 32.3, say 32. R
= 14
For the 50 tooth gear ear we have also also: : a, z, = so
v/
— '*"'"'• - = 64 *V
30 + 50 . o.s
Rt
From these numbers and the given pitch, the auxiliary circles R
can be laid off and the teeth drawn.
Low tooth numbers are not available for bevel gears, since the
errors which are involved in the method of auxiliary circles become
disproportionately great. By using not fewer than 24
teeth for the bevel gear, a minimum of 2S for the auxiliary circle
is obtained, and the evolute system can be used to advantage.
This form of tooth is best adapted for this purpose, on
account of its simplicity of form, notwithstanding the minor
defects which have already been noticed.
The loss from tooth friction in bevel gears is approximately
equal to that of their corresponding auxiliary gears
0 i8°30' 26°40 / 36=50' 45° 53°io / 63°2o'7i°3o 76 0
= sin ;, = 0.242 0.317 0.449 0.6000.7070.8000.8940.9480.970
Either of the wheels R2, R3, can be used with the plane gear
A, if the number of teeth have the ratio given by the value of
sin y2. Although this limits its application, yet the plane gear
is frequently found very useful for angular transmissions*
C. HYPERBOLOIDAL GEAR WHEELS.
I 218.
BASE FIGURES FOR HYPERBOLOIDAL. WHEELS.
Hyperboloidal wheels are used to transmit motion between
inclined, non-intersecting axes. The figures upon which they
are based are hyperboloids of revolution having a common
generatrix. These may be determined in the following manner.
§ 217.
THE PLANE GEAR WHEEL.
FIG. 598.
Internally toothed bevel gears are not used, on account of the
practical difficulties involved in their construction. There is,
however, an interesting form of gear wheel which lies intermediate
between the external and internal forms. If the numeri­
cal ratio between a pair of bevel gears is = cos a, one of the solutions
for the base cone gives for the latter a plane surface, 5
E, Fig. 598.
FIG. 599-
The supplementary cone in this case becomes a cylinder, and
the radius of the construction circle becomes infinitely great,
hence the tooth outlines are similar to those used for rack teeth.
If the evolute system is used the teeth are very simple, and the
plane gear in some cases becomes a very convenient form of
construction.
As already stated, the ratio is
R, , ,
— = cosa (193)
from which, if for example a = 6o°, we have If the
angular relation of the axes is given it follows that but one velocity
ratio cau be obtained. This is determined from the angle
)2, which is one-half the apex angle of the cone R2, and from
the ratio - - = sin }'.,.
It is sometimes very convenient to arrange a plane gear so
that it may work with both of a pair of bevel wheels. This is
shown in Fig. 599, in which the gears R.,, R3 have the semi-apex
angles >.,, y.„ and have their axes at right angles. We then have :
y = tan y2 = cot y:),
A",
from which we obtain the following values :
A,
In Fig. 600 is given a projection normal to the line of shortest
distance between the two axes. The angle a is divided iuto two
parts ,3 and pv in such a manner that the perpendiculars let fall
from any point A, of the line S A, upon the two axes, shall be
inversely proportional to the revolutions of the gears. 5 A is
theu the contact line of the hyperboloids ; A B = R' and A C
*The so called "Universal Gears" of Prof. Beylich, introduced in 1866,
should be considered as a variety ot conical gears in which the angle of the
axes may be conveniently varied. These may be used for axes of angles
varying from o° to 180° As shown in the illustration, these wheels are
formed of globoids of the III Class (see ^224), the meridians forming the
teeth and spaces. They ha^e found but limited application. A model of
these gears is in the kinematic cabinet of the Royal Technical High School.

14 ENGINEERING MECHANICS. [January, 1892.
= R\, are projections of the radii of the hyperboloids intersecting
at A. We have
_R'_ sin g
sin 8,
z_
A,
(•94)
The actual radii A and A, are yet to be determined, as well as
the radii S D = r, and S E = >\ of the gorge circles.
For the latter we have :
tan 3
tan
4- cos a
+ cos a
[195)
that is, r and ?-, have the same relation to each other as the portions
A Aand A G of a perpendicular to the line of contact.
If we call the shortest perpendicular distance between the axes
= a, we have :
1 " 1
f\_
a
T -! cap, a
+ 11.
~ —
"1
« +
-ay (i96)
+ •*• '•+(*)
The radii A' and A, are hypotenuses for the triangles whose
sides are R' and r, RA and r, (see the left of the figure) or :
A = \/A 7r + >- 2
Rx = SR'* + ri>
(197)
R' and Rd being determined as above, when the distance S A
= / is given. For the angles 8 and 8, we have the general expressions
:
sin a ~\
tan /?:
tan /}, = -
-f- cos a
+ cos i
J
(198)
As in the case of bevel gears, two solutions are possible according
as the angle a, or its supplement, is taken in determining
the line of contact S A, Fig. 601. The choice of solution
FIG.601.
governs the direction of rotation of the driven gear, and one of
the solutions renders it practicable to make au internal gear ;
although this construction has been little used, and has but little
practical value.
If the angle of the axes a = 90" we have
— = tan 2 3 :
r.
(*)'
(*99)
also :
tan /3 =
n,
ir + ni
id
ir + 11
(200)
In the construction of the wheels, corresponding zones are
chosen on the two hyperboloids. If the distance between the
axes is small, the zones lying in the gorge circles are generally
unsuitable, but when the distance is greater they may be used
and the figures approximated by truncated cones.
Example
FIG. 602.
H, (see Example 1, in § 221), a = 4"
R'
We have -=-. = l A,
«l
0.5 -)- cos 4o J 1.266
2.766 0-4577,
r\ 2 -f- cos 40
2
-532
= 0.31398,
S.064
Also tan 8 ;
0
a 1+2 cos 40 0
r 1+2X2 cos 40" -)- 4
r =0.31398 X 4= 1-256",
r, = 4 — 1.256= 2.744".
sin 40 0 _ 0.6428
2 -f- cos 40 0 2.766
01 = 40° - 8 = 26° 55-.
If we take 5 A = I = S" we have R' = I sin 13 0 5' = 8 X 0.226368 = 1.81"
R,'= 8 sin 26 0 • = 0.232393 = tan 13
55' = 8 X 0.452634 = 3.62"; finally
0 5', and
R = t/ (I.SI)S + (1.256)2 = 2.2" and
Ri=>/ (3.627= + (2.744)2
' 4-54
Example 2
n
si = 20 ; a = 0.75". We have from (197)
T 'l 5
9° • — = or say the number of teeth Z = 36, and
r = (9\* = !'_
r = " X g2 _ °-75 X 81
r\ \ 5 / 25
- 3.24, and from (200)
5= + tp 106
= o-573",
°-573
and >'! =
3.24
0.177".
"1
For 8, we have tan 8 = '^ = i.S, hence 8 = 6o° 57', and 0! = 29° 3'.
If we make R = 1", we have from (197):
Rl = \/ & — r- = v/2 2 —0.573= = 1.916",
and hence R,', according to (194) is = (j RS = 1.063", hence
Ri = \A 1.063'- + 0.177= = 1.078".
The appearance of such a pair of gears is shown in Fig. 602. According
to the table in *j 202 the pitch for the larger gear is: t = A— = -JL = 0 „»
1 0,8 5 ' 73 5 ' 73
and for the smaller gear t, = * ' = o 110"
3.18
OJy '
Examples « = 9°°, ^- = ., 8 = 45 0 , ^ = n, A'= A>,. In this case the hyperboloids
become similar (see Example 4, \ 221.)
Example 4. In the special casein which 5 = cos a, and the position of
the contact line, which is determiued by 8, lies in the supplement to a, so
that f- = cos a, the base figures become, the one a normal cone and the
Preced1,fl a form^f^, 0l0id ' S % e A S , 6 ° 3 " This construction is similar to the
work w"t g h a trai,fnF " e and v evel gears ' and ma >' be conveniently used to
Stfon7£r V?A« common bevel gears, although but few practical applications
occur, partially owing to the fact that the prolonged axis of the bevel

January, 1892.] ENGINEERING MECHANICS 15
gear r passes passes through through the the plane plane gear gear. For a = 60", -1 = — % = —cos 6o° we
obta' tin the plane gear. We have tan 8 = \ v/ITC = 3°°, 'an 0i = °°, Pi = 90
Also
..] 3111 yu
TT "l
n be negative and less
grear
0 .
R f sin 30 0 . . — .
Ay = lln 90° = °' 5 If it is desired to approximate to the hyperboloidal zone by
the use of a conical surface, the apex must be determined. In
this case the generatrix S A is rotated about the axis IIS until
•'=•'. '1 = •'. ^ -=

10 ENGINEERING MECHANICS. [January, 1S92.
For a = 90 0 we have cot - = —. Such spiral wheels, when
11
the teeth are well made, transmit motion very smoothly, but the
surface of working contact is very small. When the axes are
at right angles and the wheels the same size, it is often inconvenient
to use spiral gears on account of the large si/e required.
FIG. 607.
Example. Fig. 607, Let ' — 3, and a = 90 0 . We have from (203) -
FIG. 60S.
into the other gear, or (c) the wear which is at first caused by
running the approximate forms together may be disregarded
until the parts have worn themselves into smooth actiou. From
these reasons a widely varying practice in the construction of
spiral gears will be found. One of the most important applies
tions is that of the worm and worm wheel, Fig. OoS. In this
case a = 90 0 and Z = 1, the teeth of the wdieel A, being inclined
at an angle y with the edge of the wheel, whence tan , /
2 T A
609, we have
- y In the arrangement shown in Fig
A
a = 90 — ; and the teeth on A', are made parallel to the axis.
The pitch of the screw is here made —'— for a pitch /, of the
CCS }
wheel. The velocity ratio of transmission, according to the
fundamental formula (186) is /;, : 11 = Z : Zx, or this case it
equals 1
A:
* In the illustration Z, o, whicli
A'i ..oo R, aud y -- B8.i°.
203) for a true spiral would require
In mauv cases the worm is made a true spiral and the consequent
wear disregarded, but in more careful work the method
(b) is adopted and the worm wheel cut with a hob, which makes
the proper modification in the shape of the teeth.
The friction between the worm and teeth of the worm wheel
is very great, as the thread slides entirely across the teeth. We
have for the coefficient of friction/ for the ratio between the
actual force P and a force A acting at the same lever arm on
the screw, but free from frictional resistance, approximately :
For /"= o. 10 we have practically
A /
A
1 + /. 2 T A
1 -ft_
It follows that to obtain the minimum of frictional loss
(205)
must be made as small as practicable
Morin gives the rule R t, which makes J— r = 4 ; Red-
(-2-)' : 9 and from (2041. cot -, 3, whence y --180 -c- , and •)-] =
34'. The sliding velocity is .' = .- (3 4- 0.333) il's The small value of the
angle y makes it undesirable to use the smaller gear as the driver. These
objectionable features are of increasing importance aud for example,
= s, and - = 10,-we get ,. = 25. and K^, and 1 about 1 ij c I"
tenbacher makes A = 1.6 /, whence
— = 2.6. If we make
P>
A
A' = .' we eet J— = 2, and this is as low as — cau well be
5 p t
and 55°. The made. In this case it will be seen that a higher efficiency thau
n A, ".
50 per cent, cannot be obtained, aud it is also apparent that the
difficulty of cutting the teeth on the lathe also increases, as may readily be worm must be the driver, since the resistance of friction would
seen.
just balance the reverse driving actiou. The ordinary tooth
?. 221.
friction and the journal friction must of course be added.
APPROXIMATELY CYLINDRICAL SPIRAL GEARS.
If. of the preceding conditions, only those of formulae (2Ci1
aud (203) are strictly observed, the difficulties of construction
are much reduced aud at the same time satisfactory wheels obtained
Three methods may be employed : (a) a slight modification
from the correct spiral form may be given to both wheels, (b)
one gear may be made a true spiral, and the variation all thrown
The tooth outlines for both worm and wheel are the same as
for a rack aud gear wheel, taken on a longitudinal section
through the axis of the worm. The evolute tooth is especially
applicable, and Zx must not be less than 28 (| 209). The surface
of eoutact is theoretically only a mathematical point, but in
practice there is a small flattened surface of contact, and if a
larger surface is desired the wheel must be cut with a hob of the
same form as the worm which is to work with it.
Wheels which have a contact bearing of a point only, may be
called precision-gears, as distinguished from power-transmitting
gears. The difference, however, cannot be sharplv maintained,
for as already shown, worm gearing is used for the transmission
of both large and small forces.
The possible variations of the pitch angle permit a great variety
of spiral gear combinations, as the following examples
show :
Examplex. Given - J,the perpendicular distance between axes a
K + R,. and the angle between axes a = 40°. If we make y 6o°. we have
rrom(Jaao)vi = i8o—40—60 8o°(seeFig.6zo),andfrom(--oi) — = s *° Yl ** 1
„ . A", sin v 11
, sin 8o° 0.5 X 0.9848
"' sin t-0 0 " 0.8660 "' °-5 6S6 ' lro,u which R and A, may be readily
determined. If we make a = 4" we have
A,
4
1 5686
A,
».5S"
and A' = 1.45", For Z 20, z,
a X n \ 1.4s \ 0.866
4„, the normal pitch r = t sin • 2 TT A* siuy
Z
°-*7-'\i-45 0.394"
The circumferential pitch .'
0. |Q4
The sliding velocity .', according to (202)' c (cot 60^ + cot So*)'= c (0.5774
.- 1763) 0.7537. v
/•.i.j mpie Ut order to make .-' a minimum, we may make y = -y, '
= 70^, see Fig. 6u. We then have J, A, ^ 2.666,
I T X 1.333 *' 0.9397
= 0.394", t — ti — — = o.4iq, and
0.9397
c = 2 cot 70 0 \ , = 0.72S c. It will be seen that the value of .-' iu Example 1
approached very closely to the minimum.
(To be continued.)
9S4S
A

January, 1892.] ENGINEERIN
a b which any vertical line determines between tlie polygon uu,l
the chord, through the polar distance d, is Ihe same for all the
funicular polygons of forces considered.
Let us consider, therefore, auy determining vertical, betweeu
the polygon aud its chord, an ordinate a b.
Let us suppose that this be the side 2'. 1' of the funicular
polygou which is fouud cut by this vertical.
Let us prolong the side 2'. 1' to its intersection at /with the
chord. From the fundamental property of funicular polygons
U 33). the point /where this side cuts the chord T. 8' belongs
to the resultant A of the forces situated between the verticals 8
and a b. Here these are the two forces having for lines of action
8 8' and I i', and for magnitudes u a --. S and a C = i.
The magnitude and position of this resultant are independent
of the funicular polygon chosen to determine them. Another
polygou would give another point / of the vertical A, but the
distance of this new point to the vertical a b, would be always
equal to / i. As for the magnitude of A represented on the
polygon of forces by the difference S — I = a C, it does not depend
either ou the funicular polygou employed.
Xow the two triangles, Iba and OCu, are similar; hence,
the side Ou is parallel to the chord T 8'; as the solution of
problem I, \ 42, indicates, the side 1' . 2' is parallel to the radius
1.2 or O C, and the two other sides are vertical. Consequently,
the bases a b and Cis of these two triangles are together
as their altitudes, whence, by calling the polar distauce d,
ab _I_i
Cu d
or
a b X d - Cu x Ii
or
z X d= Co X H,
by designating, as we shall do habitually, by z the vertical ordinates
such as a b, determined between the perimeter of a funic­
ular polygon and one of its chords.
The second member, being independent of the funicular poly­
1 MECHANICS. 7 7
^Copyrighted.]
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION
Ao li.. and let A and B be the points of intersection of the second
polygon drawn with the line A /.'. By the construction
BY MAURICE LEVY.
itself, the points Ao and sl are one and the same vertical, as
THEOREM VII.— If we construct any funicular polygon of a well as the points J!,, aud P. Now, if we wished to construct a
system of parallel forces (virtual to fix the ideas), if we prolong funicular polygon passing through the points sl and A and with
its two sides to their junctures at 7' and'8' with two fixed ver-
the polar distauce d, it would suffice, from the equation (a)
tical lines, but chosen arbitrarily, and if we draw tlie chord
above, to take the ordinates z so that they be to the corresponding
ones z in the relation do : d.
T. 8' which joins these two points, the product of the segtnent
COROLLARY II.—/A in particular, we take the ordinates of z
equal to those of z„, the new funicular polygon will have the
same polar distance as the old.
\ 44-
NUMBER OF CONDITIONS NECESSARY TO DRAW A FUNICU­
LAR POLYGON.
In order to determine a funicular polygon of a system of forces,
it ic sufficient to know : i°, its pole ; 2°, the point of departure,
i.t -, a point through which the first side of the polygon is to
pass.
In order to determine a point in a plane, it is necessary to
know two lines upon which it is to be found or, which amounts
to the same thing, its two co-ordinates ; that makes two conditions.
To subject a point to be found on a given right line, or, inversely,
to subject a right line to pass through a given poiut, is
to impose on it a single condition.
So, to give the pole of a funicular polygon is to give two conditions,
while to subject its first side (or generally one of its
sides) to pass through a point is to give a single condition.
Hence, it follows that a funicular polygon relative to a system of
forces is entirely defined by three conditions.
If they be given, the pole and the point of departure are defined
(there can be several solutions, but not an infinity). If
only two be given, the pole can describe a right line or curve,
in the plane, and at each point of this line one or a limited
number of polygons answer. If but a single condition is prescribed,
all the points of the plane or each, at least, of the
points covering an area and forming only a simple line can be
taken for poles, and at each of them answer, in general, one or
a limited number of polygons.
If no condition be given, not only all the points of the plane
can be taken for poles, but at each of them an infinity of polygons,
answers, since the point of departure can be taken arbitrarily.
gon considered, it must be the same as the first.
\ 45-
The proposition can again be stated under the following form : PROBLEMS RELATIVE TO THE DELINEATION OF THE FUNIC­
THEOREM VII. bis.—Let any two funicular polygons be con­
ULAR POLYGONS.
structed, having one and the same system of vertical forces with PROBLEM I —To find the locus of the poles of the funicular
the polar distances do and d ; let two fixed verticals be drawn polygons of a system of forces, whose two extreme sides are sub­
which cut the two extreme sides of the first of these polygons ject to pass through given points.
respectively al A0 and B0 (Figs. lS and ig, Map V.), the two Let us suppose (Fig- 14, Map III.) that the four lines furnished
extreme sides of the second respectively at A and B; let the with arrows 1, 2, .'}, 4 are the lines of action of four forces
chords A0 So and- A B be drawn ; the ordinates z0 and z deter­
represented on the polygon of forces (Fig. 14J by the sides
mined bv any third vertical between cat h polygon and
are in the inverse ratio to the polar distances :
its chord 1, 2, 3, 4-
It is required to find the locus of the poles of the funicular
polygons of these forces whose extreme sides pass through two
(a) z X d = z0 X do.
given points A and B.
We know by Theorem III. of ? 4'J that the locus sought is a
COROLLARY I.—Having drawn a first funicular polygon of a
right line, and this theorem, combined with Problem III. of
system of parallel forces, from .my polar distance da, let us cut
i- 4-2, indicates the following way :
it by a right line entirely arbitrary A,, B„ (Fig. lS, Map V.);
To determine the resultant A of the given forces, which re­
then, starting prom another right line itself arbitrary A B, let
quires the drawing of any funicular polygon (not subject to the
us draw (Fig. 19) vertical ordinates c proportioned lo the corre­
conditions of the present problem).
sponding ordinates =0 of the first polygon counted from sl, If,,
Let 5. 1. 2. 3. 4. 5 be this polygon whose pole is O.
and beiug lo these laiter iu a relation arbitrarily chosen d0 : tl:
Let 5 R be the line of action of the resultant represented on
we shall have a new funicular polygon of given forces, with
the polygon of the forces by the line a b, and formed by the
the polar distance d.
intersection of the extreme sides of the polygon delineated.
Therefore, let Ao and B0 be the points of intersection of the Through the given points A and B, let us draw A a and A/3
extreme sides of the funicular polygon with the right line parallel to R to their meeting in 12 fi with these two sides.

i8 ENGINEERING MECHANICS. [January, 1892.
Through the pole 0 let us draw a parallel to the right line a 8
which closes the polygon ; the point So, if the point of meeting is
not too far removed, we shall have the summit 3o and so on
one after another.
The new polygon obtained is still a funicular polygou of the
given forces ({! 43 bis, Corollary II.).
Let us lay off, starting from A B, on the lines of action of the
given forces, ordinates equal to the corresponding ones of this
last polygon ; we shall form a polygon A 1. 2. 3. 4. 5 A which
evidently passes through the three points A, B, C.
Moreover, it is still a funicular polygon of the given forces
(§ 43 bis, Corollary I.) : therefore, it is the polygon sought.
PROBLEM IV.— To determine the. funicular polygon of a system
of parallel forces whose extreme sides are subject to pass
through two given joints and whose polar distance d is given.
Let us draw a funicular polygon having the polar distance d
and otherwise arbitrary. Let (the same figures as in the preceding
problem) Ao lo' 2 / 3o' 4

January, 1892.] ENGINEERING MECHANICS. !9
forces are parallel to the lines of action of the forces ; in short,
the elements, infinitely small, taken on the curve of the forces!
which hold the locus of the sides of the polygon of the forces!
represent the magnitude of the forces acting at the corresponding
points of the funicular curve.*
Thus, let (Fig. 20, Plate V.) A A be auy curve whatever
which is regarded as the funicular curve relative to the pole 0
(Fig. 20), of a system of forces whose curve of forces is a b.
If we draw any polar radius Op, then if we draw a tangent to
the funicular curve parallel to this radius, the point of contact
/'will be the poiut of the funicular curve correspouding to the
poiut p ; likewise, if we draw a radius 0 q, we obtain a corre­
sponding point Q. By reason of the fundamental mechanical
property (§ 37) of funicular polygons, applicable to funicular
curves, the point 4*1 where the tangents at A and 0 cut one an­
other is a point of the resultant of all the forces of infinite num­
ber acting between Aand Q, and this resultant itself is repre­
sented by the chord p q. The resultant of all the forces passes
through the point of meeting of the extreme tangents A Aand
A T' parallel to the extreme polar radii O a and 0 b, and it is
represented in magnitude, direction and construction by the
right line a b which extends from the origin to the extremity of
the curve of the forces.
If Op and 0p' are two radii, infinitely close to which the
points Aand P' correspond, the resultant of the forces acting
ou the element A A', passes through the point s where the tan.
gents cut each other at their extremities, is parallel to the
corresponding element p p', and is represented iu magnitude,
direction and construction by this last.
All these considerations exist if the forces are parallel, i.e.,
if the curve a b is replaced by a portion of the right line a, b.
Let us suppose that the funicular curve be circumscribed by
any funicular polygon A T S T' B whose sides have for points
of contact the extremities A aud A and the intermediate points to
any number P, Q The resultant 1 of the forces acting
between A and Apasses through the point T, and is represented
on the curve of the forces by the chord a p = 1 ; the resultant
2 of those which act between A and Q passes through the sum­
mit JJ of the polygon circumscribed and is equal to p q = 2;
likewise, the resultant 3 of those which act between the points
of contact 0 and A passes through the summit T' and is equal
to q b = 3.
Thus, every polygon circumscribing a funicular curve is a
funicular polygon of a finite number of forces, viz. : the patcumscribe
the funicular curve ; but its extreme sides would
always coincide with the extreme tangents of this curve.
Hal resultants of the forces which act between the successive
points of contact of the curve and polygon.
Let us suppose inversely that, given forces succeeding one
another continuously, we mark the lines of action of a certain
number from among them, viz. : the line of action A A parallel
to the tangent at a of the curve of these forces, the lines of
action A A,, Q Qx, • • • , S A, respectively parallel to the tan­
gents at/>, q b and that, by some means, we find the par­
tial resultants 1, 2, 3, . . . of the forces to infinity acting re­
spectively between A Al and A A„ betweeu A A, and Q Qx, . . . ;
these forces are represented by the chords 1, 2, 3, . . . consti­
tuting the sides of their polygon of the forces. If we construct
a the funicular polygon of these forces, having the point 0 as
a pole and the point A as the point of departure, we shall find
* See also notes III. and III. bis.
between those of A /', and O O, having- 2, 2 for a resultant, and
so on one after another, an entire funicular polygon of any pole
0 of these resultants circumscribes the funicular curve, liaving
the same pole and having the same point of departure of the
given forces. Furthermore, the points of contact are on the lines
of separation of the groups A Au P I\ . . . .
REMARK I.—If the given forces are all vertical, the lines of
separation A Ax, P Px, . . . of the groups ought also to be verti­
cal. The points of contact of the curve aud the circumscribed
polygon will be on these verticals, while the summits of the
circumscribed polygon will be on the verticals 1, 2, 3, . . .
representing the lines of action of the partial resultant.
REMARK II.—As we have said at the beginning, all the proper­
ties of the funicular polygons belong also to the funicular curves.
It suffices, in the statements, to substitute for the words sides of
Ihe funicular polygons and polygons forces the words tangents to
the funicular curves and curves of forces.
Among these theorems we shall cite this one, which is a particular
case of the preceding, and which results also from
Theorem II. (*S 43) :
THEOREM.— The extreme tangents of a funicular curve of a
system of forces are not changed when replacing these forces by
other equivalents, whatever they be.
In other words, continuous forces being given, if we construct
a funicular curve of these forces with a pole and a point of de­
parture given, then if we construct with this same pole and
this same point of departure the curve or the funicular polygon
of a system of forces, infinite or not, equivalent to the given
forces, the extreme tangents of this second curve or the extreme
sides of the polygon will coincide with the extreme tangents of
the first curve.
We see how this proposition differs from the preceding. If
we substitute (Fig. 20 and 20, Plate V.) for the continuous
forces given, the equivalent system found by the forces 1, 2, 3,
we not only do not change the extreme tangents of the funicu­
lar curve, but we do not change either the tangents to the points
P Q . . . , placed on the line of separation of the groups. But
that requires that the groups are separated by lines of action of
the given forces themselves. If we took other systems of forces
equivalent to the given forces, this second property would not
exist ; but the one relative to the extreme tangents would exist
always. The funicular polygon obtained would no longer cir­
CHAPTER V.
CONDITIONS OF EQUILIBRIUM OF THE NATURAL BODIES FREE
OR NOT.—GRAPHICAL SEARCH OF THE REACTIONS
OF THE SUPPORTS.
?46.
CONDITIONS OF EQUILIBRIUM COMMON TO ALL BODIES.—If a
body, whatever it be, solid or not, is in equilibrium or at rest
under the action of certain forces, it will remain a fortiori at
rest if the various points of it happen to be bound together in
such manner that their mutual distances become absolutely in­
variable ; whence it follows that the conditions necessary to and
the polygon A TS T' B, i.e., a polygon circumscribing the
sufficient for the equilibrium of forces acting on invariable sys­
funicular curve having the pole 0, the points of contact being
tems remain necessary when these same forces chance to act on
on the lines A sf, A A,, Q Qx, Hence :
any body.
THEOREM.—Given forcessucceedingone another continuously,
Hence, in order that a body, whatever it be, be in equilibrium
if we can separate them into groups, each group being limited
under the action of forces all situated in a plane, it is necessary
by the lines of action of two of the given forces and, besides,
that the polygon of these forces be closed, just as one of their
such as we know how to find the resultant of the forces which
funicular polygons chosen arbitrarily.
compose it, viz.: the group of forces whose lines oj action arc-
This proposition may be stated in another way : in order that
comprised between those of A Al ami A A,, having 1, 1 for re­
forces acting on any body be in equilibrium it is necessary lhat
sultant ; the group of forces whose lines of action are comprised
they be two by two equal, directed according to the same lines,
and of opposite plow or equivalent (? 20) to such forces.

20 ENGINEERING
• We shall prove here this proposition for the case which will When the displacements are considerable, as happens in
occupy us more especially, with forces all situated in a plane. bodies made of India rubber and, more practically, in springs,
The demonstration in the most general case should be easily- it is necessary, in fact, to determine them, and the problem of
deduced from it.
Statics is indissolubly bound to the one which the mathematical
We know (\ 34) that forces situated in a plane and acting ou theory of elasticity raises, or, in a less strict point of view, but
any body can always be replaced : i° by forces two by two equal,
directed according to the same right lines and of opposite flow ;
2° by two forces directed according to the extreme sides of one
of their funicular polygons.
In order that the polygou of the forces aud the funicular
polygon be closed, it is necessary that these last be themselves
equal directed according to the same line, and of opposite flow.
8 47-
CONDITIONS OF EQUILIBRIUM OF FREE ELASTIC SOLIDS.—
The natural form of an elastic solid is the one which it affects
when no force, not even that of weight, acts on it, and when,
besides, all its points are at one and the same even temperature.
If any forces whatever happen to be applied to such a body
supposed to be at rest, the points of application of these forces
and, consequently, all the points of the body are displaced, and
the body loses its form ; but it may happen that, after having
undergone a change of form more or less great, it will return
to rest and will remain there as long as the action of the forces
will last. These are then said (\ 18) to be in equilibrium.
But I said that, when it is a question of a solid body, whatever
be its degree of elasticity, this condition is not only neces­
of a natural solid body, we apply two equal forces, directed
according to the line A B and of opposite flow, the body loses
its form, the line a B is displaced and changes in length ; but if,
during its displacement, the forces remain constantly directed
according to this movable line, if, besides, they are not applied
suddenly, but if, starting from zero, they increase very slowly to counter-pressures which it undergoes on the part of the supports.
the strength which we wish to assign them, then, at each of Hence it follows that the problem of the statics of bodies not
their strengths, and particularly at their definitive strengths, a free admits of two very distinct questions.
form of equilibrium will answer.
i° The research of the conditions of equilibrium, i. e., the re­
It is the same if, instead of a pair of such forces, we apply
any number, provided that they satisfy the condition which we
have just indicated.
Hence, supposing (reserving the right to return farther on to
this important question) that the forces are within the desired
limits in order not to break the body and that they are not
applied suddenly,* the condition of being two by two equal,
directed accordiug to the same lines and of opposite flow, is
here not only necessary, but also sufficient.
Besides, if the forces are in one and the same plane, we know
that it is necessary and sufficieut, in order that it be fulfilled,
that the polygon of the forces and one of their funicular polygons
be closed.
But we must not lose sight of the fact that it is not on the
body taken in its natural state, but ou the body supposed to
have arrived at a definitive state of rest that the condition is to
be verified ; consequently, to be able to make this verification,
strictly speaking, it would be necessary to begin by solving this
problem, one of the most difficult of mathematical Physics.
imum pressure or tension per surface unit which each material
can practically resist (see Note I.f on this subject), we shall know
II'hat are the displacements which given forces cause to be whether the given body will or will not be able to resist the
made at the various points of a given elastic body?
forces which it will have to support. There is, therefore, a third
* If they are applied suddenly, they cause vibratory movements which,
theoretically, can be prolonged indefinitely, but which practically are rapidly
destroyed by exterior resistances.
MECHANICS. [January, 1S92.
more practical, that of Resistance of materials. But, for bodies
employed in constructions, the definitive form differing very
little from the natural form only known beforehand, we are
satisfied to make the verification on this latter form, and then
it experiences no difficulty, and is always made by the simple
rules developed in the preceding chapter.
8 48.
CONDITIONS OF EQUILIBRIUM OF THE ELASTIC SOLIDS NOT
FREE. REACTIONS OF THE SUPPORTS.—When material obstacles
prevent a body from moving with an equal facility in all
directions, it is said not to be free.
The presence of a material obstacle is always equivalent to
one or several forces applied to the body.
Hence, if a body rests 011 a plane by a point, it exercises a
certain pressure on the plane, and undergoes on its part (I 22)
a counter-pressure equal and of opposed flow, which is called
the reaction of the support
The material obstacles, whatever they be, acting on a body
only by the counter-pressures or reactions which they exercise
on it, cau always be conceived to be suppressed, on condition
Iu order that forces can be in equilibrium ou any body, solid that there be applied to the body forces exactly equal to those
or not, it is necessary, as we have just proven, that they be two which these obstacles would cause. Hence, a body not free can
by two equal, directed according to the same lines aud of oppo­ always be treated as if it was free, provided that to the forces
site flow.
which are applied to it we unite other forces equal to the reactions
of the supports.
The first, which are the ones given in the problem, are called
sary, but sufficient, provided : i° that the acting forces aie not the forces directly applied.
great enough to break the body • 2° that thev are not applied The latter, on the contrary, are not known a priori ; they are
suddenly.
unknown auxiliaries which are introduced into the problems.
Experience proves, therefore, that if, at two points A and B But their determination offers a great interest, especially iu the
art of engineering, since, in flow almost, they represent the
pressures exercised by the body on its supports, aud it is necessary
to know these pressures, in order to give to the supports
the solidity necessary to resist them, and to the body itself the
dimensions necessary in order that it may be able to sustain the
lations which ought to exist between forces applied directly,
which are the given ones of the problem, in order that the
equilibrium of the body be assured ;
2° These conditions being supposed to be fulfilled, the determination
of the reactions of the supports.
8 49.
FORCES EXTERIOR, INTERIOR ; RESISTANCE OF A BODY —
The actions which a body experiences on the part of other
bodies are called exterior forces ; those which the various parts
of the body exercise upon oue another are called interior forces.
The forces directly applied to a body, as the reactions of
the bodies with which it is in contact, form the sum of the ex­
terior forces. The exterior forces cause at each point taken in
the interior of the body of elastic forces (\ 23), pressures or
tensions which form the sum of the interior forces.
It is equally necessary to determine these forces.
When they are known, as we know experimentally the max­
problem which arises in consequence of those stated in the preceding
paragraph or jointly with them.
t Note I is in the supplement and consists of 10 sections, or 29 pag
laws laid down by Woehler, a German scientist.

January, 1892.] ENGINEERING MECHANICS. 21
? SO.
GENERAL DISTINCTION BETWEEN THE PROBLEMS WHICH
DEPEND SOLELY ON STATICS AND THOSE WHICH DEPEND
PARTLY ON ELASTICITY—Upon the three problems which have
just been established, to know :
1° The Research of the conditions of equilibrium,
2 0 The Determination of the reactions of the supports,
3° The Determination of the interior forces,
the first cau always (thanks to the approximation admitted
in 8 47) be determined by the simple rules of Statics; the third
can never be ; * the second, sometimes.
Therefore, whatever be the material obstacles which are opposed
to the movement of a body, the latter having been rendered
free by the adjunction of the reactions of the supports,
in order that it may be in equilibrium, it is necessary and suffi­
cient (| 47) that the polygon of all the forces (the reactions of
the supports be comprised iu it) which give rise to it be closed,
just as one of their funicular polygons. These conditions, easy
to verify, thus always solve the problem 1°.
The necessity of satisfying these conditions, in which the
given forces (directly applied) and the unknown reactions are
interposed together, always admits of determining all or part of
these latter. When it determines them entirely, the problem 2°
depends only on the Statics.
But we understand that iu general that ought not to happen.
Let us suppose, for example, a bar of metal of weak trans­
verse dimensions to be resting on a horizontal plane, its two
extremities touching, but not pressing, two vertical planes per­
fectly fixed.
Let us admit that the bar be heated ; it will strive to enlarge,
and as the vertical walls will hinder it, the bar will exercise on
them very rapidly-increasing pressures, and will experience
from them reactions equal and opposed.
Statics furnishes immediately the condition of equilibrium of
the bar ; it teaches us, therefore, that, the reactions produced by
the two walls being the only forces acting, they ought to be equal,
both directed according to the axis of the bar and of opposed flow ;
but whatever be their common magnitude, the equilibrium will
be thus assured, aud consequently Statics will be able to teach
us nothing about this magnitude. In fact, it depends essentially
on the degree of dilatability of the bar through heat, and on its
elastic nature, so that, in this example, however simple, the
theory of heat combined with that of elasticity is necessary to
determine the common intensity of the two unknown forces.
But it will not always be thus ; it is with cases where the
Statics of the invariable systems suffices to furnish the reactions ;
these cases can be specified in some way a priori by the follow­
ing consideration : the conditions of equilibrium of the invaria­
ble systems, sufficing also, as we have proved, for natural solids,
require only operations purely graphical, relative to the force
polygon, and to their funicular polygons.
If these are the analytical methods which we prefer to employ,
there will be, as we shall see, operations wholly equivalent on the
projections and the momenta of the forces which we shall have
to make. In both cases, these operations have this remarkable
character of being absolutely independent of the form of
the body; hence, there will be able to be furnished, by
pure Statics only the reactions of such supports which they
influence in no respect on this form : i. e., of supports not hin­
PROFESSOR DEWAR has made a highly interesting communi­
cation to the Royal Society. He has resumed the investigation
of the properties of liquid oxygen, of wliich he gave some beau­
tiful illustrations at the Royal Institution at the time of the
Faraday centenary in the earlier part of this year. Faraday,
more than forty years ago, proved that oxygen alone among
known gases is magnetic, and Professor Dewar sought to deter­
mine what effect a temperature of 180 deg. Cent, below zero
would have upon its behavior in the magnetic field. Having
previously ascertained that liquid oxygen does not moisten or
adhere to rock crystal, and consequently maintains in contact
with that substance a perfect spheroidal condition, he poured
the liquefied gas into a shallow saucer of rock crystal, and placed
it between the poles of a powerful electro-magnet. He expected
some such result as the total or partial arrest, under magnetic
stress, of the violent agitation caused by the ebullition of the
spheroidal mass. But on the magnet being excited, the whole
mass of liquid oxygen was literally lifted through the air and
remained adherent to the poles until dissipated by the heat of
the metal. The feeble magnetism of oxygen at ordinary tem­
peratures had become a force to which no solution of a magnetic
metal offers any parallel. Thus was strikingly and beautifully
exemplified the relation between magnetkm and heat, of which
the entire loss of magnetic qualities suffered by iron at a red
heat is a familiar illustration. The experiment, interesting and
suggestive in itself, derives an added interest from the fact that
the electro-magnet employed is the historic instrument with
which Faraday qarried out many of his classic investigations.
IN his presidential address to the Junior Engineering Society,
Sir E. J. Reed raised the question of the best form of a ship's
hull. As is well-known, he is not a believer in a form of least
resistance. To illustrate his views he considered the case of a
perfectly calm sea, any portion of which can be instantaneously
frozen solid. Making use of this supposed power an ice ship of
the form of least resistance is obtained. This ship is supposed
to have an ice skin i in. thick, and carries a cargo of water.
The expansion of the ice in freezing is neglected, and hence the
solidification of its shell has not changed in any way the condi­
tions of equilibrium. Now by hypothesis we have here a ship
of perfect form for the speed at which it is intended to run and
capable of carrying a given cargo. If, however, the shell of ice
is converted into one of steel, and the same cargo has to be car­
ried, it is evident that the displacement must be increased,
which leads to a shortening and broadening of the boat, and a
departure from tbe theoretical form of least resistance. Hence
the proper form for a ship depends on the average weight of the
materials of which it is built. The old view of a best form led
to the conttruction of long and fine warships, the offensive and
defensive powers of which were no greater than those of a short
vessel of the same speed and costing very much less. In refer­
ence to a number of the new cruisers Sir Edward suggests that
they have too fine lines forward and are not sufficiently fine aft.
Great fineness forward weakens them when used as rams, whilst
if they were given a finer run the screw would work iu more
undisturbed water, and hence more efficiently. To thoroughly
test this view, Sir E. J. Reed suggests that careful experiments
should be made.
dering the free change of form of the bodies, whether it results DURING the year 1890 the Pennsylvania Railroad lines east of
from elasticity, or dilatation through heat, or from any other Pittsburgh carried nearly 7,000,000,000 tons of freight one mile.
physical cause. When the supports are numerous enough to If the locomotive expenses and cost of train services had been
hinder this free change of form, the determination of the reac­ as great relatively to the tonnage hauled on this liue as it was on
tions which they cause ought to be of necessity from the spring the Scotch road, the expenses of the Pennsylvania Company
of the elasticity and from that of heat (if the temperature comes would have been increased over $5,000,000. These surely are
in).
weighty facts, which may, in part, account for the average freight
rate on British roads being x%d. = 2>< cents per ton per mile,
* Except in the ideal case of simple lines or material surfaces supposed
whereas here, on our through lines, it is a very little over one-
perfectly flexible.
(To be continued.)
half a cent.

22 ENGINEERING MECHANICS [January, 1892.
THE power furnished by the steam-engines of the whole world
represents the labor of 1,000,000,000 men ; that is, of more than
twice the number of workingmen in existence.
In this calculation the United States stands first, being put
down as having steam-engines with a total of 7,500,000 H. P.;
Great Britain has a total of 7,500,000 H. P.; Germany, 4,500,000
and France, 3,000,000.
These figures do not include the locomotives, the total number
of which in the world is estimated at 105,000, representing
a total of 5,500,000 to 7,000,000 H. P.
All the steam-engines of the world, including locomotives,
would produce a force equivalent to 49,000,000 H. P. if working
together.
THE PORTELECTRIC COMPANY, which has recently been
incorporated under the laws of Virginia, proposes to transmit
mail matter between New York and Philadelphia in forty minutes
when it gets into operation. The incorporators are mainly
prominent New York men. The nominal capitul of the company
is |5,ooo,ooo, and the promoters are sanguine that their
system will make a sufficiently favorable showing to warrant
the investment of abundant capital to build and equip the
lines.
The company has, for some time, been operating an experimental
line at Dorchester, Mass., and Professor A. E. Dolbear
estimates from the results attained that a speed of 150 miles an
hour will be possible when a regular line is built. The Dorchester
experiments have been made on an endless oval track
2,7S4 feet long, and despite the sharp curves and other disadvantages,
a speed equal to thirty-three miles an hour was made
with a loaded car. Other expert electricians who have examined
the plant predict that it will achieve the success predicted
for it.
The track is elevated, ar.d consists of an upper and a lower
rail, each formed of bar steel. The car is merely a hollow projectile
of wrought iron, pointed at each end. This car is 12 feet
long, and 10 iuches in diameter; but the cylinder in which the
letters are placed is only 8 feet long. It weighs 500 pounds,
and has a capacity for 10,000 letters, weighing 175 pounds.
There are two wheels above and two beneath the cylinder.
The power to propel the car is provided by a series of hollow
helices of insulated copper wire, which encircle the track at
intervals of six feet. The current is transmitted to the helices
from a central dynamo station, and from the helices tlirough
the wheels and running gear of the car. The intention is to
load mail and other light ma'ter requiring quick transit into
the cylinder car and start it on its journey. On arriving at its
destination, the speed is slackened automatically by the normal
action of opposite currents through the terminal helices. The
company does not expect to carry passengers or freight.
It is claimed that letters can be transmitted between the
maiu post office and Harlem by this system in about five minutes,
whereas it now requires about an hour. The incorporators
say that a practical line of several miles' length will be
built in a short time to give a better idea of the possibilities of
the system than are afforded by the experimental line at Dorchester.
THE problem of generating electricity direct from heat, without
the intervention of the steam-engine and dynamo, has occupied
the attention of electricians for some time, and now Mr.
Edison has so far succeeded that he has applied for a patent for
his invention, giving the following general description : " The
object I have in view is to generate electricity directly from
carbon, coal, or other carbonaceous material, without the loss
caused by the indirect method heretofore employed of converting
the same into a motive power, from which electricity is
produced by mechanical motion. This I accomplish by employing
carbon or carbonaceous material for the generating or soluble
electrode of a generating cell and in using therewith as au
active agent oxides, salts or compounds of elements, by the decomposition
of which the carbon or carbonaceous material will
be acted upon at high temperatures. The cell is constructed
and adapted for the application of heat externally thereto, aud
the conducting or negative electrode of the cell is made of a
substance which in the presence of carbon at high temperatures
is not attacked to any great extent by the active agent em­
ployed."
AN English journal gives this rather gloomy view of labor
prospects in England : The prospects for labor for the incoming
year do not brighten as we near the close of the present year,
1891. The demand for labor has lessened, overtime has in many
cases ceased where for a long time past it was systematically
worked, and where it has not ceased altogether it has very much
decreased, by the exercise of no virtue on either side. The list
of unemployed is extending in nearly all trades, and present
contracts are being completed without a sufficient weight of new
orders to replace them. Then there are complaints of the cost
of labor and materials, and indications are not uncommon of
either a further slackening off in production or a reduction in
wages, so as to encourage manufacturers to increase their stocks.
It does not appear that either fuel or materials will be very
much reduced at present, notwithstanding which the prices of
manufactured articles are undoubtedly tending lower aud lower.
This is just the time when prudent and conciliatory action is
needed on all sides in order to avert, or at least to minimize,
what invariably happens, namely, strikes in a falling market.
Disputes at such a time only hasten that which all would wish
to see averted, depression in trade. In all our great industries
there is a quietening down, and what is worse, there is a want
of confidence in the near future which may create the very
symptoms all desire to avoid. The tide is turning and ebbing
very slowly at present, but the ebb may be increased in volume
by any untoward incident. There does not appear to be any
real danger so far, but haste may initiate it.
IN the first formula of Parabolic Roof Truss, page 277, December
issue, the dropping out of a figure 2 occurred. The
Wx\ . . W x
formula should read- - instead of-
A PAPER was recently read before an English Engineering
Society, on the Pietzka Patent Puddling aud Heating
Furnace. The inventor of the furnace is Mr. Gottfried Pietzka,
manager of the puddling and rolling mill departments at the
Witkowitz Works, in Austria, where altogether about 10,000
men are employed. The novel features of the furnace are a re
versible hearth, or rather a double hearth mounted on a platform
turning on a hydraulic ram. The pig iron is charged on
to one division of the hearth, and when melted the double
hearth is raised about four metres by the hydraulic ram and
turned right round so that the other division of the hearth receives
a fresh charge of pig iron, whilst that already melted in
the first division is being puddled. The heating too is done by
gas fuel instead of by coal as in the ordinary puddling furnace
a recuperator being erected in close contiguity to the furnace'
At the Witkowitz Works the furnaces have been in operation
for about twelve months, and the average saving there during
the past half-year has been 10s. per ton, the loss of iron also
being 2 to 3 per cent, less than in an ordinary furnace.
THE World's Exposition tower will be built of mild steel and
of wrought iron; wrought iron being used only iu the lighter
members. The principal columns are of square box section,
fitted with man holes and interior ladders for purposes of inspection
aud convenience of workmen. These columns below the
second platform will be 40 in. square, and above the second
platform they will taper, decreasing from 40 in. at the base to
16 in. at the lantern. All the interior columns will be built of
plates and and angles with open laced sides. All bracing and
stiffening members will have riveted connections, so that nothing
can get loose ; the compression members are generally square
made of four angles at the corners and with all four sides laced •
the tension members are made of four bulb angles placed in
pairs, back to back, with a single line of lacing.

January, 1892.]
THE "SPHINX
ENGINEERING MECHANICS.
ADJUSTABLE DRAWING TABLE.
[PATENT AFPLIED FOR.)
T H I S adjustable Drawing Table is of a very simple and durable
construction. The legs of the Table are firmly
keyed to the ties by means of wedges, and these together
form the trestle. One of the ties at the same time acts as a foot
rest. Lugs are fastened underneath the Drawing Board and
these are tightly screwed to the trestle, allowing the Board to
swing around. The front part of the Board is also provided
with lugs, to which the other two adjusting racks are screwed.
These racks have inclined indentations, equally divided, aud
rest on pins with a head, to prevent their slipping off Each of
these racks swing separately, so that, should the draughtsman
by accident remove one of them, the board will not slip down.
The lowest indentation iu the rack will set the board horizontal
and brings the table to an average standing height ; while sitting
at it, it can easily be adjusted to any desired inclination, without
the draughtsman moving from his place. Tlie Board is made of
the best seasoned Pine-wood, with clamps, trestles and racks of
heavy Ash-wood, shellaced. A box the length of the trestle is
attached to the latter, for holding all necessary drawing tools,
and to the right side of trestle is screwed a two-armed bracket,
holding a wooden platform, for instruments, pencils, ink, etc.,
while at work.
Various sizes of Boards cau be used on the same trestle. The
whole Table stands perfectly firm, and cau be easily taken apart
by simply removing the wedges from the ties and loosening the
screws on the lugs. Sold by F. Weber, 1123 Chestnut St., Phila.
IRON and steel plates are now being coated in England with
nearly pure lead, the bath being 98^ per ceut purity. The
articles to be coated are first pickled to remove scale, then
passed through a lime bath, then through clear water. They
are then immersed in a fourth bath, consisting of a neutral
solution of zinc and stannic chlorides, obtained by dissolving
granulated Zn and Sn in hydrochloric acid. From this bath
they are passed into a drying chamber heated by steam, where
the moisture on them from the last bath is evaporated, leaving
behind a deposit of the mixed metallic chlorides, which protects
the plates, &c, from oxidntiou. When dried these plates are
ready to be passed into a bath of molten lead. On issuing
from this bath the plates are found to be coated with a uniform
and very adherent layer of lead. Though perfectly uniform
this layer is nevertheless very thin. The ductility and strength
of the iron are not decreased by the process, and a plate cau be
bent and closed, and again opened out, without breakiug the
coating. Shop plates have been successfully coated with 2 oz
per square foot of plate, and then riveted without breaking
coating. There is no sediment, aud no action on the material
of which the bath is constructed.
DODD, MEAD & Co., New York, have issued a work entitled
" Robert Fulton, his Life and Results," by Robert H. Thurston.
A TRAVELER from Europe saw, a few weeks ago, at Lake Zurich,
a small boat built of aluminum. The amount used was
600 pounds. The ribs, plates, castings of engines and the rudder,
he says, are made of this metal, and the entire weight is
97° pounds. The launch will hold twelve people, and in the
trial trips a greater speed was developed than in boats of equal
size in wood.
THE Swiss rifle will fire 20 aimed shots a minute when used
as a single loader. With the magazine in action it will fire
30 aimed shots in the same time, and 40 shots without aiming.
The successive shots can be fired without removing the rifle
from the shoulder. The weight is 9>< lb. The total length of
the barrel is 30.7 in. ; the calibre .295 in. ; the number of
grooves in the rifling is three, and they make one turn in 10.6
iu. The bullet is of hardened lead, in a steel envelope; its
length 1.13 in., its diameter .32 in, and its weight .0302 lb. The
charge of smokeless powder is 31 grains. This gives an initial
velocity of 196S ft. a second.
"THE contract for Gainesville, Fla, Waterworks has been
awarded to Hartfort, Herbert & Co., of Chattanooga, Tenn.
The Steam Pumping machinery will be furnished by The Laidlaw
& Dunn Co., of Cincinnati, Ohio. The capacity is two and
one half million gallons."
THE Equitable Building, in Atlanta, Ga., when completed,
will be the finest in the South. The contract for the Steani
Heating and Steam Plant has been awarded to the Hunnicutt
& Billingsrath's Co., and the Steam Pumping Plant for Elevators,
House Service aud Boiler Feeding, will be furnished by the
Laidlaw & Dunn Co., of Cincinnati, Ohio. The aggregate
capacity of these Pumps will be eleven million gallons (11-
000,000) in twenty-four hours. Two of these pumps will be
14 & 20 x 1 2 x 18 Compound Duplex.
THE construction of stone railroad bridges has never been
hardly fouud in the United States by the stock-holding firms,
but engineers themselves have never ceased to recommend stone
wherever practicable. In Germany a large number of masonry
bridges have been built, and the tendency is to that kind of
structure. The abutments are generally made of Portland
Cement concrete and for arches under 98 feet.
LONDON Engineers are busy with deep tunnel schemes, three
or four schemes being under serious consideration, for the construction
of tunnels for the accommodation of the enormous
traffic crowding the surface lines and the present limited under­
ground facilities.
THE Khojak Tunnel, the completion of which has recently
been announced, is one of the great tunnels of the world. It
carries the Indian Frontier Railroad under the summit of the
Khojak Pass iu the Himalaya Mountains, and is 12,000 ft. long.
The workings were carried on from both ends and from two
intermediate shafts, and have been chiefly in hard rock, the
greatest delays coming from seams full of water, met with from
time to time.
23

24 ENGINEERING MECHANICS. [January, 1892.
FIG. 1.
RiMARKABLE PERFORMANCE OF A STEAM ENGINE GOVERNOR,
AS RECORDED BY SCOTT'S NEW ELECTRIC REGISTER.
It is commonly believed that certain kinds of work are most
severe ou an engine, because of the variable character of the
load. This is not true, however, to the least degree, since the
engine accepts only the reciprocating pressures distributed by
feet adjustment for quick changes of
load without being affected by the violent
surging which generally occurs.
When subjected to this strain they rapidly
deteriorate with their effort to
satisfy the demands upon them, while
obstructing devices which insure a
smooth, easy action of the governor
have the very opposite effect upon the
engine and the work it does.
Probably the severest duty imposed
upon an engine governor is found in
electric railway work, where the
changes of load are practically instantaneous,
and often through a wide
range, while the character of the service
demands a constant speed. It is
customary and considered sufficient in
such work to measure the speed over a
considerable interval of time, and the
rate of speed per minute represented
as the actual number of revolutions in
that time, yet, extreme fluctuations of
load might change' the speed (even if
but momentarily) far above or below
this reading without in the least affect­
ing the average.
With a view to thoroughly investigate the efficiency of the
Westinghouse Compound Engine Governor in this respect, a
supplementary test was made upon an iS and 30.x 16 Engine of
this type at the power-house of the Federal Street and Pleasant
Valley Electric Street Railway, by C. F. Scott of the Pittsburgh
Laboratory of The Westinghouse Electric and Manufacturing
ncl Engine Tests^Curves of Load Se corresponding Curve of Variation of Speed
its valve, and no change of load can make these changes of Company. A special instrument was designed by Mr. Scott,
pressures more numerous or violent than would occur under reading to one-hundredth of oue per cent, variation of speed
constant load. A change to a longer cut-off merely continues and registering every half second.
the pressures through a greater part of the stroke; while a Referring to the Cut (Fig. 1) the following is a description of
Curve illustrating variations of Speed in Stea
Figure 3.
shorter cut-off has no effect in making the reversal of pressures
less sudden at the end of the stroke.
the apparatus : A milled center inserted
rn that of the engine's shaft
revolves a large wooden drum
(whose circumference is 25 inches)
at the same speed of the engine
(250 revolutions per minute), while
a belted screw feed moves au electro
magnet, whose armature supports
a pencil, longitudinally along
the cylinder. Another part of the
apparatus is a pendulum adjusted
to beat nearly at the speed of the
engine and make electric contact at
the center of its motion to operate
the armature and pencil upon the
drum. A strip of paper stretched upon the drum receives the
impressions of the pencil, and when developed displays a line
Engines whose governors are actuated by Centrifugal force alone--
The real trouble experienced is an acknowledged inability, in of elongated dots at an angle to the edge of the paper whose
the great majority of governors ou the market, to effect a per
inclination varies with the speed. The measured distance, in

January, 1892.] ENGINEERING MECHANICS. 25
inches, of two dots that represent four revolutions of the engine,
or 100 inches of the drum, is the per ceut. of variation of the
engine's speed from that of the pendulum ; and a plotted series
of these measured distances from a base line, shown in Fig. 2,
with a connecting line drawn through them, is the record of the
governor's performance. A horizontal distance of one small
square corresponds to two revolutions of the engine, or an in­
terval of one-half second of time; while a similar vertical dis­
tance represents a change of speed of oue per ceut. The curve
ELECTRIC LIGHT PLANT,
above this illustrates the change of load by ampere readings
over the same period of time.
It will be seen that the engine changes but one per cent, each
side of the neutral line representing the time of vibration of the
pendulum through a total-change of current equivalent to two-
thirds of the rated power of the engine.
Figure 3 is a similar curve illustrating the action of a governor
which depends upon centrifugal force alone for its change of
positiou, as tested by this instrument during moderate changes
of load. After each new load the speed changed nearly one per
cent beyond the point at which it should have settled and grad­
ually worked back to the proper place. This governor was per­
fectly free from obstructing devices; yet, it is indicated plainly
that adjustment did not even commence until the speed had
changed considerably. However, this is not surprising when it
is considered that it depends on this variation of speed for the
force of adjustment. Indeed the record is not at all a bad oue
so far as centrifugal governors go, and the extra momentary
h e of speed would never be noticed in the average service,
buUt would be wholly unfit for electric railway work.
In their new Compound Engine Governor, the Westinghouse
Machine Company disclaim broadly the originality of the prin­
ciple of inertia in shaft governing, but insist that they have beeu
the first to so successfully apply the principle, and exhibit iu
these curves the evidence of the degree of perfection they have
secured by the application.
THE SPRECKELS SUGAR REFINERIES.
Although about two years since the Spreckels' Refinery com.
menced operations, there has beeu little loss of interest in the
undertaking, owing to the aggressive character of its management,
and the open, active opposition of its competitor, the Su­
gar Trust. .
When it first became known that Claus Spreckels inteuded to
establish a refinery at Philadelphia, the general impression
seemed to be that he would be unable to maintain his independ­
ence, and that sooner or later his isolated plant would be forced
to yield to the pressure certain to be brought against it, and that
it would be absorbed iuto the Trust. To say the least, it was by
many persons regarded as a mistake iu judgment; but so far
there is no indication that this institution has beeu at all embarrassed
by the opposing combination of producers; on the
contrary, it has seemed to be a continual source of uneasiness
to its opponents.
Considering the feeling which has existed between these par­
ties it is not strange that every detail in the construction of the
new refinery was jealously guarded as a trade secret; and on ac­
count of the very natural desire of the Trust to gain some in­
side information, this secrecy was pushed to such an extreme at

26 ENGINEERING MECHANICS. [January, 1S92.
one time that eveu the members of contracting firms were refused
admittance. Repeated attempts were made to penetrate
this secrecy by the Trust and the Press, but they have been invariably
unsuccessful, and so far, nothing really reliable has
been published regarding the new plant. The rigid exclusion
ol all visitors has been most effective in preventing any investigation.
In the short time the plant has been running, however, Mr-
Spreckels has proved to his own satisfaction not only the complete
success of his new venture, but that owing to his improved
methods he can refine sugar with less cost than the other companies.
The complete demonstration of these results has lately
been the cause of removing in a great measure the restrictions
as to visitors, and the courtesy of Mr. Charles Watson (the engineer
and manager of the plant), enables us to submit the first
reliable description of the refinery in general, together with
some interior views from photographs of some of the more interesting
departments.
When it was fully decided to erect the refinery, no time was
lost in executing the plans, and the work was rushed night and
day to completion. As an evidence of the speed and perfect
order that was maintained, we may incidentally note the details
of the construction of the electric light station.
It was noticed early in the course of construction that a want
of proper illumination at night was very materially delaying the
work, so that it was decided to finish the light station as soon
as possible. This conclusion was reached at II o'clock, A.M..
aud at 4 P.M. of the same day forty men were at work on the
excavation for foundations, and in ten days light was distributed
from this center. To fully appreciate the amount of work done
in the interval it must be understood that both engines and
dynamos were unordered and at their warehouses at the works
of the Westinghouse Companies in Pittsburgh. Furthermore.
the work was not at all of a temporary nature, but was intended
as a permanent part of the refinery. In this short space of time
the contracts were let, the building erected, aud the machinery,
consisting of three 150 H. P. Westinghouse Standard Automatic
Engines, aud three Westinghouse Alternating-Current Dynamos
with Exciters, and a capacity of 4,500 incandescent lamps, connected
ready for use, with all the necessary wiring of lamps and
fixtures.
It is perhaps not out of place to give here some of the credit
for this work to the contracting and constructing engineers, M.
R. Muckle, Jr. & Co., of Philadelphia, and to note that the station
is still running as it was started, no changes having been
found necessary notwithstanding the haste with which it was
finished. It may be that this early success of Mr. Spreckels is
in great part due to the ability of his management to select
competent and responsible contracting engineers, as the same
degree of permanence is a characteristic throughout the plant.
A full detailed description of the process of sugar manufacture
will be impossible in the limited available space, but it will be
necessary to briefly outline the successive operatious upon the
raw material to intelligently understand the results that have
been obtained.
The raw sugar is unloaded from the vessels at the covered
docks, which are owned by Mr. Spreckels, and built for this
purpose. On one side is a power hoist and platform traveling
at the rate of 18 feet per minute, and on the other is au electric
crane and electric car to facilitate the transportation to the re.
finery. Placed upon either conveyance the crude sugar requires
handling but once, and no further attention until it arrives
where it is needed. Both systems are entirely successful, and
are in themselves a considerable factor in the economy of operation
of the plant; but between them they are competitive aud
are to determine the character of the similar mechanism for additional
docks soon to be built. Neither plan must be considered
in the light of an experiment, as the success of both was assured
before their installation, but one will probably be found more
convenient than the other, and settle the type of conveyor for
the new docks. Compared with the costly plan of laboriously
rehandliug many times by horse and man (which is in general
use) neither of these methods suffers, and it would appear that
the advantages of either would show better by contrast.
The first operation upon the sugar is to dissolve or technically
melt the impure article in water, and at this point the proper
mixture of the different grades is made, which will insure the
best results as to product.
From here, a system of piping carries it to the filters, which
subject the liquid to a double operation. The coarser mechanical
impurities are first removed by a filtration through special
baggings, which as fast as they become clogged are washed, and
the water used is returned to the beginning of the process, to
serve in liquifying a new supply. The solution with the remaining
mechanical impurities, which are held in suspension, together
with the coloring material and organic impurities is next
passed through the bone charcoal filters, which remove the remainder
of the impurities of all kinds. These filters are 112 in
number, each 10 feet in diameter and 40 feet high, and when
these become obstructed, besides being washed, the charcoal is
reburned to destroy the organic material.
Up to this point any waste is returned tothe beginning of the
stage of refiuement at which the waste occurs, but after this any
leak which may occur is carried back to the first operation of
melting.
The next in the series of processes, after leaving the filters,
is through the vacuum pans, where the sugar is reconcentrated
and crystallized at a temperature corresponding to the degree of
vacuum which is maintained.
Here, the water which has been acting as a carrier for the sugar,
in solution is removed by evaporation, as it is no longer required,
and the remaining operations are upon the crystallized
article. This is the most particular operatiou in the series, since
the evaporation must be checked at precisely the proper point,
or the result will be a complete failure. If carried too far—even
a slight degree—the whole mass will solidify in the pan, while '
if the evaporation be stopped too soon the proper degree of
concentration will not be reached.
From the vacuum pans it is dumped into the Magma Tanks,
where it is kept constantly in motion by means of propeller
blades until ready for the final treatment in the centrifugal machines.
These are in reality centrifugal dryers, where the semifluid
mass is thrown by centrifugal force against the perforated
sides of the vessel as it revolves at a high speed, and the crystals
of sugar are separated from the syrup. A stream of clear water
directed against the surface is rapidly forced through the sugar
by the centrifugal action, and serves to still further clear the
sugar of the adhering syrup, and the result (after a few minutes'
run, to insure a complete separation of the liquid from the crystals),
is allowed to fall upon an endless belt running below, and
is taken away as a finished product (if we accept the immaterial
features found in the drying and granulating department), while
the liquid separated forms the basis of the syrups.
In this last process of the series, probably the most radical
departure is made from the usual practice. Each machine is
worked from a common platform, running the whole length of
the room, and belted direct from a 60 H. P. Westinghouse Standard
Automatic Engine. These are in two rows, on either side
of the room, and are governed by the operators from the platform
above ; yet the 27 engines, running at the rate of 320 revolutions
per minute in the third story of the building, stopping
and starting every few minutes, aud as often changing from full
load to a frictional one, have no perceptible effect in causing a
vibration of the building. An interesting perspective of one of
these lines of engines will give a good idea of the arrangement,
and show at the same time the location of the centrifugal cages
above and back of the engines.
The advantages claimed for this form of connection is that
the viscid mass is more evenly and rapidly distributed over the
surface by the constant pull of the engine, until it reaches the

January, 1892.] ENGINEERING MECHANICS. 27
CENTRIFUGAL ROOM. FIG. 2.
speed of its regulation, which is in about 15 seconds. Iu the
case of centralized power with friction clutches, the whole adjustment
may be destroyed in an instant, as the machine reaches
its speed with a surge however carefully the power may be applied.
Throughout the whole plant, the same careful consideration
of the conditions affecting the economy of operation of the plant
is seen.
The exhaust steam from the engines is used for heating purposes
as far as it will go, and the water of condensation is
trapped back to the boilers, which are of the Babcock & Wilcox
type, fitted with Roney Mechanical Stokers, and aggregating
7,500 H. P. In the steam mains are inserted separators, whose
water is also returned to the boilers.
Sixty-seven engines are used in various parts of the buildings,
of which 61 are Westinghouse, and the others are parts of the
machines they drive, so that we have here an excellent example
of subdivided power.
The buildings cover a surface of nine acres of ground, and
vary from one to nine stories in height. The capacity of the
plant is 6,000 barrels or 1,200 tons per day, but this amount has
occasionally been exceeded. The returns have been so rapid
and certain that the capacity of the plant will be increased as
quickly as possible to 2,500 tons per day by an addition nearly
duplicating the present system.
From the foregoing it will appear that the perfect success of
this venture, in the face of so much opposition, has been obtained
by a careful attention to details and the exercise of a high
grade of engineering ability, rather thau by auy secret process.
No expense has been spared in the purchase and installation of
the best quality of modern machinery, and the wisdom of this
course is fully justified in the results obtained.
THE Engineers' Club of Philadelphia is to be complimented
in the election of a secretary.
THOSE present at the station of the Edison Electric Illuminating
Co , Paterson, on Saturday witnessed a very pretty sight
when the new compound engine of 250 H. P., built by The Ball
& Wood Co., was started. Little Elizabeth Brock, four-year old
daughter of the General Manager of the Company, after some
climbing successfully reached the throttle valve, aud exertiug
all her strength, gave it a twist which threw 2500 more lights
into the dark places of the city.

28 ENGINEERING MECHANICS. [January, 1892.
THE BUFFALO FOUR-FIRE STATIONARY FORGE.
T H E modern technical and training school can hardly con­
sider its smith shop fully equipped without a forge outfit,
which does not consist of a lot of brick forges, occupying
considerable space, but of improved designs of iron forges,
especially adapted to the situation. Very few students or
graduates from these institntions will need to be told that in
all of the leading, and most of the smaller, mechanical colleges,
not only throughout America but foreign countries as
well, " Buffalo" Forges, Exhaust Fans for removing the smoke,
and Blowers for blast are used. The Buffalo Forges are made
by the Buffalo Forge Co., Buffalo. N. Y., who have from time
to time gotten out numerous special forms, to best suit the
equipping of various blacksmith shops. These have been
designed for large manufacturing concerns, where extra heavy
work is handled, and also for experimental shops requiring
lighter machines. The accompanying engravings show a forge
M»^;; ; :/,7""-.,
\ A?w\A A" >":i,f
.v'^^i'ii'ii'i'."'/; 7 '. ">//•''•
^-^A\AA'fA„A"AA-.-'
.> V }\,/ ,, 'I'U'I'''',,/
especially designed for the Texas State College. It will be
observed that four students can operate conveniently upon the
forge at the same time.
Our readers are well aware of the trouble and delay caused
by the old style forge, when it becomes necessary to clean the
fire. The live coals must be removed, before the ashes and
clinkers can be reached ; time is then lost waiting for the fire
to come up. One of the latest improvements of the Stationary
Forge consists of a patent tuyere, intended to obviate this difficulty.
This is adapted to the Texas College Forge, though
first designed for all the larger stationary forges for heavy
work. As will readily be seen by the outline cuts of the
device here presented, the construction of the tuyere is such
that all clinkers, ashes, etc., can be dropped out at" the bottom
of the forge, while the fire is still held in position undisturbed
Before adopting this device to any great extent, it was thoroughly
tested in various shops for a wide range of work, and
its efficiency thus insured.
JAMES M. QUEEN & Co. have located at 1010 Chestnut St.,
Philadelphia, where they have in use a building with floor
space of 26,000 feet. Fvery necessary facility has been secured
to accommodate their increasing business. The departments
of philosophical, electrical and chemical apparatus will occupy
the second floor,—floor space 5,300 feet. This room, extending
from Chestnut to Sansom St., is well lighted and specially
equipped for testing and proving purposes. In the " experi­
mental room " water, gas and electricity will be at command.
The departments for engineering, mathematical, meteorological
and microscopical apparatus are perfect, and displays can
be made to good advantage.
THE new plant of The Ball & Wood Co., builders of the
Improved Ball Automatic Engines, is so far completed that
shipments of engines have commenced, and the works have
been running night and day since October first, to clear up
their order books.
During the recent meeting of the Society
of Technical Engineers, in New York, The
Ball & Wood Co. had the pleasure of enter.
taining many of the members, who took
advantage of the proximity of the works to
run out and inspect them, and extend their
congratulations upon having the most complete
and convenient plant in the country,
for building and shipping engines.
Among others, orders for the Improved
\ \ BaU Engines have already been executed as
follows: 150 H. P. for the State House, Trenton,
N.J. ; two 150 H. P. for the Edison Electric
Illuminating Co. of Paterson, N. J. ;
75 H. P. for the Saugerties Electric Light
Co., Saugerties, N. Y. ; 100 H. P. for the
Meriden Electric Light Co., Meriden, Conn.;
75 H. P. for the Edison General Electric Co.,
Rockledge, Fla.; 100 H. P. for the Leominster
Worsted Co., Leominster, Mass.; 150
H. P. for R. H. Macy & Co., New York ;' two
75 H. P. for the Four Seasons Hotel, Cumberland
Gap, Tenn. ; 150 H. P. for the Electric Light Co
Madison, N. J. ; 150 H. P. for the Laconia Car Co, Laconia,'
N. H. ; 300 H. P. Gross Compound for the Edison Co. of Paterson,
for street railwav service.
THEB. & O. R. R. have now in service on its Southwestern
Limited Express train, running to Cincinnati and St. Louis an
entirely new equipment, built expressly for this train by'the
famous Pullman Cempany. The new cars embrace all the
features that have rendered the Royal Blue Line trains so universally
popular, and include the safety vestibule, steam heat
Pmtsch gas light, the anti-telescoping device, and convenient
toilet accessories for men and women. The Royal Blue Line
train, leaving Philadelphia at .1.30 A. M., makes direct connection
with the Southwestern Limited at Baltimore, where coach
passengers change cars. The sleeping cars run through from
New York and Philadelphia to Cincinnati and St. Louis without
change, arriving at Cincinnati next morning at 7.45 and St
Louis next eveuing at 6.25.
THE Shultz Belting Co., of St. Louis, Mo., have just sold two
Woven Leather Link Belts to Citizens' Electric Railway of
Decatur, nis.; fifteen in State of Montana ; five in State of
Washington; one flat belt 48- double to Municipal Electric
Light and Power Co., of St. Louis, and who have been us ng
one of their 48" double belts nineteen months. Also ol
"^.VfeSr;: Mass - 3o// wide -* -~—-

January, 1892.] ENGINEERING MECHANICS. 29
BRITISH INSTITUTION OF CIVIL ENGINEERS.
The following is a list of subjects suggested by the Council of
the British Institution of Civil Eugineers for the consideration
of members who may desire to present Papers for the Session
of 1891-1S92 :
1. Observations on the Strength of Materials, and on the
Apparatus employed for Testing the same.
2. The Theory of Alternating Stresses in Elastic Bars, with
regard to the estimation of the ratio of the Kinetic Safe Load
to Statical Safe Load.
3. The Influence of Continued Vibration and Impact from
Rolling Load, as affecting the physical properties of wrought
iron, cast iron and steel.
4. Ship Canals, and the Canalization of Rivers.
5. The laying out and equipment of River Ports, such as
Frankfort-on-Main, with reference to improved methods of
trans-shipping merchandise.
6. The Action of Weirs in times of Flood.
7. Description of any new or peculiar types or applications of
Mountain Railways for very Steep Gradients or other local peculiarities.
8. The Design and Construction of Ship Railways.
9. Machinery and Appliances for Tunnelling.
10. Comparison of the various Systems of Mechanical Ventilation
for Mines, Long Tunnels, Underground Railways, Sewers,
&c.
11. Friction at different Velocities, the comparative value of
different Lubricants, and Apparatus for testing them.
12. Speed Indicators, Couuters, and Recording Apparatus.
13. The various Systems of utilizing Compressed Air, Water,
and Liquefied Gases for Motive Power.
14. The Utilization and Distribution of Water Power in Mines.
15. The Continuous Running of Steam and other Engines,
with details of construction.
16. The Increased Efficiency to be derived from Superheated
Steam.
17. The best -Arrangement of Engine for auy given Electric-
Light Station.
18. The recent developments of Mechanical Refrigeration,
and its necessary apparatus.
19. Quadruple-effect Evaporators for the recovery of Soda-Ash
from Black Liquor, for sugar manufacture, &c.
20. The Design and Construction of Railway Passenger Car­
the use of Steam Rollers for the repair of country roads, and
the various types of highway bridges of moderate spans.
22. The Use of Sea-Water for Municipal Purposes, e.g., for
watering roads, for fire extinction, for public and private baths,
and for flushing sewers.
23. The Application of Electricity to the Treatment of Sewage.
24. Forms and Construction of Masonry Dams for Reservoirs.
25. Methods for the Prevention of the Waste of Water, and
for the detection of the same.
26. The Design and Construction of Modern Gas-Holders of
large size.
27. The Technology of Simple and Carburetted Water-Gas.
28. The Carburetting of Gases for Illuminating Purposes.
29. Tools used in the building of Iron and Steel Ships, and in
33- Machinery aud Appliances for Shipping and Discharging
Coal.
34. The Manufacture of Small Arms.
35- The Design and Manufacture of Quick-firing Ordnance.
36. Tools used in the Manufacture of Small Arms and of
Quick-firing Guns.
37- The Surface-Arrangements of Collieries ; appliances for
banking, cleaning, sorting and screening coal, and siding or
shipping accommodation.
38. The Systems of Underground Haulage in Coal and other
Mines, with methods for balancing the weight of Colliery Winding
Ropes.
39- The best means of Utilizing the Slack on Non-caking Coal,
including briquette making.
40. The Modem Practice in the Manufacture of Iron and Steel
having regard to economy of manual labor.
41. The Influence of the Minute Admixture of Alloys on the
properties of Metals for Engineering Uses.
42. The Effect of Annealing Steel for Machinery and for
Structural Work.
43- The Welding of Mild Steel, with special reference to boiler
work, and the influence of welding generally on the strength
and elasticity of the material.
44. The Dressing of Minerals, including earthy minerals, such
as barytes, phosphates of lime, &c.
45. The treatment of Gold and Silver Ores in the United
States.
46. The Electro-deposition of Copper.
47. On Pyrometers of various kinds ; the different objects they
are applied to ; and their practical use and working.
48. Electrical Traction for Roads and Railways, and the adaptation
to such purposes of the vehicles at present in use.
49. Electrical Motors for (a) Inland Navigation ; (b) Ocean
Vessels.
50. The most suitable Form of Electric Light Mains, having
regard to durability, economy of conducting material, and facility
of making aud laying house connections.
51. The application of Electricity to Smelting and Metallurgical
Operations.
52. Electrical Measuring Instruments—such as ammeters, volt
meters, power meters, and supply meters.
53. Telemeters for military and engineering use.
THE following table shows the volume of various substances
riages, having reference to (a) strength and safety ; (b) ease and
for preventing radiation when used as non-conducting covering
smoothness of motion ; (c) durability ; (d) moderate deadweight;
on steam boiler and pipes, according to experiments conducted
(e) facility for entrance and exit; (/) lavatory accommodation ;
by W. Hepworth Collins. Prof. Ordway's method was followed.
(g) provision for refreshments; and (h) sleeping arrangements.
The material used was one inch thick, and subjected to a heat
21. The Management of large Highway Districts, including
of 310 degrees Fahr. The heat transmitted was calculated in
the construction of Boilers.
30. The comparative merits of Triple and Quadruple Expansion
Engines for marine purposes.
The most recent types of (a) Passenger and Mail Steam-
3»ers
; (b) Cargo :
Steamers; and (e) Warships.
32. Mechanical Propulsion for Life-boats and for small undecked
vessels.
pounds of water heated 10 degrees Fahr. per hour:
Substance i in. Thick (in
Mass); Heat Applied, 310
deg. Fahr.
1. Hair felt
2. Cotton felt
3- Jute "
5. Loose cotton felt . .
6. Carded cotton . . .
7. Rabbit-hair " wool" .
8. Poultry feathers . .
9. Cork powder . . .
10. Sawdust powder . .
11. Asbestos " . .
12. Fossil meal .....
13. Plaster-of-paris . . .
14. Calcined magnesia .
15. Compressed calcined
16. Fine sand .....
Pounds of
Water
Heated 10
deg Fahr.
per Hour
through 1
Square Foot
11.4
10.6
13-2
11.7
9-3
8.1
7-i
6.2
•3-6
'4-2
47-9
5 2 -I
36.2
'4-7
53-4
66.3
Solid Matter
in 1 Square
Foot 1 in.
Thick, Parts
IOOO.
189
75
162
64
17
16
43
44
06
141
67
78
371
24
291
533
Air Included
Parts iooo.
957
930
921
753
99o
987
912
976
931
793
961
910
598
979
711
473

Ill ENGINEERING MECHANICS. [January, 1S92.
COLD ROLLED STRIP STEEL AND ITS
ADVANTAGES
It is perhaps not generally known that
the Cold Rolling of Sheet or Strip Steel
greatly improves its quality for all kinds
of difficult Pressed, Stamped aud Drawn
work. The tensile strength is greatly
increased, according to Prof. Thurston's
reports, aud the grit and other impurities
which are so injurious to fine dies are by
our process wholly eliminated. This in a
large measure lessens the cost of the
manufacture of Sheet Metal Goods, as
the expense for repairs or maintenance of
tools is materially reduced.
Iu many cases this saving alone will
more than offset the difference between
the cost of our COLD ROLLED STRIP
STEEL and ordinary hot rolled steel, and
the customer can always market his
goods to better advantage when they
possess the smoothness of surface always
obtained by our Cold Rolling process.
This steel can be furnished iu any degree
of stiffness which the work may require,
and in many cases a much thinner gauge
of Cold Rolled Steel can be used and still
produce articles which are equal in
strength to those which have been made
from hot rolled steel or sheet brass, and
the great smoothness of surface renders
it unequalled on which to Nickle or Brass
Plate or Enamel, Tin or Japan.
It can be had Coiled in ioo to 300 feet
lengths suitable for feeding into automatic
machinery and sheared to auy EXACT
width or cut to specified lengths.
THE WILMOT & HOBBS MFG. CO.,
Bridgeport, Conn.
AT the third annual dinner of the institution
of Electrical Engineers Prof. William
Crookes, in proposing the toast of the
evening, "Electricity in relation to Science,"
said that they had happily outgrown
the preposterous notion that
research in any department of science
was mere waste of time. The facts of
electrolysis were by no means either completely
detected or co-ordinated. They
pointed to the great probability that
electricity was atomic ; that an electrical
atom was as definite a quantity as a
chemical atom.
It had been computed that iu a single
cubic foot of the ether which filled all
space there were locked up 10,000 foot
tons of energy which had hitherto escaped
notice. To unlock this boundless store
and subdue it to the service of man was a
task which awaited the electrician of the
future. The latest researches gave wellfounded
hopes that this vast storehouse
of power was not hopelessly inaccessible.
JWIY new Catalogue of
Fine Tool s is now
ready. It contains s:. pages
of illustrated matter interesting
to every progressive
mechanic and live hardware
dealer. It shows new
tools and quotes reduced
prices. Send for a copy.
L. S. STARRETT,
ATHOL, MASS., U. S. A.
O.F HOLYOICE
STEAM PUMPS,
WATER WORKS ENGINES.
JAT,- ,

February, 1892.] ENGINEERING MECHANICS. 29
ENGINEERING MECHANICS.
Devoted to Civil, Electrical, Mechanical, and Mining Engineering.
Published Monthly by Englneering-Meclianics Put). Co., 430 Walnut St., Phila.
Entered at the Post-office in Phil.idelf.hia as Second-Class Mail Matter.
SUBSCRIPTION RATES.
Subscription, per year $2 oo
Subscription, per year, foreign countries 2 5°
PHILADELPHIA, FEBRUARY, 1892.
LAST vear houses and structures of various kinds, whose
frontage would extend 54 miles, were erected in Chicago at a
cost of $54,000,000.
THE Baldwin Locomotive Works are able to render additional
satisfaction to their customers by making complete aud exhaustive
tests of engines. This company have all the necessary facilities
to make tests aud have kept a competent engineer in
charge of this department.
IF the civil engineers in government service were as good
politicians as they are engineers, the work of coast defense
would be going ou more rapidly. After the earnest urging by
two or three administrations aud the special efforts of officials
of these administrations, there is scarcely anything done. The
Senate Committee of Coast Defense has again reported. 111
favor of appropriating £100,000,000 for defenses, ill which floating
batteries and torpedo beats will figure conspicuously.
IT is stated that a good deal of interest is felt in the coming
session of the American Society of Mechanical Engineers
to be held in San Francisco next May. President George
Richards, of the Technical Society of the Pacific Coast, has already
made considerable progress in the arrangements for the
convention aud the entertainment of the Eastern visitors. The
trip will be a memorable one. There is much for the engineer
to see and learn on the Pacific coast and in the gold and silver
mining regions.
ENGLISH ship builders are receiving inquiries from many
maritime quarters relative to the cost, equipment and efficiency
of whalebacks, the construction of which lias been entered
upon abroad. The original design of the American make s
retained; but certain modifications thought to be improvements
have been introduced. That whalebacks can safeh
plow the Atlantic has been demonstrated, and this fact brings
up the question, To what extent are existing methods of sailing
likely to be invaded by this late intruder
ENGLISH engineers are in a quandary as to what to do to
effectively increase speed of locomotives. But few would have
SJ-K"lAAA: At - of ,*— 1. *_» «•
niinished.
„ .j report on the French Navy it appears that
FROM the: c.« ^ ^ ^ ironcladS| 2g cruisers> lS torpedo
^Tdiratch cruisers, and 57 torpedo' boats. England will
have 31 ironclads, 69 cruisers, 15 torpedo and dispatch cruisers,
and 150 torpedo boats. Germany, Austria and Italy will together
have 17 ironclads, 22 cruisers and 14 torpedo boats. The
report acknowledges that Italy has gone ahead of France in
large ironclads, the former liaving 8, while France has only 6,
and in 1895 the two powers will be scarcely on a level, French
dockyards being very slow, though this is being remedied by
the use of the electric light, and the report recommends a relay
staff. M. Cochery acknowledges that the Ministry of Marine is
beginning to shake off its routine; but he insists on the necessity
of further improvements.
AMONG the more important metallurgical operations of the
year in England may be mentioned the success which seems to
have attended the Elmore Copper Depositing Company in the
production of steam piping. It is stated that an Elmore tube
., in. iu diameter aud */g in. thick has been tested aeainst the best
brazed tube obtainable, of similar size, made by the ordinary
system. The tests showed that the brazed tube burst in au uneven
manner at 44S lb. pressure. The Elmore tube stood 145 6
lb. pressure, being over three times as strong, aud then gave way
gradually and evenly. Unfortunately, however, the Elmore
process does not seem to be applicable to the production of
bends, and it now remains to be seen whether or not it is possible
to design a machine which could bend to a right-angle with
a curve of easy radius such a pipe as that we have just named.
It seems to us possible that some method of rolling out the tube
on the outer side of the bend might be devised. In France it is
stated that M. H. Bertraud has devised a modification of the
Bower-Barff process, by wliich magnetic oxide is formed on iron
to protect it. The process consists in depositing by one or other
of the galvanoplastic methods a metal, susceptible of volatilization
at about iooo deg. C After being coated with this metal
the articles are placed in a furnace and heated to iooo deg. C.
Notwithstanding the envelope, the iron articles become oxidized,
but without permitting the oxygen to accumulate in sufficient
quantity to form sesqui-oxide of iron. At the same time the
oxygen is enabled to penetrate in such quantity as to form
magnetic oxide, and in four or livn minutes the process is
complete.
INTEREST iu nickel steel is increasing in Great Britain.
Plates 4 to 5 inches thick have been tested to as high a breaking
strain as 47 tons per square inch, with an elongation of 23 per
cent measured on 8 in. Compare this with the ultimate breaking
strength of ordinary boiler steel, whicli is about 28 tons per
square inch, with an elongation of about 23 to 25 per cent. The
importance of the use of this material would have been well
Ulustrated had it been adopted in the construction of the boilers
of the huge Cunarders now being built at Fairfield^ In order
to provide for the very high pressure of steam to be used in
these vessels the shells of the boilers (constructed of best
Siemens-Martin boiler steel) are of plates exceeding . •- in. m
thickness. The total weight of the boilers for one vessel is not
s than 800 tons. If nickel steel of the strength given above
had been used the thickness of the plates cou^i with safety
ha e been reduced one-third, and the total weight proportion
ate.v reduced. Further, the bending aud working of plates
more than .'< in-thick is a much more delicate and serious
"era ion than would be that of the working of nickel stee
X i of ' in. in thickness. It is true that the cost of nickel
steel of he quality here referred to is very great, but the reducon
of weight would not only lessen the first cost but would
also help to minimize the bugbear of the naval architect < deadwelht"
But, besides all this, nickel steel of this quail y is
alios 'impervious to oxidation or corrosion, and of what importance
is the increased cost a few thousand pounds on an outfay
sta ed by rumor to be over half a million, an outlay on the
ptfrctase o/a metal having tbe admirable properties to which
we have referred.

3° THE CONSTRUCTOR. [February, 1892.
Translated by Henry Harrison Suplee.
Translation Copyright, 1890.
Example x. If so desired we uny make v 9 ' '• when one wheel will be- Example 9. a = go°, yj 9o'
ome an ordinary spur gear, Fig 612, and we have y, 180-—40—• 90 = 50 .
[ 0.7663 0.383, A*] = 0.348', < = T,

February, 1892.J ENGINEERING MECHANICS. 31
The tooth fr
friction may be reduced to a very small amount by
reducing the bearing surface of the teeth of one gear to a point
01 contact, or practically to a knife edge. Such gears (devised
by Hooke) are onlv of use for
cases are found serviceable.
The space s between teeth at the middle of the gear, is called
in the Westphaliau shops the "spring" of the teeth. If it is
desired lo approximate to the frictionless action of the teeth,
purposes of precision, but m some this "spring" must be slightly greater than the pitch.
FIG. 623. 024.
Instead of the edge bearing, a rounded surface may be used,
with its highest part corresponding to the lineal bearing as already
shown by Hooke and by Willis. The tooth outlines for
both gears are determined as usual, and then one or both profiles
are redrawn within the original curves, Fig. 623, and the
modified outlines used to form the tooth spiral; teeth so constructed
running nearly free from friction. Iu such cases the
length of flank /, and face k may be reduced as shown. Such
forms are more properly to be considered as screw thread profiles
than as gear teeth. Willis has shown that in both gears
the flanks may be made radial and the crown of the teeth semicircular,
Fig. 624. Since such teeth are weakest at the base, it
is preferable to use a modified form of the evolute tooth, FTg.
625. This may be approximated to by using a circular arc of
smaller radius thau S S =s R cos a, the centre B' being taken
on the normal -V N, through the poiut of contact.
M ,.--*>
FIG. 625.
yi'
A m
I A
FIG. 626.
A similar form to the preceding gears is the so-called stepgearing,
Fig. 626, frequently used in planing machines (by
Shanks,' Collier and others). ' The tooth profiles may be modified
as above, to reduce friction, but the gradation s should be
as great or greater than the pitch A Fewer than four sections
should not be used.
An objection to the use of spiral gears is the axial pressure
A', this, however, can be eliminated by the use of double gears
of' opposite inclination. Such gears have been known for a
long time (White, 1808) and for moderate service, have been
frequently used, as in spinning machinery, tower clocks, etc.,
and more recently they have been applied to heavy work, notably
for rolling mi'll gearing, both in Germany and America.
The pinions used in rolling mill work are made with 9 to 16
teeth with pitch diameters from \" to 24" and over. Evolute
teeth are used, with a base angle from 62 to 69°. The face length
of the teeth is made about 0.22 t.
If the evolute curve is accurately made, the tooth contact is
practically the same as with ordinary spur gears, and the surfaces
of contact can readily be discerned, extending diagonally
across the teeth. When such a surface of wear is visible, ot
course the teeth are not free from friction. Fig. 627 shows a
cast steel pinion of ten teeth, for rolling mill service. I his gear
is cast in one piece with its shaft and coupling ends, although 111
many cases the shaft is made separately.
* These gears have been used in physical apparatus by Breguet Tor speeds
exceeding 2000, or according to Ha ton, as high as 8000 revolutions per second
or 480,000 per minute.
t s
FIG. 627.
For very large transmissions the gears may be made in two
parts. Fig. 628 shows a pair of such gears for a reversing rolling
mill by the Hagener .Steel Works. The pitch diameter is
43 y, the pitch %A"i the face of each gear 20", and the total
weight 24,200 pounds. The teeth are made with double reverse
angles on each gear, so that the conditions are the same when
running in either direction, and the whole is a masterpiece of
machine work in steel.
SPIRAL BEVEL (".EARS.
\ M3-
Spirally formed teeth are sometimes used on bevel gears, and
in this case the distance a, between the axes becomes zero, while
the angle a remains to be given. For the curvature of the teeth
it is best to use a conical spiral of constant pitch, the projection
of which on the base of the cone is an Archimedean spiral.
Frequent applications of such wheels are to be found in spinning
machinery, and they are operated successfully at quite high velocities.*
The same varieties may be made in bevel, as in spur gears,
and in Fig 629 is shown a reverse spiral bevel gear of cast iron,
as made by Jackson & Co., at Manchester. Similar gears are
made of cast steel by Asth'.ver & Co., at Annen 111 Westphalia.
Stepped teeth are also used in bevel gears, and 111 Fig. (.30 is
shown such a wheel by A. Fiat fils, of Paris.
For a machine for the correct construction
gear
see Genie Industriel, \ ol. XII, p. 255.
the teeth of spiral bevel

32 ENGINEERING -MECHANICS. [February, 1892.
FIG. 630.
-24.
GLOBOID SPIRAL GEARS.
If a circle is revolved about au axis A A, coinciding with one
of its diameters, and at the same time a radius CS is moved
about the centre C, with an angular velocity proportional to that
of the circle itself, the circle will generate a sphere and the
point of the radius which is at the surface of the sphere will
trace a form of spiral curve. This may be called a spherical
spiral,'- aud adjoining lines of the spiral on the same meridian
are equidistant.
-(—-.
FIG. 6-, 2.
--S
cJ^^U
»\
Jhnr^
If the radius CS passes the axis of rotation, the new spiral
will intersect the one previously traced, as at A,. Instead of a
mere radial line, may be substituted a poiut which at the same
time traces the outline of a tooth space, so that a spherical screwthread
is generated with which a spur gear will engage at any
point, Fig. 032. If the axes sl and B are maintained in their
proper positions, the spiral when driven, will operate the gear
in the same manner as a worm and worm wheel, i< 221.
The practical value of this especial form is extended by the
fact that the axis of rotation need not coincide with a diameter
of the circle. Under these conditions there may occur a number
of forms of bodies of revolution bearing au affinity to the
sphere, and to which the writer has given the general name of
globoids. The corresponding spirals may be called globoid
spirals and the resulting gears, globoid spiral gear wheels. Many
of these may be made of practical use. (See F'ig. 633.)
There are numerous forms of globoids according to the posi
tion which the describing circle holds to the principal axis. The
axis about whicli the radius C S turns is called the counter-axis.
It stands at right angles to the starting position of the describing
circle, and either intersects the principal axis, or is inclined
to it without cutting it. We have then r, for the radius of the
describing circle ; a the shortest distance between the axes A
and C, c the distauce of the centre of the describing circle from
the plane of the principal axis, c\ the angle which the principal
axis makes with the plane of the describing circle, extending
from 0° to oo°. This gives four classes of globoids, as follows :
I. a - 0, c = o.
II. a = o, r chosen at will-
Ill, a chosen at will, c = o.
IV. if and e chosen at will.
A right globoid is one in whicli r, giving a socalled
cylindrical ring, or right globoid ring, Fig. 637 a, and
when a < r, the apple shaped globoid, Fig. 637 b.
If ri is an acute angle, the globoid is flattened, Fig. 638 ; the
globoid of Class I is the limiting case. The spiral curves are
globoidal cycloids, which become plane figures when b = 90 0 ,.
and the globoid becomes a plane ring or plane cone.
FIG. 634. FIG. 635. FIG. 636.
The fourth class gives the highest forms, Fig. 639, in which
b = o, aud we may have a > r, a = r, or a

February, 1892.] ENGINEERING MECHANICS. 33
IV. In the valve gear of Stephenson's locomotives. Fig. 640, is
found a globoid worm of class III, using the middle part of the
globoid apple, Fig. 637 b, (a < ;-). In this case the reversing
lever B is really a part of au internal gear with a radius R, =
the radius r of the describing circle.* In this case the internal
gear has but a single tooth, although more might be used.
FIG. 637. FIG. 638.
It will be seen that the globoid/orms can be used as internal
gears. This is shown in Fig. 641, which represents a worm
formed as a globoid screw. Its form is practically the same as
that of the hole in the right globoid ring, Fig. 637 a. The section
shown in the figure is of such length that it includes onefourth
of the entire circumference of the worm wheel B, although
it could be extended so as to include almost one-half.
FIG. 639.
The most important point to be considered is the formation of
the teeth. A\ is again made equal to ;-. Since the globoid is
used in the internal form, the two tooth profiles, on r aud A\ ,
fall together. The sliding is in the plane of a normal section
through B and A A, and uot endlong, and hence the shape of
the teeth is absolute.
\ ! /
A '
\ '
V
Co'B
! f
1
FIG. 640.
(Internal gear tooth, with R = R, ). The teeth can be made
of straight profile in the worm wheel as well as in the worm.t
The production of the globoid worm in the lathe is not difficult.
This form has beeu frequently used in recent work. The
advantages appear to be in the simple form of tooth and in the
completeness of the engagement.
* The worm and internal worm-wheel, Fig. 621, is another example of the
An interesting modification is that of Hawkins, Fig. 642*. In
this case the wheel B is composed of friction rollers of quite
large size and the friction is thereby greatly reduced. Instead
of there being only four teeth, as would at first appear, there
is iu reality an ideal number of teeth, a condition referred to in
PI * Hawkins' Worm Gearing. Sci. Am. Supplement, No. 104, p. 1648.
t ThiTfornils described by Smeaton as used in a dividing engine by Hind­
t See Uhland's Prakt. Masch. Konstrukteur, also Engiueer, Vol. 24, p. 493.
ley, see also Willis. Principles of Mechanism, ist edition, 1851, p. 163.
I A,
the fundamental discussion in 5 200. If for every revolution of
the globoid screw, one tooth of the wheel engages, there must
for each space formed between the rollers be 10 teeth to a quarter
revolution, so that instead of 4 teeth in B, there are 4(1-)- 10)
= 44 teeth.
FIG. 642.
The gearing used in Jensen's Winch, Fig. 643. belongs to the
globoid class IV, of the form shown in Fig. 639. Usually in
this form a = r, although sometimes a < r, as in Fig. 639 c.
R, is again made - - r, and the interual globoid form used. The
ratio is so chosen that a slow motion can be converted iuto a
I
FIG. 643.
fast one, as may also be done with the form shown in Fig. 641
if the pitch of the worm is made sufficiently great. The use of
rollers iustead of teeth makes a very satisfactory construction.f

34 ENGINEERING MECHANICS. [February, 1892.
If in the first two classes of globoids the supplementary axis
is removed au indefinite distance, the globoids become plane
surfaces, and the globoid screws thereby reach the limit. The
limiting case of Class III is the ordinary worm and worm wheel,
and another form is Long's spiral gearing, which also belongs
to Class III; a is chosen at will, C — O, d = o. The globoid becomes
a plane cone and the globoid screw becomes an Archimedian
spiral. If R becomes indefinitely great we obtain a
disk with a spiral groove engaging with a rack, the middle section
having full tooth contact from top to bottom.* When this
is brought into Class IV, we obtain the Archimedian spiral in
its most general form, i.e., the evolute of a circle.
\ 225.
E. CALCUI.A TION OF PITCH AND FA CE OF GEARING.
PITCH OF GEAR WHEELS. TOOTH SECTION.
whence :
The dimensions of gear wheels must, for the same pressure
on the teeth, be increased to meet shock in proportion to the
increase in initial velocity. For slow running gears this action
can be neglected. We may in this respect, therefore, divide
gears into two classes, viz. :
Hoisting Gears and Transmission Gears ; and includes under
the term hoisting gears all those having a linear velocity at the
pitch circle of not more than ioo feet per minute, and under
transmission gears all those running at a higher velocity.
For a pitch /, face b, length of teeth /, and base thickness oT
tooth //, we have for a tooth pressure /^corresponding to a stress
S, the general formula:
b t = 6
y \ A )
(212)
and for the proportions of length and thickness already adopted
we have:
b t= 16.S ''
(2,:
S
This assumes that the resistance of the teeth is propor'ional
to their cross section, wliich is also equally true for those which
have the same ratio of b to / to each other, a condition which is
often of much service iu practice.
i 226.
PITCH AND FACE OF HOISTING GEARS.
I'or a hoisting gear of cast irou let:
(P R) = the statical moment of the driving force,
7. = the number of teeth,
R its previously determined pitch radius, in inches,
/ = the pitch,
we have for the given dimensions:
A (PR) t A (PR R)
(20)
/ = o.o45 V— ^—, — = 0.0145 V—--g-
the face b being made
b = 2 t
(215)
These are intended to give a fibre stress 6' of about 4200
pouuds. The actual stress is properly somewhat less, because
the thickness of the tooth at the base is usually more than ft t,
as assumed in (213).
PR
Since the value of —-— is the same as the pressure P, we can
Ri
I'
T '
ind R':
AcZ
^ c
5
S'
a
c
r A
Z'
S
A' (1)'
(217)
R' 7A t'
->/
(218)
~R ~ AT
The value of C depends upou the ratio of the teeth, and upon
the value of 5 for the material used. If we assume the latter to
be the same for both cases, the number of the teeth alone remains
to be considered. A reduction in the number Of teeth
increases the pitch, according to (217) ; and according to (218)
reduces the radius.
Example 1. Z = 11, Z' = 7, hence
e 3/77 3/
7•= V 7 = V , - W? = , * ,6i
»' = !('- 1.16 /•.
>•'«,; 'sJ::^:h—'
so that the 7 toothed gear will be about % as large as the n toothed gear, or
a 42 toothed gear for the same case would be about ;4 as large as a 66 toothed
gear, and with 1.16 times greater width of face.
FIG. 644.
The constant C, for a given series of gears, should be invariable,
aud for ordinary spur gears may be taken equal to 16.8, as
iu (213). For the so-called " thumb teeth," (? 212), the constant
may be much smaller, and hence permit au important reduction
in dimensions. The value of —- for wheels of more than ten
teeth is not less than 0.7, and introducing this value we get C
= S.4, that is 0.5 C; hence '' thumb shaped '' profiles are capable
of sustaining twice as great a load as the ordinary form.
Example 2. If, for a given moment (/' A') the thumb profile is substituted
L°j£!f.°[j " a .y.r°'_ w i^ out red ucing the number of teeth, the pitch may
(216) be reduced in the proportio
''='V^»-5 ! 79 ',
or about o 8 times, with a proportioual reduction in diameter and face
for the° W ?tch r '
leeth arC take " iU the a b ° V e rati ° of ** ; 7. we would have
4.
use (215) in cases in which A 3 only is given, as for rack teeth.
In discussing the preceding formula;, consideration must be
given to the elements which are usually given or selected in
practice.
Let t' and / be the pitch for two cases respectively, and Zand
base
7A the
of
number
the teeth,
of teeth.
aud let
Also
the constant,
let 5 and
6
S'
(
be
—
the stress at the
.which
(I)
in (213) is made equal to 16.8, be called Cor C ; we then have,
accordiug to (214):
t-

February, 1892.] ENGINEERING MECHANICS.
Example 3. For comparison between a wrought iron gear of 7 teeth of
thumb
we have
shaped
:
outline, with a cast iron gear of 11 teeth of ordinary shape,
R & •• 0.47 R,
A
and A' _ o 7 b.
f --- t
HT1
I & 0.393. 0.7 t.
Ill Fig. 644 the five cases given iu the last three examples are
shown on the same scale, side by side. In order to indicate the
fact that the moment (PR) is the same in all cases, the shaft
diameter has been shown. It will be apparent that there is no
definite relation between the diameter of the shaft and the radius
of a gear.
The invariability of the moment, which has been maintained
in the preceding examples, does not exist of the tooth pressure
/"upon the driven gear is again transmitted through a second
so-called compound gear. If the pinion of a radius R, driving
a gear A", compounds by a pinion R., on the same shaft into a
rack RA, for example, with a given pressure P, we have from
(214)
Iflx\
/ = Const.
^ 5' ~7~
whence
This gives
. - - > / •
A'./
AA a
c
s
S'
7
7A
*-**-&• ?f !§)'
But A., = 7, t and Rd = 7A IA, aud from formula (215) :
Hence we get
T :
/, N 1
C
C S' > r' S'~ YA '7/
By selecting the number of teeth we may make
7A 7A
and then obtain
and for the radii :
R'
A
Z,
Zf
Az
c s_
S'
s_
^ C
A
1219)
(220)
(221)
The proportion of the results of the last two examples is
shown in Fig. 645. The force P on the teeth of the rack is the
same in all three cases.
The statical moment on the main shaft is, however, reduced
with the reduction in A", as is consequently that of the intermediate
shaft.
The advantages of steel as a material for gear wheels have already
been referred to in \ 222. Its greater strength enables
much lighter wheels to be used for the same service, than with
cast iron. For a gear of cast iron and of steel, to act against
the same moment, all other things being equal, we have, taking
5'= 14,000, and 5 = 4200 _, and also -A^°-l = about — in
favor of the steel. ...
This gives for the ratio of weight ( 2 3) 3 , that is 0.3, the same as
the ratio of 5 to S', or say three to one. This advantage also
exists for transmission gearing, although not to the same extent.
If the velocity ratio in a compound train is comparatively
great it is interesting to note that the most advantageous ratio
35
between gears lies between 1 : 9 and 1 : 10, this giving a mini
mum of shafts and of teeth.*
t
A
H
A
A*
X
Ai
1%
Ai
2
*A
\ 227.
"S
FIG. 645.
TABLE OF CAST IRON HOISTING GEARS.
R
127
200
287
39i
5n
70S
1150
'564
2044
3200
I'R
~Z~
10
20
35
55
82
160
__277
440
658
1284
t
Tt
0.15
is.20
0.25
0.30
0.35
0.40
0.45
0 50
0.60
0.70
p_(PR)
R
107
190
297
428
5^.3
761
963
1020
1712
2330
(PR)
z
8.67
20.56
40.16
69.40
no 20
164.50
186.00
320.50
555-20
S81.70
Example 4. A rack with a tooth pressure P, geariug with au 11 toothed
pinion is driven bv a larger gear which again engages with an 11 toothed
pinion, Fig. 645, the teeth being of the usual shape, and the material cast
iron. „ , . . . .
This is to be replaced bv making all parts of wrought iron, and reducing
the number of teeth in the rack pinion to 4, as shown in ji 212, all teeth being
also altered to the thumb-shaped form. We then have C'= 0.5 t, 5" = 2 .S,
and hence: f = \7 *z£ = l A t, and R' = R A \I 'A = ci R-
It will be noticed that in this case the ratio between the larger
gear and the pinion on the same shaft is such that in (217) and
(218) both are determined for the same moment (PR.)
Example 5. If, in order still further to reduce the dimensions, steel is used
instead of wrought iron, thus permitting a stress of 14,000 pounds, we have
ti _ t Example i. A force of ioo pounds is exerted ou a hand crank of 15 inches
radius ; what should be the pitch and face of a 10 toothed pinion for the further
transmission?
Here we have = = 150, and the nearest value in the table
Z 10
in the third column, is 160, which corresponds to a pitch of 1% iuches. The
face is = 2 t = 1% inches.
Example 1. A rack is to work with a pressure of 2000 pounds on the teeth.
This would give a pitch of about 2 inches, or as given in the 4th and 5th
columns, a pitch t : 0.65 TT, which is practically the same, and the width of
face = 2 t. If the rack is made of wrought iron, we have t = 0.707 X 2 =
1,414", and the face — 2.S".
§ 228.
PITCH AND FACE OF GEARING FOR TRANSMISSION.
, or about i, R. The fibre stress S, which is exerted upon the teeth by the action
of a given force P, should be taken smaller for transmission
gears as the circumferential velocity v increases, since the
*If be the total ratio, and k the number of pairs of gears, and the ratio
between each pair be x = —f we have 0 = x . The total number of teeth
I n 0
?
the number of teeth and the number of pairs gives
{In 4>Y- Z' (1 -f x)
'*" JTiTT?
Differentiating and making the differential coefficient equal to zero we
setlnx - which equation is satisfied by .r = 9.19. Forexample:
= 600, and the number of teeth in smallest pinion 7. We have the following
combinations :
(a) .J. 20 30, gives jr - = 7 (2 + 20 + 30) — 364, r /.- — 72S.
(ti) 4, 4.5.5.6, gives ^ = 7 (4 +4 + 5+5+6)= l68 , y k = °7 2 -
(c) 0 -4 6.10 10, givesy 7 (3 + 6 + 10 + 10) = 203,.!' k - 609.
The last solution is the best, for although it requires more teeth than (Ai
it has one less pair of gears, and for solution (a) the number ol teeth, viz.;
2jo is inconveniently great.

36 ENGINEERING MECHANICS. [February, 1892.
dynamic action of shock and vibration also increases
iron we may take :
9,600,000
v + 2164
For cast
in which v is the lineal velocity in feet per minute. For steel If we give to A the successive values 30,000, 25,000, 20,000,
5 may be taken 3 ' -, times, and for wood fa times the value thus 15,000, 10,000 and 5,ooo, we get the following numerical rela­
obtained. For cast iron we obtain, for :
tions :
77= 100
,S= 4240
200
4060
400
3744
Cast Iron .
600
3473
Soo
3238
For Steel
IOOO
3034
1500
2620
2000
2302
2500
2068
14,112 13,520! 12,467! 11,565110,782110,103187251766516886
And for Wood:
S 2544 | 2436 | 2241. | 2083 | 1943 | 1S20 | 1572 | 13S1 | 1240
The velocity v may be obtained when 11 and R (the latter in
inches) are given, by the following formula :
termined, the choice of the number of teeth Z is unrestricted.
In such cases we have for the width of face b:
396,000 N
b = ~A-' AAA
Common and Thumb Teeth. Common Teeth. Thumb Teeth.
b — -
Pn N N 504.000
= 2 - l R = ^ 2 Zi' t== -nS- ;i
30,000
252,000 \
n S
Pn
N N 420,000 , 210,000
b = = 2-5-77 ='54-^; l=~
25,000 A
?.—J t' = n S
b=
Pn
20,000
X
3-'5 -,,-
A
.N . 336,000 168,000 j
: I9S l =
Zt' '~ ATs~' AAsA
» =
2 ~ R n
—
...
= 0.5236 R 11
, ,
(223)
The selection of a proper value for v will be discussed below.
It is also found that the breadth of face b should increase with
the increase of P. Tredgold states that the pressure per iuch
P
of face, that is should not exceed 400 pounds. This, however,
is not to be followed implicitly, since pressures as high as
1400 pounds have been successfully used in practice. It is better,
however, to consider the question of wear from the product
of P
into 11, which should not exceed a predetermined niaxib
P_
mum. It is fouud that if — x n exceeds 67,000 the wear be-
b
comes excessive. In a pair of wheels where the teeth of both
are made of iron, the greatest wear comes upon the teeth of the
smaller wheel. In this case we may make
Pn
—.— = not more than 28,000 '224)
b
and if possible it should be taken at less thau this value. For
smaller forces this constant, which we may call the co-efficient
of wear and designate as A, may readily be made as low as
12,000, and even 6,000, without obtaining inconvenient dimensions.
When the teeth are of wood and iron the wear upon the
irou may be neglected, as the wear conies almost entirely upon
the wooden teeth. For wooden teeth the value of A should not
exceed 28,000, and is better made about 15,000 to 20,000.* It is
impossible to give exact values in such constructions, and it
must be left to the judgment of the designer as to how far it
may be advisable to depart from the values obtained from existing
examples.
It must be remembered that the different values of A do not
appreciably affect the strength, but rather control the rapidity
of wear. When sufficient space is available and a low value can
be given to the co-efficient of wear, it is advisable to do so ; if
this cannot be done, the co efficient which is selected will give
an indication of the proportional amount of wear which may be
expected.
In cases where a number of wheels gear into one other wheel,
it is better to take, instead of the number of revolutions of the
common wheel, the number of tooth contacts, that is the product
of the revolutions and number of wheels in the group.
If R is given, as is often the case with water-wheels, fly-wheels,
&c, Pis also known, and since sl can be chosen we have, taking
,V to be the horse power transmitted :
b
Pn_
Pn N , N , 252,000 126,000
(227)
6 =
15,000
4-2^^26.4—• R
^
R 7t
11 ._;,;/ S = _ n S
N
1.
63,000 _V
AT ~~ A~ ~R
hence from (213) for ordinary teeth,
t
16.8 P __
S b
16.8 A
S 11
(225)
and for thumb shaped teeth,
8.4 P AA-L
S b S n
If, however, as occurs in many cases, R is not previously de-
* See case 10, in \ 229 set/.
P y , 168,000 84,000
" f.
b = 6.3
39-6 jr\ t= n '-— S ;t' = —
10,000 A
" *• n S
P11 , N N 84,000 42,000
*= -5,000 = 12 ' 6 R= 79 - 2 zr i = AAs-' r = AAs~
For transmission gears the minimum number of teeth should
not be fewer than 20, in order that the unavoidable errors of
construction shall not cause excessive wear; for quick-running
gears it is desirable to have still more teeth. The gear wheels
on high speed turbines seldom have fewer than 40, and often as
many as 80 teeth. Wheu wood and iron teeth are used, the
least wear is produced when the wooden teeth are on the driver,
because the action begins at the base of the tooth and passes
toward the poiut, while on the driven gear the action is reversed.
If desired a number of teeth Z can be calculated which will
give a desired ratio b : I. If we combine formuke (225) and (226)
we obtain the useful relation :
7-- 396^000 n2 S 2 N
' A.S r A i
(22S)
(T)
This shows the important influence of A upou Z, and the effect
of the number of teeth upon the wear; also the important
relation of the tooth profile, since the constant 16.8 (or for
thumb teeth 8.4) appears in the second power. It is also seen
that 7 is dependent ou the square of ;/, and the square of .?,
other things being constant. These points iudicate the methods
of obtaining the least stress.
The value of — is sometimes made as great as 5. For wider
faces and sometimes for narrower, the rim of the gear is made
of two adjoining parts.
Example :.—A water wheel of 60 horse power, 26 feet, 3 inches in diameter
moving with a velocity at the circumference of 2s6 feet per minute is to be
provided with an internal gear wheel, the pitch circle being 16 inches less
radius than that of the water wheel, and gearing into a pinion which is to
make 40 revolutions per minute.
We have :
and
40 256(
al--, •y = 3.14 + 26.25 : 3-t
17-5- •16
33000 •- 60
- =230 ft per minute. P= ?eA2
*57-5
230
= 860S lbs. This gives permissible stress 5 4100 lbs. nearly. We will
Pn
choose for the smaller wheel
25,000
b'
25,000, which gives - - =J
25,000
b ni
:
625, hence b P_ _ 860S
40
625 62.5 nA". We then have from (227) t
420,000
2 77 R _ 2 IT I41.5
= 2.56", We then have Z =
40 X 4100
2.56
347- If we make
348 teeth the wheel may be divided into 12 segmenteof 29 teeth each. For
the driven wheel we have Zx = S. Z= 3 „ n
'- ,•: 348 ,48 = = 27, 2,. whence whence /?, p. t - ^Xa-sfi
40
Fxampie 2—A turbine water wheel of 100 horse power has a vertical shaft
making 96 revolutions per minute, and it is required "drive a horizomal
shaft at .44 revolutions, hence a pair of bevel gears are required We wit
will LZme e V,?J. bi r K*\ teeth ' aiKi ,et the w o o d teeth b -- ^
396,000 96
16.8= x 25000^ '
, , 420,000
also t = - '
96 X 1600
s 000, also
We then have from (228) Z =
X 16002 X too
= 70. We then have Zx = — .70 = 47 •
= 2.73'say:
144
. * = 3 t = S'A", v = 1536 feet per minute.
(226)

February, 1892.] ENGINEERING MECHANICS. 37
Example 3.—In a given train of gearing, Fig. 646, iu which the corresponding
wheels of both pairs are of the
same size, the force transmitted in
each case is inversely as the number
of revolutions. In order to have the
co-efficient of wear Pn alike in both
cases it is only necessary to make all
the gears of the same face. Au example
of this kind maybe found in
the back gearing of many lathes.
Example 4.—Let it be'required to
construct a pair of durable gears of
wooden and iron teeth uuder the following
conditions: N = 5, u = n\ —
60, and =2. We may make v =
500, which gives, from (222), S = 2160,
and as great durability is required
we will take A as low as 10,000. These values in (228) give :
Z =
which we may call So teeth.
We have from (227)
396,000
.8 2 X 9>oo
60 x 2160
6o2 2160- 5
1.167"
and
396,000 5
9000
• 2 33
' 80 X 1.167
or 2 /, as intended.
Example 30, 5.—Let n\ = 50 N = for 40, a n pair of iron gears with teeth
of common form, 2.5. and If we let make v = 300, 5" = 3400 and we
take A
25,000. This gives for the driver gear :
396,000 50 2 X 34°o -2 X 40
Z=
6.S-- 1 X 25,000 s " 2.5
say 42 teeth, and Z\ -= — Z =10,
and b = 2.5 t = 6.175".
we have t
420000
3
50 X 34°°
: 4i-5
If we choose the thumb-shaped teeth, and make • 3*5 " T e get:
z ^ 39 6 ,°°°_
50- X 34°°- X 40
8.42 x 25,000^ ' 35
210.000
say 120, and Z\ • t' =
50 X 3400
1.235", b = 4.32.
This gives smaller teeth, but larger radii than when the common form is
used.
When steel is used for gear wheels, special proportions are obtained. It is
not too much to say that the value of the co-efficient of wear A should be
taken twice as great as for cast iron. The stress S, however, may be taken
2V2 times that permissible for cast iron. Taking these points into consideration
in formula (228J we see that A would reduce the number of teeth by Ja,
aud .S would increase it by ( J , that is, about 11 times, so that the net in­
crease would be - , if the above values are accepted. It may therefore be
laid down as a rule that steel gears should have more teeth for the same service
than cast iron gears. The ratio of face to pitch may be made quite
large, and in the case of double spiral gears (as Fig. 627) the ratio - is some­
times made as great as 7 or 8. If the formula for thumb teeth be used, instead
of the usual shape, the constant 16.8 will give satisfactory results. The
value obtained for the pitch is that for the normal pitch T = t sin y, but the
width of face is the actual width, as 6, in Fig. 627, 2 V iu Fig. 628.
Example 6.—Suppose the wheels given in Example 5 to be made with
double spiral teeth of steel. We take A = 56,000, and — = 6, alpcS— 12,800.
We then get:
396,000 50- < 12,800- '•' 40
J.4 2 •' 56000-
8.4 X 56,000
We have T =
12,800 X 5°
also b
If we take Zx = 84, we get Z 140 and b = 4%".
t =
396,000 40
6
56,000 87 X 0.74
0
74 0 „
sin 60 o. 866 * = 0.854
: 4.4
We may take t = 0.875", which gives r = 0.866 X 0-875 :
A = 4 5 _ - • 5.93, or nearly 6.
T O.757
We have then finally R\ = it.6", R = 19.47"
\ 229.
87
* If*"
EXAMPLES AND COMMENTS.
60" we have
0.757" and
The following examples taken from actual practice will be of
interest: (see Table on following page).
No. 1. From the driving gear of the main steam engine of
Fleming's Spinning and Weaving Mill in Bombay. The toothed
fly-wheel is the driver, and the teeth are shrouded, as shown in
Fig. 651. The coefficient of wear for the driven gear seems high,
and does not indicate long endurance.
No. 2. A toothed fly wheel engaging with a pair of equal spur
gears ; 300 horse-power transmitted by each gear, making a
total of 600 horse-power. The value fo — — must therefore
b
be multiplied by 2 ; see last column of the table.
No. 5. This is from the air compressor for the atmospheric
Pn
railway of St. Germain (now abandoned.) — is evidently too
high, as would probably have become apparent had the gears
continued in operation.
p
Xo. 4. — is very high, but the small number of revolutions
b
P11
keeps the value of within reasonable limits.
b
Nos. 5 and 6. These are from the great water wheel at Greenock.
The pressure at the rim is great, but the teeth have worn well
in practice, as might have been predicted from the moderate
Pn
values of The value of the latter is almost the same for
b
No. 6 as for No. 5, hence the wear should be about the same for
both gears.
No. 7. The teeth in the smaller gear are thinner than those of
the large fly-wheel, hence the two values for .S". Probably the
larger wheel was originally made with wooden teeth.
c R"
No. 9. Notwithstanding the high pressure the value of
is reasonably small. The stress upon the teeth is quite high, as
is also the case with No. 4, and lower stresses are to be recommended.
No. 10. This is one of the most noteworthy examples of the
whole collection, on account of the very slight wear exhibited.
The wooden teeth on the large wheel, (the fly-wheel of the
steam engine of the Kelvindale Paper Mill at Glasgow) ran for
26A years, for 20 hours per day, with a wear upon the teeth,
measured at the pitch circle, of only about A inch. For the
first half of this time the engine indicated 84 horse-power, at 38
revolutions. The teeth were lubricated twice a week with talc
and graphite. The long endurance is doubtless partially due to
the great care which the teeth received, they having been cut upon
the wheel in place, but also to the moderate co-efficient of wear.
No. 11. The teeth were found too small in practice, as is indicated
by the stress of 3000 pounds; from formula (222) we obtain
S = 1734 pounds.
No. 12. Two gears with wooden teeth engage with a single
pinion on the screw propeller shaft. The teeth are in two sets
of 4 3 +" width of face each.
No. 13. Very high pressure, which must appear in the wear
upon the teeth ; apparently it should be difficult to keep them
P
in good condition, owing to the high value of -7-.
No. 15. These teeth appear weak, as has been shown by repeated
breakages. The wear must be rapid, as indicated by the
r P"
high value of— -.
No. 17. These gears, (designed by Fairbairn) were intended
ultimately to transmit double the power at first given, in which
case the stress would reach over seems 4000 pounds, too high which for is the admissible wooden
Pn
teHh
but the
;
value
it is almost
of — 7
too
— would
great
then
also
become
for the iron
rather
teeth,
too high
aud
to
it must
indicate
be remembered
very great
that
endurance.
with wooden and iron teeth, the wear comes
almost entirely upon the wooden teeth.
, No- Pn 22. These gears are from au establishment which has used
hyperboloidal No. 20. The gears value with of — much — success for power transmission.
The angle of the axes is 90°. The use of wooden teeth upon the
driver is to be criticised, as tending to increase the liability to
wear.
F. THE, DIMENSIONS OF GEAR WHEELS.
THE RIM.
?230.
The ring of metal upon which the teeth of a gear wheel are
placed is called the rim. For cast irou spur gears, the thickness
of the rim is giveu by the formula
tl = 0.4 / -j- 0.125" (229)

3§ ENGINEERING MECHANICS. [February, 1892
No. N
1
v>
:{
6
!>
IO
11
12
13
14
•
IOOO
300
270
240
192
140
140
90
82.5
5°
15 3°°
IG 300
17 240
IS
19
20
21
200
150
IOO
50
36.67
114.8
AA
IOO
60
12
44
L^L
15-14
15.14
50
30
55
3°
54-5
1.51
13-3
AL
I-.S.8
26
80
54
S3
4.o_
7-32
_774
40
50
100
Tin
_44_
44
AL
So
93_
124
AL
144.7
_93_
21S
7-'
22 l6 T,T
120
3^-25
146.5
37
19.6
~9&~
no
33
400
35-25
_K>6
•2
58.4
32
66.5
35-75
291
33
jS4._5_
24
85.4
27-75
55 J
35-8
5°-4
27-5
16.5
24-37
-15 7
-•-1-7
-'67
42
59
3'-3
24.8
-'3-1
15
io.,s
2lsS_
19
EXAMPLES OF TRANSMISSION GEARING.
144
46 ~
230
_ 58
19
95
20S
AA
AAA
72
138
76
j6o_
So
176
5o
_2_2_8_
74
AL
74
96_
52
248
48~~
93
55
44
75
?8_
50
80
60
_7o_
45
AL
32
_68_
~6o
'
5-25
4.00
6.25
3-i
2.8
3
24
'4
20.6
-125 •5
2-375 5-9 Il6 3
3- 2 5
2x4.7
'"•75
10.6
2^00 14,000 1877 5S3
1900 5,100 1614 364
Pn
A
REMARKS.
21,390 Iron and Iron.
66~,970 Steam Engine.
2 x 9107
36,400
Iron and Iron.
41,650 _ , .
616 14,-500 1S4S 694 -*-£- Iron and Iron.
8,330
240 16,230 56SS
2000 1,655 9 : 4 163
,500 3000 424
558 3,440 184S 362
104 15,500 7536 1463
6.3 32S 1,980 2420
BEVEL, GEARS.
3-> 13 1187 8200
2.7
3-5
3-8
[576 6170 3840
is 96S 84-50
n.S 1260
8 1523
1
6.3 1140
6-3 1236
51.S7
2772
2860
*3'3
3270
3697
2'33
2276
2417
29S5
3 S 4Q
1564
18 48
HYPERBOLOIDAL GEARS
j.996
5.9 S12 640
1-993
924
1250
3*4
630
6.7
8,498 iron anci; Iron.
28,110 Transmission for No. 8.
"34 Iron and Iron.
14,390 Water Wheel.
7.357' Wood and Iron.
8,175 Steam Engine.
1_I_,OI_O I Wood and Iron.
33,900 Steam Engine.
_ l ?_._S4-°__ Wood and Iron.
'-X30,040 Screw Steamship.
5.°49 Iron and Iron.
10,700 Water Wheel.
2,433 Iron and Irou.
12,570 Water Wheel.
58,660 Iron and Iroi:
31,540 Turbine.
61,700 Iron and Irou.
1.8,980
447 '9,670
437
346
454
20S
10S
Transmission for No. 1.
Iron and Iron.
Transmission for No. 3.
17,9-° Wood and Iron.
34,960 Turbine.
32,220 Wood aud Iron.
42,970 Turbine.
42,220 Wood and Iron.
65,690 Turbine.
•9,3_S_ 0 Wood aud Iron.
45,430 Turbine.
7,8io Iron and Wood.
8,851 Transmission.

February, 1892.] ENGINEERING MECHANICS. 39
See Fig. 647. The rim is thickened in the middle or at one
6
edge to — d, and also stiffened by a rib, and for gears of fine
FIG. 647,
FIG. 648.
6 i"",l .j
For wooden teeth it is necessary to have a deeper and stronger
rim, the dimensions being dependent somewhat upon the
method of inserting the teeth. The proportions for spur gears
FIG. 650.
1.5

4o ENGINEERING MECHANICS. [February, 1892.
[Copyrighted.]
THE MARINE ENGINE:
Its Construction, Mode of Action and Management.
F.Y CARL BUSLEY,
Piofessor at the Imperial Academy at Kiel.
For steam from 212 0 to 428 0 F.
log/. = a, — b. n, r + c1ftl
a, 3-743976
a = 3.025 90S
log b = 0.6117400
log c — 8.13204 — 10
log a -— 9.99S181015 — 10
lOg/3 r O.OO38I34
T = t 32
log bl = 0.4120021
loge, = 7-74'68 — 10
log a, --.- 9.99S561831 — 10
log ft = 0.0042454
7 = 1 212.
from which
-log/; jr-
AfA C \C 2
Translated by Assistant-Engineer EMIT THEISS, U. S. N.
5. Moist steam is a mixture of steam and
Moist steam. water, it being uncertain whether the water
is commingled with steam in the form of a
haze or fog, or whether it is deposited on the surfaces of the
containing vessel. The steam as it enters the cylinders of a
steam engine is usually moist, for the loss of heat before admission
will bring about the change, even after drying in a superheater.
It is to be remarked in this connection that, accordiug
to recent experiments (see \ 12), the steam furnished by a good
boiler, not forced unduly, will furnish steam either dry or containing
only a small percentage (not exceeding five percent.) of
water, which is for the most part carried over by the steam mechauically.
It was formerly held that boiler steam contained
from 1 o to 20 per cent, of moisture.
Wet steam. 6. Steam is wet, when the water contained in
it is sufficient to make known its presence in
the cylinder by interfering with the working of the piston, as
happens when the boiler primes or when much water is mechani­
Superheated
cally carried over by the steam.
7. Superheated steam cannot exist in const-earn,
tact with the water from which it was generated.
Its temperature is higher than that
of saturated steam of- the same pressure ; its specific volume is
greater, and its specific density less. Steam highly superheated
has the properties of a perfect gas (see §6, 1).
8. It is at times found expedient in practice
Mixed steam. to form a mixture of superheated and saturated
steam before admission to the cylinder,
the object being to prevent the admission of superheated steam
for reasons to be specified later (see ''/, 13, 18). The surplus heat
of the superheated steani evaporates the water contained in the
saturated steam, and the resulting mixture is slightly superheated
or slightly moist, according as the evaporation was complete
or incomplete.
't/, 9. Definition of Terms.
Pressure p. 1. The pressure exerted by the expansive
force of steam is ordinarily given iu terms of
pounds per square inch.
2. Pressure reckoned from zero, i.e., above
Absolute and a perfect vacuum, is called absolute pressure.
gauge pressure. Pressure reckoned from atmospheric pressure,
which is that recorded by gauges, is
called gauge pressure.
3. Atmospheric pressure, measured by the
Atmospheric pressure required to sustain a column of
pressure. mercury 30 iuches in height, is equivalent to
14.7 lbs. per sq. inch at the level of the sea.
Calculation of pres- 4. The pressure of saturated or moist
sure p, given the saturated steam is independent of the amount
temperature t ot water contained, and is a function only of
the temperature t. The form of this function
has not yet been theoretically determined. The following empirical
formula, deduced from Regnault's experiments, gives
the relation between pressure and temperature at latitude 45 0 T is the absolute temperature; p is pressure in lbs. per square
foot.
Introducing the proper value of the constants, we have
2938.16
tlog/-
.
For steam from 3 2° to 212° F., pressure in pounds per square
inch,
log/> - a — b a'-Y c ft' (23)
-371.85
6.1993544in
which t is temperature in degrees Fahr., p is pressure in
lbs. per sq. inch. This formula has been employed in the calculation
of the tables.
5. Vacuum is measured ordinarily in inches Vacuum.
of mercury sustained by the atmosphere
against the pressure which is to be determined.
6. The pressure existing in the condenser
and the spaces and passages of the cylinders Back pressure.
connected with it is called the back pressure.
7. The weight in pouuds of a cubic foot of Specific weight of
saturated steam is its density, or specific steam, y.
weight, y. An approximate formula by Zeuner
gives,
y = ap", where a .003008, and — = .939.
u
• (24)
8. The volume in cubic feet occupied by Specific volume, s.
one pound of saturated steam is called the
specific volume, s, of steam : it is the reciprocal of y
y y
9. Similarly the volume occupied by a Specific volume of
pouud of moist steam, or of a mixture of mixtures.
steam and water, is the specific volume, v, of
the mixture.
10. The volume occupied by a pound of Specific volume of
water at the maximum density is .01602 cubic water.
foot. In view of the fact that the increase
in volume of water from ordinary temperatures (from 65 to 75
degrees F.), to 212°, is only about 4.2 per cent.; and that the
compression for an increase of pressure of one atmosphere is
0.00050 of its volume at 32 0 , and 0.000044 at 127°, it is assumed
in the solution of practical questions that the specific volume of
water compared with that of the steam generated from it is constant
= .01602 cubic foot.
§ 10. Generation of Saturated Sleam.
I. When one pound of water of temperature 32 0 F. is converted
into saturated steam of temperature
t°, the total heat, \ must be applied. A part Total heat.
of this, the heat of the liquid, q, goes to raise
the temperature of the water ; a second part, the internal latent
heal, p, goes to change the aggregate state ; while the third part,
the external latent heat, A p u, is the equivalent of the work
done by the steam expanding against external pressure.
2. The tola! heat, '/, is calculated by an empirical
formula based on the experimental re- Formula for total
searches of Regnault. Expressed in English heat.
units, this formula is
= 1081.4 + .305 t (25)
3. The heat of the liquid, q, which goes to
heat the water, so that the generation of Heat of tbe liquid.
steam can begin, is, according to Regnault:
1}
2 Cl
q = t -\- 0.00002 t 2 -j- 0.0000003 i 3 (26)
This is for Centigrade degrees and calories. For English
units Rankine gives
q = 1 — 1 + 0.000000103 [(if — 39°.i)8 — (>-*, __ 39°.i)3] . (26a.
where f is the initial, and / the final temperature.
4- The internal latent heal, p, whicli does
the work of separating the molecules beyond Internal latent
the range of mutual attraction, is calculated heat, p.
from the formula
1061 •79' t (27)
The constants are those given by Prof. Cecil H. Peabody, and
used by him in calculating his tables of the properties of saturated
steani. Rankine gives the following formula :
log p = A B_
5. The external latent, A p 11, performs
the work of expansion of the steam against External latent
external pressure, which is equal to that of heat, A p u.
the steam generated Eet u = s — w be the
T
(A
difference in volume of a pound of steani and a pound of water
at any pressure, />, theu the work of expansion will be/, u ft. lbs.
-— A p it thermal units.

February, 1S92.] ENGINEERING MECHANICS. 4I
According to Zeuner, ,. . c .. . ,
Apu - 20.914-1096/ — ,/ (2S)
lor an infinitesimal reversible change the thermal equivalent of
the '"ternal work will be, therefore,
Total heat as the 6. From the preceding we have A d U => d q + d (x p) (35)
sum of the preced- , , and the corresponding internal work
ing. A = q+ p+A pu (29)
„ . ... , 7- As the heat Ap it disappears in doing
Heatofthesteam, J. external work, the heat contained in the
d U •=• (if q -f ,/ (x,,) l-,ca)
A
1 4.1. • x steam will be the sum ofthe heat of the liquid, 4- The quantity of heat d Q which must Derivation of dif
t,r///V U / ternal / atenlheat ' / '- T h i s ^maybe called the be imparted to a pound of a mixture of terent values for
mat oj nit sit am, J. steam and water while undergoing an in- the quantity d Q.
J—q-\-P = r\ — Ap1l (30) finitesimal reversible change is obtained from
the general equation
„ . 8. Only the quantities of heat represented , ,, , , , ... , , , ,
Heat of vaponza- by p and A p u are concerned in the genera- - A(dW-\-df-\-dL)
tl0n
-
u
fi° of steam; q only raises the temperature From equation (2")
of the water. The sum of the two former is ,/''" _L ,//—,///
called the /•

42 ENGINEERING MECHANICS. [February, 1892.
then
Substituting
d 0= (1 — x) Cd / + rd.v + A-h d 1 . . . (36c)

February, 1892 ] ENGINEERING MECHANICS. 43
ELECTROTECHNICS.
A Compilation of Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
/. Resistance.
a). Wheatstone's Bridge and Resistance Box.
Fig. 42 shows the disposition of the bridge as employed in
the English telegraph department, and called the " Post-Office "
bridge. It measures from o.oi to 5000 ohms.
If there exists an E. M. F. in the resistance to be measured
(e. g., thermo.-E. M. F.), the position of the galvanometer
needle when the galvanometer key (A'2) is depressed, is taken
as zero. The resistance between a and D is then so changed
that upon closing the battery circuit no deflection of the needle
is observed, unless it may be that due to the induction on closing
the circuit, which however is but momentary.
A very convenient bridge-box is the Universal resistance box
of Siemen & Halske, the scheme of which is shown in Fig. 43.
FIG. 43.
With these bridges it is not generally possible to obtain very
clear zero readings on the galvanometer, on account of the
abrupt steps in the variation of resistances, but the instrument
will, if sensitive, deflect either to one side or the other.
Let the deflection for the unplugged resistance 100.1 ohms be
+ 66.6, and that for 100.0 ohms be — 333,
then R 3}ff .0.1 = 100.333, or the
66.6 4- 33.3
resistance for no deflection. By interpolating in this nu lanner
very accurate results may be obtaineil.
By changing the disposition ofthe bridge, however, resistances
may be accurately determined without interpolation (Fig. 44).
FIG. 44.
900 - 1 -«— 9 •90- •900-
0,1 - 1D00 0 AAAA/VV-
X
The resistances in the bridge are 1, 9, 90, 900 ohms. To meas­
ure 100.001 ohms, plugs 1, 9 and 90 are drawn on each, side of
bridge, and 100 ohms iu box R. It is found that x > R.
The resistance box r is then placed in a shunt to the one ohm
coil on the left of bridge by plugging a ; r is altered until
the galvanometer needle is brought to rest, then is
IOO
A'
99 +
' + '
if r - 999.
99
R=
AAA
1.00001 R.
IOOO
Measurements by means of the unit aud shunt may be facilitated
by using the following table. This table gives, not the
combined resistances, but the difference, 1 — the combined re­
sistance.
If R 100 aud r 165.7 on plugging a, and 100 ohms are
unplugged on each arm of the bridge, then is
IOO
x = .100
90 + 1657
166.7
IOO
X =- .100
90.994
If /' was iu shunt to b, then would
90.994
IOO .IOO
The following table gives under x the magnitude of the shunt
compared to the unit coil, by means of which it is diminished
a certain number of thousandths as shown in first column.
,-= l -
0.001
0.002
0.003
0004
0.005
0.006
0.007
0.008
0.009
0.010
O.OI I
O.OI2
0.013
c.014
0.015
0.016
0.017
0.018
0 019
0.020
0.021
0.022
0.023
0.024
0.025
X
999
499
33 2 -3
249
199
165.7
«4l-9
124
IIO.I
99
89.9
82.3
75-9
7'-4
65-7
61.5
57-8
54-5
51.6
49
467
44-5
42-5
40.7
39-
r = 1 —
O.O26
27
28
29
30
3'
52
33
34
35
36
37
38
39
40
4i
42
43
44
45
46
47
48
49
5o
X
37-5
36.
35-2
33-4
32.2
3^-3
30.3
2 9-3
28.4
276
26.8
26.
25-3
24.6
24.
23-4
22.8
22.3
21.7
21.2
20.7
20.3
19.8
19.4
19.0
. _
0.051
52
53
54
55
56
57
58
59
60
61
62
6.3
64
65
66
67
68
69
70
7'
7 2
75
74
75
x
1S.6
18.2
'7-9
'7-5
17.2
ib.9
16.5
16.2
16.0
'5-7
'5-4
'5 '
14.9
14.7
14.4
14.2
'3-9
'3 7
'3-5
'3-3
'j-'
12.9
12.7
12.5
12.3
r = 1 —
O.076
77
78
79
80
Si
82
83
84
85
S6
87
88
S9
90
9 1
92
93
94
95
96
97
98
99
IOO
X
12 1
I2.0
11.8
11.7
n.5
"•3
11.2
11.0
10.9
10.8
10.7
10.5
10.4
10.2
10.1
9-9
9.8
9-7
9.6
9-5
9-4
9-3
9.2
9-'
90

44 ENGINEERING MECHANICS. [February, 1892.
A form of bridge largely in use is the combined resistance
box and bridge (London Post-Office pattern) shown in Fig. 45.
FIG. 45-
This combination isjnade up of resistance coils whose ends
are connected to the ends of the plug blocks, suitably placed
binding posts aud a detector galvanometer. The diagram shows
the disposition of parts and the connections.

February, 1892.] ENGINEERING MECHANICS. 45
RAILROAD DEPARTMENT.
A CALIFORNIA PALACE.
T H E engineers aud architects who together designed aud
constructed the great Hotel del Coronado at Coronado
Beach, San Diego, at the terminus of the A. T. & S. P.
R. R. in Southern California built a monument of beauty,
utility and grandeur, though of wood, that it is to be hoped
will remain for many long years to come. This superb build­
ing is deserving of study, and in its entire make-up is suggestive
of the master mind aud hand of the great Richardson,
though built by the Reed Brothers of San Francisco. It stands
as a unique model for future like hotels. Its 7% acres of floor
space, unlike most hotel floor space, is liberally utilized in
large, airy aud comfortable rooms throughout its four floors,
each fit, in its appointments, for a king. Its large halls, passages
and stairways, inside and out, and its thirty or forty private
parlors scattered invitingly throughout the buildings, ren­
der the hotel peculiarly attractive and home-like. Its 750
rooms are all cozy and comfortable, looking either towards the
ocean or the tropical flower-garden and court on the inside, or
the broad expanse on the land side, with the distant mountains
of Mexico and California as a background. Spacious public parlors,
billiard rooms, reading aud writing rooms, a vast audi­
torium and stage, and halls and rooms for sports of all kinds
are scattered around just where they ought to be for the convenience
and enjoyment of the guests. Then the glass-encased
verandas, wide, high and roomy, on the long ocean side of the
house, looking outward towards China, with islands pink aud
brown and white, some fifty miles off, changing their hues with
the changing sunlight, the wide and long west porches and the
porches to the north, all help to give an air of luxury, elegance
and quiet to the throng of travelers. The hotel is located on
the ocean edge : back of aud about it are 4000 acres of lawn and
gardens of tropical flowers and open space for future comers,
which sends a sweet fragrance of never-dying tropical flowers.
Engineers who have spent a season here will read of it with
more interest than those who have not yet seen it or enjoyed
its unapproachable enjoyableness. The unvarying climate, 65
to 75 degrees all the year around, make it a delightful spot for
eastern people who flock thither, especially in the winter season.
And yet it is unknown to thousands who could aud
would enjoy it if the truth could reach them.
The interior appointments of the house especially attract the
attention of the engineer and practical man. Mineral wells of
great medical value, as well as of commercial value, 14 miles distant,
supply the hotel and town with the purest water, through
pipes ranging from 16 iuches to 12 inches, which water is used
for all hotel purposes, both table, kitchen, etc. Besides this
there is special machinery by which a daily capacity for five
million gallons of salt water can be drawn from the bay to be
used for fire prevention. The fire system is as complete as engineering
skill can make it. Ninety hose-reels are distributed
over the house, each supplied with abundance of hose connecting
with this large source of supply. The flushing apparatus
is most complete and at pleasure 27,000 gallons of salt water
can be thrown through the sewer every 10 or 20 minutes.
Eight sets of pipes are used to conduct hot, cold, fresh and salt
water throughout the building, 011 all floors. There are in all
13 miles of pipe in and around the house, wliich is built in the
form of a vast square, with a beautiful interior full of tropical
flowers. Eight cold storage rooms give 40,000 cubic feet capacity.
All cooking is done by steam, and the exhaust steam
from the elevators is utilized for this purpose. An 800 gallon
tank on the roof serves au excellent purpose. It is so arranged
tbat cold water forces the hot water through the entire building.
Three electric light engines of 125, 90 and 37 horse-power
engines are in use.
But it is only the engiueer that finds matter of interest in the
tunnel connecting the machinery department with the house.
The rush of travel which fur several months of the years fills
this great caravansary, live not inside, but outside, for the sky is
almost always kind, and the air balmy. The long, glass-enclosed
verandas ou the ocean side afford ample room for the
hundreds of guests. The west porch has its special attractions.
The walks and drives in the grounds are always inviting, and
those who enjoy bathing find unfailing enjoyment in the surf.
The hotel is a picture of architectural beauty—a dream realized
—and the visitor can scarcely restrain au exclamation of admiration
as he first gazes upon its grandeur. The hotel is the
property of the Coronado Beach Hotel Company, of whom
John D. Spreckels, of San Francisco, and Colonel Babcock
Donualy, of Cincinnati, are chief stockholders, assisted by Mr.
J. H. Gardiner, of San Diego. The hotel is built close tothe
waters of the Pacific Oceau. (In one hand is a vast expanse of
water, broken by two or three fifty miles distant islands, and
near by Point Soma. On the inland side stretch from extreme
north to extreme south the California and Mexican mountains,
50 to 100 miles distant, stand out against the sky dressed for
most of the year in nature's finest apparel. The enclosed
region is oue ofthe most fertile aud the balmiest region on the
face of the globe, excelling, as all travelers say, even sunny
Italy, and surpassing it for magnificence of ocean and land and
mountain scenery. There is au eternal summer that is never
summer as eastern people understand and experience it, but a
sweet, continued temperature controlled by ocean breezes that
never weary, aud covered by a sky that never deals harshly
with the invalid. The busy engineer who will slip away from
work for a while, either winter or summer, will never regret the
visit. The country through whicli he will pass over the A. T.
& S. F. road is an unceasing panorama of grandeur, all through
Colorado, up into and through the mountains of New Mexico.
Then Arizona, supposed to be a State devoid of beauty aud attractiveness,
opens its arms and welcomes the traveler to such
scenes of grandeur and magnificence in mountain scenery as
are not to be seen elsewhere iu the United States. Even the
desert section has its attractions, and when California opens
upon the view, the sudden transition from desert to fertile vistas,
interspersed with orange and lemon groves and vineyards,
and with giant mountains for a back wall, and an unchanging,
balmy climate as a sure companion while he lingers, brings the
traveler to the realization of the fact that he has not to wander
beyond the oceau to find Scotland mountain scenery and Italian
climate and vineyards aud groves of tropical fruits that surpass
those ofthe Mediteraneau region.
THE statistics of the mineral, agricultural, manufacturing
and commercial development of the towns, cities and country
generally which the Atcheson, Topeka and Santa F'e system
covers with its network of lines shows what is being accomplished
by that well-managed company for the Southwest and
the country at large. The officials of that system are doing, in
a certain sense, a patriotic work in maintaining excellent facilities
over certain sections when returns are meagre, but these
deficiencies are more than compensated for by the results of the
stimulus imparted to other localities by railway facilities and
excellent service. The Santa Fe managers are looking to the
future, and are shaping their conduct accordingly. They know
the extent and character of the undeveloped resources through
which their network of road passes, and they are opening up to
capital, and for mining, manufacturing and agricultural enterprises
an abundance of opportunity which it is pleasing to note
is being taken advantage of. The great Northwest has attracted
attention of the overflow population for many years, but the
great Southwest is now under the able management of far-seeing
railway men, looming up with its boundless opportunities.
This great enterprise has its root iu Boston, and the impulses
that make it what it is go out from there. The builder of the

46 ENGINEERING MECHANICS. [February, 1892.
road, Mr. A. A. Robinson, its first Vice-President at Topeka,
Kansas, au engineer of national reputation, is, with other
managers, contemplating extensions that will make it a more
complete and compact system than it now is. The vast passen­
ger traffic interests are under the supervision of Mr. J. P. Nichol­
son, of Topeka. Its Chicago managers represent the highest
grade of railroad talent in the West, and its local agents
throughout the East are picked from the most energetic of the
rising young men whose ability and industry draw them into
special notice. The chief engineer of this system, James Dunn,
is steadily bringing the road up to a higher standard of efficiency,
and has in contemplation a number of improvements which
will soon be introduced. Under the management that this
system is receiving from Boston, Chicago, Topeka and San
Diego, it will become one of the most prosperous and oue of the
most noted systems on the American continent.
OF recent years the necessity for able and skilful business man­
agers in the various departments of the railway service has be­
come more apparent. While the very best engineering talent has
always been sought, there was in the earlier history of railroad­
ing less attention paid to business capacity. In uo service is
merit so quickly recognized. The men who reach position and
distinction in railroad service deserve them as much as the sol­
dier who earns honor by bravery. One of the systems where
merit is quickly honored and ability recognized is the C. B. & Q.
system. It has grown steadily for years from a small company
to the grand system it now has become. Its financial manage­
ment has been a great success. It has served the region
through which it passes not merely with an eye single to
revenue, but to the permanent advantage of the people. This
system is now adding to its locomotive and rolling stock
capacity, aud is contemplating additional extensions and connections
that will furnish the people of the region through
which it passes with more aud better facilities per mile, per
acre and per head of population than any other agricultural
section of the country. Its passenger service has been greatly
improved, and further improvements will be made to keep the
system up to the gilt-edge style of the best Eastern Mississippi
systems. The road-bed is kept in perfect repair. The train
service between Chicago and Denver is equal to the best on any
road East, and the engineering fraternity can do no better than
to use that line between those points when going that way.
THE Baltimore aud Ohio earnings for December on the entire
system were 12,176,155, showing an increase of f 116,866. On
the lines east ofthe Ohio there was an increase of earnings, but
on lines west, owing to increased operating expenses, there was
a slight deficit for three months ending December. The pur­
chase of $5,000,000 of the common blocks by a syndicate of
New York and London bankers will enable the country to in­
crease the general efficiency of the system. The management
has gained the entire confidence of the financial public, and it
is doing good service in opening up new opportunities for manu­
facturing and mining interests in the mineral regions through
which it passes.
The passenger service of this system is being improved not
merely in a perfunctory way, as nearly all passenger service is
beiug improved, but the zeal of such men as Chas. O. Scull is
aroused in the work, and he is not only making the passenger
service the equal of the very best roads iu the country, but he
is doing it in a way and with a success that is making the fact
recognized by the public and observant railway officials of other
roads.
IT would require the expenditure of over one hundred million
dollars to dig all the canals that are seriously projected
and greatly needed in the United States. The necessity for
more and deeper canals has been growing for several years
past, and there is no doubt whatever but that both through
government management and private enterprise, a great deal
of work of this sort will be done during the next few years.
[Copyrighted J
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
This principle will be verified in every circumstance, without
auy exception, in the most simple as well as in the most com­
plex problems ; this is why it was well to state it from now on
under the most general form ; it can serve as a guide and as a
means of prevision in all questions and admits of telling in ad­
vance the degree of difficulty of each of them.
(For text reference see p. 17.)
Iu point of view purely practical, it admits of causing at once
to arise one of the numerous advantages which are presented
by the constructions so disposed that Statics alone admits of de­
termining the unknown forces which are shown there ; in fact,
the bodies which enter into it being able to be freely dilated or
contracted without experiencing constraint on the part of their
supports, reciprocally they will not tend to overthrow these
supports, however great aud however uneven be the variations
of temperature which they will utidergo, as a whole, or in certain
of their parts. We shall observe, afterwards, many other
advantages.
0'-
Fig . 17. Fip 18.
. - - « *
d d
(For text reference see r*. 17.)
SP°°
-**-yA
' /• '
§ si.
DEFINITION OF THE BODIES CONSIDERED IN THIS CHAPTER
AND IN THE FOLLOWING CHAPTERS.—We shall consider in that
which is to follow only bodies subject to forces all situated in
one and tlie same plane and symmetrical as to this plane, so that

February, 1892.] ENGINEERING MECHANICS. 47
the figure determined by their intersection with the plane m
ay
have no tendency to go out from it.
„ v
(For text reference see p. 17.J
When we shall speak of a point ofthe body, it will be under­ point and subject to forces distributed in any manner in a plane
stood that the question will be of a point of this plane figure,
the only one, as we shall see, aud as it is easy to conceive that
it is necessary to consider as long as we are not occupied with
the elastic and calorific changes of form of the body.
Fi 20
(For text r^lereac^
?S2.
said to take place, whatever be the magnitude, direction .and
flow of the force A'.
Therefore, to render a body free which has a fixed point, it is
sufficient to adjoin to the forces which are directly applied to it
a force R' representing the reaction, whatever it is, of the point
Relatively to this reaction, we know, a priori, only a single
thing, i.e., that it passes through the fixed point.
The body beiug required to be in equilibrium uuder the ac­
tiou : i° of the forces applied directly ; 2° of the reaction ofthe
fixed point, this last force (}, iii) ought to be equal and opposed
to the resultaut R of the first. Therefore it is necessary that
this resultant R itself pass through the fixed point.
This condition is besides sufficient; for, if it is fulfilled, the
fixed point will oppose to the resultant R a reaction R' equal
and opposite, as it follows from the definition itself of the fixity
of a point.
Hence it arises also that the resultant R of the forces directly
applied represents the pressure exercised on the fixed point, since
it is equal and opposite to the reaction R' which this point exercises
on the body.
GRAPHICAL VERIFICATION.—The condition which precedes
is easy to verify graphically when all the given forces are iu
one and the same plane. It is sufficient to draw a funicular
polygon of these forces relative to any pole, by making the first
side of it pass through the fixed point, the last side will have to
pass through it equally, since the intersection of these two sides
is to give a point of the resultant.* Hence :
In order that an invariable system movable around a fixed
be in equilibrium, it is necessary and sufficient that, if the first
side of any funicular polygon of these forces pass through the
fixed point, the last side will equally pass through it.
If this condition is fulfilled, the pressure on the fixed point is
(For text reference see p. 19
Fig. 20
equal to the resultant ofthe given forces, i.e., to the geometric
sum which the force-polygon furnishes at once.
Remark.—In order that the arguments which precede be ap­
GRAPHICAL CONDITION OF EQUILIBRIUM OF A BODY SUBJECT plicable, it is not necessary that the fixed point offer, as we have
TO REVOLVE AROUND A FIXED POINT.—In order that a solid supposed, an unlimited resistance : it is sufficient that it can re­
body subject to revolve around a fixed point be in equilibrium, it
sist the pressure R which it has to undergo.
is necessary and sufficient that the resultant of the forces which
incite it pass through the fixed point.
* If this point of intersection did not coincide with the fixed point, the
first side ofthe funicular polygon would contain two points ofthe resultant,
This resultant represents, then, in magnitude, direction and
viz.: the point of intersection and the fixed point. It would then be the re­
flow, the pressure which the body exercises on Us support. sultant itself; that is evidently impossible if the pole is taken without the
A fixed point is a point such that, if we chance to apply to it right line a .'., which goes from the origin to the extremity of the polygon of
forces. If it is taken on this right line, the two extreme sides are coincident
a force R, whatever it be, the poiut opposes a resistance or re­
or parallel: in the first case, the proposition is satisfied; the second cannot
action R' exactly equal and opposite to R, so that it remains at
be produced; for the resultant of two parallel forces meets neither of them.
rest exactly in the same conditions as if, being free, it was sub­ Now it is to meet the first side because it is to pass through the fixed point
ject to the two forces equal and opposed, R and R'', and this is and because this first side itself passes through this point.

4S ENGINEERING
' \ 53.
fixed lines; it will be able to be considered as free, provided
that to the forces which incite it we adjoin the reactions of the
EQUILIBRIUM OF A BODY BEING SUPPORTED BY A POINT ON
supports, i.e., Ai 53) two unknown forces directed according to
A FIXED LINE.—THEOREM.—/// order that a body resting, by a
the normals A X and B N' to the curves.
point, on a fixed line, without friction, be in equilibrium, il is
necessary and sufficient that I lie resultant of Ihe forces whicli
are direc liy applied to it: 1° pass tlirough this point, 2° be nor­
mal to the line, f tend to supper/ /he bo.lv on this line ami not
to detach il from it.
If these conditions are fulfilled, the resultant of the given
forces represents Ihe pressure exercised on the fixed support.
A fixed material curve supposed to be perfectly smooth (we
suppose it such, whicli is expressed by saying that an abstraction
of friction is made) is a line so constituted that it offers uo ob­
stacle to a body gliding on it, but only to oue crossing it.
JFi6.27.(S 53)
Let us suppose (Fig. 27, Plate VII) a body supported on the
fixed line xy by a point A. If the resultant A'of the forces in­
citing the body satisfies the three conditions announced in the
theorem above, the curve will cause a reaction A" exactly equal
and opposite to R, and the body will remain at rest. These conditions
are therefore sufficient.
They are also necessary. In order to show it, let us observe
at first that if, to the force R, we add another directed accord­
ing to the tangent of the curve, this latter, being suppose 1 perfectly
smooth, would not be opposed to the movement which
this new force would tend to cause. This is what we mean by
saying that the reaction A", which a fixed line (abstraction of
friction being made) produces on a body which rests on it, can
be only normal to this curve.
This being the case, the body considered as free is in equilibrium
under the influence of the forces whicli are directly applied
to it and of the reaction A" of the curve. It is necessary,
for that (+.
EQUILIBRIUM OF A BODY RESTING DV TWO OF ITS POINTS IIN­
FIXED LINES; PRESSURE ON THESE LINES.—Let (Fig. 30, Plate
VIII) be a body resting by two of the points A and B on two
MECHANICS. [February, 1S92.
i°. If the two normals meet, the two reactions, whatever they
be, directed accordiug to these lines, admit of a resultant R r
passing through their poiut of intersection O. Besides, these
reactions being necessarily directed in the flows sl A'andi? N',
their resultant falls within the angle opposed through the sum­
mit to the angle A O B.
The body requiring to be in equilibrium under the action of
the resultant and of the forces directly applied, it is necessary
that these latter themselves admit of a resultant R equal and
opposed to R', i.e., passing through the poiut O and falling
within the angle si O B.
This condition is, besides, sufficient; for, if we separate the
force R, conceived to pass to O and comprised within the angle
A O B, into two others according to A N and B X', the fixed
curves will resist these two forces, which will represent the
pressures exercised on them, so that these pressures, and, con­
sequently, the reactions of the supports are fully determined.
2°. If the lines A X and B X' are parallel, the two reactions
N and N', being parallel and of the same flow, admit of a resultant
A", having the same direction and the same flow as they
and falling between the points of contact A and B. Therefore
the forces directly applied ought to admit of a resultant R par­
allel to the two lines A N and B X' falling (? 42) between
these two lines and tending to support the body on these lines.
These conditions are besides sufficient: for, as soon as they
are fulfilled, at auy point where the resultant R falls between
the points A and B, we can find two forces both parallel to R,
passing through the two points A and B, and keeping it in
equilibrium. These will lie the reactions ofthe supports which
are thus found determined.
GRAPHICAL VERIFICATION.—IU the graphical point of view,
in the case 2°, we see, on the force polygon, whether the resultant
has the direction and the flow desired ; in constructing it by
the aid of a funicular polygon, we shall see whether or not it
falls between the points A and B, if it falls there, the determi­
nation of the reactions is relegated to problem VIII solved
in \ 42.
Iu the case i°, we see at first, on the force polygon, whether
the resultant conveyed parallel to itself falls iu the angle A OB.
But it is necessary that it really pass to tlie point O; this is
what we shall verify, as has been said in I 52.
(To be continued.)

February, 1S92.] ENGINEERING MECHANICS. 49
THE accompanying cuts illustrate the most recent and
important improvement in journal boxes, for the purpose of
facilitating proper adjustment and providing for a more perfect
and continuous lubrication than is practical in journal boxes as
ordinarily made.
The Franklin Institute of Philadelphia has recently awarded
the Longstreth Silver Medal of merit for this invention. It will
be fouud especially valuable on all machinery running at a
high speed, where, owing to the ease aud accuracy of its adjustment,
a great saving will be effected in time, oil, wear and
tear, etc. Letters Patent of the United States have recently
been granted to Joseph J. White, President ofthe Pennsylvania
Machine Company, Limited, Philadelphia, for this improve­
ment, and manufacturers of machinery may acquire the right
to use it by the payment of a small royalty.
Briefly stated, the improvements consist in making the walls
A A of the casting to extend up to the height of the top of the
cap box C. These walls being planed through longitudinally 1
the cap is neatly fitted between them. To secure the upper or
cap box, instead of using bolts or screws to draw it down in the
direction of the shaft, it is clamped in position by bolts D D,
laid in grooves .V, cut transversely to the axis of the shaft across
the top of the cap and through the side walls. By tightening
these bolts the walls are drawn together, clamping the cap box
B E
firmly between them. A large oil chamber D is provided in
the upper cap. The packing of paper or wood usually found
in the ordinary journal box is entirely dispensed with here,
thus leaving room for a strip of wicking E, one edge of which
conies in contact with the shaft for lubrication, and the other
edge connects with an oil well B. Channels are provided in
the casting for carrying any excess of oil back to the well.
The journal box can be adjusted to the shaft with certain accuracv
in one tenth of the time required to properly adjust a journal
box of the usual type. This is accomplished by thoroughly
oiling the shaft where it enters the box, and placing the cap in
position where it seats itself upon the oil in accurate adjustment
; then by tightening the bolts immediately, the cap will
be rigidly secured in its proper place. No amount of strain
that can be put upon the bolts can effect the adjustment of the
cap which is even separated from the shaft by the film of oil.
Experience has shown that the clamping of a journal box in
this way is effective aud durable. This fact will be apparent
when it is considered that split pulleys are clamped to shaft­
ing, and that notwithstanding the leverage of the pulley, they
hold satisfactorily.
THE Montana Society of Civil Engineers held its annual
meeting at Helena, and elected the following officers : President,
Col. Walter W. De Dacey, of Helena ; First Vice-President,
Albert B. Knight, of Butte ; Second Vice-President, J. S.
Keerl, of Helena ; Secretary and librarian, F. D. Jones, of Helena
;' Treasurer, A. S. Hovey, of Helena ; Trustee, Elliot H.
Wilson, of Butte. The society is in a prosperous condition.
IN the new regulations issued by the French Government for
insuring the safety of metallic bridges the following rules are
given for deterinining the admissible stresses in the various
members: The maximum allowable stress in tons per square
inch is for wrought iron
I'or steel
minimum stress i
3-8i + i-9
maximum stress J '
r „ . minimum stress l
1
5-oS4- 2.54- - — \.
maximum
-•'• stress S
By taking the account of the change of sigu when the stress
changes from tension to compression, the above rules will, according
to the new regulations, be applicable to members subject
to alternating stresses. The above rules are of course applicable
for determining the stresses in long struts. For such the new
regulations give no definite formulae, but we may suggest that
for steel and for the ordinary struts in which the length does
not exceed forty times the least transverse dimension, the following
simple rule : Fixed ends : Maximum permissible stress
in tous per square inch
-0--V0 (
minimum stress
1-h maximum stress
Rounded ends : Maximum permissible stress
5-
•3 A ) \ '4- minimum stress ")
maximum stress I
where L — length of strut in feet, r = least radius of gyration
in iuches. If the stress is alternating, the factor
r minimum stress ress 1
1 -4- —:— ress /
t maximum stress
should be altered to
( '4- minimum stress
2 maximum stress )
CHIEF Inspector of Mines Haseltine, of Ohio, after testing
twenty-nine camps with the Shaw Inspector's instrument, says
of it:
•' Its services have been indispensable to the department. It
has furnished a ready aud accurate means of determining the
actual percentage of dangerous gases in the mines, and places
the Inspector in command ofthe situation, and enables him to
act understandingly in his official position."
" Ofthe twenty-nine lamps tested, twenty-two of them were
of the Davy pattern, four were Clanny's, one an improved Clanny,
and one each of the Belgium aud Stephenson make. Of
the Davy lamps tested there were four that gave evidence of
the presence of gas at four per cent., and a like number at five
and six per cents., two at four aud a half per cent., and three at
five and a half per cent., two at seven and eight per ceut. respectively,
and one at nine per cent. Of the Clanny lamps,
one gave signs at four percent., and oue at five per cent., and
two at eight per cent. The Stephenson at four and a half per
cent., the Belgian at eight per cent, aud the improved Clanny
at ten per cent. Twenty lamps showed a cap at or below the
line of explosion, while nine, or thirty-one per cent, of the
lamps, failed to give any indications of danger until the point
of explosion had been passed. The point at which the gas exploded
in the lamps was no more uniform thau the line which
first gave indication of the presence of gas. Three lamps filled
at eight per cent., which was one per cent, above the point of
explosion as established by the instrument, five at nine per
cent., four at ten aud eleven per cents, each, eight at twelve
per cent., and one at twelve and a half per cent., two at thirteen
per cent., and at fifteen and seventeen per cents, one
each."

5° ENGINEERING MECHANICS. [February, 1892.
RIVETED JOINTS.
The diagrams accompanying this article are intended to fa­
cilitate the operation of obtaining the calculated percentage of
strength of riveted joints of boilers, or other riveted structures.
They are based upon the formula ofthe Board of Trade, as set
forth in their "Regulations and Suggestions for the use of
Surveyors," etc., and of Lloyd's Register, as per their " Rules
for the Survey and Construction of Engines and Boilers of
Steamships." The calculation of the percentage of strength
of a riveted joint by the formula of either the Board of Trade,
or of Lloyd's Register, is an arithmetical operation requiring
considerable time and care to obtain a correct result whicli
result can only be considered reliable after careful checking.
By the use of these diagrams, however, the percentages cau be
obtained without any calculation whatever, beyond a multiplication
which is almost invariably merely mental. The danger
of error is therefore very slight, and the time necessary for the
operation limited, as compared with the full calculation by
either ofthe formulae referred to.
The diagrams, it will be observed, consist of two sets of
curves, carefully drawn tlirough plotted points obtained by
several hundred separate calculations. From the upper set
can be obtained the percentage of remaining plate section between
the rivets of a joint as compared with the solid plate ;
and from the other the percentage of strength of the rivets in
a joint to resist shearing as compared with tlie solid plateto
resist a tensile strain. The lower result obtained is
of course the percentage of strength of joint to be used in any
further calculation ; such as the safe working, or rupturing
pressure of a structure. The formula for obtaining the first of
these percentages—/'. c. the percentage of remaining plate
section—by both the Board of Trade and Lloyd's Rules is :
———-X 100 percentage of strength of plate ; where P pitch
of rivets in inches, and D diameter of rivets in inches. To
obtain the same result from the diagram, all that is necessary
is to find the pitch along either the bottom or top of the upper
set of curves, follow the vertical line at this place until the
curve of rivet diameter is reached, then follow the horizontal
line to the extreme left, where the percentage can be read from
the vertical scale.
The formula for calculating the percentage of strength of
rivets is more formidable. Bv the Board of Trade Rules it is
NXA
X 'oo
P X T
percentage of strengtli of rivets, when plates
and rivets are both of iron ; where N number of rivets in
one pitch, A - area of each rivet, P —greatest pitcli of rivets
in inches, and T thickness of plates in inches. In thecase
of steel plates with steel rivets, the formula becomes
N_X_A_X_23
- X IOO; and for sleel plates with iron rivets
P X T x 2S
this number follow the vertical line till the curve of rivet diameter
is reached ; then from this place follow the horizontal
line to the left, where the percentage can be read from the
vertical scale suited to the type of joint under consideration.
Should the rivets be in double shear it is necessary to multiply
the result liy 1.75.
At the bottom ofthe diagram for rivet percentages it will be
noted that four scales onl}- are provided, viz., for one, two,
three, and four rivets ill one pitch respectively. Should, however,
tlie joint to be calculated have five, or more, rivets in one
pitch, the percentage can be obtained—in the case of five rivets—
by taking out first the percentage for three rivets in one pitch,
then that for two rivets in one pitcli, and adding the results
together ; or, in the case of six rivets, by finding the percentage
for three rivets in one pitch and doubling the result ; and
so on in like manner for any greater number of rivets in one
pitch. Another method, which is perhaps quicker and simpler,
is to divide the number obtained iu the first operation—
the greatest pitch of rivets iu inches multiplied by the thickness
of plates in sixteenths —by the number of rivets in one
pitch in the joint to be calculated, and then to work from the
number so obtained, 011 the scale for one rivet in one pitcli at
the foot ofthe diagram.
It will be observed that the diagrams have a scope extending
from about TA, in. to 1 Vi in. thickness of plates, from about 1
in. to SA in. pitch of rivets, and from yi in. to 1 '2 in. diameter
of rivets.
It is thought by the designer that these diagrams will be
found of great assistance to designers and draughtsmen, and
to surveyors and inspectors of boilers and other riveted structures.
The diagrams can, of course, be considerably enlarged
to enable them to be of greater service for office use, or when
great exactness is required. Confusion and possible mistakes
in their use can lie reduced to a minimum if the operator holds
the edge of a piece of paper along the line he is following ; or
better still, if the scales to the left of the diagrams are marked
upon portable pieces of card, or other suitable material, which
cau be applied to the vertical line to be followed. The height
of the curve of rivet diameter, and the corresponding percentage
on the scale, can then be noted without fear of error.
THE Technical Society of the Pacific Coast, headquarters at
San Francisco, Cal., elected, on Jan. 15th, the following officers
for the year 1S92 : President, John Richards, Mech. Eng. ; Vice-
President, Luther Wagoner, Min. Eng. ; Treasurer, Geo. F.
Schild, Naval Arch. ; Secretary, Otto Von Geldern, Civil Eng. ;
Directors, H. C. Behr, Geo. W. Dickie, W. R. Eckart, C. E.
Grunsky, A. Schierholz. The society is in a very vigorous condition
; Mr. John Richards, the President, is an engineer of
international reputation.
N X_A_x8
THE Baldwin Locomotive Works has recently turned out for
X 100. By Lloyd's rules the formula for iron plates
PXTXU3
the Erie Road the largest compounded engine yet built on the
and iron rivets with punched holes, is X ioo; for iron four cylinder Vauclaiu System. Its general dimensions are :
1X1
Cylinders 16 aud 27 X 2S iu.
N X A
Drivers 50 m
plates and irou rivets with drilled holes — -, X 90; for steel
NXA
plates and steel rivets —- - X 85; and for steel plates and
N X A
iron rivets - *, X 70. Where the rivets are in double shear
P X 1
the results obtained by these formulte require to be increased
1.75 times. To obtain the results of any ofthe above described
formuke by means of the diagrams, it is necessary to proceed
as follows : Multiply the greatest pitch of rivets in inches by
the thickness ofthe [dates in sixteenths—in most cases merely
a mental calculation—find the number so obtained on the
scale, at the bottom of the lower diagram, suited to the number
of rivets in one pitcli in the joint to be calculated ; from
Total wheel base
Driving wheel base
Total weight
Weight on drivers
Weight of tender
Diameter of boiler
Number of tubes
Diameter of tubes
Length of tubes
Length of Wootten firebox
Width of Wootten firebox
Heating surface firebox
Heating surface combustion chamber .
Heating surface tubes
27 ft. 3 in.
iS ft. 10 in.
96^ tons.
85 tons.
45 tons.
76 in.
,r.
2 in.
12 ft.
10 ft. 11^ in!
gS*s in.
1S2!, sq.ft.
51.8 sq. ft.
2,208 sq. ft.
Total heating surface 2,443 sq. ft!
Tank capacity 4,500 gallons.

FORMULAE.
[ IOO = 5. Lloyd's and Board of Trade.
< 100 S, for iron plates anil iron rivets.
.23
2S
X 100 S, for steel plates and steel rivets. j °
X 100 = S. for steel plates and iron rivets.
13
< 100 == S. for iron plates and iron rivets. I /lunched
hold
< 90 = S, for iron plates and iron rivets. J d V' l j ed
-a
f >
< 85 S. for steel plates and steel rivet3.
< 70= S. for steel plates and iron rivets.
WHERE
P = Greatest pitch of rivets in inches.
D = Diameter of rivets.
A —-- Area of rivets.
/V= Number of rivets in one pitch.
T = Thickness of plates in inches.
S Percentage of strength of plate at joint.
S, = Percentage of strength of rivets at joint.
Board of Trade.
5-
8o-
— -O , I 4,
OJ — OO- -"*"
r_ OJ in ~
U) 5- OJ —•
to- "* 5- =
8 ° c
I •- 5 "'~ £
JS -n
a. 5~ c T-
5- - «s 5- c 50-
• « «
— 4°" nj
jo- a. —
= •
5- § 5_ S 4o-
— f-
30- 3 tn
5-
7°-
5-
a) n0- « 4°
tn ISI
5-
20-
5-
5"
30-
Where the rivets are in double shear,
multiply the above results by 1.75
5"
20-
44
9 Q
°itu
J \ V 1 \
•2 'i ^
\ \
c
h !
2 1
1 1
1 \ 1
1
1
1
1
1
20-
1 \ \
r 1
\
\ \
\
\ \
\
V \ \ V
\ \
\
DIAGRAMS FOR CALCULATING PERCENTAGE OF STRENGTH
OF RIVETED JOINTS.
\
\ *
\
11 12 13 U
\
Xtf
\
\
\
\
\
\ \
\
I I I I I I I I I I I
10 12 |, |„ |4 ji. 22 ll 26 28 .'III
\
~H li % 3
s
s*
V
Greatest pitcli of rivets in inches
i r - J/ " j- u A "" 5 *> !• v " 6 '& TJ, /, _-. A 7,
\
\
\j* 0 ^
y4 •*"
,»'
-- Curves of per-centage of Strength of plate at
joint as compared with solid plate.
fO USE DIAGRAM. from greatest pitch of rivets in incites at bottom or top
ol diagram, follow vertical line until curve, of diameter of rivets is
reached, then Follow horizontal line to etttreme left, where pes-cenui
ol strength of plate, can bz read on the vertical sc
Greatest pitch of rivets in inches
JA
A
V*
c
a
jrvi •; of per-centage 0 f strength of rivets
tjoi nt as compared with soua place/.
Pin 9.
A
w •
—P^.
TO
V
US,E DIAGRAM. Multiply greatest pilch of rivets
tn nches, by thickness of prate in sixteenths, lind trr/s
ou Tiber on scale, suited to design ofjomt, at bottom
of diagram, follow verbcal lint oil this place- unt
curve of nvet diameiier is reached then follow
4 can be read on one of vertical scales
ONE RIVET IN ONE PITCH.
I 1 1 I I I I I I 1 1 1 I 1 I 1 I I I 1 I I I I I I I I I I I I I I
;n; 38 10 42 14 46 lb 50 52 51 56 58 III' 62 til llli UM "ll 72 71 7li 7.4 80 82 41 Mil MM 11(1 92 HI 96 981001021
TWO RIVETS IN ONE PITCH.
I I I I I I I I I I I I I I I i I I I I I I I I I I I l I I I i I I I
15 IM HI 21 27 :til :i:l :ili 811 42 45 IM 51 54 57 III) III 66 tt'.t 72 75 7M Ml 84 M7 90 '.fi !lti '.111102 1115 1114 111 III 117
THREE RIVETS IN ONE PITCH.
I I I I I I I I I I
126 U!i 1.12 1.1.7 Ills 111 111 117 1511 1511 15
I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I I I I I I I I I I
20 24 26 52 36 111 41 IM 52 56 60 6-1 6b 72 76 MI. M4 88 92 H6 100 104 108 112 116 120 124 128 132 136 140144 148 152 156 160 164 168 172 176 180 184 188 192 196 200204
FOUR RIVETS IN ONE PITCH.
Greatest pitch of rivets in inches mult/plied by thickness of plates in sixteenths.
5>

52 ENGINEERING MECHANICS. [February, 1892.
THE FIRST-CLASS CRUISER "EDGAR."
The Edgar is the first of the high-power cruisers to be commissioned
under the Naval Defence Act, and the satisfactory
speed and power results obtained are particularly gratifying in
view of past failures in the case of vessels of great power constructed
under what is called the old programme. She is a powerful
cruiser, being well protected by au armored deck, aud by
minute subdivision. The class, of which she is the prototype,
comprises nine vessels, designed for the express purpose of protecting
commerce on the high seas, and in such a case good offensive
powers and high speed were essential. It was also ne­
cessary that the cruisers should be able to keep the seas for a
long period or make fast voyages to distant parts without coaling,
so that it was necessary to reduce all weights to enable the
vessels to carry a large fuel supply, aud the measure of success
is the fact that on a displacement of only 7350 tons they have
bunker capacity for S50 tons, so that they could cross the Atlantic
at full speed, and might steani 10,000 miles at a speed of 10
knots. For this result much of the credit is due to the minimising
of weight, consistent with efficiency and safety, in the
design of both ship and machinery.
It is scarcely necessary to state that the engines are of the
triple-expansion type, with three inverted cylinders and three
cranks. There are separate sets for driving each of the twin
screws, the engines being fitted in separate compartments. The
high-pressure cylinders are 40 in. in diameter, the intermediate
pressure cylinders are 59 in. in diameter, and the low-pressure
cylinders are SS in. in diameter, and each is adapted for a stroke
of 4 ft. 3 in. The cylinders are all independent of each other
and are steani jacketed. The high-pressure cylinders are each
fitted with a liner of forged steel, and those of the medium
pressure aud low pressure are fitted with cast iron liners. All
the cylinder covers are of cast steel. Each high pressure cylinder
is fitted with a piston valve, aud the medium and low pressure
cylinders are each fitted with double ported slide valves, all
of which are worked by the ordinary double eccentric aud link
motion valve gear. Balance cylinders are fitted to the intermediate
and low pressure valve gear; these valves are also fitted
with relieving rings at the back. The reversing engines are of
the all-round type, with worm aud wheel gear, and the lowpressure
levers are fitted with a slot and adjusting screw to allow
of the expansion in the cylinder being altered. The back columns
are of cast steel fitted with separate guide faces pinned
on, and the front columns are of forged steel. The engines are
so arranged that the starting platforms are in the wings of the
ship. The main condensers are placed alongside the starting
platforms aud are of cast brass. The steani is condensed outside
the tubes, the circulating water passing through the tubes.
There are two large centrifugal circulating pumps of guu metal
in each engine room. They are worked by independent engines
made by Messrs. Tangye, Birmingham. The feed, bilge and fire
engines are all independent of, and separate from, the main engines,
the steani being supplied by a special range of pipes. All
the exhausts are led into an auxiliary condenser of cast brass,
having a small air and circulating pump, one of these condensers
being fitted in each engine room.
The crank, tunnel, and propeller shafting is of forged steel
and hollow, supplied by Messrs. J. Brown & Co., Sheffield. The
crank-pins are fitted with centrifugal lubricating apparatus.
The propellers are of gun metal, each propeller having three
adjustable blades constructed to work outwards.
Steam is supplied by four double-ended boilers, 16 feet in diameter
and 18 ft. long, each with eight furnaces, and one singleended
auxiliary boiler, 12 ft. 11 in. in diameter and 9 ft. 3 inches
long, having three furnaces. The furnaces are corrugated and
are 3 ft. 9 in. in diameter. The total number is 35, and the
heating surface in all the boiler totals 20,108 square feet. The
tubes are of naval brass. The working pressure is 155 lbs. The
boilers are arranged in two water-tight compartments, the
steam pipes being so arranged that the steam from the boilers
in either boiler room can be used for the engines in either or
both engine rooms. There are two funnels, one to each boiler
room. As usual in vessels of the British navy, the boiler rooms
are so fitted as to be closed and the boilers worked under forced
draught when so desired.
Owing to the Edgar being the first of her class to be tried
under steam, a most exhaustive series of trials of the vessel
have been made. The first official trial took place outside Ply­
mouth on the 31st of October, but had to be abandoned after
about two hours' steaming on account of the stormy weather
and rough sea. On the 4th of November the eight-hour official
natural draught trial took place, when the engines developed
10,178 indicated horse-power with 99 revolutions. Before mak­
ing the full-power trial it was considered advisable to dock the
ship and alter the pitch of the propeller. This having been
done the four hours full power forced draught took place on the
19th of November, the result being 12,463 indicated horse-power
with 104.5 revolutions. The average speed ofthe vessel during
the four hours was nearly 21 knots per hour, thus making the
Edgar the fastest vessel in the British navy. To ascertain the
efficiency of the ship and machinery the vessel was taken to
Stokes Bay measured mile, and a series of progressive trials extending
over two days were carried out. On the full-speed mile
trial the engines developed 13,101 indicated horse-power average,
or 13,460 indicated horse-power maximum. During the whole
of the trials the engines aud boilers worked most satisfactorily,
without the slightest hitch, aud with an entire absence of vibration
when at the highest speeds. The boilers maintained an
ample supply of dry steam under an air pressure of about seventenths
for full power, and on examination at the conclusion of
the trials they were found to be in good order and perfectly
tight. These boilers are the largest yet constructed for the
British navy ; they are double-ended, and have a common combustion
chamber to each two furnaces, and not the slightest
trouble was experienced iu the working.—Engineering.
DETECTING FLAWS IN METAL.
A N E W instrument called the " schiseophone" has been
lately invented by Captaiu De Place (a French
officer). The object of the instrument is to reveal the
presence aud the place of any blow holes, flaws, cracks or other
defects which may exist in the interior of a piece of metal.
When these defects are very great, the blow of a hammer on
the piece of metal soon betrays their presence; but for small
blow holes, although these may also be very dangerous, there
is not enough difference in the sound giveu by the hammer
striking the piece of metal for it to be detected by the ear. The
schiseophone, however, will enable that difference to be heard.
The apparatus consists of a pin which runs through a microphone
of a special construction, which, as usual, is put in connection
with the current of an electric battery. Without giving
more details of the complicated mechanism of the instrument,
one can understand that, when the pin strikes on a good part
of the metal tried, a sound is produced the vibrations of which
affect the electric current in a certain way, aud then a certain
sound can be heard in the telephone attached to the instrument.
When the pin strikes on a part of the metal where
there is a defect, the sound produced is different; the microphone,
the current and the telephone are then affected differently,
and the defect existing in the metal is revealed by the
difference in the sound heard at the telephone. The ear must,
of course, be used to the different sounds to be able to distinguish
them ; but the necessary skill is not very difficult to
acquire. Trials with this instruments have beeu carried out at
Ermont, at the works ofthe Northern of France Railway Company,
in the presence of many engineers, to find defects in the
rails. The telephone of the apparatus was placed at a long
distance from the rails, from which it was also separated by a
wall. The points where the instrument intimated a defect in
the metal were carefully noted; the rails were then broken at
those places, aud the defects were actually fouud.

February, 1892.] ENGINEERING MECHANICS. 53
o
a
K

54 ENGINEERING MECHANICS. [February, 1892.
ALTERNATE CURRENT MOTORS.
T H E transmission of power by electricity has now attained
an importance wdiich threatens to eclipse that of all other
methods. Already we hear of numberless projects in Switzerland
by which the waterfalls are to be made available for manufacturing
needs, while the Niagara Commission have pronounced
in favor of electricity for the vast scheme under their consideration,
although they admit also the feasibility of using both air
and water for the conveyance of some part of 12c,ooo horse-power
which they propose to generate. The precise methods to be
adopted at Niagara have not yet been determined, but a few
months ago the Commission were in favor of the employment
of continuous currents. Whether they still adhere to the opinion
has not been made public, but it is noticeable that all the
chief power installations in Europe, in which the distance
between the generating aud the motor stations is considerable,
are beiug laid out on the alternating current system. It has
been usually held that a difference of potential of 3000 volts is
quite as much as can be dealt with on the commutator of a continuous
curreut motor, and only in the spring of this year Mr.
G. Kapp, in his Cantor lectures, laid down this as the extreme
limit of what was practically safe. For a moderate distance
this pressure enables current to be transmitted with a fair
amount of economy, but the limit is usually fouud, according
to circumstances, between five and ten miles. Beyond that distance
higher pressures must be used, unless the power is so
cheap in the first instance that economy may not be considered,
or an immense sum can be spent in copper mains. Al Niagara
it is proposed to go as high as 5000 volts with continuous currents
in the twenty-mile transmission to Buffalo, and the names
of those who make such proposals are evidence of its possibility,
although there can be uo doubt that it would involve difficulties
of considerable gravity. The competitors who favored still
higher potentials, with one exception, proposed the use of
alternate currents, and it is noticeable that many of the longdistance
transmission plants that are beiug erected in Europe
are to be worked with alternate currents. Among those we may
cite the Lauffen-Frankfort transmission of 110 miles, which was
one of the leading attractions at the late Exhibition, aud the
driving of the Oerlikon Works, among many others. The difficulty
of finding a good alternate current motor has hitherto
hindered the adoption of this form of transmission and still
continues to do so. Were it feasible it is probable that all electric
transmission would be worked by alternating currents.
The absence of commutators, aud the possibility of transforming
the curreut to any desired voltage, constitute of themselves
two immense advantages. But it can scarcely be stated with
certainty that a good motor does exist. Those in use may be
divided into two great classes, the synchronizing and the nonsynchronizing.
The former have been brought by Mr. Mordey
and other to a high degree of efficiency, aud within tlie limits
imposed by their principle they are very successful. But their
range of adaptability is bounded, on the one hand, by their inability
to utilize the current unless they are rotated by some
external agent until they attain the speed of the generator, aud
on the other hand by the fact that wheu overloaded they stop
suddenly and completely, and need to be again put into rotation
before they can be set to their work afresh. These are serious
defects, and for some purposes, such as driving tramcars, they
are practically insuperable. In a large manufacturing installation
it would be very possible to arrange-for the starting of these
motors, either by means of the exciter and an accumulator battery,
as proposed by Mr. Mordey, or by means of a gas or oil
engine, but for small plants there are great objections to the
introduction of such complications. The non-syiichronizing
motors are of very recent origin. Those of Tesla and Ferraris
have not proved satisfactory, and it is only the multi-phase
machine that has the promise of practicability, though whether
that has "come to stay " is somewhat doubtful. At present we
have no official figures of what efficiency it has attained at
Frankfort, and the rumors which are afloat are somewhat contradictory.
The fact, however, that such a capable electrician
as Mr. C. E. L Brown is an advocate of this method of transmission,
is strong evidence in its favor. It has the advantage
that the motor will start from a state of rest, and that even with
some considerable load on it. If the load should be increased
during work the machine will gradually slow down, aud as soon
as it is released will get away again at its old speed. These are
great advantages over the conditions in which the synchronizing
motor works, but probably they are purchased by some loss of
efficiency.
The multiphase machine has the further advantage that there
are no sliding contacts. Its coils are directly connected to the
conductors, while the moving part, or field magnet, has its cir"
cuits closed on themselves, and without any connection to outside
conductors. For the benefit of those of our readers who
have not followed the latest development of electric construction
we may give a brief description ofthe machine employed in the
F'rankfort-Lauffen installation. .The motor consists, as is usual,
of an armature and field magnet. The latter is mounted on an
axis iu the usual way, aud consists of au iron laminated cylinder
ring with fifty-four copper rods, parallel to its axis, threaded
in holes bored as near as possible to the surface ofthe cylinder.
The free ends of these rods, at both sides, are connected by
copper rings. The armature is stationary, and is also formed of
rods let into holes iu an iron ring which is concentric with the
field magnet. There are ninety rods of 40 square millimetres
section, the total weight being 20 kilogrammes. The breadth
of the armature is 200 millimetres (8 in.), and the outer diameter
500 millimetres (19J) in.). In the armature there are three
circuits joined up as in the Thomson-Houston dynamo, and the
winding is so arranged that there are produced four rotating
poles. That is, these four poles rotate around the armature
when the latter is fed with a three-phase alternate current, the
phases being displaced with regard to each other by 120 deg.
Thus the net result is just the same as if a four-pole field magnet
were mechanically rotated around the central magnet.
There is practically very little variation of magnetism, for the
volume of the three currents remains nearly stationary. The
moving poles induce currents in the rods in the central magnet,
and cause it to rotate. The magnet can never synchronize with
the rotation of the poles, for in that case there would be no
current. It must lag behind or slip by an amount which can
be settled in making the design, and the greater the load the
greater will be the slip.
If it should be proved that the three-phased motor gives good
efficiency, it may be confidently expected that its use will
rapidly increase in districts where water power has to be con­
veyed from long distances. The mechanical arrangements of
the motor are so simple that they constitute a great argument
iu its favor. There are no commutators nor rubbing contacts;
each couductor is separately insulated and inserted in its own
cell, while the magnet is entirely self-contained. Some care
needs to be exercised at starting to reduce the curreut by means
of resistances, but that is also requisite with continuous current
generators.
For small users deriving current from central stations neither
the synchronizing nor the multi-phase motor is likely to be of
any use. The hope of the companies must feed itself on the
invention of a self-starting motor to be worked by the ordinary
alternating current. We do not think this is beyond the range
of possibility. When it comes it will find a wide field ready for
it in America, and perhaps by that time there may also be some
opeuiug for it in this country.
THE lively town of North Baltimore, Ohio, is putting iu water
works. The contract for the two compound pumping engines,
boilers, etc., has beeu awarded to the Laidlaw & Dunn Co., of
Cincinnati, Ohio.

February, 1892.] ENGINEERING MECHANICS. 55
THE POWER SYSTEM OF THE BALDWIN LOCOMOTIVE WORKS.
The distinction between the real and apparent relative economies
of steam plants is seldom observed, yet conditions may
very easily be such that one is the exact reverse of the other.
In other words, it is perfectly possible to make a change in a
steam plant that, according to most experiences, would seem to
favor au iucreased economy, while as a matter of fact the net
results might prove a considerable loss. An expensive economi­
cal device may be imposed upou a system with tlie effect of actually
lowering the efficiency of the combination in that particular
case. For instance—a vacuum is almost certain to raise
the economy of an engine under almost any condition, but if
the circulating pump uses more steam in that particular case
than is saved by the engine, a mistake has been made. The
quality of au oil usually improves as the price increases, but it
would be a positive error to use au oil whose increased useful
effect would be insufficient to justify the greater cost. On the
other hand, it would be just as false economy to use an oil of
half the cost, if it required more than twice the quantity to pro­
duce the same effect. If the saving caused by an expensive attachment
will not pay for the interest 011 the investment, cost of
maintenance and operation, etc., then the plant is better off
without it. An improvement is not au improvement if the in­
creased production will not pay for it, and it is poor engineering
that lets a dollar pass to save a cent. At the same time, it is
an unnecessary expense to continue with an inefficient machine
when a change can be shown to be a considerable benefit.
The Baldwin Locomotive Works realize all this most thoroughly,
and show their appreciation of it in a very practical
way.
Years ago they used Corliss Engines to drive their works,
whose indicated water rate would probably be in the neighbor-
hood of 28 pounds, but on substituting Westinghouse Standard
Automatic Engines, with an indicated water rate of about 32,
the apparent loss becomes nearly 15 per cent. Practically, how­
ever, by splitting up the power and distributing it around wherever
needed, the saving by the consequent loss of friction
amounted to considerably more thau this, so that the net fuel
consumption was less by the amount of this difference.
They had hardly finished substituting these high-speed engines
for their Corliss type, wheu The Westinghouse Machine Com­
pany put ou the market their high duty compound, and a comparative
test at the locomotive works showed that this new engine
would, under the same conditions, save them about 30 per
cent, of the fuel consumed by the single-expansion engine of
the same type. It was rather disheartening, considering that
they had barely finished replacing one lot of engines, but they
set manfully to work, and now have nearly all Westinghouse
high-speed compounds in place of the standards that in their
j.:m.s ... :
ENGINE ROOM.
time replaced the Corliss. They say it pays them, aud they
ought to know, inasmuch as they are builders of locomotive
steam engines themselves, and are regarded as iu the very front
rank of the steam engineering and mechanical profession. Wheu
this firm pays for the change, and are more than satisfied with
the result, it is pretty good evidence that they have made no
mistake.
We illustrate from a photograph an interior view of one of
their engine-rooms, which, while it exhibits nothing of particular
interest, yet is a fair type of what may be met with iu works
of such magnitude.
Engines are here regarded as simply a means to an end. They
are the laborers of the plant, and aVe housed accordingly. At
the present time there are eighteen Westinghouse engines iu
use by the Baldwin Locomotive Works.

56 ENGINEERING MECHANICS. [February, 1892.
THE MOUNT MORRIS ELECTRIC LIGHT COMPANY.
T H E accompanying illustration from a photograph of the interior
of the Engine-room ofthe Mount Morris Electric
Light Company, of New Vork, shows the disposition of
the engines and the method of transmitting the power.
As originally intended, this was to consist of three Green Improved
Corliss Engines alone, side by side, belted to the dynamos
on the second floor through a countershaftiug. Only two
of these engines were installed, however, and the third foundation
will probably never be occupied.
Since then, three High-speed Engines have been added, and
the cut serves incidentally to compare the two systems of subdivided
and centralized power.
At present the power conststs of:
2 Green Improved Engines, 26" x 48".
2 Ball High-speed Engines, 12" x 13".
1 Westinghouse Compound, iS" and 30" x i6 // .
And these engines drive dynamos for supplying 11,000
Westinghouse Alternating-current Incandescents.
600 Schuyler Arcs.
100 Wood Arcs.
150 Excelsior Arcs.
Steam is generated in five Climax Boilers, rated at 300 II. P.
each, which at a recent test evaporated 12.26 pounds of water per
pound of coal, from and at 212, while the boilers were worked
at an overload of 35 per cent., aud a Calorimeter test showed a
slight superheat in the steam during the trial.
At the present stage of development of the F.lectric Motor, it
will be interesting to know that this Company furnishes 45 H. P.
in motors on the same day circuit with 52 arcs from Excelsior
Arc Generators.
Lest it be inferred that the Green Engine has beeu a failure
iu this Station, we correct the impression in advance since there
is really no objection wdiatever to it. No trouble has beeu experienced
with it and the Company consider it an excellent
engine of its kind ; but the inevitable result of a competitive trial
of a Corliss and a High-speed Direct-belted Engine in a Light
Station is the defeat of the Corliss ou all points. As a power
of Electric Stations the Corliss Engine is hardly in the race,
and is often replaced with advautage by High-speed engines
even of a recognized lower economy.
Extensive additions will soon be made at this Plant with several
more High-speed Engines to be belted each to a single
dynamo and the geueral choice seems to be iu favor of the
Westinghouse High-duty Compound. When it is considered that
a maximum economy and efficiency iu regulation is combined
with a high rotative speed and such simplicity, it is not strange
that this Engine should prove so great a favorite in Electric
work. Iu the present case it is especially valuable as it is quite
probable that no other form would permit the necessary concentration
of power in the limited space.
Tin; officers of the Engineers' Club of Philadelphia for the
ensuing year are :
President. I 'ice-Presidents.
James Christie. Frederick H. Lewis, Pedro G. Salom.
Secretary. Treasurer.
Directors.
John C. Trautwine, Jr. T. Carpenter Smith.
John E Codman, Strickland L- Kueass, H. W. Spangler,
George V. Cresson, Wilfred Lewis, David Townsend.
The club membership is now 421.

[February, 1892. ENGINEERING MECHANICS. 57
IMPROVEMENT IN BALL COMPOUND
ENGINES.
The accompanying diagrams were taken
from a 250 Horse Power Cross Compound
Engine just installed in the station of the
Edison Electric Illuminating Company of
Paterson, N. J.
The engine was designed aud built by
The Ball & Wood Co., at their Elizabethport
shops, and embodies some new feat­
ures in the arrangement of low pressurevalves.
The steam chest of this cylinder
is placed directly underneath, and contains
two valves, both of which are double
ported, giving large and direct ports with
very small clearance. The diagrams speak
for themselves as to the efficiency of this
arrangement. The dimensions of cvlinders
are as follows : High Pressure, 16" diameter
X 16" stroke. Low
Pressure, 25" diameter X
16" stroke. Speed, 220
revolutions.
Fig. I is a reproduction
of cards from high pressure
cylinder, and Fig. 2 simultaneous
cards from low-
pressure cylinder. Fig. 3
represents a combination
of the cards, showing their
relation to each other and
the measure of loss between the cylinders
up to point of cut-off. In Fig. 4
the cards from both cylinders are referred
to the low pressure cylinder iu
the usual manner, and show the effi­
ciency of the system. The theoretic
expansion and compression curves are
shown in dotted lines.
No tests of economy have yet been
made; but the very small losses between
the cylinders and in back pressure
promise an excellent showing.
This engine being the first of its
kind, and not having been tested at
the works for lack of time, consider­
able interest was manifested in its start,
and quite a number of people assembled
to witness its first move.
ELECTRIC RAILWAYS are at
present to the fore in Berlin.
Siemens and Halske's large
project for a net of overground
electric railways has been followed
by another, at the head
of which is a syndicate comprising
several large industrial
firms, who have already applied
for concessions. A third plan,
emanating from the large All-
gemeine Electricitiits Gesellschaft,
which supplies a great
portion of the electric light
used in Berlin, proposes a sys­
tem of underground electric
railways between the different
parts of the town. This latter
project comprises three differ-
Improved Ball Compound No. 5005
Cylinder 16 and 25"by 16"
Rev. 220 Total I.H.P. 265.59
THE BALL &. WOOD COMPANY, NEW YORK.
Improved Ball Compound No. 5005
Cylinder 16 and 25"by 16"
Rev. 220 Total I.H.P 265.59
THE BALL & WOOD COMPANY, NEW YORK.
Improved Ball Compound No. 5005
Cylinder 16and 25 by16
Rev. 220 Total I.H.P. 265.59
THE BALL & WOOD COMPANY, NEW YORK.
Improved Ball Compound No. 5005
Cylinder 16and 25 by18' •
Rev. 220 Total I.H.P. 265.59
THE BALL & WOOD COMPANY, NEW YORK.
Fig. 1.

Ill ENGINEERING MECHANICS. [February, 189*:
ent lines. One of these is to go straight
from north to south, the second from east
to west; the third is an interior ring
line, proceeding from the Hallesche Thor,
following Kouigsgriitzerstrasse, touching
Potsdanier aud Brondersburger Thor, un­
derground the whole way, then to Friedrichstrasse
Railway station, over the
Alexanderplatz aud Moritzplatz back to
Hallesche Thor. These three lines would
be laid at different levels so as to avoid
all complications. At the points where
the lines cross each other it is proposed
to combine the various stations by stairs.
The north to south line will have double
tracks, aud although this is the highest
level of the three, it will be 9 metres
below ground. This line, which it is
intended to take first in hand, is proposed
to be carried through an iron tunnel
covered with cement. Its time of
construction is calculated at two years.
It is to follow the carriage road of those
thoroughfares under which it runs ; but
it is distinctly stated that its building
will in no maimer interfere with the traffic.
The well leading down to its starting
point will be the only visible sign
until it is completed. There are to be
fourteen stations, which are to be of two
kinds. On such places where there is
available space over grouud, it is the
plan to build waiting rooms, from which
by steps or elevators there will be connection
with the station underneath.
Whera there is no such open space it is
proposed to rent the ground floor of a
house and transform it into a waiting
room, with similar connection as in the
former case. It is proposed to run the
trains every three minutes, each traiu to
consist of an electric locomotive and three
carriages, with aggregate accommodation
for 120 persons. It is proposed to have a
uniform fare of about 2)- ceuts for the
whole line. The calculated cost is $3,000,-
000, which, it is understood, has already
been secured.
THE Aqueduct Tunnel under the Mersey
in which are to be laid pipes for conveying
the Vyrumy water into Liverpool
is 10 feet in diameter and 805 feet long.
The cast iron segments used are 18 inches
by 20 inches circumferentially, and
are interchangeable, and the metal is
x\\ inches thick. Two lines of mold
steel pipes will be laid 32 inches in
diameter, between which will be placed
a cast iron flooring resting on timbers.
Hydraulic pumps placed in a cast-iron
chamber below ground and driven by
water pressure in the mains will keep
the tunnel drv.
CYRUS BORGNER,
23d St., above Race,
PHILADELPHIA, PA., U. S. A.
FIRE BRICK
AND
CLAY RETORTS.
O.F HOLYOKE
STEAM PUMPS,
WATER WORKS ENGINES.
WRITE FOR ILLUSTRATED CATALOGUE,
Deane Steam Pump Co.
HOLYOKE, MASS.
72 Cortlandt St.,
NEW YORK.
49 N. 7th St.,
PHILADELPHIA.
9 S. 4th St.,
ST. LOUIS.
54 Oliver St.,
BOSTON.
226 Lake St.,
CHICAGO.
1710 Blake St.,
DENVER.
ELECTRIC STREET RAILWAY INSTALLATION.
AT OMAHA AND COUNCIL BLUFFS RAILWAY & BRIDGE CO.,
COUNCIL BLUFFS, IOWA.
m jpyJEP jEEJj'M jIH! * E3 323! iM
PITTSBURGH. PENNA.U.S.OF A.

March, 1S92.] ENGINEERING MECHANICS. 57
ENGINEERING MECHANICS.
Devoted to Civil, Electrical, Mechanical, and Mining Engineering.
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
Entered at the Post-office in Philadelphia as Second-Class Mail tral Matter. station, located at the mouth of a coal mine somewhere
PHILADELPHIA, MARCH, 1892.
RAPID transit schemes are stirring the commercial interests
of several of the larger cities, notably New Vork, Brooklyn,
Chicago and Philadelphia. The Rapid Transit Commission
appointed by the City Council of Chicago has reported in
favor of elevated terminals for all steani roads, the exclusion of
all horse-cars from the heart of the city, and the repeal of the
ordinance forbidding more than three cars in a cable train.
Some of the other plans proposed are quite radical, but in the
main the report is a good one, and if followed will relieve the
crowded condition of the cars and streets during the morning
and evening hours. The Mayor of Chicago has prepared a
proposed ordinance to compel the railroads entering the city
to elevate their tracks. He will also propose to the wholesale
merchants to establish a system of warehouses on the out­
skirts of the city to be connected by a belt line road, so that
goods can be easily stored until sold without blocking the
traffic in the heart of the city.
One charter for a system of elevated roads fourteen miles in
length has been granted in Philadelphia, and another is now
under consideration for a system of about equal length. The
problem of rapid transit in New Vork is a too serious one for
satisfactory solution to both commercial and engineering in­
terests at present.
It is not only in cities that rapid transit is being urged and
promoted, but schemes are now in a forward state for establish­
ing better facilities between cities. A St. Louis company has
issued a serious prospectus in which it is proposed to run trains
between that city and Chicago at the rate of one hundred miles
per hour. Three routes are proposed, which are about thirty-
three miles shorter than existing railway lines, and the travel
will be done at night. A long, low electric car will be used,
having two pairs of driving wheels, each of which are driven
by a separate and distinct electric motor. One account says
the whole weight of the car, with its passengers, and of the two
electric motors, comes upon these two pairs of driving wheels,
and is, therefore, all available for traction or adhesion between
the rails and the wheels, through the agency of which the car
is propelled. The top ofthe car stands only nine feet from the
rail, which is three feet lower than the ordinary street car.
This brings the centre of gravity very low and near to the
track, which decreases immensely the danger of jumping the
track. It has a wedge-shaped nose or front for cutting the air,
which has the effect of decreasing the air resistance (a most
important factor in high-speed locomotion) and of helping to
keep the car down upon the track. The motor-man stands im­
mediately back of this wedge-shaped front, and between his
department and the rear wheels is the compartment for the
accommodation of passengers. In the rear of this is a separate
compartment for mail and high-class express. The driving
wheels are six feet in diameter and are capable of making five
hundred revolutions in one minute. The weight of the entire
car, with its motors, is but ten tons. These electric carriages
or cars will be illuminated and heated by electricity, and will
contain all the modern appointments for the comfort of passengers.
There will be no conductors and no brakemen. It will
be possible to stop the car within half a mile by means of the
motors themselves and auxiliary electric brakes. " Through "
cars will run at intervals of an hour or oftener, according to
the requirements of the traffic. Accommodation cars will run
every half-hour, stopping at all points along the line.
According to the plans ofthe general manager, Dr. Welling­
ton Adams, the proposed road will be operated from one cen­
near the centre of the road. The railway company will operate
SUBSCRIPTION RATES.
this mine by means of electric mining locomotives, electric
Subscription, per year $2 00
drills, electric cutters and electric lights, which will greatly
Subscription, per year, foreign countries 2 50
cheapen the present cost of the ordinary system of mining
coal.
Three bills are now before the New York Legislature asking
for franchises to build bridges across the East River, aud one
in the United .States Senate to build a bridge across the Hud­
son. The first bridge will be built at BlackweU's Island. A
series of bridges are also projected connecting Long Island
City with New York. There will be connecting bridges over
the Harlem River. This northern system of bridges will be
comparatively cheap to build on account of the short spans re­
quired, the longest being about 650 feet between pier lines.
The span between Long Island City and Ward's Island will
have to be a high level bridge, probably cantilever, but the
other spans over the Harieni River and Kills will be low grade
bridges, with draw spans like those of existing bridges over the
Harlem. This system is intended to serve foot-passengers and
ordinary vehicles, and, at the same time, to accommodate
heavy railroad traffic. Another projected bridge will cross the
East River from Delancey Street, New York, to Broadway,
Brooklvn. This is to be a high level bridge, with a clearance
of at least 135 feet above high water in the middle of the East
River, and is intended to unite the elevated railroad systems of
New York and Brooklyn. The bill also authorizes the con­
struction of a second bridge starting from a point betweeu
Little and Bridge Streets in Brooklyn, across the East River to
some point between Jackson and Scammel Streets in New York,
with approaches extending to a point between Delancey and
Rivington Streets, where a junction is to be made with the
first bridge.
The railroad bridge projected by the New York and New
Jersey Bridge Co. has received a setback in the Senate by the
introduction of a bill providing that any bridge hereafter
erected across the Hudson or East Rivers at the City of New
York shall be constructed with a single span over the entire
river between existing pier-head lines ou either side, and at an
elevation above ordinary high water of at least 140 feet at the
pier-head lines and 150 feet at the middle of the stream.
PROF. W. H. BURR gives some mathematical reasons against
the claims made for the parabolic roof truss described in the
December issue. A 70-foot truss of this description was constructed
by F. Schmemaun several years ago over the Keystone
Market, on Third Street, above Girard Avenue, Philadelphia,
and also a span of 36 feet. It has done excellent service ever
since. The same engineer also built 42 and 30-foot spans for
the Stow Flexible Shaft Co., at 26th and Callowhill Streets, for
their machine-shops, and they are well spoken of.
NAVAL authorities are revising their conclusions with refer­
ence to naval warfare because of the importance of the rela­
tively new factor of quick-firing guns. Admiral Long, of the
British Navy, in a recent paper on the subject of the efficiency
of quick-firing guns in defeating torpedo boat attacks, says :
About twelve shots a minute is considered the highest prac­
tical speed on service, although some guns fire up to fifteen
rounds per minute. With cordite or other smokeless powder,
the lecturer suggested that a torpedo boat attempting to get
through the zone of fire by daylight was engaged in a forlorn
hope. In actions between ship and ship, it seems probable that
a vessel might be put out of action iu half-an-hour by quick -
fire without armor-piercing guns coming into play.

58 THE CONSTRUCTOR. [March, 1892.
Translated by Henry Harrison Suplee.
Translation Copyright, 1890.
Example— Let a wheel have 6 arms, and 120 teeth of 2 inch pitch, the face Ratchet gearing may be divided into two main divisions
being 4 inches. If we make li -= 2/ at the centre of the wheel, we have according to the nature of the checking action. When the
- = 2, and - = 20, hence we yet from the table = 0.35, andfi 4 movement of the checked member is impeded in only one
0.35 = 1.40". If this is considered too thick, we may make h = 2.25 t, which
direction we have what may be called a Running Ratchet; and
gives f3=4X 0.2S = 1.12".
when the movement is checked in both directions, a Stationary
Ratchet.
For gears with wooden teeth, and for the iron wheels gearing The distinction will be understood by reference to the accom­
with them, the dimensions of the arms may be made 0.8 times panying illustrations, in which Fig. 653 shows a ratchet wheel
that given by the preceding rules. If more accurate dimensions and pawl a b c, the shape of teeth and pawl permitting motion
are required, the best plan is to determine the pitch oi the of the wheel in one direction, and hence forming a Running
equivalent iron teeth, and use this value iu the calculations.
''/. 235-
GEAR WHEEL HUBS.
The hub for a gear wheel generally tapers slightly each way
from the arms to the end, the length /- — />, or somewhat
4
more for wheels of very large diameter, and the thickness of
metal about the bore is made w 0.4/1 + 0.4", iu which /; is
the same as in the preceding section. In cases of much importance
reference should be made to formula (66), ji 65.
If the wheel is not to be secured by shrinkage the thickness of
metal at the ends ofthe hub may be made = A W. The key way
is cut the entire length of the' hub, and for wheels which are
subjected to heavy service the metal should be reinforced over
the key way. Instead of this, the hub may be strengthened by
wrought iron rings, forced on one or both ends. Such rings are
usually of rectangular cross section, the thickness being % tc,
and add greatly to the strength of the hub. See Chapter III.
\ 161 to the end.
2 254.
WEIGHT OF GEAR WHEELS.
The approximate weight G of gear wheels proportioned according
to the preceding rules may be obtained from the following
:
G = 0.0357 b I 2 (6.25 Z + 0.04 Z 2 ) • • . .(233)
The following table will facilitate the application of the
formula as it gives the value of ^-^77- for the number of teeth
0
b lwhich
may be given, aud the weight can at once be found by
multiplying the value in the table by b P.
z
0
2
4
6 S
20
30
40
5°
60
70
80
90
IOO
120
140
160
180
200
5-o+
7-99
11.09
"4-74
lS
-55
22.1.5
27.02
31-69
3663
47-4o
59-.;o
72-35
86.54
101.88
5.60
8.61
11.90
I5-4S
19 35
25-50
27-93
32.66
37-67
48 54
60.56
73-73 .
88.05
103.48
6.1S
9.24
12.59
10.23
20.15
24.56
28.85
33-63
3S.70
49-69
61.82
75.10
89.52
104.98
677
9-8.)
LV30
17.00
20.97
25-24
29.79
34-''2
39-75
50.85
65.10
76.39
91.02
106.70
7.38
10.52
14.02
17-77
21.80
26.12
30.73
35-
320 118.56 120.08 122.15 123.52
( FIO. 653. FIG. 654.
Ratchet Gearing, while in Fig. 654 the rectangular notches and
pawl for a Stationary Ratchet Gearing. The lifting of the pawl
is called the release, and the falling into gear is called the engagement
of the ratchet gearing.
If the two members b and c are held, a becomes the intermittent
mover, while if a be held, the parts b and c possess the
intermittent action ; as for example, the sustaining pawl and
ratchet wheel of a common hoisting winch in the first case, and
the reverse lever and quadrant of a locomotive in the second
case.
Ratchet gearing is a portion of constructive mechanism which
will repay close investigation. F'or this purpose the following
six groups may be considered :
1. Ratchets pure and simple, such as a ratchet wheel and
pawl for the mere prevention of rotation. Examples: the
ratchets of a windlass, or of the beam of a loom.
2. Releasing Ratchets ; those which act to release members
which are under stress, and which by such release are permitted
to perform aud determinate work. "Examples: the pawls which
release the drop of a pile driver, the trigger of a gun, or the trip
valve gear of some steam engines.
3. Checking Ratchets ; those which arrest parts which are
already in continuous motion. Example; the safety check
ratchets upou elevators, and upon mine hoists.
4. Continuous Ratchets; those in which a combination of
pawls acts to drive a member in a given direction with practi­
'3
40..Si
52.05
64.27
77.90
92-54
108.34
cally a continuous motion. Examples : a ratchet-driven windlass
; some forms of counters.
5. Locking Ratchets ; those which act to detain certain members
in a fixed relation against the action of external forces
until released. Examples: some forms of car couplings aud of
releasing shaft couplings, also the mechanism of locks.
6. Escapements ; those forms which permit a member under
the actiou of au impelling force to make a regularly intermittent
motion in one direction. Example: the various forms of
clock and watch escapements.
By following this classification, the various principal fundamental
forms may be briefly examined.
I 236.
125.27
TOOTHED RUNNING RATCHET GEARS.
Example—For a cast iron gearwheel, proportioned according to the foregoing
rules, with 50 teeth, 2" pitch and 4" face, we have b t- — 16, and by the
table the multiplier for 50 teeth is 14.74, and the weight = 16 X M-74 = 235.84
lbs., say 236 pounds. For a gear of 50 teeth, i 1 In running ratchets, the direction of motion which is not
checked by the pawl is called the forward motion, aud the reverse,
the backward motion. The teeth on the ratchet wheel
must therefore be so shaped that wheu the pawl is iu engage­
'," pitch and tty2" face, we have
it f-A 3.90625, which multiplied by 14.74 gives 57.62 pounds.
ment the backward motion only must be impeded. It is also
For bevel gears or for gears with wooden teeth aud lighter
important that the form should be so chosen that the first ten­
arms (as given at the end of * 232) the weights will run slightly
dency toward a backward movement should act to produce an'
less than given by the table.
engagement oT the pawl with the teeth.
In determining the form of teeth, Fig. 655, we observe that
CHAPTER XVIII.
RATCHET GEARING.
the most effective point upou the circumference of the wheel for
the action of the pawl is that at which the joining line 1.2 of
the centre of the wheel 1, with the poiut of the pawl 2, is at
I 235-
CLASSIFICATION OF RATCHET GEARING.
right angles with the pawl radius 3.2. If we describe a circle
upon the diameter 1.3, or the distance between centres of wheel
and pawl, the intersections 2 and 2' with the pitch circle of the
Ratchet gearing mav be considered as a modification or extension
of wheel gearing. The object of ratchets is to check the
action of certain portions of a machine or train of mechanism
and so modify an otherwise continuous motion into some intermittent
form.
ratchet wheel will give the two most advantageous points of
application. If the point 2 be selected, the attempted reverse
movement of the wheel will subject the pawl to compression,
while if 2' be chosen the pawl must be of the hook shape shown,
and will be subject to tension. If the teeth of the wheel are to
be of straight outline, the flanks should be radial. If a point of

March, 1S92.] ENGINEERING MECHANICS.
H1c.11 2, or 2,„ in front or behind 2 or 2', be chosen, the
eeiianism will be operative, but less advantageously than when
instructed as above, tor the lever arm of the force couple act­
ing upou the wheel will be less, and hence the pressure greater.
The angle of the flank, whicli will cause the direction of the
force upon the pawl to pass through the axis 3, is found by
erecting a perpendicular from 2, or 22 upon 2, . 3 or 2., . 3.
It is not necessary to bevel the end of the pawl so that it shall
bear in but one point of the tooth, as it is not difficult to shape
the tooth profile so that the force Pshall piss through the axis
3, when the pawl engages with the tooth. This is accomplished
bv making the profile of the flank of the tooth a circular arc
struck from 3 as a centre, as in Fig. 656 a.
FIG. 657. FIG. 658.
The same result will be attained by giving this curve to the
end ofthe pawl, and making the point ofthe tooth the bearing,
as at b, or both pawl and tooth may be formed to the curve, as
FIG. 659.
ance the force which acts upon the pawl has no tendency
le it to lift out of gear, wheu constructed as thus described
we may rail this form of tooth the "dead" ratchet tooth-
Oilier forms oi teeth will be considered hereafter.
Internally-toothed ratchet wheels may also be made with the
pawls adapted to act either in tension or compression, as at 2
and 2', Fig. 657. The axis 3 may be within tlie wheel, Fig. 65S,
in which case the above given conditions for the best positiou
of the point of action cannot be fulfilled.
If the radius ofthe ratchet wheel lie made infinitely great we
have a ratchet rack, Fig. 659, in which a is a pawl' acting iu
compression, aud b a form acting iu tension.
Au important application ofthe ratchet rack is shown in Fig.
660, which is the upper portion of the lifting frame for a screw
propeller.*
FIG. 660.
The two ratchet racks a, which support the frame as it is gradually
lifted, are in the middle plane of the ship, being fast to the
walls of the propeller well. Iu order to insure the engagement
of the pawls b b, they are held in gear by the loop springs of
r ubber. The frame is raised and lowered by a rope tackle, the
sheaves of which are shown, the so-called " cheese-coxnplva^"
(see ''1. 156), permitting the propeller to be lifted, when its tongue
and groove are in the proper vertical position. The pawls are
held out of gear by means of lines, during the operation of
lowering. The frame aud ratchet racks are both made of bronze.
The bent lever is another pawl which engages in a notch in a
blade of the propeller, aud prevents it from revolving during
the operation of raising or lowering. There are two wooden
struts, the bronze shod ends of which cau be seen ou each side
just above the pawls/., their function being to hold the frame
firmly in its lowest position, when the propeller is revolving.
i
FIG. 661. FIG. 662.
Ratchet racks are also used extensively iu connection with the
hoisting machinery in shafts of mines, etc.
•See F'ig, 323, ^ 117, where one of the bearings for the same propeller is
shown.

60 ENGINEERING MECHANICS. [March, 1892.
Instead of giving the ratchet wheel an infinitely great radius,
the arm 2.3 of the pawl may be made infinitely long. This
simply means that the motion of the pawl is guided in a straight
line, in some form of slide. In Fig. 66 [ such an arrangement is
shown for a ratchet wheel, and in Fig. 662 for a ratchet rack,
such forms being not uncommon.
I 237-
THE THRUST UPON THE PAWL.
The condition that the thrust upon the pawl, iu a ratchet gearing,
shall pass through the axis of the pawl, is not always fulfilled,
and in some cases it is impracticable to attain such a
relation of the parts. The mutual action of the pawl and ratchet
wheel upou each other must therefore always be considered.
If the flank of the tooth of a spur ratchet wheel (or a tangent
to the flank ofthe outline is curved) does not form a right angle
with the plane 2.3 of the pawl, there may exist, under some circumstances,
a tendency to force the pawl into the tooth, or in
other cases to throw it out of gear.
FIG. 663.
In Fig. 663 the various cases are examined. If at the point of
contact 2 a normal N A', to the plane of the tooth flank be
drawn, this normal may bear one of three relations to the triangle
1.2.3. The "thrust-normal" N -V, may fall without
the triangle, or within the triangle, or it may fall upon one of
the sides of the triangle.
If it falls upon 2 . 3, the thrust is neutral ; if it falls upon 2.1,
the thrust is zero ; that is, there will be no action of the pawl
upon the wheel, or vice versa,, barring the action of friction.
The angle

March, 1892.] ENGINEERING MECHANICS. 61
123s.
THE SI.II.ING FLANKS.
We have discussed the action of the flanks of tooth and pawl
which work together during the thrust. It is obvious that
greater liberty is permitted iu the form of the sliding flanks. It
is only necessary that the form shall be such that the forward
movement ofthe ratchet wheel shall lift the pawls properly out
of gear. The forms fall under cases 4 to 7. The usual form is
the common zig-zag ratchet, but others are also used, as in
Figs. 666 and 667, in both of wliich the teeth are symmetrical.
FIG. 666. FIG. 667.
If it is desired to have the end of the pawl symmetrical, as in
Fig. 667, this may be done, and the pawl may be reversed for a
reverse movement as shown in the dotted lines. This form is
used on the feed motion of some machine tools.
For some purposes it is desirable to form the thrust flank
upon which the impelling force acts, in the same manner as the
sliding flank, in which case the pawl must be held in gear by
some extraneous force capable of resisting the maximum impelling
force which it is desired shall act.
SPRING RATCHETS. QUADRANTS.
The form of ratchet last described possesses au especial property,
that is, the action of the spring tends to force the pawl
into the space as soon as the point is over the middle of the
tooth. This causes the pawl to spring into engagement, hence
the name spring ratchet, and this action causes an acceleration
of the motion either forwards or backwards as the pawd is forced
into the space. Applications of this form are found iu repeating
watches, in which the wheel is star-shaped, and hence called
the star, while the pawl is called the star pin or springer.*
A modified form, Fig. 669, is used in Thomas' Calculating
Machine. In this case the spring itself acts as the pawl, being
attached directly to the arm without joint, forming a plate link.
(See \ 1 So.)
Instead of using an entire ratchet wheel, a portion only need
be made, if the required movement is but small, and in some
cases reduced only to a single tooth, as in F'ig. 670.
FIG. 671.
Sometimes the two members may be made of similar form,
each working alternately upon the other, Fig. 671. Examples
of this are found in the valve gear of some Cornish engines.
These belong to the so-called "dead" ratchets, and are called,
more or less appropriately, quadrants, or sextants.
''/. 240.
METHODS OF SECURING PAWLS. SILENT RATCHETS.
The engagement ofthe pawl with the ratchet wheel is usuall
secured by the weight of the pawl, sometimes assisted by additional
weights, as in Fig. 659. This may also be accomplished
by means of a spring. It is desirable to give such springs but
little movement, and small frictional resistance. It should
therefore be placed near the axis 3, and is best placed in the
line 1 . 3, so that 3 . 4,5, shall line in the same straight line,
Fig. 672 a. If this cannot be conveniently done, it may at least
FIG. 672.
be made nearly so, as at b. A weak spring with much movement
may be seen below in Fig. 680, yet at the same time the
line 3 . 4 . 5, is only slightly varied from a straight line. In
FIG. 668.
spinning machinery spiral springs of steel are used, and rubber
springs have been used iti propeller hoisting frames, Fig. 660.
Such a form is shown in F*ig. 66S, which is similar to the nut- In devices in which the pawls are sometimes above and somelocking
device shown previously in Fig. 241.
times below the wheel the springs are sometimes replaced by
usiug several pawls. This is shown in Fig. 673, which is Wil-
\ 239.
ber's ratchet for use in lawn mowers.
•This is shown later among the releasing ratchets.
FIG. 674.
Three pawls, with half journal, are here used, and as the axis
1, lies in a horizontal positiou some one of the pawls is always
in engagement by its weight. The movement of the teeth
under the pawl, and the dropping of the latter into the spaces
produces wear upou the parts, and to avoid this action various
devices have beeu made ; these being known as silent ratchets.
A very useful form of silent ratchet is shows in Fig. 674.
The pawl is made with a projection 5, which is connected to a
friction baud tl, which is carried upon a hub 4 on the ratchet
wheel. When the wheel begins to move forwards, the arm 4 . 5
lifts the pawl b out of gear. The lift of the pawl is limited by
the pins at 5. As the forward motion continues, the baud slips
upon 4 ; if reverse movement begins the pawl is at once thrown
into gear. This is used in spinning mules, also in Pouyer's
coupling, F'ig. 453, in which two pawls, each with its own device
are used. The principle involved in this device is capable
of wide and useful application, as will be seen hereafter.
Another form of silent ratchet is shown in Uhlhorn's coupling,
Fig. 454. In this case the pawls b, lie close against the flanks
of the teeth. They arc thrown into gear again by auxiliary
ratchets, the spring pawls of which are not silent. These lift
the pawls b, through a small angle when the engagemeut is

62 ENGINEERING MECHANICS. [March, 1892.
completed by the self-closing action of the tooth flanks, Case
4 or 6, I 237.
Ratchet drills, etc., are often made with silent ratchets. Wilber's
ratchet, Fig. 673, may be used for this purpose. If it is
placed so that the axis, 1, is vertical, the friction of the pawls
against the case will lead them into gear in the forward movement
and draw them out on the return movement, the friction
in this case taking the place of any operating gear for the
ratchets. Various other forms of silent ratchets are in use.
z 241.
SPECIAL FORMS OF RATCHET WHEELS.
In spur ratchet gears the axes 1 and 3 of the wheel and pawl
lie parallel to each other. These axes, however, may be placed
in the same manner as with gear wheels so that they are
inclined or intersect each other. A great variety of forms of
ratchet gearing may thus be made. The variations do not at
first appear as important as they really are, but this will appear
in the further discussion.
A form of ratchet for inclined axes is the crown ratchet, Fig.
675, which is used in capstans; the wheel, a, is stationary, and
the arm and pawl, b and c, revolve.
FIG. 675. FIG. 676.
The forms shown in Fig. 676 and Fig. 677 are for non intersecting
axes, and use crown wheels also, and hence are called
crown ratchets.
FIG. 677.
By making the wheel, a, in the form of a plane wheel, and
substituting a bolt for the pawl, some useful modifications are
made. F'ig. 678 shows a form of ratchet used on a wine press,
in which the bolt can readily be lifted out and placed in the
successive holes as the lever arm is moved backward and
forward.
The ordinary jaw clutch coupling, Fig. 441, is really only a
form of crown ratchet with bolt pawl. The portion on the shaft
A is the ratchet wheel, aud the part fitted to slide on the shaft
B corresponds to the bolt b.
I 242.
MULTIPLE RATCHETS.
It is frequently desired to construct ratchet gearing so that
the minimum limit of movement shall be less than the pitch of
the teeth on the wheel. This is accomplished by using two or
more pawls acting at corresponding sub-divisions of the teeth.
Such multiple ratchets exhibit a wide variety of forms and find
many useful applications, and in many cases their true nature
is not fully understood.
Fig. 679 is a multiple ratchet of common form, with three
pawls, in which the pawds are set a distance from each other
FIG. 679.
equal to \ of the pitch. From this arrangement the wheel can
be moved spaces equal to
A. 2 3. T > ' '.1. ' 2 3. e tC.,
of the pitch, that is, through ' < the pitch and any multiples of
the same. This is sometimes used in saw mill feed motion,
where a fine feed is required with a coarse pitch ratchet.
FIG. 6S0.
A double ratchet is used in Weston's Ratchet Brace, Fig. 680.
The pawls b, and b., are placed oue above and one below the
arm c, and act on the two parts of the double ratchet wheel
FIG. 6S1.
a., a... Another ratchet drill, also by Weston, with four pawls
is shown in Fig. 6S1. This has an internal ratchet wheel with

March, 1892.] ENGINEERING MECHANICS. 'j
five teeth. Double ratchets are also found in Uhlhorn's coupling,
Fig. 454, and Pouyer's coupling. Fig. 455.
If it is desired, the pitch may be halved, or divided into any
two chosen portions, in which case the pawls may be made iii
one piece, Figs. 6S2, 683.
FIG.6S3
In each of these there is one pushing and one pulling pawl
upon the axis 3, the pitch being halved and the pawls acting
alternately. One form shows a spur wheel, the other au internal
wheel. The form of the double pawl has caused this to
be called au " anchor" ratchet.
If the wheel is a so-called " face " gear, that is, with the teeth
projecting from the face of a disc, two similar pawls may be
used, both pushing or both pulliug, and forming the same
anchor, Figs. 681, 6S5.
FIG. 6S4. FIG. 68S
If the teeth are set alternately in two concentric rings, the
two pawls may be merged iuto one, as in Fig. 686. This latter
form appears to be new.
? 243.
STEP RATCHETS.
A very instructive form of multiple ratchet gearing is obtained
by combining more than two pawls into one piece, and arranging
two such pawls to work together, and this form is capable of
\
FIG. 687.
/ \ .-'*•.
very extended application. Iu the ratchet combination a b e,
Fig. 687, we have such a combination of two multiple pawds,
with " dead " engagement, released by lifting the pawd b. The
part a, which is impelled in the direction of the arrow is thus
released, but is arrested again by the shoulder 2'. If the flank
a 2' is formed in the arc of a circle from the center 3, a farther
lifting of /' will cause, without resistance, a fresh release of a,
again arrested at fi 2", and a similar action again for the flank
y 2'" ; the points 2, a, fi, ; all lying on a circle struck from the
centre 1. Thus a continuous lifting of b will product: three successive
advances of a. The angle of each advance of a may be
called the angle of advance, and the corresponding angle of lift
of b the angle of release. In this case the angles of advance
are all made equal to each other, as are also the angles of release.
When the position in wliich 2 is arrested by the flank
) 2'" is reached, the angle of thrust a becomes so small that
further travel cannot well be obtained. If it is required to provide
for still further movement it can be done by making additional
teeth behind 2, as II, II', III", etc., whicli will engage
successively with b at 2'". Tlie construction of "dead" form
of teeth is clearly shown in the diagram. As before, the angles
of advance and release are made uniform. The mechanism as
constructed will give nine successive engagements. The
ratchet surfaces ou b are struck from 2, aud the sliding surfaces
ou a from 1 ; the flanks ou .; with a radius 3.2'" = 3 y, the flanks
on b with a radius 1.2.
It is to be noted that the two parts a and b are interchangeable
in their functions, so that when the extreme notch II" of
a has been reached, a may be reversed in movement and b
follow step by step to its former position.
Such step-ratchets are seldom used in practice, but many useful
applications are possible.
Iu Fig. 688 is given a form of step ratchet arranged to give a
uniform angle of advance together with uniform drop of the
pawl. The pawl a is acted upon by the force indicated by the
arrow, aud teeth are upon a cam-shaped disc.
FIG. 6SS.
An arc with radius 1.2 passes through 3, the angles of release
on b are 30 0 , and the successive angles of drop of a are 5 0 . This
form of ratchet is used in the striking mechanism of repeating
watches, and is known as a "snail" movement. The arm

64 ENGINEERING MECHANICS. [March, 1892.
In the preceding step ratchet (Fig. 687) the angle of drop and
of release were given the ratio 1:2. In this case the points of
the teeth were on cycloids, those on a being on a pericycloid,
those on b on a hypocycloid. The contact point of the generating
circle falls without the figure on 3.1 prolonged. Since the
radii of the circles are as 1 : 2 with internal contact the hypocycloid
becomes an ellipse. A portion of the curve is given in
the figure ; 3 X , and 3 1'are the semi diameters. The simplest
form for the line of the teeth will be obtained by making
1.2 = 1.3, since for this case the ellipse for one diameter of the
base circle on b becomes the straight li--e 3 A.
\ 244-
STATIONARV RATCHETS.
FIG. 690,
A stationary ratchet may be considered as a combination of a
pair of running ratchets with the teeth facing in opposite directions.
The scheme of such a combination is shown in Fig. 690.
From the four possible positions ofthe parts 2.2', II and II' we
may make the following double combinations :
2 with II,
2 with IE
2' with II',
2' with II.
The first two combinations are practically identical with the
stationary ratchet, Fig. 691. The flanks ofthe two wheels give
a notch for the space, while the teeth assume a dove-tail shape,
and this form of stationary ratchet may be called a notched
ratchet. The wheel will be firmly held by the so-called "dead "
tooth, or when (90 0 — a)

March, 1S92.] ENGINEERING MECHANICS. 65
The cylinder b may be entirely cut through as in Fig. 698, so
that the segment shall fall entirely within the surrounding
circle. When it is placed opposite
the teeth the wheel may
be revolved iu either direction
as far as desired. If this movement
is to be limited, as, for
example, to a given pitch, it
can be accomplished by cutting
a corresponding space in
the cylinder, such as is shown
in Fig. 699 a.
It is not necessary that the
spaces iu the wheel a should
conform to the circular profile
of the cylinder b (see (J 237) ;
the thrust is at two points on
the right and left of 1 . 3, and
it may be formed as at b, or
pin teeth used as at c. This
FIG. 698.
last figure shows the modification
made in the notch of
Fig. 69S to reduce the back­
lash of the wheel a. Iu Fig. 699 a the pitch circle of the pin
gear a passes through the axis 3, aud the gap in the cylinder is
increased proportionally. When the wheel is impelled in the
direction of the arrow, the pin 2 slips into the space in the
FIG. 699.
cylinder as soon as the opening is turned towards it far enough,
but cannot pass out until the cylinder has turned back the same
distance in the opposite direction, thus forming au intermittent
pitch movement.
This idea is more fully carried out in PTg. 699 e. In this case
the inner profile of the space is concentric with the outside of
the cylinder, as was also the case with the form shown iu Fig.
697. In this case the tension and compression pawls are practically
combined in one. When the opening moves into the
proper position, the pin 2 moves to the paint 2', aud completes
the remainder of the pitch movement wheu the cylinder moves
to the left again. This form may be made free from backlash
by making the outside of the cylinder fill tbe space between two
teeth, as in Fig. 700. If it is required that the intermittent
movement should divide the pitch into two equal parts, the arc
of the pitch circle of a, which is the measure of the thickness
of the teeth, must be equal to the arc cut off by the space in the
cylinder. If backlash is permissible, the thickness of tooth
may be reduced.*
and all the modified forms obtained. The interchangeability
of the two parts gives the midway form shown in F'ig. 701, in
wliich both pieces are the same, each being wheel and pawl for
the other.*
FIG. 701.
For the varied positions which may be given to the axes, a
wide variety of cylinder ratchets can be made, many of these
possessing useful applications. If the axes are at right angles,
the cylinder may become a disc, as iu F'ig. 702 ; this form being
used in Thomas' Calculating Machine, in which case the wheel
a is made with but a single tooth.
FIG. 702 FIG. 703- FIG. 704.
The form shown in Fig 703 is derived from the globoid gearing
of Class III, (S 224, the ratchet being a cylindrical notched
ring. F'ig. 704 shows how a pitch ratchet cau be made ou this
principle.
An examination ofthe preceding forms of stationary ratchets,
in which the pawl consists of a revolving member with a gap
cut in it, will show oue common property in all of them. This
is the fact that au intermittent motion produced by successive
release and engagement may be made either by a continuous
rotation of the cylinder or by an oscillating movement. If,
therefore, we have a continuously revolving shaft to deal with,
or a vibrating member, the desired release or intermittent action
of the part to be acted upon may in either case be obtained.
Both forms are found successfully applied in actual
practice.

66 ENGINEERING MECHANICS. [March, 1892.
Mi Figs. 706 and 707. In the latter case the pawd assumes the
form of a bolt, shown in the illustration with several notches.
FIG. 706. FIG. 707.
The practical applications of ratchets of precision are numerous,
and examples will be given hereafter.
shown such an arrangement made for a stationary notched
ratchet. The wheel b engages as a pawl with the wheel a at 2
and 2', and if it revolves a space of one-half a pitch, a is released.
If a, however, revolves any given odd number of halfpitch
angles only, b will be checked, and a become the pawl.
In both cases we have a ratchet of precision of the same type
as in Fig. 706.
The pitch ratchet with anchor pawl may also be thus derived ;
it is true the anchor form cannot so readily be shown as a pair
of similar wheels, but it is clearly only another form of the
same problem. The zig-zag ratchet, notched ratchet, step
ratchet, or their combinations are all reducible to this general
form, the only condition being that the direction of the force in
the position of engagement of the checking member shall be
such that the checked member cannot revolve. The intermediate
forms show the "pawl lifting" action, * 237. It is evident
that iu some cases the checked member may have a forward
movement, and in others a reverse movement. Since here, as
in z 2 -5, we may consider the link c as a checked member when
the wheel is held fast, we may, from the combination of these
parts, obtain four kinds of ratchets, viz. :
I 247.
DIMENSIONS OF PARTS OF RATCHET GEARING.
The great variety of ratchet gears in use makes it almost
practicable to prepare any compact rules for the determination
of the dimensions of the various parts. The general proportions
can be obtained for the various forms by comparison with similar
preceding devices. For spur ratchet wheels similar proportions
may be used as for spur gears with thumb-shaped teeth.
7; 212. The action of the pawl tends to produce shocks and this
must not be overlooked in determining the thickness of the
teeth. It is generally most convenient to give the pawl a curved
profile, in which case the discussion of combined resistance, {! 18,
is to be considered. Pawls which are subject to frequent vibration
are best made of steel, as are also those in which the superficial
pressure is high.
2 24S.
RUNNING FRICTION RATCHETS.
I 246.
The mechanical devices which are constructed to modify the
GENERAL FORM OF TOOTHED RATCHETS.
relations between two moving bodies by means of friction, may
be called by the general term of friction clutches* Such a de­
We have already seen that several forms of ratchet mechanism vice, when so arranged that one member opposes a positive
which have been described possess numerous points of similar­ frictional resistance or check to the motion of the other in one
ity, and may be reversed and derived from each other, and direction under the actiou of an impelling force, constitutes a
hence it is not unreasonable to expect that some general foim
may exist from which the various special modifications can be
friction ratchet. Such devices
may be divided, as
(
derived, and in which the distinction between ratchet wheel before, into running and
and pawl, or checked and checking member, shall not exist, stationary ratchets,

March, 1892.] ENGINEERING MECHANICS. 67
Pa
But Q is a function of P, aud iu fact we have =0tano
a A b
This gives: sin o cos a —/sin a a + «i
=/ [ £_+fi
a+4
a + 6
«,rf
V

6S ENGINEERING MECHANICS. [March, 18912.
[Copyrighted.]
THE MARINE ENGINE:
Its Construction, Mode of Action and Management.
475
gives uniformly negative values for /;. It follows from this d that Q = A p d v, i. e. :
for x = 1, d Q is positive for decreasing temperature aud pres­ during expansion all the heat imparted is converted into work;
sure, and negative for increasing temperature and pressure.
These relations continue while
x > 0.5 for/. < 2 atm. and
x ~> 0.6 for/ 15 A atm.
As the steam in the cylinder of a steam engine never contains
water in such quantity as to make x = 0.6, it follows that, if the
quantity of steam is to remain constant, heat must be added
during expansion and abstracted during the period of compression.
Unless heat is added or abstracted as indicated, the
phenomena referred to at the conclusion of par. 5 will make
their appearance.
Internal work, U. 14. The internal work U for steam expanding,
the weight of steam remaining constant,
is a decreasing quantity. For by (35)
AdU = dq + d'xp)
and in the present cate
A d U=dq + xdp
It was showu above that we may place
d q = C d I
By (27), p — 1061 — .791 t
Hence A d U= C d t — .791 x d t
, dU
A Tt" C— .791
aud the final states respectively. For the equation to the isodynamic
curve we have, therefore,
Vx = JTj 7/, -j- W
BY CARL BUSLEY,
Professor at the Imperial Academy at Kiel.
q -f x p — qx
xx =
Translated by Assistant-Engineer EMIL THEISS, U. S. N.
It is a hyperbola (see Plate i, Fig. 4, Curve IV.), whose asymptotes
are the axis of A'and a straight line parallel to the axis of
vx = W
Pl
q 4- x p — qx
| «j (44)
V, distant from it a length = (1 — x) w. F'or dry steam, for in which qx, px and ux may be regarded as functions of the ter­
which x = 1, the above equation becomes,
minal pressure pv F'rom the preceding we have
P
(4*0
_ q + x P~Ah - _i_ (£ +
For / in kg. per sq. cm., n — 1 064963 or 1.065 nearly ; a =
1.76133. For p expressed in lbs. per sq. inch and v in cu. feet,
Rankine uses the following values for pressures below 8 atmospheres
and ratios of expansion below 16,
n = 1.0625 A?
16
x p ) ~ (?• + x p ^
Pi
For steam expanding, therefore.
and this for the reason that for expansion, the steam weight
remaining constant, U diminishes and therefore
Quantity of heat, 13. The quantity of heat, d Q, to be itnd
Q. parted to a mixture of steam and water while
undergoing an infinitesimal change of state,
the quantity of steam remaining constant, is obtained from
(36c) ; d x = 0, and
dQ=l{i—x)C+xh]dt (43)
For dry steam, x = I, and
d Q — hd t (43a)
While [(1 — r) C+
C
x /•] < 0, i.e., while x > -~—-T-> d @' S
li-ipositive
for negative values of d /. Equation (37),
. r
h = .305 —,
x Pi, therefore diminishes less rapidly than it
would were xx left unchanged. The isodynamic curve will
therefore approach the axis of X less rapidly than the curve'of
constant weight of steam.
16. The quantity of heat to be imparted Quantity of heat.
to accomplish an infinitesimal change of d Q.
state, the internal work remaining constant,
is given by equation (36):
d Q = d q 4- d (p x) + A p cl v
d q 4- d (p x) = A d U, and as in
the present case d Ll = o, we obtain
during compression all the work applied is converted into
heat.
17. VI. Change of Stale Without Applica Adiabatic curve for
Hon or Abstraction of Heat. In equation mixtures of steam
(36 b), placing Q = 0, and water.
o=dq+ Td QA\
Dividing by T,
dq + d
For the sake of brevity call
As C'= 1, and as the maximum value of x = 1, the value
, a 4- b x — a,
v, = ,r, 11, \ w = w + —-—_ ! u • (45)
found above for A — is always positive ; and as d t and dp are
b,
44s av b„ and ux are functions of /„ equation (45) gives us
both negative during expansion, cl U, also, must be negative, a value of z, as a function of pv The curve corresponding to
i. e., the internal work must decrease. Duriug compression, on the change of state under discussion is the adiabatic curve
the other hand, it will increase.
(Plate 1, Fig. 4, Curve V.)
Isodynamic curve 15. V. Changes of Stale while the Internal 18. The adiabatic curve for saturated steam Table forconstruct-
for mixtures of Work Remains Constant. For U- a constant approaches the axis of X still more rapidly ing adiabatic curve
steam and water. equation (34) becomes,
than the curve for constant quantity of steam, for a mixture of
q -\- x p = constant =

March, 1892.] ENGINEERING MECHANICS. 69
kg. per
sq. cm.
O.IO
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.25
1.50
••75
2.00
2.25
2.50
2-75
3.00
3-25
3-5°
3-75
4.00
4-25
4-50
4-75
5.00
5-25
5-5o
5-75
6.00
6.25
6.50
6-75
7.00
7-25
7-5o
7-75
8.00
8.25
8.50
8.75
9.00
9-25
9-5o
9-75
IOOO
10.25
10.50
'0-75
11.00
11.25
H.50
11.75
12.00
12.25
12.50
'2-75
13.00
'3-25
*3-5o
'3-75
14.00
14.25
14-5°
14-75
15.00
16.00
17.00
18.00
19.00
20.00
21.00
22.00
25.00
24.00
25.00
26.00
27.00
28.00
29.00
30.00
p. n
Ibs. per
sq. in.
1.42
2.84
Table of values of
4-27
5-"9
7.1 1
8-53
9-95
11.38
12.80
14.22
•7-77
24-33
24.89
28.44
3199
35-55
39 "
42.66
46.21
49-77
53-3 2
56.88
60.43
63.9S
67-54
71.lo
74.66
78.22
81.76
S5-32
88.86
92.42
95.9S
99-54
103.10
106.64
110.20
"3-7 b
117.32
120.S7
124-43
127.98
*3i-52
135.0S
13S.63
142.20
*45-75
i49-3°
152.85
156.42
159.96
163.53
167.08
170.64
174.18
177-73
181.30
184.86
1S8.42
191.97
I95-5I
199.08
202.62
206.1S
209.72
213.28
227.51
241.72
255 94
270.17
2S4.40
298.62
312.86
327.08
341-3°
355-5°
369.69
383.90
39S.11
412.40
426.60
a
0.1546
0.1984
0.2252
0.244S
0.2(104
°- 2 734
0.2846
0.2944
°-5°32
0.3111
0.32S2
0.5424
0-3547
°-3655
0-375'
°-3S39
0.5919
0-3993
0.4061
0.4125
0.4185
0.4242
0.4296
°.4347
°-4395
0.4442
0.4486
0.4528
0.4569
0.4609
0.4647
0.4685
0.4719
°.4753
0.4786
0.4819
0.4850
0.48S1
0.4910
°-4939
°-49 b 7
°-4995
0.5022
0.5048
°-5°73
0.5099
°-5i23
°-5H7
0.5171
°-5i94
0.5216
05239
0.5260
0.52S2
°-53°3
°-5323
°-5344
0.5364
0.53S3
0.5403
0.5422
0.5440
o.5459
0-5477
0-5495
0.5512
055S1
05645
0.5706
0.5765
0.5821
0.587S
0.5927
o.5977
0.6024
0.6071
0.6115
0.6159
0.6201
0.6242
0.6281
1.8041
1.6975
1.6544
I-5S93
• -554 •
1-5252
1.5007
1-4793
1.4605
1-4436
1.4076
1.3781
!-35JO
1-3312
i-3ii9
1.2046
1.2789
1.2645
12513
1.2390
'•2275
2 I OS
I.2067
1.1971
1.1880
1.1794
1.1712
1.1634
'•'559
1.1468
1. 1419
I.135 2
1.1288
1.1227
1.1167
1.1 110
1.1054
I.IOOO
1.0947
1 0896
1.0847
1.0799
1.0752
1.0706
1.06b 2
I.0618
I.0576
1-0534
I.O494
1.0454
I.O4I5
I.0378
I.O34O
1.0304
I.O268
I.O234
I.OI 99
I.OI66
1.0133
1.0 00
1.006S
1.0037
1.0006
0.9976
0.9946
0.9917
0.9804
0.9698
0.9598
0.9503
0.9413
0.9527
0.9244
0.9165
0.9090
0.9017
0.81)48
0.8880
O.s.815
O.S752
0.8691
cu. m.
14.8904
7-7354
5-279S
4.0279
3-2650
2.7S10
2.3796
2.0984
1.8779
1.7002
1-3794
1.1621
1.0053
0.8867
o-7937
0.7188
0.6=172
0.6059
0.5616
0.5238
0.4909
0.4620
0.4163
04135
°-393°
°-5744
°-357 6
0-3423
0.3282
0.3154
0-3055
0.2924
0.2822
0.2727
0.2638
0.2555
0.2478
0.2405
0-2336
0.2271
0.2210
0.2152
0.2097
0.2045
0.1995
0.1948
0.1903
0.1860
o. 1820
0.1781
0.1743
0.1707
0.-673
o. 1640
o. 1608
0.157S
0.1549
0.1521
°-'493
0.1467
0.1442
0.1418
o 1594
0.1371
°-i349
0.1328
0.1285
o. i 215
0.1149
0.1092
0.1039
0.0993
0.0950
00911
0.0875
0.0844
0.0811
0.07S2
0.0756
0.0731
0.070S
525.S
273-2
186.5
142.3
115.5
97-!5
S4.04
74.11
06.31
60.04
48.72
41.04
35-51
31-32
2S.03
25-39
23.21
21.39
19-83
18.50
•7-34
16.32
i5-4i
14.60
.3.8S
13.22
12.63
12.09
n.59
11.14
10.72
10.33
9.966
9.650
9-3'7
9.024
8.751
8.494
8.250
8.020
7.S06
7.600
7.406
7.221
7.046
6.880
6.721
6.569
6.42S
6.290
6.156
6.028
5.908
5-791
5-679
5-573
5-471
5-372
5.272
5.181
5-°93
5.008
4.924
4.841
4.764
4.690
4-53S
4-284
4.058
3-857
3.669
3-5°7
3-355
3.218
3-°9'
2.981
2.864
2.762
2.670
2.582
2.500
19. The external work, L, performed by a Exact formula for
mixture of steam and water expanding from external work, L.
volume v to z', without gain or loss of heat,
the weight of the steam per pound of the mixture changing
from X to .11 and the pressure falling from /> to/,, may be calculated
from equation (36) :
Integrating
,1 Q = dq+ d (x i>) + .1 p d .
. I p d :• = — ,/ q — d ( .ro)
sl /.
./
1
'It + -1 /'

7o ENGINEERING MECHANICS. [March, 1892.
The pressure /, determines the value of it,, and from equa- 23. The various curves of expansion are Comparison of the
tion (35) :
shown in Fig. 4, Plate 1. They are drawu different curves of
for x = I, /'. e., for dry steam, and the sup- expansion.
.t'i u, 4 w position is that enough water is added or
abstracted to keep the steam saturated. It is seen that the
and the quantity of steani contained
ture is
The work done
by (46a),
L
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41
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k-=;
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in a pound of the mixcurve
for constant weight of steam and constant internal work
(isodynamic curve) almost coincide. The adiabatic curve constructed
with Zeuner's exponent of 11 = 1.135 closely approaches
these two, aud coiucides with them the more nearly, the greater
the percentage of moisture of the steam. Rankine's equation
(48) for the curve of constant weight of steam is / v J-J =• constant;
aud for the adiabatic curve of saturated steam / z/-'g° -= constant.
He recommends the former for dry or nearly dry steam, the latter
for steam moderately moist, but adds that the difference between
the results obtained from the two formuke is so small as to be
. lhs (49) of uo practical consequence, the use of oue equation or the
other being rather a matter of convenience than of accuracy.
in compressing a pound of the mixture is,
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193.3 161.9
197.8 166.5
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S.

March, 1S92.] ENGINEERING MECHANICS. /i
THE PARABOLIC ROOF TRUSS OF FR. SCHMEMANN.
The paper by Mr. Schmemann in the December (1891) number of
MECHANICS presents not only certain matters of truss and girder theory
of considerable interest and importance, but also a mass of mathematical
work almost appalling in character. Both of these features will be
considered in that which follows.
The fundamental equations (I), (II), (III) and (IV), given on page
277 of MECHANICS, arc correct, it being understood that a- is measured
from the centre of the span; also that E and £,,. are the quotients of
moments of inertia of cross sections, normal to the directions of the
stresses B, divided by the distances of the most remote fibres (in which
the stress intensities B exist) from the neutral axis ofthe sections.
The well-known properties of the parabola are correctly stated; but
a typographical error in the line at the bottom of page 277 leads to
some confusion. That line should show tan a =
WA
The results in the first column on page 27S are correct down to the
twelfth line from the bottom; but the superfluity of mathematical work
and the redundance of operations are simply blinding and utterly inexcusable.
As the two girders meet in a point at the apex of the roof,
the value of £c = /,c can on]y be corrrect by assuming
4
that d and dx are the internal and external diameters of the pipe forming
the horizontal tie, and that a very short horizontal section of tlie
same pipe is virtually found between the upper extremities of the girders
at their apex. For this reason it is quite inadmissible either to assume
(as is done in the fourth line from bottom of first column page 278)
•Be .
that is the stress in the inclined upper chord at the centre or
COS tl
d' 1 dsection
of a round pipe should be —, instead of that given.
cos a cos a
In the fifteenth line from the top of the second column of page 27S,
the method of dividing Bz hx and BEX by cos a for finding the stress
in any inclined pipe is indicated and used constantly thereafter. This
is a serious error, and affects nearly all remaining results. Bx is the
total stress in the pipe at the point x, and it must be multiplied by cos a,
if hx (normal depth) is to be divided by the same quantity. The
method of demonstration of Eq. (IV) makes hx the normal depth of
girder between centres of chords, and if it is transferred to the vertical
depth by dividing by cos a, then Bx must be multiplied by cos a.
-"..gain, and similarly, since the direction of B is properly taken along
the pipe in which that stress is supposed to exist, the " moment of re­
sistance" Ex belongs to a section normal to the pipes forming the parallel
chords of a girder, and nothing is to be gained or found by dividing
it by cos a; the operation is therefore meaningless and erroneous.
Again, the author of the article in question, in the second column . if
page 278, divides the same quantity Ex fir.t by cos a for the " moment
of resistance " of the straight inclined pipe, and then by cos a, for the
"moment of resistance " of the parabolic chord or pipe, as if each in­
dependently enjoyed its own "moment of resistance," instead of contributing
a component part of the moment of the entire section. Such
operations have no meaning, and simply becloud the subject with an
empty complication. Finally, for the stress Bx in the "upper chord"
and horizontal tie, he uses the vertical depth at section I from inclined
pipe to horizontal tie, and ignores the existence of the parabolic pipe
which is cut by the same section. Similarly, at the bottom of second
column of page 278 and top of first column of page 279, he finds an
erroneous neutral axis by again ignoring the existence of the parab .lie
pipe, and then proceeds to find, by the use of this wrong position and
&
the equally wrong chord stresses (first described), a value for the stress
in Ihe parabolic chord, slill more in error. As a matter of fact, the
common theory of flexure as expressed by the second members of Eqs.
(I) and (III) can be properly applied only to beams or girders with
parallel sides or flanges. This fact Mr. Schmemann lias ignored for
the section through the apex of his girder and those- at I and 2, as well
as a great deal more.
The errors are constantly repeated in the operations applied to Sections
2, 3, 4, 5, 6 and 7 on pages 279 and 2S0 (upper half of first col­
umn), although sections 3,'4 and 5 can be considered as belonging to
a girder with parallel chords. Near the centre of the first column of
page 279 there is found the explicit statement that 2 — is the moment
cos a.,
of resistance of the pipe forming the straight inclined upper chord, and
immediately following, the further statement that the cross section of
the girder consists of the vertical sections of the pipes (two) in the
upper (inclined straight) chord and lower chord or horizontal tie. In
the first of these instances cos a is probably intended; but this correction
leaves the serious fundamental error untouched, and in the second
instance the parabolic pipe is again ignored. Further on, Bx is again
divided by cos a, while the vertical depth, even for the sections 3, 4
and 5, is invariably taken instead of the normal. In section 2 the
same erroneous method of finding the stress in the parabolic chord is
used as that shown in connection with section I. These errors run
through and vitiate every result depending on them to the bottom of
the first column of page 2S0, including the numerical results given in
the two tables. At about tiie middle of that column it is stated that tlie
stress on the vertical end of the parabola at the lower end of the girder
W
is equal to the reaction in the abutment, 1. e., equal to —. This is
apex, or that that stress is equal toy? X vertical {elliptical) cross section inconsistent w-ith the result found for the lower chord at Section 7. If
of inclined pipe. The stress in the straight inclined pipe forming the the inclined stress of 0.575 Sexists in the lower chord at 7, its vertical
upper chord is affected by the existence of the parabolic chord, and,
\V
as a matter of fact, is nowhere found, in the analysis, between the apex component would have to be added to — in order to determine the
and point 3. The assumptions just indicated, therefore, are entirely
gratuitous and thoroughly erroneous. The results flowing from these
2
stress in the vertical end of the parabola. As a matter of fact, neither
of tbe stresses considered can exist, in consequence of the absence of
assumption:, as found in the first five lines at the top of page 278 (sec­ all requisite truss bracing.
ond column), are equally erroneous. It should also be observed in In all that has been stated heretofore it has been virtually assumed
passing that the numerator of the expression for the vertical elliptical that the bracing or web members necessitated by the chord stresses
sought at the different sections, I to 7, are to be found in the truss or
girder. This is not the case. No internal truss members for transferring
shear are designed to be used. The posts shown at the different sections
simply divide the truss outline into quadrilaterals. Hence the truss
element is entirely lacking and no transference of shear can take place.
Consequently the chord stresses of the true truss cannot exist and the
computations made to determine them have no bearing on Mr. Schmemann's
girder. The only stiffness or stability that it can have is due to
the transverse stiffness of the individual pipes, as individuals solely, and
not as components of a truss.
Near the top of the second column, on page 2S0, the general expres-
IV
sion tu x is given for the stress on any post. It is not clear just
4
what the author means by this formula. It is not the correct expression
for the shear; and inasmuch as no transference of shear can take place,
as explained above, it certainly cannot give the stress in the posts. For
x =7 — the formula gives no stress for post 4, although the author's
W
table shows —. The reasons just given show that the values in the
64 ' "
table are all in error and possess no meaning;. The posts as shown
act only like the rungs "f a ladder when turned into a vertical plane.
The stresses in thsm cannot lie determined by any truss analysis.
The statement that tlie parabolic portions of the girders are free from
any shear except tlie vertical components of the stresses in the parabolic
pipes, found at the opening; of the fifth paragraph in the second column
of page 280 is also an error. A girder with a parabolic upper chord
with a vertical axis passing through the centre of the span, needs, it is
true, no web members to carry the shear of a full uniform load, but that

7- ENGINEERING MECHANICS. [March, 1892.
case is far removed from the present. Even such a girder, however, is
not without web shear under any other condition than that of uniform
load over the entire span.
There remains to be noticed the analysis given by the author in connection
with the figure on page 280, having for its object the determina­
tion of the alleged bending of the posts. lie draws the usual diagram
for the common theory of flexure and then assumes that the load on any
post, which acts along its length, in some way produces a transverse
bending which is represented by the longitudinal internal stresses of a
bent beam. Although this assumption possesses not even a show of
validity, he draws the false conclusion that one component of this erroneous
post load (as given by the table) will act parallel to tlie chords and
at one-sixth of the girder depth from one of them. Nothing could be
more irrelevant to, or disconnected from the thing sought than the gratuitous
union of these features of beam analysis. The operation has no
rational sequence, and the results have no meaning whatever. As a
matter of fact the posts arc subject to no direct flexure, nor, indeed, any
other stresses that can be directly analyzed, as has been already observed.
The claims advanced for the girder cannot, therefore, be admitted in
any respect whatever. WM. II. I'L'kR.
The whole theory of liquefaction, as commonly stated, is that
it can only be brought about by the steam coming into contact
with something colder than itself. This assumption is taken for
granted ; it is held to be capable of convincing proof that so
long as steam is kept in a vessel, the walls of which are at its
own temperature, no condensation cau take place. We are
quite willing to grant this, but with a limitation ; that is to say,
it is quite true of steani kept at rest. The point in doubt is
whether it is or is not true of steam in motion. A recent experience—not
an experiment—throws some light ou this ques­
tion. Drains fitted to certain steam pipes, all supplied by the
same battery of boilers, showed that small steam pipes invari­
ably supplied wetter steam than larger pipes. The steam pipes
were all carelully clothed, clothed indeed to a quite unusual degree,
and the loss by radiation must have been very small ; but
small or great, there was the water. It is very difficult to believe
that in this case—concerning which we may have more to
say at another time—the temperature ofthe metal ofthe steam
pipe could have had much to do with the amount of condensa­
tion. I,et us consider for a moment what is the nature of the
fluid—steani—with wliich we are dealing. It is of all others
perhaps the most unstable that it is possible to produce. A
NEW YORK CITY, 9th Feb. 1S92.
touch with a feather is sufficient to upset the balance in the
solid iodide of nitrogen, and an explosion ensues. A touch
with a drop of cold water suffices to upset the equilibrium of
steam, and the water molecules fall together like a flash. Again,
we know that if a permanent gas expands, doing work the
while, its sensible temperature falls ; but when steam expanding
does work a portion of it is liquefied. Here there is no
question of transfer of heat from a hotter to a colder body.
THE CONDENSATION OF STEAM.
Again, we can go on compressing gas within comparatively
It is known that in all steam engines liquefaction takes place enormously wide limits without producing liquefaction ; but in
in the cylinder, and this is invariably explained on the assump­ case of steani, if there be water present in sufficient quantity—
tion that the metal being cooler than the steam with which it somewhere about 50 percent, will suffice—after a certain degree
comes in contact, a transfer of heat rakes place from the steam of compression has been reached, no further rise in pressure
to the iron, condensation ensuing as a natural consequence. can be obtained. The steam proceeds to liquefy. The action
No doubt this is the truth, but is it the entire truth? Is this ex­ is as though the water present absorbed it like a sponge. Here,
planation consistent with facts and phenomena taken as a again, we have liquefaction without transfer of heat from a
whole? Is the hypothesis competent to explain everything hotter to a colder body. Thus, then, it will be seen that steam
connected with liquefaction in steani cylinders ? There is reason will liquefy whether it is doing or has work done upon it; and
to think that the reply must be in the negative ; and if so, then the action is often apparent in actual indicator diagrams, lique­
we are presented with a very interesting region for physical refaction taking place because of the presence of water during the
search ; one that cau be better explored, moreover, by the compression period. But this is not all. The presence of some
physicist than by the engineer, because it is easier to carry out solid body appears to be essential to liquefaction. It has been
the requisite experiments with the great accuracy required in shown by Mr. John Aitken that if air—that is space, for the air
the laboratory thau in the engine-room. Our object now is to plays a secondary part—saturated with moisture be cooled,
state the case for inquiry ; not to dogmatize, but to suggest. the moisture will not deposit unless there are dust particles
It was at oue time held that cylinder condensation largely de­ present ou which condensation can take place. During the depended
for its amount on the range of temperature in the cylinlivery of a very interesting lecture on liquids and gases delivered
der. We have heard it stated, for example, that if the range of by Professor W. Ramsay, on May Sth, 1891, at the Royal Insti-
temperature in a cylinder were, say, 100 deg. aud the condensatutiou, he showed an experiment to illustrate Mr. Aitken's
tion X lb. per hour, then, all the other conditions remaining un­ statement of fact. " If," said the lecturer, " air be suddenly exaltered,
if the range of temperature were doubled the condensapanded it will do work against atmospheric pressure, and will
tion would become 2 x lb. per hour, and engineers holding this cool itself. This globe contains air, but the air has been filtered
view very naturally said that the compound and triple-expansion carefully through cotton-wool, with the object of excluding dust
engines were more economical thau simple engines, mainly be­ particles. It is saturated with moisture. On taking a stroke of
cause the range of temperature iu each cylinder of the multi- the pump, so as to exhaust the air in the globe, no change is
cylinder engine was reduced, as compared with the range iu the evident; no condensation has occurred, although the air has
single cylinder. Reasoning of this kind is seldom or never been so cooled that the moisture should condense, were it pos­
heard now ; because it is well known that cylinder condensation sible. On repeating the operatiou with the same globe after
is greater in the triple than in any other form of expansion admitting dusty air—ordinary air from the room—a slight fog is
engine, unless it be the quadruple engine. In a word, facts all produced, and owing to the light behind, a circular rainbow is
go to show that cylinder condensation is largely independent of seen; a slight shower of rain has taken place. There are compara­
range of temperature. But if this is really, as it is apparently tively few dust particle's, because only a little dusty air has been
true, then it seems to be clear that we must seek for some other admitted. On again repeating, the fog is denser, there are more
cause of liquefaction. Furthermore, tbe amount of liquefaction particles on which moisture may coudeuse. This is a highly-
shows itself to be royally independent, bearing no fixed relation suggestive experiment, if regarded in a proper spirit. The dif­
to any condition. Thus iu two engines practically identical ference between vapor suspended in the atmosphere aud steam
and working under similar circumstances, we shall find one of any pressure is little more than one of degree. If vapor,
condensing far more steani than the other.
although cooled, will not condense unless dust particles are
present, it is fair to assume, first, that steam would not condense;
and, secondly, we may proceed to ask, What effect a
difference iu the size of the dust particles and in their material
would produce on the phenomena?
We believe that in the face of all the facts we have briefly
placed before our readers, it is impossible to maintain that
steam can only be liquefied by the direct abstraction of heat.

March, 1892.] ENGINEERING MECHANICS. 73
We may now proceed a step further, and consider what may
happen when steam is in rapid motion round turns and bends.
Let us take it for granted, for example, that steam, rushing into
a cylinder through crooked ports, comes into contact with metal
just of the same temperature as itself, and the conditions are
such that this metal can never get hotter than the steam. We
have seen that the fluid with which we have to do is in a state
of unstable equilibrium. The water molecules are only kept
apart by the energy which has been imparted to them by the
beat called "latent," but which is really no longer heat. If,
now, something occurs to initiate liquefaction, there is no reason
why it should not proceed until at least the metallic surface becomes
covered with moisture, and the steani is no longer in
contact with it. What, it may be asked, cau initiate liquefaction
under such conditions ? The answer can be only tentatively
suggestive. The thermo-dynamic theory of gases is supposed
to apply to steam. According to it,.the molecules are iu rapid
motion, bombarding the surfaces of the containing envelope,
from which they recoil without loss of energy ; but this recoil
without loss of energy can only hold true of molecules which are
perfectly elastic. So long as the steani is not in motion—and
the motion of a current of steani must not be confounded with
its intra-molecular motion—the difference in elasticity between
steani and a perfect gas is too small to produce an appreciable
effect.
Let us suppose now that we have an india rubber ball,
which, when dropped on the floor, will always return to the
hand so long as it is only thrown down with a certain force, but
let the force be augmented sufficiently to injure the ball and it
can no longer return. Or to take another case, a steel shot is
driven against an armor plate which it is unable to penetrate
with a given charge of powder, aud it rebounds uninjured from
the plate. The charge of powder is increased and the shot
breaks up. Now it is evident that the molecules of steam
which first rush into a cylinder when the port is open, are
driven clear across to the other side aud violently impelled
against the metal ; aud knowing how fine is the distinction be­
tween steani and water, how nice the balance of forces, is it too
much to say that the imperfectly elastic molecules, will not rebound,
but will part with some of their energy to the metal, and
falling together will assume the condition of water. All this is
pure hypothesis. But it is hypothesis which is consistent with
existing theories and existing experiments. Let us, on the
other hand, reject the idea that the kuocking of steam about,
its collision with cylinder walls, the bends in steani pipes, and
such like, can have auy effect; let us take it for granted that it
is impossible, do what we may with steam, to condense it so
long as it is in contact with a surface possessing the same sensible
temperature.
How are we, then, to reconcile this proposition with the
facts which we meet with at every turn — the enormous
amount of condensation which takes place in the welljacketed
high-pressure cylinder of a triple-expansion engine ;
the increase in condensation due to the use of small or crooked
be made with a tube of the same length and dimensions, but
put together with numerous sharp bends. Different experiments
of this kind will suggest themselves. It has long been
known to engineers that steam engines with short straight ports
are better than engines with crooked and long steam passages.
It would be instructive to ascertain to what the economy of the
former is due. Is the cylinder condensation less in one case
than the other? Finally, we would repeat what we did at the
outset, namely, that we do not pretend to dogmatize ; all that
we have attempted is to show that there is a good case for further
inquiry concerning the phenomena of condensation. The
subject should be approached with an open mind, and the inquirer
should not let himself be persuaded that everything is
already known about steam that can be known.
MESSRS. SIEMENS AND HALSKE, in Berlin, have prepared
plans for the construction of a network of elevated railroads in
the city of Berlin, which will use electricity as a motive power.
All cars will be equipped with motors, and will be run separately
every two or three minutes. In cases, however, of great
traffic, trains are to be formed of two to four of these motor
cars. A service of eighteen hours a day is proposed. It has
been estimated that each car on each run between the terminal
points of the line will carry 40 passengers, and that 15,000,000
to 75, o0o ,°oo passengers will be carried in each year. The cost
for constructing these elevated railroads of double track has
been calculated to be ^"120,000 per mile. The present plan is
to construct only the south line, of only five and a half miles
in length, provided, of course, that governmental sanction can
be obtained, which is considered doubtful.
PUIVIPS AND PUMPING MACHINERY.
BV WILLIAM KENT, M.E.
THE DUPLEX DIRECT-ACTING STEAM PUMP.—Mr. Henry
R. Worthington, who invented the single cylinder directacting
steam pump about 1S40, as already stated, also became
about 1S60, the inventor of the Duplex Pump which bears
his name, and has become of worldwide reputation. The history
of the invention of this pump is given in Mr. Worthington's
pamphlet, published in 1S76. After describing the engine
built by him at Cambridge, Mass., in 1S56, which was a single
cylinder pump of the relief valve type, the steam engine being
an annular compound, and which gave in a test over 70,-
000,000 pounds duty, he says: "It soon became evident to my
mind that the small engine at Cambridge, economical in the use
of coal, and durable as it proved itself, was fully as large as it
was desirable to build an engine of its character. The sudden
reciprocation produced ajar and a recoil, which, while comparatively
insignificant on this small engine, threatened to be distressing
if not destructive upon a larger one. The problem was
plainly indicated. How should a pumping engine be made to
steam pipes, as compared with those that are larger or straighter ; reciprocate quietly ? A careful consideration ofthe causes at
or the circumstance that steani separators, which depend for work, suggested the answer. To think of the difficulty was al­
their operation on the "knocking" of the water out of the most to find the remedy. It required no large departure from
steam, often prove failures, taking out a good deal of water, and ordinary practice, no great invention, no remarkable exhibition
vet leaving the steam nearly as wet as they received it?
of mechanical skill, to apply it. Very little was to be done but
It is, we think, time that the questions we have raised were that little was of vital consequence. Let us for a moment fol­
fairly and dispassionately examined. Either it is or is not true low a stroke of a double-acting pump piston, from one end of
that other influences thau mere differences of temperature can its cylinder to the other, one single stroke and no more. Be­
cause steam to part with its heat. It would not involve the exhind it is an open supply valve through which the water is
penditure of very much time, trouble, or money to carry out at pouring, to meet the demands ofthe receding piston. Before it
least a preliminary trial, which would throw a good deal of an open force valve, through which the water is pressed by the
light on the points at issue. Thus, for example, a length of ioo advancing piston. It reaches the end of its stroke and stops,
ft. of straight steam pipe might be fitted up, steani at a giveu for we are only dealing with one single stroke. What follows?
pressure allowed to flow through it, and the amount of con­ The water continues to press by its momentum into the cham.
densation measured by collecting, at the end furthest from the ber, filling every inch of space. As the current gradually ceases,
boiler, th*e water deposited. A similar experiment might then the supply valve gradually and quietly settles to its seat ; at the

74 ENGINEERING MECHANICS. [March, 1892.
same time the delivery valve falls quietly through the water,
which fails to keep it lifted. Both valves arc now at rest, having
fallen by their gravity through the gradually subsiding currents
which tended to open aud hold them open, while the chamber
behind the piston is thoroughly supplied with water. After this
interval of time let us make the return stroke. The piston met
by its full resistance, takes up its work quietly, while the delivery
valves before, and the supply valves behind it, opeu under
gradual pressure. We need follow the motion no
further to see that the remedy for concussion is rest
for the pistou at the end of the stroke. Contrast
this with the action of a pump compelled to recip
rocate in the manner common to most engines.
There the reverse motion takes place so suddenly
that the supply and delivery valves of the preceding
stroke are caught almost at their highest lift, not
liaving had sufficient time for closing. The water
of supply has not been able to fill up behind the
rapidly retreating piston, which, as a consequence,
meets a vacuous space at tbe instant of return, with
every valve in wrong position. Before one set can
be seated aud the other lifted, the engine, by a
sudden jump, strikes the water heavily, and pouuds
the valves to their seats. Hence the noise, which r
always has, and always will, to a greater or less de- [
gree, mark the self-destructive action of an ordinary
reciprocating pump. I claim that it should be accepted
as proved, that the cessation of motion at
the end ofthe stroke, for a length of time sufficient
to allow the seating of the valves by gravity, instead
of by the action of the return currents, will
completely obviate this noisy, imperfect and injurious
actiou. To this extent, the desideratum is accomplished.
Another requisition remains, and that
is for uniform, unbroken movement of the water
iuto and through the delivery pipe."
Mr. J. F. Holloway, in a lecture delivered at Sibley
College, Cornell University, iu 18S9, thus refers
to the invention of the duplex pump :
" While the single-acting steam pump, as built by
its inventor, had come into extensive use for feeding
boilers and supplying moderate quantities of
water under moderate pressure, it still had features
which were objectionable, and which prevented it
from being used for places where large quantities
of water were required to be forced through long
lines of pipes. This objectiou to the class of pumps
just described grew out of the fact that the action
of the pump plunger or pistou, was au intermittent
one, that is, the column of water was started iuto
motion at the beginning of each stroke, and came
to a stand at the end of each stroke; thus not only
making the flow of the water irregular but also
subjecting both the pump, the connecting pipes, and their joints
to severe aud often serious strains. Feeling how incomplete
was an invention which did not provide against such results, Mr.
Worthington devoted much time and much study in order to
correct this trouble, and a few years later on he brought out an
improved pump which, iu its simplicity of parts, certainty of
action, and cheapness of construction, more than rivaled the
original invention itself. This pump is now universally known
as the 'Worthington Direct-Acting Duplex Steam Pump.' "
In the main, the construction ofthe steam ends, and the water
ends, of the duplex pump differs but slightly from that of the
single-acting pump, but the mechanism which operates the steam
valves is different, and the effect on the water column was marvelously
different. The principle upon which it operates is
this:
Two pumps of similar construction are placed side by side. A
lever attached to the piston-rod of each pump connects to the
slide valve of the opposite steam cylinder ; thus the movement
of each piston, instead of operating its own slide valve as iu the
single pump, operates the slide valve of the opposite cylinder.
The effect of this arrangement is, that as the piston or plunger
of one pump arrives at or near the end of its stroke, the plunger
or piston of the other begins its movement, thus alternately
taking up the load ofthe water column and producing a regular,
steady, onward flow of the water, without the unusual straius
FIG. 38. THE WORTHINGTON DUPLEX PUMP.
(Sectional View, with separate parts.)
induced by such a column when suddenly arrested or started
into motion.
THE WORTHINGTON STEAM PUMP.—Fig. 38 is a sectional
view of one side or half of a Worthington Steam Pump, of ordinary
construction, together with cuts of separate parts, numbered
and named in the following list :
I. Steam Cylinders (Nos. i, 2).
2. Steam Cylinder Head.
3- Slide Valve.
4. Valve Rod Nut.
5- Valve Rod.
6. Valve Rod Gland.
7- Valve Rod Head.
S. Steani Chest.
9- Steam Chest Cover.
10. SLeam Pipe.
11. Lubricator.
12. Piston Ring.
Piston Follower.
J 3-
M
i,S
16
17
18
19
20
21
22
23
24
25
26
Piston Follower Bolts.
Piston Rodv.
Piston Tongue.
Piston Tongue Spring.
Piston Tongue Bracket.
Piston Rod Stuffing-box.
Piston Rod Stuffing-box Glatil
Steam Cylinder Foot.
Exhaust Screw Flange.
Piston Rod.
Valve Rod Head Pin.
Valve Rod Unk (long or short ?)
Long Eever.

March, 1892.] ENGINEERING MECHANICS. 75
27.
28.
29.
So­
il-
32-
33-
34-
35-
36.
37-
38.
39-
40.
4»
42.
Short Lever.
Rock Shaft Key.
Upper Rock Shaft.
Lower Rock Shaft.
Crank Pin.
Spool.
Spool Position Pin.
Spool Key.
Cradle.
Cross Stand.
Blow Cock.
Water Cylinder.
Water Cylinder Head.
Plunger.
Plunger Ring.*
Casing.
4.5.
4 1-
45-
46.
47-
43.
49.
5°-
5*-
5 2 Binder.
Plunger Hub.
Water Cylinder Hand-hole Plate
Force Chamber.
Force Chamber Hand-hole Plate
Valve Guard.
Valve Spring.
Brass Valve Plate.
Valve.
- Valve Seat.
53- Delivery Tee.
54- Air Chamber.
55- Suction Screw Flange.
56. Suction Hand-hole Plate.
S7- Piston Nut.
58. Plunger Nut.
It exhibits generally the great simplicity of the interior ar­
rangement of the pump aud especially of the steam valve.
This valve is an ordinary slide valve (3) working upou a flat
face over ports or openings.
The motion of the valve is produced by a vibrating arm,
which swings through the whole length of the stroke with long
and easy leverage. As the moving parts are always in contact,
the blow inseparable from the tappet system is avoided.
This valve motion is the prominent and distinguishing pecu­
liarity of the Worthington pump. To it it owes its complete
exemption from noise or concussive action. The one piston acts
to give steam to the other, after which it finishes its own stroke,
and waits for its valve to be acted upou before it can renew its
motion. This pause allows all the water valves to seat quietly.
As one or the other of the steani valves must be always open,
there can be no dead point. The pump is, therefore, always
ready to start when the steam is admitted, and is managed by
the simple opening and shutting of the throttle valve.
THE ARRANGEMENT OF THE DOUBLE-ACTING PLUNGER
SHOWN AT 40.—It works through a deep metallic packing ring
FIG. 39. "REGULAR PATTERN" WORTHINGTON PUMP.
Size, 10 X 6 X 10.
(41) bored to an accurate fit, being neither elastic nor adjustable.
Both the ring and the plunger can be quickly taken out, and
either refitted or exchanged for new ones, and if it be desired
at any time to change the proportions between the steam pis­
tons and pumps, a plunger of somewhat largersize, or decreased
to any smaller diameter, can be readily substituted.
The plunger is located some inches above the suction valves,
to form a subsiding chamber, into which any foreign substance
may fall below the wearing surfaces. The water enters the
pump from the suction chamber (56) through the suction valves,
then passes partly around and partly by the end of the plunger,
through the force valves (51), nearly in a straight course, into
the delivery chamber (46), thus traversing a very direct aud
ample waterway. The bottom and top plates furnish a large
area for the accommodation of the valves. These consist of
several small discs of rubber or other suitable material, easy to
examine and inexpensive to replace.
Fig. 39 illustrates the Worthington Pump of ordinary pattern,
having two double-acting plungers, and fitted with water valves
of rubber or metal as required. These pumps are designed for
boiler feeding, fire, hydraulic elevator and general service, where
the water pressure does not exceed 150 pounds. The following
is a list of regular sizes. The stated capacities of the pumps
are based upou a piston speed of about 50 to 100 feet per minute.
In case of fire or other emergency, this speed can be consider­
ably increased.
t-
OJ
••=
G
g
a
V
tfi
0
u
V
V
in
IH
a
S
4 3-57 75 to 12
'4 12 IC 4-89 75 to 125
16 12 IC 4-^9 75 to 125
i&'A I 2 IC 4.89 75 to 125
20 I 2 1C 4.89 75 to 1.3
lS),' '4 lc 6.66 75 to 123
20 '4 IC 6.66 75 to 125
17 IO '5 5.10 50 to IOO
20 I 2 it 7-34 50 to ICO
20 '5 '5 H-47 50 to IO'
25 •5 H-47 50 to IOC
6 c A IJ
.2 5 =
P
20 2X
40 4
80 5
IOO 5H
125 (>rt
'5° 7
170 6X
230 VA
300 S!4
410 9A
410 9
410
610
5" 610
365" 610
365" 610
365" 610
5jo" 890
530" 890
53o" 890
53°" 890
53o" S90
730" 1220
73°" 1220
75°" 1220
7jo" 1220
990" 1660
990" 1660
510" 1020
73°" 1460
'145" 2290
"45" 2290
7 As
9 7 V.
Ir, W
'X 2 4
2
\?'A 4
2 2>2 5
2 \2}/2 6
2X 3 6
A 2X|3 6
12 2X3 6
12 2^3 6
12
2X3 6
12 3 3X 6
12 . 4 :5 6
14 A 2X 3 S
14X Az3 8
2
'41-t A\3 8
14'+ 3 UX S
MX 4 Is S
2
17 X 3 10
•7 A''iA 10
17 3 3X
17
•9X
19-V
14
17
21
21
IO
4 5 10
3 3X 12
4 5 12
3 3X 10
4 5 12
ii
p.
oi
s
.JI
oj
a
K
.5
A.
A\ A' "+
X' X, 2
X|'X 2X
1 'X 3
1X 2 4
1 X 2 '4
ai
a
OJ
be
l~
cd
JZ
u
Q (/J
I
I>2
I><
2
In addition to the sizes given in the above list, a large number
of other sizes and combinations can be supplied to meet the re­
quirements of any particular service.
3
3
3
3
4
5
5
5
5
5
5
5
5
7
7
7
7
7
8
8
8
S
10
10
8
10
THE WORTHINGTON COMPOUND PUMP (Fig. 40).—In the ar­
rangement of steam cylinders here employed the steam is used
expansively, which cannot be done in the ordinary form. Having
exerted its force through one stroke upon the smaller steam
piston, it expands upon the larger, during the return stroke,
aud operates to drive the piston iu the other direction.
Compound cylinders are recommended in auy service where
the saving of fuel is an important consideration. Iu such cases
their greater first cost is fully justified, as they require 30 to 33
per cent, less coal thau any high pressure form, on the same-
work.
OH the large sizes a condensing apparatus is often added.
Any of the ordinary forms of Worthington steam pumps can
be fitted with these compound cylinders, and in proportions to
suit any service. Au extra pipe connection is sometimes em­
ployed that permits steam to lie admitted directly from the
boiler to the low pressure cylinder, whereby a greatly augmented

76 ENGINEERING MECHANICS. [March, 1892.
water pressure for fire or other emergency is very readily se­
cured.
Compound cylinders are extensively applied to hydraulic ele­
vator pumps, tank pumps, fire pumps, pressure pumps, mine
pumps, and to engines designed for the water supply of small
cities and towns.
The principle of expansion, without condensation, cannot be
used with advantage where the steam pressure is below 50 lbs.
When required, the speed of the pumps may be considerably
increased beyond the figures stated in the list.
UI
G
a
V
X
0
U
FIG. 40. WORTHINGTON "COMPOUND" STEAM PUMP.
Size, 14 and 20 X 12 X to.
WORTHINGTON DUPLEX POINT. COMPOUND
ji
V
bit
P*
U
D
u
•fl
0
4.
OJ
a
£ tc
||
.5

March, 1892.] ENGINEERING MECHANICS. 77
[Copyrighted.J
as if there was no other condition than the fixity of a single
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION, poiut C; we are then to expect this time to find the same con­
BY MAURICE LEVY.
ditions of equilibrium among the forces as in the case where it
Remark.—The principal condition which the resultant is to had only this condition to fulfil. But, if the requirement for
fulfil is to pass through the poiut 0. This condition is the same the poiut a to describe the arc x' y' constitutes a condition geo­
as if the body, instead of being subject to be supported on the metrically superfluous, the material presence of this curve, for
two fixed curves at A and B, was subject to turn around the the same reasou that it is useless, will prevent the free dilatation
point O; in a rotation infinitely small around O it would glide, of the body according to the direction C AA Therefore we are
in fact, on the two curves, the points A and B describing as to expect, according to the rule of \ 50, that Statics no longer
arcs of the circle A a and B b the tangents to these curves. It suffices to determine the reactions of the supports, the reaction
is fully explained by that why the condition for it to be in equili­ at A' depending essentially on the co-efficient of dilatation of
brium, i.e., for it not to be able to move, even very little, ou the the body, whether by heat or by the power of elasticity. Hence,
curves, is found to be the same as that necessary for it not to be to sum up, according to the general principle stated iu \ 50, it
able to turn very little around the point O-
cau be foreseen that we ought to arrive at the following results :
2 55.
EQUILIBRIUM OF A BODY HAVING A FIXED POINT AND BEING
SUPPORTED BY ANOTHER POINT ON A FIXED DINE. QUESTION
OF INDETERMINATION OF THE REACTION OF THE SUPPORTS.—
would have, moreover, the reactions of the supports.
When a body is subject to turn (Fig. 35, Plate IX) around a It is no longer the same if the point of support, instead of
fixed point C, i.e., around a fixed axis perpendicular to the being at A, is at sl', in such manner that the normal A' N' to
plane of the figure and projected at C, and when, besides, it is
to be supported on a fixed curve xy, these conditions suffice in
general, to determine entirely its position, that is, to insure its
immobility, whatever be the forces which incite it, provided
they tend to support it on the curve and not to remove it from
the curve.
We ought then to expect (j 50) to have in general no other
condition of equilibrium between the forces directly applied
than that which we have just indicated.
Besides, in entirely determining its position, the subjections
to which the body is submitted do not subject it to a fixed form
and do not hinder its free change of form. We are to expect
that Statics will be still sufficient here, as in the preceding ex­
amples, for the determining of the reactions of the supports.
There is, nevertheless, one case of exception. Suppose that
the body be subject to turn around the fixed point C, and be
supported no longer on a curve x y chosen arbitrarily, but on a
material arc x' y' described with the fixed point fas a centre.
Let us call A' the point of contact considered as belonging to
the fixed curve and a this same point considered as belonging
to the body C.
This time, the conditions imposed, although of the same
number as in the general case, no longer determine the position
of the body ; this latter will be able to turn freely around the
point C, as if the condition of being supported on the curve
x' y' did not exist. That amounts to this, that the point a,
through that very thing by which the point C is fixed, describes
of itself the arc x' y': the condition that is imposed ou it to
describe it is, therefore, a geometrically needless or superfluous
condition.
Thus, the fixity of the body is not assured, and everything is
i° in the general case, uo condition of equilibrium among the
forces (save this evident one that they tend to support the body
on the fixed curve and not to remove it from it) ; besides, a pos­
sibility of determining the reactions of the supports by the aid
of Statics alone ; 2° in the exceptional case where the normal at
the poiut of support passes through the fixed point, a condition,
for the resultant of the forces, to pass through this point, as if
the fixed curve did not exist, and, besides, an impossibility of
determining, by Statics, the reactions of the supports.
These previsions are verified in all points.
Let us consider at first the general case where the point of
contact with the curve xy is auy point A, and let us suppose,
iu the first place, that the forces which incite the body admit of
a resultant Ii.
Let /be its point of intersection with the uormal A ,Vto the
curve of support. We can always resolve this force into two :
one directed according to / C, the other according to IA ; the
first will give the pressure on the fixed point C, the second, that
on the curve ; this latter, for equilibrium, will have to be directed
from /towards A, which requires that R be in the angle CIA.
If the acting forces be reduced to a couple, we would proceed
in like manner for each of the two forces of the couple, and we
the curve of support x' y' pass through the fixed point. Then,
/' being the point of intersection of this normal with the force
R, it is, in general, impossible to resolve this force according to
/' (Taud /' A', these two lines coinciding ; that is only possi­
ble if the force R pass through the point C. This condition
ought then to be fulfilled, aud, if it is, we shall be able to resolve
this force into two others, one according to C A', the other
according to another line C Z of an arbitrary direction passing
to the point C. Equilibrium will be assured, whatever be the
direction chosen. The component, according to CA', will be
the pressure exercised ou x' y' at A', aud the component, accor­
ding to CZ, the pressure exercised on the fixed point. We see,
therefore, that one of the two forces can be chosen arbitrarily,
aud then the other follows. We may suppose that, ou x' y',
no other pressure is exercised and that the pressure is entirely
supported by the fixed point, or that some part of the pressure
is supported by the curve x' y'
Statics ought to leave uudetermined the reactiou of the curve,
because it is really so.
Let us suppose, indeed, that it is actually zero, if the tem­
perature ofthe body happens to increase, the line Ca not being
free to extend, exercises a pressure on the curve ; if the tem­
perature lowers again, this pressure diminishes and may be
reduced to zero.
Therefore, let us suppose, before drawing the line Ca in place,
when the body had its natural form, that this line had had a mag­
nitude slightly greater than that which it has on the figure, i. e.,
in its definitive positiou. It will then have been necessary, in
order to put the body into position, to force it, to exercise an
effort great enough to compress it, in order to reduce the pri­
mary length C a to that of C A''. According to the difference

78 ENGINEERING MECHANICS. [March, 1892.
between the natural length of C a and its final length C A', the
effort of being put into place will have been more or less great,
and the reaction of x' y' will itself be more or less great.
We see, then, that this reaction depends ou things given absolutely
foreign to Statics, and that the theories of heat and elas­
ticity can alone be used. While we are not sure of these given
conditions, while both the temperature of the body aud the
conditions in which its position has been effected cannot be
pointed out precisely, the reactions are really undetermined.
The fact that Statics can not always determine the reactions
of the supports is therefore not a paradox, as was still
thought in the first quarter of this century. If there is a
paradox, it rests rather in the contrary fact, in the fact
that Statics can sometimes furnish the reactions, i. e., that
we can sometimes find them without knowing either the form
of the body which produces them, or its nature or its tempera­
ture.
But the observations of \ 50 explain this circumstance and
show, at the same time, that it can have only au exceptional
character.
GRAPHIC VERIFICATION.—Let us return now to the general
case where there is no indeterminatiou, and let us see how, the
forces directly applied being given, whatever be their number,
we shall be able to deduce from them the reactions of the sup­
ports.
Let (Fig. :$2, Plate VIII. I 1, 2, H, 4 be the surface of action
of the forces applied to a body, these forces being represented
by the sides i, 2, 3, 4 of the polygon of the forces
(Fig- 32).
Let us adjoin to these forces the reaction of the surface x y
according to A N. We shall designate by 5 its unknown magnitude
and by 5 its line of action A N. Thanks to the adjoining
of this force, the surface can be suppressed and the
body considered as entirely subject to turn around the fixed
point C. Now we know (

March, 1892.] ENGINEERING MECHANICS. 70
ELECTROTECHNICS.
2. Measurement of Resistances above 100 ohms (Fig. b)
The galvanometer G is inserted between g., aud d, battery
between h and i, x between g and f.
The straps 111 and k are closed, / is open, and f plugged, /
again serving as battery key. Iu this case
17 : iooo = r : x.
3). Calibration of bridge wire.
FIG. 49.
G \"*.c l -^^tAtsRj^AtAA.Ky^yAcLAAA-A-
The wire is taken as it comes from the drawing bench (neither
bent nor coiled), and stretched between two brass blocks A and
B (Fig. 49). Beside is placed a board in which holes for mercury
cups a, b, c, etc., have been bored. These cups are connected
by resistances coiled on wooden spools and soldered to
thick copper wires.
The resistances a, b, c, etc., should together be approximately
equal to resistance of wire A B. A current is now sent through
the two branches by connecting battery to A and B. One terminal
of a suitable galvanometer is connected to the mercury
cup a, the other terminal to a sliding contact on A B. The
contact is moved until no deflection takes place in the galvanometer,
which may be at 1 (Fig.).
In a similar manner the poiut on A B is found, which is at
the same potential as b. Let this be the point 2. The length
1 — 2 is then measured, and the resistance a — b is interchanged
with b — c. The points of equal potential (3 aud 4) on A B are
again determined, which correspond to the ends of the resistance
a — b in its second position. This operation is continued
throughout the entire length of the wire, and it is found that
the resistance a — b is equal to each of a number of short lengths
of the wire A B, which lengths are equal to each other if the
wire rs homogeneous. This, however, never occurs exactly, and
a table of corrections is made. To each reading there is added
a correction to reduce the length to that of a wire of the same
cross-section throughout. This method may be conveniently
arranged by choosing about 20 equal (within 0.0001) resistances
whose total resistance is 1 ohm (.05 each). In this case, A and
B are mercury cups, in which the terminals of the resistances
are immersed, whereby the resistance of connecting wires is
eliminated.
A galvanometer is placed in circuit between A and B, oue
pole of the battery is connected to b aud the other to the sliding
contact, which is moved about until no current is detected in
the galvanometer. The reading is taken, and similarly, cd, etc.,
are connected with battery, and contact adjusted as before.
Iu this manner the wire is accurately divided into 20 equal
parts. The corrections for the readings are obtained by sub­
tracting those lengths which are found by multiplying ,', of the
A Compilation of Rules, Tables and Data.
total length of the wire by the number of resistances between
BY CHARLES M. SAMBS, ELECTRICAL ENGINEER.
A and the mercury cup connected to battery.
Another method consists in passing a weak but constant
1. Measurement of Resistances below 100 ohms (Fig. a).
current through the wi
The galvanometer C is placed between dexi&g; the battery z
between /• aud /', and the resistance x between /; and g*', The
strap m is opeued, / and k are closed, and /is plugged. /' is a
battery key. Theu is
a : iooo — a x : 1 (where r 1, 10 or ioo ohms).
If x is very small, the bridge wire should be lengthened to
10 ohms ; then is
a : 10000 — a x : r
If still smaller resistances are to be measured, the strap k is
taken off and a rheostat inserted between the binding posts, by
means of which the bridge wire may be sufficiently lengthened.
r e, and measuring the difference of potential
between a succession of points at small equal distances
from each other.
Two metal contacts with knife edges are fixed to slider of insulating
material separated by a distance of say 50 mm. Wires
are run from both the contacts to the terminals of a suitable
mirror galvanometer. A Daniell cell, or better yet, an accumulator
iu series with 100 — iooo ohms gives sufficient current for
the measurement. For comparison, the potential differences
between the ends of the wire are observed before and after the
calibration, which, of course, should be equal. If the wire is
1 metre long aud the distance between the sliding contacts 50
mm., the correction in mm. = 50 ( — 1) ; where i is the
throw of the galvanometer for the potential difference at the ends
of 50 mm. ofthe wire, aud A the throw for the entire length of the
wire. The table of correction is made by taking for lengths of
100, 150, 200 mm., etc., the algebraic sum ofthe corrections corresponding
to the single parts making up these lengths. The
wire may be tested for homogeneity by sliding the two contacts
along the wire. If the deflection of the galvanometer remains
steady during this movement, the wire is homogeneous. F'or
practical purposes long lengths of homogeneous wires are
selected ; for exact measurements, a table of corrections must be
prepared.
c). The method of Hockin and Matthiessen (Fig. 50) for
measuring low resistances is based on the same principles as
the calibration of a bridge wire.
FIG. 50.
Let the resistance R — 0.01 ohm.
This may be the parallel resistance of ten 0.1 ohm coils
which can be very exactly measured. Mercury cups should be
on the copper blocks to which the wires are soldered.
A B is a calibrated bridge ware. The points a, b, c, d, which
are at the same potentials as a', b', c', d', are determined by
means of a galvanometer.
0.01 a' b' ,
Then
c' —,— d' ohms.
It will be seen that in this method the contact resistance is
eliminated, and that the constancy of the current plays no part.
d). Method of measuring resistance by measuring the potential
at the terminals of two resistances (F'ig. 51).
This method is adapted to the simple determination of low
resistances, such as those of dynamos for electro-deposition,
the determination of the conductivity of copper wire, etc.
The resistance-V to be measured, a comparing resistance A 5 ,
accumulator A, key S, and rheostat Rlt are connected in a circuit.
The intensity of the current is regulated by the rheostat,
so that X and R are not appreciably heated.
From the terminals of A' and R heavy wires of practically no
resistance run to a switch key, from there to a commutator,
thence to a galvanometer, along with its resistance r.

80 ENGINEERING MECHANICS. [February, 1892.
ist Method.—On depressing the key .S, the switch is turned
so that the terminals of X are connected to galvanometer, aud
the deflection is noted. Similarly with R, again with A", and
so on until no uneven numbers are obtained from mean values,
which is as follows (see Currents) :
mean.
f
1
'^vD-r^HO
y^Hh^
s
2d Method (Uppenborn, 1SS9).—The first method may be
greatly simplified as follows if the resistances X and R are
about equal.
r is made equal to

March, 1892.] ENGINEERING MECHANICS. 81
ENGINEERING PROGRAMME FORTHE COLUMBIAN EXPOSITION.
OFFICE OF
EXECUTIVE COMMITTEE OF ENGINEERING SOCIETIES,
COLUMBIAN EXPOSITION.
78 La Salle Street.
Chicago, III., funitary, 1S112.
EXECUTIVE COMMITTEE—CIRCULAR NO. 2.
To the Members of the General Committee of Engineering Societies :
Simultaneously with your organization to provide for Engineering
Headquarters and an International meeting of Engineers in 1893, the
matter of Congresses was taken up by the " World's Congress Auxiliary."
The " World's Congress Auxiliary " is an adjunct of " The World's
Columbian Exposition," maintained by the latter for the purpose of pro­
moting a series of World's Congresses in 1893. The address of the
President of the Auxiliary, Hon. C. C. Bonney, to the delegates of the
Engineering Societies which met in Chicago on the 15th of last May,
will be found in the report of that meeting.
It was at that time contemplated by the " Auxiliary" that the Engi­
neering Congress should be made a sub-division of either the department
of Science and Philosophy, or of some department of applied science,
but the delegates ofthe Engineering Societies, before adjourning, passed
the following resolution :
" Resolved, That it is the sense of this Committee, that the importance
of Engineering entitles it to the place of an independent department in
the World's Congresses to be held in 1893, under the auspices of the
World's Columbian Exposition."
We now have the pleasure of reporting, that this recommend tion has
been fully accepted by the governing authorities of the " World's Con­
gress Auxiliary;" that Engineering has been made an independent de­
partment, and that its conduct has been entrusted to a General Com­
mittee of the Auxiliary on Engineering Congresses, appointed by Presi­
dent C. C. Bonney, which consists practically of your own Executive
Committee, already appointed by the Engineering Societies of the
Lfnited States and Canada.
We enclose herewith copies of the circular of Hon. C. C. Bonney,
President of the Auxiliary, stating the scope ofthe Engineering Depart­
ment and the objects of the Auxiliary, also copies of the preliminary
announcement of the General Committee of the Auxiliary on Engineer­
ing Congresses, containing a scheme of organization and of classification
and a proposed order of proceedings. The following list of sub-divisions
indicates the classification. It is proposed to assign the work of organi­
zation and management of the various diusions as stated below :
Division A.—Civil Engineering, to American Society of Civil En­
gineers.
Division B.—Mechanical Engineering, to American Society of Me­
chanical Engineers.
Division C.—Mining Engineering, to American Institute of Mining
Engineers.
Division D.—Metallurgical Engineering, to American Institute of
Mining Pingineers.
Division E.—Electrical Engineering, to American Institute of Elec­
trical Engineering.
Division F,—Military Engineering, to Engineer Officers, U. S. A.
Division G.—Marine and Naval Engineering, to Engineer (Ifiicers,
U. S. N.
The order of proceedings, and the list of subjects from which selec­
tions may be made for the work of the congress, are tentative, and sug­
gestions are cordially invited.
There will probably be occasion for several joint ses.ions of two or
more divisions, to discuss questions of general interest, and these,
together with the programme and the order of papers and discussion,—
to avoid duplication or mutual interference,—will be in immediate
charge of the General Committee of the Auxiliary, in consultation with
the officers of the several divisions.
It is desired that the various bodies to whose care these several divi­
sions are entrusted, shall take early steps towards organizing their divi­
sions. I laving already their own organizations and established relations,
they are in the best position to begin the preparatory work at once, and
to prosecute it to a successful termination with scarcely any expense.
Tlie usual plan heretofore in vogue for organizing International Con­
gresses in Europe, has been to appoint in advance a number of Honor­
ary Presidents, who act virtually as patrons, two Chairmen and four to six
Vice-Chairmen, to provide for unexpected disabilities, four or five Honorary
Secretaries and one General Secretary, also an Advisory Council com­
prising both home and foreign members : in addition to which foreign
and domestic kindred societies have been invited to send delegates to
the Congress.
The various Engineering Societies to whom the several divisions are
assigned, may either pursue this plan, or they may, if they prefer, organ­
ize the division through their own regular officers, making such addi­
tions thereto, as suggest themselves, to give a representation to kindred
organizations, elc. They may also prefer to have this Congress take the
place of their regular summer meeting, including therein all local socie­
ties and delegates of Engineering Societies throughout the world.
All this may be done subject to approval by the General Committee of
the Auxiliary, as seems best to each society, but the important part of the
work to be done, would appear to be to provide in advance for the selec­
tion of interesting subjects for discussion : the preparation of analyses of
subjects, and the perfecting of arrangements wdiich will insure desirable
contributions to the discussion; also the securing of valuable voluntary
papers, their examination, etc., and arranging for their discussion.
These papers should be invited from engineers all over the world, in
order to make the Congress truly international, and should preferably
treat of new and important constructions, machines, processes, methods,
etc., provided they are in actual use, or experiments and investigations,
including proposed standards of tests and measurements. Advance
copies or abstracts will be printed at the expense of the " Auxiliary " or
ofthe Associated Engineering Societies, as may hereafter be determined,
and the papers and discussions or translations thereof, if the original be
in French, German, Spanish, etc., may be included in the transactions
ofthe society organizing the division. It is moreover expected that they
will also be printed in the publication contemplated by the " World's
Congress Auxiliary," which is to furnish also the halls and rooms for
holding the Congress.
While there is sufficient time for the work contemplated, during the
eighteen months yet to elapse before the Congress, there is none too
much. It is therefore hoped that the various bodies to whom the work
of organizing the divisions is assigned shall enter at once upon its per
formance, or shall promptly notify the undersigned Executive Committee
that they decline to undertake it, so that it may be assigned to other
parties.
BUSINESS OF THE DIVISIONS AND SECTIONS.
The work of every Division will consist in :
First: The discussion of subjects chosen by the officers of the Division.
Second : Reading of selected voluntary papers, and discussion thereon.
The officers of each Division will be expected to cause Analyses of
the Engineering subjects selected, to be prepared by specialists in ad­
vance, to serve as an introduction to the intended discussion ; and also to
endeavor to secure the attendance of engineers prepared to discuss them.
Voluntary papers to be solicited from engineers throughout the world,
in either English, French or German, not to exceed fifteen minutes in
presentation, and not previously published or communicated to any
Society, are to be sent in advance to the Secretary of the Division for
which they are intended, and passed upon by its officers. Papers or
Abstracts will be printed and distributed if received in time, and the
discussions will be under such rules as may be formulated by the under­
signed General Committee of the World's Congress Auxiliary.
The Committee therefore bespeaks the co-operation of all engineers in
making this Congress a success It is only through their aid that its
work can be made satisfactory.
The following tentative classification of subjects is submitted, and sug­
gestions are invited in relation thereto, and in regard to all other matters
connected with the Congress, to be used in the formation of the final
plans.

82 ENGINEERING MECHANICS. [March, 1892.
Civil Engineering.
SUBJECTS.
GENERAL DIVISION—A.
RAILWAYS.—Location, constniction, equipment, operation, maintenance
and terminals.
CANALS.—Construction and operation.
WATER WORKS.—Dams, aqueducts, filtration and distribution. Pumping
and Gravity Systems. Reservoirs and aeration.
Rivt-R IMPROVEMENTS.—Regulation and control.
HARBORS.—Jetties, breakwaters, lighthouses and other signals, piers,
docks, wharves and dredging. Removal of obstructions to navigation.
DRAINAGE.—Sewage and sanitation.
ROADS.—Highways, streets, pavements and curbing.
RECLAMATION OF MARSHES, SAND DUXES.
FOUNDATIONS.—Independent piers, piles, coffer dams, caissons, pneumatic
and other methods.
TUNNELS.—Subways, shafts and deep wells, Ventilation of tunnels.
STRENGTH AND EMPLOYMENT OE MATERIALS. Testing machines,
tests.
SURVEYING.—Land, cities, public works, etc.
STREET RAILWAYS.—Animal, cable and electrical, etc.
INSTRUMENTS OF PRECISION.—Transits, levels, etc.
MASONRY.—Viaducts, arches, aqueducts, bridges, walls, etc.
BRIDGES.—Truss, plate-girder and suspension. Cantilever- and
arched-girders.
CONSTRUCTION OF BUILDINGS AND TOWERS.
HANDLING AND STORAGE OF GRAIN, COAL, ORES, ETC.
ELEVATED RAILWAYS.—Underground Railways.
IRRIGATION.—Artesian wells, hydrography.
CONSTRUCTIONAL APPLIANCES.—False works, cranes, etc.
GENERAL DIVISION—B.
Mechanical Engineering.
SUBJECTS.
MOTORS.—Steam, air, explosive, hydraulic and wind.
MACHINES.—Excavators, dredges, cranes. Planting, cultivating and
harvesting machinery. Animal, steam and manual power machinery.
Brewing and distilling apparatus. Wood-working machinery, pulp
making and wood preserving apparatus, logging tools and machinery.
Tanbark, turpentine and charcoal manufacture. Hydraulic rams and
SUBJECTS.
EXTRACTING ORES.—Iron, coal, copper, zinc, lead, tin, nickel, etc.
DRIFT AND PLACER MINING.—Gold, silver, diamonds, and other
precious metals and stones.
BORING.—Petroleum, natural gas, salt water and prospecting.
PREPARATION OF ORES.—Roasting, concentration, etc.
EXTRACTION, SEPARATION .\NI. RRFINING OF PRODUCTS.
EXPLOSIVES.—Gunpowder, nitro-glycerine and allied explosives.
Location, loading and firing of blasts.
MINE WORKING.—Timbering, ventilation and safety appliances.
Draining.
ORE WORKING MACHINERY.—Boring and cutting, crushing and
pulverizing apparatus.
ASSAYING.—Methods employed and comparison of results.
SURVEYING.—Prospecting and mapping. Instruments of precision.
GEOLOGY-.—Mineralogy.
QUARRYING AND ALLIED INDUSTRIES.—Graphite, asphalt, asbestos,
clay, building stones, limestone, marble, cement, gypsum, salt, borax,
phosphate, slate, etc., quarries and mines.
Metallurgical Engineering.
SUBJECTS.
GENERAL DIVISION— D.
SMELTING.—Furnaces, stacks, stones, direct processes.
IRON.—Manufacture of various grades of cast and wrought iron.
Fuel, waste products, economy, etc.
PUDDLING.—Furnaces, malleable iron processes. Mechanical puddlers.
STEEL.—Bessemer, basic, and open hearth processes, etc.
ROLLING MILLS.—Plates, rails, beams and shapes of various kinds.
Long pieces, rolling from fluid metal.
STEEL.—Working and tempering of steel for tool and constructional
uses.
WIRE.—Manufacture, sizes, strength.
FORGINGS.—Methods of manufacture. Sizes.
Ai 1 MINIM.—The pure metal and its qualities. Its alloys and their
qualities. The manufacture.
ALLOYS.—Gun metal, type metal, bronzes, etc. Their manufacture
and qualities.
FUELS AND FLUXES.—Their nature, costs and effects.
REDUCTION AND WORKING OF OTHER METALS.—Copper, zinc, lead,
tin, nickel, etc.
GENERAL DIVISION—E.
Electrical Engineering.
TELEGRAPHY.—Systems: duplex, quadruplex, multiplex, etc. Rapid
telegraphy. Cable telegraphy and instruments. Batteries and telegraph
dynamos. Circuits. Induction telegraphy.
TELEPHONES.—Systems, transmitters, switch-boards. Automatic apparatus.
Magneto bells. Long distance telephony. Induction and
retardation.
LAMPS—Arc lamps and carbons, incandescent lamps and filaments.
Manufacture and durability. Sockets.
Wi RES. — Overhead systems, underground systems, cables. Insulation.
DISTRIBUTION.—High tension, direct; low tension, direct; alternating.
Simple circuits, compound circuits. Series and parallel systems.
BATTERIES.—Primary and secondary.
< GENERATING MACHINERY.—Dynamos, alternating and direct. High
and low tensions. Armature and field windings. Methods of regula­
presses, elevators. Fire apparatus, engines, ladders, standpipes, chemition. Commutators. Mechanical details.
cal engines, etc. Sawing, planing, moulding and veneering machines. MOTORS.—Direct and alternating current motors. Armature wind­
Stone working machines. Ventilating and warming machinery, stoves, ings. Regulating devices. Commutators and mechanical details
ranges, hot-air and steam heaters. The phonograph.
APPLIANCES.—For measuring and controlling currents of electricity.
INSTRUMENTS OF PRECISION.—Scales, meters, measures, etc. Switches, rheostats, meters, safety appliances.
TOOLS.—Lathes, planers, emery wheels, presses, drills, punches, saws, TRANSFORMERS.—Methods of winding, loss in conversion, heating,
shears, wood working tools, etc.
designs.
ROLLING STOCK.—Locomotives, traction engines, cars, power brakes. MINING AND METALLURGY.—Boring, drilling and firing, pumping.
POWER TRANSMISSION.—Cables, shafting, belting, compressed air, Reduction of ore.
steam, hot water, hydraulic pressure.
\\ ELDING,—Welding, brazing, soldering, tempering and forging.
HEAT TRANSMISSION.—Steam, hot air and hot water.
TRANSMISSION OF POWER—Short distances, long distances.
STEAM GENERATORS.—Boilers and settings, furnaces and grates, SIGNALS.—Bells, annunciators, automatic calls, individual calls, etc.
mechanical stokers, stacks, forced drafts, fuels, smoke consumers.
RAILWAYS.—Single and double wire systems, rail transmission sys­
GAS MAKING.—Coal gas, water gas, vapor gas machines. Distributems, geared and gearless motors, generators. Trolley and underground
tion, consumption and measurement.
systems. Storage battery systems.
TESTING MACHINES.—Tests.
ELECTRO-PLATING.—Current, solutions time, etc.
REFRIGERATION.—Ice making and cooling machines.
HEATING.—Resistance devices. Thermostats.
CARLE RAILWAYS.—Pneumatic railways. Rack railways.
EXECUTION.—Apparatus for destruction of life.
PUMPS, filters, blowers, fans and miscellaneous machinery connected
with engineering work.
PHOTOCRAPHY.—Electrical devices for same.
SANITARY ENGINEERING AND APPLIANCES.
GENERAL DIVISION-F.
PETROLEUM.—Pipe lines. Distilling and refining.
Military Engineering.
GENERAL DIVISION—C.
SUBJECTS.
Mining Engineering.
FORTIFICATIONS.—Breastworks, arsenals, magazines, pits, mines.
Protection of rivers and harbors.
ORDNANCE.—Light and heavy guns, rifled bores, breech-loading.
Small arms, magazine guns.
PROJECTILES.—Balls, bombs, shells, bullets.
EXPLOSIVES.—Gunpowder,gun cotton,high explosives,compressed air.
TRANSPORTATION.—Roads, bridges, pontoons, transport boats, wagons
and animals.
ACCOUTREMENTS.—Tents, ambulances, camp utensils and balloons.
SANITATION.—Water supply and drainage.
ARTILLERY.—Light and heavy, and their accessories.
SIGNALING.—Methods and systems, range finders.
SURVEYS.—Topography, mapping.
GENERAL DIVISION—G.
Marine and Naval Engineering.
SUBJECTS.
SAILING VESSELS.—Ocean, lake, yachts, ice boats. Methods of rig
and oi handling sails.
STEAMSHIPS.—Steamboats, tugboats, steam launches, etc.

March, 1892.] ENGINEERING MECHANICS. 83
NAVAL MOTORS.—Steam, hot air, electrical, gas, etc. Boilers, auto
matic stokers, engine regulators and kindred appliances.
DESIGNS.—Hulls, interiors, rigs, etc.
WAR SUITS.—Armored, monitors, gunboats, cruisers, etc,
ORDNANCE AND ARMOR.—Offensive and defensive.
TORPEDOES.—Torpedo boats, guns and nettings.
SUBMARINE VESSELS.
DIVING APPARATUS.—Armor bells.
HYDROGRAPHIC SURVEYS.—Deep sea soundings.
VESSELS FOR SPECIAL SERVICE.—Ocean and lake freight or passenger,
fisheries, etc.
APPARATUS, ACCESSORY.—Capstans, windlasses, steering machinery,
blocks and tackles, anchors and allied appliances.
SIGNALS.—Lights, rockets, flags, systems, etc.
LIFE-SAVING APPLIANCES.—Boats, rafts, life-line guns, kites, etc.
INSTRUMENTS OF PRECISION.—Sextants, chronometers, compasses, etc.
The special object of this address is to elicit from engineering organi­
zations and individuals, suggestions for the promotion and success of the
proposed Engineering Congress, and to inaugurate consideration of the
subjects to be discussed, and of the special papers to be prepared. All
periodicals and individuals to whom this address is sent are cordially in­
vited to favor the Committee, at their early convenience, with such
recommendations as they may deem conducive to the desired end, and
to co-operate in making the Engineering Congress a success.
Inquiries and communications should be addressed to the Chairman.
E. L. CORTHELL, Chairman, 205 La Safe St., Chicago, 111.
J. D. WHITTEMORE, Vice-Chairman.
O. CHANUTE, JOSEPH HIRST,
C L. STROBEL, E. M. IZARD,
JOHN W. CLOUD, WILLIAM FORSYTH,
THOS. APPLETON, ROBERT W. HUNT,
F. W. GROGAN, E. M. BARTON,
I. O. BAKER, H. L. HOLLIS,
General Committee.
NOTE.—The Committee is authorized to state that the assignment of
Electricity to the Department of Science and Philosophy, as well as to
the Department of Engineering, is to be regarded as merely a double
assignment of an important subject. In the former the scientific, and in
the latter the practical aspects of the subject will have the leading place,
but each of the departments will be free to consider the subject in any
relation within its scope. This rule will also apply to any other case of
a double assignment of a subject.
SOME EXPERIMENTS TO DETERMINE THE STRENGTH OF
AMERICAN VITRIFIED SEWER PIPE.
BY MALVERD A. HOWE, C. E.
By Civil Engineering Rose Polytechnic Institute.
This is the title of a pamphlet sent us by the author, a reprint
from the "Journal ofthe Association of Engineering Societies."
The author details in it the methods used and results obtained
in an exhaustive study of the properties of vitrified sewer pipe
as furnished by different makers from various parts ofthe coun­
try, the manufacturers knowing that the pipe was to be tested.
To insure impartiality the pipes were lettered and numbered as
soon as received and thereafter known by such signs only. Five
tests were made as follows :
I. The Hydrostatic Test, to determine the bursting strength
ofthe pipe and also the tensile strength ofthe material.
II. The Drop Test, to determine the relative capacity of the
pipe to resist " percussive action."
III. The Concentrated Load- Test, to determine the strength
ofthe pipe when subjected to a concentrated load.
IV. The Uniform Load Test, to determine the strength of
the pipe when subjected to external pressure under the condi­
tions found in practice.
V. The Cementfoint Test, to determine the strength of joints
made of cement when subjected to hydrostatic pressure.
Then we find a description of apparatus and methods employed
with illustrations. In the determination of bursting
strength three methods were used with a view to the determina­
tion of their respective merits. In the first method the ends of
the pipe were closed with wooden lids covered on one side with
shut rubber, the lids larger than the pipe, drawn together by iron
bolts near the circumference ; considerable end pressure was thus
brought to bear upon the pipes. In the second one of the lids
was made to fit into the bell resting ou the inner flange, reliev­
ing the bell from pressure. In the third method the pipe was
closed by heads supplied with cup-leathers, as in an ordinary
pump, no end pressure being exerted ou the pipe. In all three
methods water was forced through one of the heads by means
of a force pump until the pipe burst, the water pressure being
read from a gauge. Details of apparatus are fully described and
figured.
The drop test was made with a gravity hammer of hard wood
loaded with iron weighing 18 lbs. The pipe was supported on
two pine strips 2" wide and 16" from centre to centre ; then,
with rounded face, was allowed to fall from a height of 12" for
five blows. If the pipe remained unbroken the fall was increased
by 6" for five blows, and so 011 until the pipe was fractured.
The concentrated load test was made in the ordinary manner.
The uniform load test was made by placing the pipe in a box,
surrounding it with sand, and applying pressure on a heavy lid
by means of a hydraulic press of 15 ton capacity.
The cement joint test was made on two lengths of pipe ce­
mented together, in the same manner as the hydraulic test for
bursting, under the two conditions of the ends of the pipe being
prevented from separating and ends free to separate.
Results are tabulated in two tables, together with description
and conclusions.
Tables I. to V., give the results for such pieces of pipe tested.
Table I. Hydrostatic test gives the ultimate strength per sq.
iu., calculated in the ordinary manner, mean diameter, average
thickness, pressure in lbs. per sq. in. required to burst the pipe
and the method employed.
Table II. Drop tests. Dimensions of pipe as above. Maximum
height of drop required to break, number of blows struck, and
two values, II' h and W V, designed for comparison of different
pipes.
Table III. Concentrated Load tests. Dimensions of pipe,
pressure required to crack, and pressure required to entirely
break the pipe.
Table IV. Uniform load test. Dimensions, pressure to crack,
maximum load applied (the pipe in most cases could not be
collapsed), depth of sand above pipe.
Table V. Strength of cement joints. Dimensions of pipe,
character of joint, cement used, age, pressure required to break
joint, remarks. The four last tables are condensations of the
previous one and are given on the next page. The letters in the
column class have reference to the manufacture of the pipe only.
The extremes for tensile strength differ very widely even
from the average 600 lbs. per sq. in.; a I2 /7 pipe broke under a
pressure of 12 Ibs. per sq. in., giving an ultimate strength of 68
lbs. per sq. in.; a 10" pipe stood 365 lbs. per sq. in. before burst­
ing, giving a tensile strengtli of 1825 His. per sq. in. The aver­
age 600 lbs. per sq. in. was based on tests by the cup leather
apparatus. As was to be expected, the pipes usually failed by
splitting longitudinally. Strong pipe shows even fracture of
uniform colors, gives a peculiar bell-like tone ou being struck
with a light piece of steel; pipes showing a series of concentric
laminae were as a rule weak.
The drop test shows wide extremes, breaks from oue blow
of 12" fall being recorded up to 30" and 139 blows; 79 pieces
were twisted in this manner, 20 breaking from the I2 -/ blows.
The concentrated and uniform load tests do not show such
wide variations. In the uniform load test, pipes, after cracking
frequently, withstand the entire pressure of the machine, the
pieces probably forming a kind of arch.
The cement joint tests are very interesting, the joints seem­
ingly being very unreliable, blowing out under very small pres­
sure. When the pipes are prevented from separating, it seems
that the ring joiut is superior to the bell aud spigot joint.
Wuen bell and spigot en Is were roughened, the joiut was much
stronger. The extremes were from failing under immeasurably
small pressure to 148 lbs. pressure per sq. iu. in the pipe.

s4 ENGINEERING MECHANICS. [March, 1892.
TABLE VI.
The Average Ultimate Tensile Strength in Pounds per Square Inch of
the different sizes of Pipe of the different classes respectively.
(Compiled from Table I.) •
• Ultimate Tensile Strength for the sizes given below.
E
F
G
H
1
J
*K
L
M
N
P
2
3
1
2
3
1
2
3
1
2
3
3
3
3
3
3
3
3
3
-399
-596
-476
-457
-226
-493
I—581 2—266
1—284
2—476
2-487
2-7 5S
-714
-301 1—504
• • , 1—436
1—142
2—243
3—494
1—376
2—846
i-345
'—745
870 i 1—931
3-314
775 2—547
&54
723
213
1—39'
1—261
2—635
1—988
1—124
1—68
2—501 3—762 3—503 1—832 3—785
1—492 3—471 . . . 1—587 2—250
. . . 1—329 1—461 2—528 2—720
1—9 lS 1—673 3-393 • • - 2-781
1—800 1—908 1 2—1070 1—S47 1—959
1—9S3 1—1095 . . . i—S60 1 — S36
1—430 1—1660 1—963 1—1825 1—531
• • • 3—S77 3—766 1—416 4—360
* K 3 18 in.—1—529. 21 in.—3—617. 24 in.—2—856.
NOTE.—The figures on the left indicate the number of results combined.
TABLE VII.
The Average Tensile Strength in pounds per square inch of the Pipes
of different classes and tested by different methods. (Compiled
from Table I.) Also the colors of the fractures corresponding to
the greatest strength.
Class.
Average Ten-f 1 . . 245.8 476.0 576.0 .
sileStr'ugth I 2. 582.8 359.5 424.0 455.7 470.8 727.3 271.0 . .
by method . t 3; 814.0 616.3 435-S 744-7 • • • • 252.0 665.3
No. of results
combined .
Average Ten-
inlbfpe^s* j I 669 ' 5 442 ' 9 442 ' 9 582 ' 9 47 °' 8 727 '3
inch . . .
Color of frac-'
ture corresponding
to
greates t
strength . .
1
rf c
"5 is
SS
--;
u
*J
(j V
v
i/i rt
^5
p
0,
O .
co-S
0
tie
••5 fi
-c 0
•5 fi P
-a 0
V
C
tf* tf* CiQ O
CJ
-1
TABLE VII.—(Continued.)
Average Tensile f 1 ' . .
Strength by ^2
method . . . . " ( . 3 427.4 547-7 647.7 939.0 943.5 1081.8 618.6
No. of results combined
Average Tensile J
Strength in lbs. - 427.4 547.7 647.7 939.0 943.5 1081 8j 618.6
per sq. inch ... J
Color of fracture")
corresponding to -
greatest strength . J
Brick
Red.
Terracotta
Red.
'3
TABLE VIII.
Dark Dark Dark Dark
Stone Red sh Red'sh Reddish
Drab. Brown Brown Brown.
Dark
Stone
Drab.
The Thicknesses of the various sizes of Pipe under the assumption
that the ultimate strength of the material is 600 pounds per square
inch, that the pipes are subjected to a hydrostatic pressure of 100
pounds per square inch, and that the pipes are on the point of
bursting.
nn . i . n
Nominal Diameter in Inches. 2 in. 3 in. 4 in 5 in. 6 in. 8 in.
Thickness in inches .
Average thicknesses as '
manufactured . . .
Nominal Diameter in Inches.
Thickness in inches 0.83
Average thicknesses as man- ]
ufactured / '"
0.16 0.25 0.33 0.42 0.50 0.66
0-63 , 0.59 0.64 0.64 0.76 0.S2
* Extra heavy.
TABLE IX.
1.00 I 1.50 1-75
2.00
1-05 1-39 '1.89 '2.02
The Average Ultimate Strength in Pounds per Square Inch of the dif­
ferent sizes of Pipe. (Compiled from Table I.)
Nominal Diameter in 1
T u 4 in.
Inches.
1 3 6 5 2 -6
General average of}
methods i, 2 and 3 / 3 * 7 '~
Number of resuhs ( ,•
combined . . . . /
6 in.
289.0
532.1
761.0
677.8
25
3 in. 10 in. 12 in. 18 in. 21 in. 24 in.
^59 0
351-5
6 5 1 A
55*-9
26
554-5
7998
701.7
•5
608.5
5S95
592-1
29
529.0
529.0
1
617.0
617.0
3
856.0
856.0
We give here a brief, very much condensed table of the
tests:
AVERAGE RESULTS OF TESTS OF THE STRENGTH OF
Jj
z
a j
c c
c.S
"A
4
6
8
10
12
18
21
24
-5 1!
u, C 3
tj oj a*
|s§.
8-i-s.d
"S5.S.S
X
517.2
677.8
55'-9
701.7
592.1
529.0
617.0
S56.0
VITRIFIED SEWER PIPES.
a-i S
0 c°
S .

March, 1892.J ENGINEERING MECHANICS. 85
We have but little comment to make upon the tests and dis­
cussion as a whole, believing it to be a most important aud
valuable contribution to our knowledge of the properties and
strength of American sewer pipe ; the only tests heretofore
made were on English pipe. Mr. Howe certainly has shown
great skill iu the arrangement of apparatus and much patience
in their execution. All practical men who have to use sewer
pipe in their work will be greatly aided in writing specifications
and selecting pipe by this investigation, though the
designation of the pipe is somewhat mysterious. In tests such
as made by Mr. Howe, the aim should be to make them conform
as nearly as possible to actual conditions under which
the pipe is usually laid and put; this seems to have beeu well
kept iu mind by the experimenter, though in the table of Drop
Tests we find two columns headed Wv and Wh, betokening
that there was a desire to combine theoretical aud practical as
usually expressed.
We are disposed to agree with the author that ll'h is fully as
expressive of the information sought to be conveyed—namely,
comparative strength of pipe—as ll'v. Neither, however, seems
to us to be of great value. We must, iu both cases, take into
consideration the number of blows struck ; in this necessary
repetition of blows, we produce with each blow some fracturing
which produces a new physical condition for the subsequent
ones. Quibbling over the manner of expressing tbe strengtli
seems unnecessary. What we want to know is whether if a
careless workman rolls a boulder iuto a 6 foot deep trench ou an
uncovered pipe, the section will have to be taken out. It would
have been interesting and valuable to have made a series of
experiments upon the effect of continued vibrations transmitted
through gravel or frozen soil to the pipe,—a condition
likely to arise in railroad practice. In the hydrostatic tests the
method by cup leathers seems the only fair one, as pipes were
broken by the end pressure in the experiments before water
pressure was applied. In the cement joints we find food for
reflection. It is certainly evident that they are extremely unreliable
as made iu ordinary practice. We regret that the
author made no experiments on joints caulked with spun
yarn or oakum and cement, and trust that we may hear from
him again. Bends, K's, etc.,'are also interesting subjects for
investigation.
It is evident from the results obtained by Mr. Howe that
sewer pipe, as ordinarily furnished, is a very uncertain quantity.
We trust engineers will bear this in mind, and that Mr.
Howe will continue his work. We hope he may at some time
devise a readily applied test by means of which we may ascertain
the quality of the pipe. That it should be tested before
used is evident from Mr. Howe's results. We should also be
benefited by some form of specification by which we could better
insure control in public works. We add oue modest wish,
that he may devise some joint which should be cheap and
effective, equal to the strength of the pipe, and so arranged
that it could not be put together in a slipshod manner,—the
great temptation to contractors.
The experiments, as far as carried out, will undoubtedly be
classical, and should be carefully studied by both manufacturers
and engineers. They show a great amount of labor,
care and intelligent design in their performance. We trust
that means may be found to continue them.
LLOYD'S have issued a circular calling attention to the
straining which takes place in the structure of petroleum bulk
steamers through the improper use of water ballast. The cir­
cular says: "Sufficient care has not been taken to insure that
the tanks have been quite filled, and kept filled; and a deep
empty tank has even sometimes been run up at sea whilst the
vessel was encountering heavy weather. By these means great
strains and damage have been caused from masses of free water
being brought against the bulkheads internally. Carrying
liquid iu bulk, independently of the nature of the cargo, causes
considerably more straining on the plating and riveting of vessels
than would occur in carrying general cargo. Provision
should be made so that the consecutive tanks in the midship
part can be quite filled. These spaces should be subdivided,
particularly at the fore end, to such an* extent that the trim of
the vessel will admit of the tanks being quite filled, without
the statutory depth of loading being exceeded. Experience
has also shown that danger arises from not filling tbe water
spaces at the end of the stokehold with water, so as to prevent
oil finding its way into the coal buukers and saturating the
coals."
The Graphite Industry is fittingly represented by the Company
whose founder first gave it birth.
The Joseph Dixon Crucible Co., Jersey City, N. J., was founded
by Joseph Dixon in 1S27, who, at that time, began the manufacture
of black lead crucibles aud completely revolutionized
the crucible business. All crucibles used at the present day for
melting brass, steel, copper, gold, silver, nickel, etc., are made
of blacklead (the common name for graphite), and by the Dixon
process.
The Dixon Company have not only been progressive, but they
have been aggressive, and have pushed their goods into all parts
of the civilized world. During the past year they made extensive
changes in their factories, aud we take pleasure in showing
bv the illustration above the main works and offices located in
Jersey City. Their graphite mines are at Ticonderoga, N. Y.,
aud their cedar mills are at Crystal River, Fla.
The nature of graphite, sometimes called Plumbago, or blacklead,
is not generally understood ; aud therefore, its great value
in the mechanical arts has not been fully appreciated. Graphite
is oue of the forms of carbon. It is not affected by heat, cold,
acids, alkalies or any known chemical solvent. It is also the
best solid lubricant known to science, a remarkable conductor
of heat and electricity. The peculiar qualities of Graphite have
given it a wide range of usefulness. It is used in the manufacture
of lubricants for all purposes, crucibles, stove polish, lead
pencils, foundry facings, electrotyping graphite, graphite paint,
etc.
The Dixon Co., are miners as well as importers of graphite in
all its forms, and use no graphite that they do not mine or prepare.
Their mines are located in Ticonderoga, N. Y., and they have
every facility in the way of chemists and expensive machinery,
etc., necessary for completely freeing the graphite from the
silica, sulphur and other impurities which it contaius when it
comes from the mines.
The company's illustrated catalogue of graphite productions
is an interesting pamphlet and well worth reading. It is sent
free on application.
THE town of Oluey, 111., is putting in water works. The contract
for pumping engines, boilers, heater, etc., has been awarded
to The Laidlaw & Dunn Co., of Cincinnati, Ohio.

86 ENGINEERING MECHANICS. [March, 1892.
THE SAWYER-MAN ENGINE ROOM.
The capacity of the Sawyer-Man Electric Co. is a production
of 10,000 Incandescent Lamps per day, and as each lamp requires
a tenth of a horse power to test and standardize it, the
power to operate such a plant for its Electric purposes alone
must necessarily be considered.
An interior view of the remodeled Engine-room of this Company
shows the Engines ranged in a single row down one side
of the room and belted direct across to tbe Generators.
The Engines are io in number, as follows:
1 SA'' x 5" Westinghouse Standard Automatic,
1 TA" x 7" Westinghouse Standard Automatic,
1 10" and 18" x 10" Westinghouse Compound Automatic,
1 i5 // aud22 // x 13" Westinghouse Compound Automatic.
6 14" and 24" x 14" Westinghouse Compound Automatic,
aggregating 1,125 H. P.
With the exception of the I3 // and 22" x 13", whicli drives
the Machine Shop together with 20 geared or belted vacuum
pumps, these engines are used to drive the dynamos alone, as
follows :
2 Westinghouse Alternating Current, each delivering 35
amperes at 1,000 volts.
9 United States Alternating Current, each delivering 300
amperes at no volts.
1 Westinghouse Direct Current, delivering 1,000 amperes
at 80 volts.
6 Westinghouse Direct Current, each delivering 300 amperes
at 110 volts.
1 Umited States Direct Current, delivering no amperes at
110 volts.
3 United States Direct Current, each delivering 300 amperes
at 110 volts.
7 Thomson-Houston Direct Current, each delivering 300
amperes at 750 volts.
Iu the case ofthe 14" and 24" x 14'' Engines, these dyn a
are driven in groups of four by overlapping belts, two from each
side of the Engine.
Ou account of the recent substitution of the Westinghouse
Compounds for the originally placed .Single Expansion Engines,
the daily coal consumption has been reduced from 18 tons to
g'A tons; and right here it is proper to remark that a difference
in Engine water rates is not a perfect measure of the change in
fuel consumption. It is really but an index of the direction of
the change which is ordinarily much greater than the indication.
Although the actual saving by the gain in water rate was
probably not more than 30 per cent, in the present case, the
commercial result was nearly 50 per cent, gain ou account of
the decreased leakage and condensation with fewer boilers in
operation.
A TORPEDO BOAT, recently built for the French Navy by
Messrs. Augustin Normaude aud Co., has just completed its
trials with very satisfactory results. The boat in question is
11S ft. long by 13 ft. broad by S ft. 7 in. deep. It is armed with
one fixed tube in the bow, a swiveling tube in the stern, intended
for firing Whitehead torpedoes 18 ft. 9 in. long, and 15
in. in diameter, for which compressing pumps are provided.
In addition, two 37-millimetre Hotchkiss machine guns are
carried, as well as a couple of search lights and the necessary
dynamo. Two trials of the boat were made : the first, which
was intended to determine the quantity of fuel required to
steani 1800 marine miles at a speed of 10 knots, took place on
the 13th and 14th of November last. At the commencement of
the trial the torpedo carried io'2 tons of coal in addition to its
complete armament. On the first day of the trial the observations
extended over eight hours, and showed that the amount
of fuel consumed was 12.23 lbs. per marine mile; and ou the
second day, during a similar period of time, it averaged 12.48
lbs , showing a mean of 12.36 lbs per mile, whence tbe amount
required to carry the boat 1S00 marine miles at 10 knots per
hour is 9.93 tons. At the speed trials, which took place 011 the
24th of the same month, equally satisfactory results were attained,
the mean speed during a two hours' run being 23 6S4
knots, the boat being loaded with 9.93 tons of coal, and fitted
with her complete armament. During the trial tbe engines
ran at a speed of 329.3 revolutions per minute, and the boilers
of the Temple type, gave a good supply of steam.

April, 1892.] ENGINEERING MECHANICS. 87
ENGINEERING MECHANICS.
Devoted to Civil, Electrical, Mechanical, and Mining Engineering,
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
Entered at the Post-office in Philadelphia as Second-Class Ma il Matter.
SUBSCRIPTION RATES.
Subscription, per year
Subscription, per year, foreign countries .
PHILADELPHIA, APRIL, 1892.
. . $2
IN preparation for the next siege of Paris the French War
Department has taken steps toward the construction of an immense
establishment iu the city for the preservation of meat by-
freezing. Similar establishments on smaller scales will be attached
to the forts encircling the capital. The cold air will be
supplied to all from a central station operated according to a
new compressed air system.
THE objective point of builders of engines for ships of war
is the decrease of the ratio between the cylinders of the triple
expansion engines and cutting off earlier in the stroke. In
order to get as much power as possible from a giveu weight of
steam, it is desirable to reduce the drop between the cylinders
. by making the ratio of expansion in the succeeding cylinder
equal to the ratio between that cylinder and the preceding
one, and thus realize the ideal indicator card. Practice has
not yet determined satisfactorily whicli ratio of cylinders in
triple expansion engines is better, viz., I : 2-6 : 7 for 160 lbs.
boiler pressure, or 1 : 2 : 5 : 4-5.
THE electrolitic possibilities of common salt have never been
tested practically or theoretically ; but of late the turning to
economical account of electrolysis in its application to alkali
and common salt to the commercial production of the bases of
soda and chlorine is receiving more consideration. .Soda and
chlorine can be readily produced experimentally by passing
an electric current through a solution of salt, with suitable
electrodes. To produce these products from salt 011 a large
scale requires tanks, electrodes, connections and automatic
gear; but there is a special difficulty encountered in the manipulation,
viz., the disposition of the chlorine gas given off
from the electrolytic tanks. With lime, bleaching powder can
be produced, or with water, bleaching liquor. But setting this
aside, a greater difficulty presents itself in the construction of
the electrode at which the chlorine is given off. The metals
wliich will resist its active properties in its allotropic conditions
cost too much, and the use of peroxides is dangerous.
Carbon is not found to answer because of its rapid disintegration
through the action of the nascent oxygen. Electrical engineers
have a problem to solve in taking care of the chlorine
evolved in this process. Tbe commercial possibilities involved
will stimulate earnest effort iu the prosecution of investigation
in this direction.
J. WENDELL COLE, M. E., has issued a very neat pamphlet
embodying "Some Points about Grinding Tools," in which
he enumerates the advantages of the Sellers tool for grinding.
Tbe machine is furnished with former plates for grinding
all the forms of roughing tools we have found most useful iu
our practice, and also means to enable new former plates to be
originated from a sample tool made by hand or otherwise.
It is also provided with :
1. A chuck for circular or round nose tools, which is also
used in connection with former plates furnished to grind
curved-face roughing tools, right or left hand, and at any angle.
2. A holder to be used in grinding the side or base of the
shank of tool.
50
3. A chuck by means «.f which any bent tool can be ground
011 all its faces without changing its position iu its chuck, with
as much ease as the grinding of straight tools.
4. A chuck to bold splining or key-setting tools in the same
ill.inner.
5. A crane for lifting the heavy wheel cover, changing the
wheel on its spindle, or lifting tbe chucks, etc.
6. Tables or diagrams supported on a convenient holder,
upon which are figured fifty-six different kinds of plain-face
tools, showing all the angles and the position of the chuck
that holds them ; nine different shapes of either right or lefthand
tools, covering seven sizes of each, from ', inch to 2
inches, indicating the former plate to be used in each case ; a
table of circular tools which the machine grinds perfectly
without the use of former plates, and embraces all sizes from
'4 to 2 '+ inches diameter of circle.
7. Countershaft complete, and all necessary wrenches.
The directions furnished with this machine will permit the
reproduction of all the forms of cutting tools we have in use
in our own shop, representing years of experiment, and the
best form of fixed tools to enable machine tools to be used to
the best advantage. No matter how strong or well made a
machine tool may be, "its efficiency will depend wholly on
the form of the cutting edges of the fixed tools used in it, and
by means of which it produces its results."
A DEPARTMENT of Marine Engineering and Naval Architecture
has been established in the Cornell University, at Ithaca,
N. Y., where young men who have been properly prepared can
receive instruction in the above branches. The absence of such
special schools in this country has rendered it difficult for ship
and marine engine builders to obtain draughtsmen and designers
specially qualified for such work. The .School is under the
special charge of Prof. Wm. Frederick Durand and Assistant
Professor of Naval Architecture, George Robert McDermott.
The first three years of the course are devoted to Mechanical
engineering, aud the fourth to special instruction in Marine
construction. The various general systems of ship building and
their peculiar points will be studied, and all the innumerable
details of ship construction will be gone into. The subjects of
Marine Machinery, Ship Design, Naval Architecture, Specifications,
Contracts, Estimates and Laboratory work will all be covered
iu the course. The Board of Trustees have entered upon
this work with the determination to make it a valuable feature of
the University. There is great need of young engineers, possessing
a school familiarity with Marine construction, and it is
well that the opportunity has been opened for them.
AN English firm is making a new rope, which is called the
anti-corrosive and self-lubricating strand wire rope. In the process
of its manufacture, the cores and all the wires in the
strands are, we are informed, thoroughly coated with a preservative
composition called glissantoliue, which fills up the
interstices of the rope, aud makes it perfectly impervious against
corrosion, as by bad water, steam, or other deleterious matter
found in the workings of mines or elsewhere. It at the same
time acts as a lubricant to the individual wires, and insures
greater flexibility.
IT is stated that Commodore Folger, the Naval Chief of Ordnance,
has closed a bargain with the Harvey Steel Company, of
Jersey City, by which the Navy is enabled to use the process of
Harveyizing the surface of armor plates. The figure is much
lower per pouud than the Ordnance experts had thought it
likely the Harvey people could guarantee as the cost for admin­
istering the process of surface hardening. Plants fitted to carry
out the contract just entered into will be erected at the Carnegie
aud the Bethlehem works, where armor plates for the new ships
are beiug manufactured.

88 THE CONSTRUCTOR. [April, 1892.
Translated by Henry Harrison Suplee.
It is desirable to examine the value of the coefficient of friction/,
in order to increase it at the point 2. This cannot well
be done by choice of material, since wood can scarcely be used
in many cases, and lubrication of the rubbing surfaces is essential.
The application of wedge profiles to
wheel and friction block enables greater friction
to be obtained, Fig. 718, as in the case of
f wedge friction wheels, \ 196. Instead of the
f
coefficient/", we have the value --' -—-. If
sm A "
the wedge angle 8 = 6o° this gives 2/; for 8
= 30°, nearly exf. By combining this principle
with the preceding forms, some very
useful devices may be made.
It is desirable to arrange the application of
the force A" so as to exeit as small a distorting
actiou upon tbe parts as possible. This may
sometimes be done by arranging two or more
friction pawls of similar kind to act upon one
wheel. Some examples of such devices will
ii;
FIG. 718.
be found in the following section. It must
not be forgotten that the conditions for

April, 1892.] ENGINEERING MECHANICS. 89
th m S the curves at 2 and 3 portions of the same circle, and
corresponding curve at 3 so found as to produce the required
clamping action.
The clamping piece
b becomes a cylinder,
Fig. 727.
If we make the
angle 0 2 3 = t\
prolong the radius
3 O to V, then will
3 OiVbethe normal
to the curve at the
point of contact
with b at 3, since
the angle 3.30 =
1 . 2, or 111 other words the effectiveness
The pressures of the at clamping 2 and 3, Fig. action 728, is are
O T
not T impaired = '—, as R the cylinder
is reduced bv wear.
cos cr' COS 0
0
~, , whence 0 = /'
cos-o- V (a A

9o ENGINEERING MECHANICS. [April, 1892.
rotation of the wheel. Such a ratchet is shown in F'ig. 737.
I and 4 are parallel axes, the block acts with a radial pressure
Q, such that for the
circumferential force
± /'the following conditions
may exist:
Qf(a+ ax) > Pa, or:
(236)
If O is less thau
the right baud expression,
/-"will only be partially
opposed, there
FIG. will be motion from a
til-
toward d, with slipping
at 2, or in other words, we have a brake, see \ 24S.
This construction is frequently applied, although it requires a
relatively large force at Q', acting through the lever c c', giving
increased pressure 011 the axle aud much wear on the block.
Various forms of lever connection are used to modify tbe ratio
O' : Q. By clearing the angle
which the axes 1 and 4 make
with each other, various convenient
modifications may be
made. The general scheme
of such constructions is indicated
iu Fig. 738, in which the
toggle connection gives a high
ratio of Q' to Q ; the block
being guided in slides. By
making a au internal wheel,
a very practical arrangement
is obtained as shown in P*ossey's
coupling, Fig. 450.
Koechlin's coupling, Fig. 449,
is also another form of friction
ratchet gearing, the pressure
in this case being applied
by the medium of a right and
left hand screw. The same is
true of other forms of friction
coupling, and the various methods
of applying the pressure
FIG. 738.
?25
RELEASING RATCHETS.
and reducing the wear, given
in \ 24S, may also be applied
in the design of mechanism
for the purpose.
Following the classification given in "j 255, we have first discussed
the various forms of ratchets for the general meaning of
the term, and the five special classes remain to be considered,
the next being the so-called Releasing Ratchets. Such ratchets
must be considered primarily with regard to the question of release.
When the release is to be effected by hand, various
forms of handles or other connections to the pawls are readily
devised. Iu most cases, however, the release is automatically
effected, in which event, some mechanical tripping device is
required.
The resisting force in such gearing is practically the same as
the force required for release. It is applied usually by weights,
springs, steam or air pressure, etc., and is variously intended to
cause the released member to act with a predetermined velocity,
either slow or rapid, as may be required. Many millions of releasing
ratchetsbave been made for gun locks, and the various forms
of releasing valve gears for steani engines, introduced by Corliss,
but first invented by .Sickles,* are of this class. In designing
releasing valve gears, it is important that tbe valves should be
closed quickly yet without sudden shock, and hence some form
of buffer is essential. It is in the various devices for applying the
force, for releasing, aud for cushioning the released force that
the many gears differ from each other. The original form of
Corliss valve gear, and the modified form of Spencer & Inglis,
are but little used on the continent, but these are well known,
and hence examples will be given of some of the numerous
modified trip valve gears which have been put into practical use.
trigger is that part of the pawl upon which journal 5 of the releasing cam
is carried. The tooth profile at 2 should be " dead," but this is not the case,
as the curve is struck from the centre 3. The bearing points 011 pawl and
sector are of steel, separately inserted. The force which closes the valve is
FIG. 739.
exerted by a spiral spring acting on the rod/, and the valve is opened by the
rod connecting the arm c, with the engine motion. The cushion is effected
by an air dash pot, also acting through the rod f, and the instant of release
is determined by the governor.
Example 2.—Valve Gear by Wannich, of Briinn. In this case there are two
Example J.—Valve gear by Cail & Co., Paris, Fig. 739. a is the driven
piece, a sector with one tooth, fast to the valve stem ; b is the pawl; c the
arm, loose on the hub of a ; 1/ is the pawl spring; d the releasing cam. The
FIG. 740.
vry
* F. E. Sickles, of Providence, R. I., took out his first patent for a " trip
flat slide valves to be operated by the reciprocating movement of the piece c
cut-off" valve gear iu 1842.
It will be seen that this is a forin of ratchet rack gearing. The valves are

April, 1892.] ENGINEERING MECHANICS. 9*
closed by steam pressure acting upon small auxiliary steam cylinders on the
1 S "A cuslllon A third form is that used iu Shanks' planing machine, Fig. 744.
being provided by air buffers as in the preceding exam­
In this case the lever, with
ple. There are double pawls b, b, with "dead" tooth profiles, faced with
its axis a, is at right angles
steel; c is the pawl carrier, moved back and forth by the rod c'; b' b' are the
to b, and the latter is pro­
! c'
triggers, and rfdthe releasing stops, the latter shown in three successive
0 Sj
vided with a roller. The
positions ; e is a guide rod. The rod ct receives motion from an eccentric on
limit of measurement of a
i
the engine shaft.
is between 2' and 2".
f
Example 3—Valve Gear by Powel, of Rouen, Fig. 741.* This is a form of
I
2' i
rod ratchet gearing with bolt pawl. Here 6 is the driven piece in which the
The forms of tumbling
ratchets described iu # 239, J
^f..--tT---.
may be adapted as releasiuggears,
but it must not be
forgotten that in such mechanisms
provision must
T\T T.*be
made for the middle
position of the ratchet.
A fourth form of tumbling gear, of which, indeed, there are
many varieties, is the so-called "loop" of Hofmann's valve
gear, Fig. 745. The loop a is made in the arc of a circle from a
< AnP
.
—•-*•-*«,
--L
2°
r; ~J
FIG. 744-
FIG. 745. FIG. 746.
FIG. 741.
centre at 2, b is a heavy roller, with additional weight suspended
bolt b and its spring are carried. The rod a is moved up and down by an at d'. When the loop or curved link is in either of the positions,
eccentric. The piece c is guided at Cn. The trigger d acts sooner or later, as 3Q or 3', the weight acts to continue the motion in the direction
the governor changes the position of the trip e. Ihe force to close the valve in which it started until the limit of travel is reached.
is steam pressure acting on the upper part of the rod C\, which also carries A swinging arm b may be substituted for the slot aud roller,
an air buffer.
Fig. 746, and it will be seen that during the movement from the
The use of releasing ratchets in valve gear of steani engines position 20 30 to 2' 3' the tumbling action will take place and the
is very old, being found in the old Newcomen pumping engines, arm a be carried over. The similarity to the previous tumbling
and in the Cornish engine a similar gear is used to-day, while gear will be apparent. If 2. 3 be made infinitely long, the loop will
in recent times trip valve gearing of various designs have come become straight and the two forms will coincide. Hofmann has
into extended use, and some of the forms are shown in Figs. made the analogy to a ratchet train more complete by placing a
670 and 671, not only for closing the valves, but also for opening
them. These latter valve gears are intended to be operated
ratchet so as to engage with the point 3 in the positions 30 and 3',
the release beiug made at the proper time by means of a cataract.*
by direct connection with the piston movement, while those in In some cases it is desirable to make a gearing which shall be
the preceding examples are operated from revolving crank released by the action of a very small force. For this purpose
shafts.
a second releasing gear may be introduced, itself being readily
Releasing gears which are to be operated by reciprocating released, and by its action permitting a blow to fall upon the
members, are sometimes constructed on quite a different prin­ trigger of the main gear. Such a device forms a releasing gear
ciple, viz. : that of a weighted lever in nearly unstable equi­ of the second order. Such au example is shown in the hairlibrium,
so that it can be caused to fall to the right or left by trigger of a rifle.J Releasing ratchet gearings of higher orders
means of a slight thrust, and so operate a releasing member. A are also fouud in textile machinery, as in the Jacquard loom,
form which was formerly much used, in which the lever is also in the striking gear of tower clocks and of repeating watches.
carried on a horizontal axis, is shown in Fig. 742.
Another example is fouud in the relay of the Morse telegraph, besides
mauy other applications which will be considered hereafter.
FIG. 742. FIG. 743-
When the weight G is in the vertical position 1 . 2, the pressure
acts directly downward upon the axis, the journal friction
acting as a ratchet. The form is sometimes used on planing
machines, screw-cutting machines, etc.
Another form is shown in Fig. 743. Here the pressure is due
to a spring, acting through a liuk 3-2 upon 2.1.
* Further details of this and the preceding gear will be found iu the Austrian
Report on the Exposition of 1878. Section on Steam Engines by A.
Riedler, Vienna, 1879.
S253.
CHECKING RATCHETS.
Checking ratchets are used iu a great variety of machines, but
their principal applications are found
iu machinery for hoisting and lowering
heavy loads, as in mine lifts, elevators,
and the like, to guard against
accidents in case of the breakage of
the 2 ropes. In the opinion of the
writer these devices have not been as
yet regarded as they should be,
merely special cases of ratchet construction,
aud as such capable of utilizing
all the various priuciples heretofore
considered. When examined
in this light their study will be greatly
facilitated.
As a scheme of a general system for
checking ratchets a rod friction ratchet
may serve, Fig. 747, iu which the rod
a is held stationary, the loaded member
d carries the ratchet, and the pawl
c and friction block b are held out of FIG. 747.
* See Zeitschrift des Vereins deutscher Ingenienre, i860, Vol. IV., p. 209.
t Such hair-triggers were ingeniously applied in former times upon crossbows.
J-*"

92 ENGINEERING MECHANICS. [April, 1892.
engagement by the releasing lever / and rod e as long as the
hoisting connections g and h, are under stress. If the tension is
released, the ratchet is thrown into gear and the parts clamped.
If a toothed ratchet is used instead of a friction device, the
block b is omitted. According to the manner in which the
various constructive details from a to h are arranged, we obtain
the various systems of checking ratchets which have found
practical application.
A collection of such devices was exhibited by the Industrial
Association (Verein fur Gewerbfleiss) in 1879* More than 80
designs were shown, of which only a few cau be described.
Many of the devices were rather designs for improved construction
as regards strength and rigidity, rather than examples of
mechanical ingenuity.
In most cases the clamping action takes place upon the upright
timbers of the shaft ; sometimes guide ropes are used.
The greater number of designs shown used friction clamps,
those of the type of Fig. 724 being shown, the thumb pawl
being roughened, however, or finely toothed. The one which
showed the most evidence of careful constructive design in
accordance with the principles previously laid down in ''/. 248,
was that of Hoppe, shown, as attached to each side of the
hoisting car, iu Fig. 748.
FIG. 748.
The form of friction pawl used is similar to that shown in
Fig. 713, there being four pawls on each side ofthe car, or eight
in all. The clamping action takes place upon the guide bars a,
made of T iron, as shown. At 1 are the guide rods between b
and a; at 2, the double clamp blocks of hardened steel, which
are connected at 5 to the coupling rods c, e. The actuating
springs is a torsion spring (see Fig. VII, p. 64 ; also Fig. VIII,
p. 64), secured to the roof of the car at^", g, and operated by
the releasing gear/ at 8, and transmitting action from 6 to 5 by
the rods e, e, the connection being made by the links 9 to the
double chaiu in such a manner that the arm/cannot be drawn
too far out of position. The proper adjustment of the pawl
arms is obtained by the keys ou the rods c, c. Hoppe has taken
into consideration the fact that the angle a, see (255), must not
pass beyond certain limits, or too great pressure would be exerted
on the frame d, d, and hence has provided stops in the
frame for the tiavel of the pawls c, c. The parts are so proportioned
that a load of double that ever placed upon the car wou'd
be supported by the friction clamps before there would be an
appreciable elastic yielding of the frame. The adjustments of
the rods c, c provide for the change of relations due to wear.
This apparatus does not bring the lowering car to a sudden
standstill in case of breakage of the hoisting gear, but the shock
is avoided by the gradual action of the friction brakes.
By using the author's device, shown in Fig. 717, at 3, the
value of a might be maintained constant, or by proper construction
of the guides the wedge friction pawls, similar to Fig. 718,
may be used ; the blocks acting on both sides of the guide.
This would reduce the stress upon the frame very materially.
The system of brakes used upou railway trains are really
* Berliner Verhandlungen, 1879, p. 345. Prize essay by Dr. F. Nitzsch, on
Safety Checking Devices for Mining Apparatus. See also Mairs, Berg und
Hutteumann, Z., 1879, p. 361.
forms of friction checking ratchets. The shocks due to sudden
stoppage are also to be avoided, aud if the wheels are braked
too firmly the sliding action is simply transferred to the rails.
2 254.
CONTINUOUS RUNNING RATCHETS.
Continuous ratchets (? 235, No. 4) consist of such combinations
of pawl mechanism as act to drive a member in a given
direction with practically a continuous determinate motion.
This may be effected by combining two single running ratchets
in such a manner that they both act upon the same wheel, one
pawl attached to the arm c, which is stationary, the other swinging
about the axis 1, Fig. 749, this being a very common form.
FIG. 749.
In this case 3 . 2 is the checking pawl, and 3' . 2' the driving
pawl. A movement of the driving pawl, if a little more than
one tooth space, moves the wheel one tooth; a little more
movement than two spaces moves it two teeth ; and a regular
back and forth motion gives a forward movement at intervals of
a single pitch space.
If this device is made with step ratchets, as in $ 243, the pitch
may be subdivided into 2, 3, 4 or more parts, and for some purposes,
such as saw-mill feed motions, this is very desirable.
If the arm which carries the feed pawl swings about an axis
4, removed from 1, F^ig. 749 b, there will be a movement between
the pawl and the point of application 2 on the wheel;
while in the arrangement shown at a the motion of the two is
identical, aud hence no wear occurs.
The two pawls may be connected so that both of them become
drivers. If they are arranged so that their movement is
alternate, as in Fig. 750 a, the wheel will be moved forward for
FIG. 750.
the movement of the lever in each direction, giving a doubleacting
ratchet motion, the so-called Lagarousse Ratchet* This
may be also accomplished in various ways, as in Fig. 750 b.
For any movement of the arm which is less than 1 and more
than *2 the pitch, the wheel will be moved 1 pitch for each
vibration, and hence for a half vibration a feed of a half tooth
may be obtained. Step pawls may also be used with these devices
to obtain further subdivisions.
If, in Fig. 750 a, we hold the lever e, c2 rigidly, and instead
permit the arm d to vibrate with the same angle about the axis
4, the wheel moving with it, we obtain the same relative feed
motion.! This has beeu used by Thomson in a telegraph
apparatus.
* Named from the inventor, M. de la Garousse, and used in 1737. Belidor
Arch. Hydraulique. '
t This is the ordinary kinematic inversion.

April, 1892.] ENGINEERING MECHANICS.
A continuous ratchet gearing may be so arranged that backward
movement of the wheel is utilized to compel a uuiform
division of motion.
This is the case with the feed motion used by Gebriider
Mauser, of Oberndorf, in their revolvers, Fig. 751. In this case
FIG. 751. FIG. 75 2 -
a crown wheel is used (see Figs. 677 and 678). The wheel is at
a; bis the feed pawl, jointed at 3 to the slide e, the whole being
carried in the frame d. The zig-zag profile is formed in the rim
of the crown wheel, one portion being parallel to the axis, the
other spirally inclined, so that the angle of thrust is o < 90 0 —
tp and > 0 (| 237, cases 4 and 5). The movement of the pawl
produces a backward movement of the wheel. It should be
noted that at 2' and 2" steps are made in ends ofthe tooth profiles
in order to guide the pawl into the proper path and keep it
from reversing.
The anchor ratchet of Fig. 682 maybe used for a feed motion,
as in Fig. 752, in which there is also the reverse action of the
wheel, in accordance with the notation of \ 237- Here the wheel
is at a and the anchor at b' b". When the latter is moved into
the position shown by the dotted lines, the wheel is moved
backward A pitch, and the return vibration completes the pitch
movement. In order that the anchor shall enter the teeth properly,
the movement should be quick, especially at the entrance
of the pawl into the space. This is well obtained by electromagnetic
action.
FIG. 753.
I 255-
CONTINUOUS RATCHETS WITH LOCKING TEETH.
If it is desired to use ratchets according to the method given
in Fig. 749, additional parts must be devised to move the pawl
FIG. 754.
FIG. 755.
93
111 and out of gear. A simple method of accomplishing this result
is to use a single tooth wheel for the driver, and operate
the pawl in the same manner as in F'ig. 753.
Before the single tooth 5 begins to drive'the wheel a, the arm
6 lifts the pawl b and lowers it into the next space just as the
tooth ceases to drive. Iu this case the usual gear tooth profiles
may be used. Still better is the "dead" tooth profile of Fig.
754, in which the entrance and withdrawal of the pin tooth
both lock the wheel while the pawl is beiug lowered.
This form may also be used for rack feed movement, Fig. 755.
Iu this case the profile of the pin tooth is formed in several
arcs ; 1' 2'" being struck from 3, aud 2" 2'" and 2' 2'v being
the paths of the corners of the space (see j) 203).
By using the cylinder ratchet, as shown in Fig. 696, the number
of parts can be reduced, since the driving gear and checking
pawl may be combined in the same member. The resulting
forms, Figs. 756 to 758, are variously called: Maltese Cross;
FIG. 756. FIG. 757- FIG. 758.
Geneva Stop, used in Swiss watches, in which case one of the
tooth sections is filled out ; or after Redtenbacher we may call
them single tooth gears, although this is hardly correct, for the
general form of Fig. 758 may have several teeth, and a second
tooth is dotted in Fig. 756.
A great number of variations may be made of these cylinder
ratchet motions. An interesting form is the iutermittent gearing
of Brauer, Fig. 759.*
FIG. 759. FIG. 760.
The pinion a is the driver, and the wheel b is driven, and
between the passage of each tooth of the pinion the driven
gear remains stationary for a short space, about \ of the pitch.
The points of the teeth of the driven wheel here act as ratchet
teeth, iu a similar manner to the arc of repose of the single
ratchet gearing of Fig. 756.
The cylinder ratchet gearing of Fig. 760 is similar to that
shown in Fig. 700, aud is used in the counting mechanism of
English gas meters. In Fig. 761 is a modified spiral ratchet of
FIG. 761 FIG. 762.
the same general type as F'ig. 702, with only a portion of the
path of b in a spiral, and a similar variation of Fig. 704 is showu
in Fig. 762.
; Royal German Patent, No. 5583, 187?.

94 ENGINEERING MECHANICS. [April, 1892.
LOCKING RATCHETS.
3256.
Locking ratchets include all the numerous devices by which
the parts of a mechanism are firmly held against the action of
external forces, and yet readily aud definitely released when
desired (see jj 235, No- 5) ; thus the various clutch couplings are
included, also car-couplers and similar devices.
Locking ratchets occur frequently in the mechanism of firearms,
especially to prevent the danger of premature discharge,
etc. The great refinements which have been introduced in such
weapons during the last ten years include especially the application
of various forms of ratchets. The following single instance
will serve to illustrate :
The mechanism of the well-known Mauser revolver may be
divided into two series; one to effect the discharge and the
other to unload or remove the empty shell from the chamber.
The first may be called the discharging mechanism, the second
the unloading mechanism. We then have the following details:
A. Discharging Mechanism.
This includes the revolving chamber, barrel, hammer, spring
and accompanying smaller parts, giving as combinations :
I. Hammer, spring-rod and trigger = ratchet rack, as Fig.
659.
2. Spring-rod and trigger, acting as locking ratchet for the
above, as Fig. 664.
3. Spring-rod, pawl aud revolving chamber = continuous
ratchet with crown wheel and bolt pawl, as Fig. 751.
4. Securing pawl and revolving chamber — locking ratchet,
as Fig. 677.
5. Revolving chamber and pawl, forming a ratchet gearing
with limited travel.
6. Tumbling ratchet and securing pawl — ratchet gearing
for three positions, Fig. 669.
7. Catch on the axis of hammer = locking ratchet, as Fig.
695.
8. Trigger guard and pin = locking ratchet and stationary
pawl.
9. Checking-plug and trigger = locking ratchet with stationary
pawl.
10. Rifled barrel and bullet = screw and nut.
B. Unloading Mechanism.
This includes an axial slide which catches under the rim of
the empty cartridge shell to withdraw it, actuated by a toothed
sector and revolving clamp and axis called the ring clamp.
These include the following combinations :
II. Unloading slide and sector = slide with rack and pinion,
Fig. 3S1.
12. Axis of revolving chamber, with pawl to prevent endlong
motion, = locking ratchet gear, as Fig 695.
13. Ring clamp, barrel and chamber bearing = locking ratchet
gear with stationary pawl, as F'ig. 654.
14. Ring clamp axis and axis of securing pawl = locking
ratchet, as Fig. 701, forming with (13) a locking ratchet
gear of the second order.
15. Ring clamp axis upon the reverse motion of the ring
clamp forms, with the axis of the securing pawl, a
locking ratchet gear, which combines with (4) to form
a similar gear of the second order.
16. Securing pawl acts as a catch for the axis of the ring
clamp in the axial direction to form a locking ratchet
gear, as Fig. 695, forming also with (4) a similar gear of
the second order.
17. Ring clamp hub aud axis of securing pawl = locking
ratchet, as Fig. 695, and with (4) gives one of the
second order.
This analysis shows that in the Mauser revolver there are 17
mechanical combinations ; these are composed of 26 pieces.
Classified, these are as follows : 1 releasing ratchet, 1 continuous
ratchet, 2 driving ratchets, 11 locking ratchets, of which four
are of the second order, 1 screw motion and 1 slide motion.
A very important application of locking ratchet mechanism
is found in the signal apparatus of Saxby & Farmer for use on
railways, and made in Germany by Henning, Busing and others.
This includes many ratchets of higher orders, reaching to the
tenth, twelfth, or even higher. When this is used in combination
with the electric systems of Siemens & Halske, as in the
block system, we have the further combination of two systems
of the higher order with each other.
A branch of locking ratchets which exhibits a great variety
of applications is found in the different kiuds of locks, such as
are used for securing doors, gates, chests, etc. These extend
from the most primitive forms, made of wood, to the most re­
fined productions of exact mechanism, and their study possesses
an historic and ethnographic interest in addition to their mechanical
value.
A door forms itself a ratchet combination ; the door beiug
the part b, the strike the part c, and the bolt or other piece
which keeps it from being opened is the part a; doors with
latch bolts being ruuning ratchets, aud doors with dead bolts
being stationary ratchets.
A simple lift latch
aud door, as the furnace
door shown in Fig. 763,
is really a section of
a crown ratchet wheel
with ruuning ratchet
gearing.
A door with sliding
dead bolt, as used on
common room doors, is
a similar section of rat­
chet gear with stationary
ratchet.
In key locks, the key
is the releasing member
FIG. 763.
of the ratchet train, and also serves to actuate the bolt after it
is released. The key and ratchet mechanism are arranged in
most ingenious manners, so that numerous permutations can be
made to effect the release.
Some of the most important systems of lock construction are
giveu as examples :
Example /.—The common so-called French lock, Fig. 764, is similar t
ratchet of Fig. 753. The bolt is a sliding rack, the " tumbler " b being often,
FIG. 764. FIG. 765.
as in this case, made in one piece with its spring. The case of the lock corresponds
to the frame for the ratchet mechanism, and the key acts as the
releasing and actuating member.
Example 2.—-The Chubb lock, Fig. 765, which is always made with a
bolt, forms with the door and door frame a ratchet gearing similar to Fig.
691. The bolt is secured by means of several ratchets of precision, as in Fig.
706, and is moved by a ratchet as Fig. 755. The key, the axis 4, and the vari­
ous bittings ofthe key form a system of pawls. The whole is a ratchet system
Example of the second j.—The order Bramah with lock precision Fig. gear. a and Fig. 766 b, is differently constructed.
In this case the dead
bolt is actuated through the
medium of a cylindrical driving
ratchet gear, which does not
contain the mechanism of security,
the latter being in a
distinct portion of the lock,
Fig. 766 b. This consists of a
number of sliding precision
pawls, as Fig. 707, the number
being 6 to 8 (in tlie illustration
5). The member a of Fig. 707
is here made in the form of a
FlG. 766(?.
ring with internal teeth, se­
of precision
cured to the escutcheon a by
extreme position when the key is withdrawn^ screws. The key is a prismatic
adjuster of the slides, and the
whole is a locking mechanism
ofthe third order with ratchets
The spiral spring around the pin restores the slides to their
FIG. 766 b.
Excwi/tlej.—Thz Yale lock, Fig. 767 a and b, is also a system in w
mechanism of security is separated from the bolt mechanism. This is
again a system of the third order, with ratchets of precision. The key is a
flat prism (corrugated in recent locks) aud serves to place precision bolts, or
I

April, 1892.] ENGINEERING MECHANICS.
pin tumblers in proper line, and also operate the bolt. The figure shows
the method of connecting the cam 6Q to the plug a.
The so called combination locks are locking ratchets with precision pawls,
operated without a key by being placed successively in the positions for
release in accordance with a previously selected series of numbers and dial
marks.
The most general examples of uniform escapement are found
in watches. Iu these impulses are isochronous, and obtained
from the inertia of a vibrating body. Tbe wheel a is called the
escape wheel. The vibrating member, or balance wheel, makes
its oscillations in nearly equal times for great or small vibrations.
If, therefore, in a watch escapement, the time ofthe fall
of the pawl is less than tbe time of oscillation, the most important
requirement is fulfilled, namely, that for uniform periods
of time the same number of teeth of the escape wheel shall pass,
aud the corresponding angle may then be used as a measure of
time. A given amount of work may also be abstracted from the
motive power and used to produce the impulse. These important
points have been fulfilled in the design of escapements,
aud it has been made possible to measure time with a great
degree of accuracy. When the highest accuracy is demanded
FIG. 767.
the greatest care must be given to the construction and execution,
and to the reduction of friction and compensation of the
balance.
The numereus systems of Arnheim, Ade, Wertheim, Kleinert, Polysius, In the case of watches the duty of the impelling force is
Kromer, and"others are mostly locking ratchet systems of the fourth order,
simply that of overcoming the resistance of the mechanism,
or combinations thereof The American manufacturers, especially the
Yale and Towne Manufacturing Company of Stamford, Connecticut, have
the function of the escapement being to provide against any
shown great ingenuity iu this industry.•••
acceleration of the rate motion, aud the impulse which is required
to operate the escapement may be considered as a por­
2 257.
tion of the resistance of the mechanism.
A systematic discrimination between the various kinds of
ESCAPEMENTS—THEIR VARIETIES.
watch escapements will show that they vary as to the checking
Escapements may fairly be considered as among the most
ratchet
im­
device, the impelling device, the release and the accelerating
device. We may have Simple or Compound escapeportant
mechanical devices, since it is by their means that the
ments of the lower or higher orders. Some examples are here
elementary forces are used to regulate mechanical work. For
this purpose they are used in the greatest variety, all forming
given.
ratchet devices in which the driven member is alternately released
and checked. The arc, angle or path through which the
driven member passes between the interval of release and check
A. Simple Escapements.
is called the " range " of the escapement. During the passage
over this range there elapses a definite amount of time, which
may be called the "period" of movemeut of the escapement.
This is followed by an amount of time wheu the driven member
is stationary, called the period of rest. The sum of the two
forms the " time of oscillation." The range and the period of
oscillation may be (a) constant, (b) periodically variable, or (c)
variable at will.
We therefore have
a, Uniform escapements,
b, Periodical "
c, Variable "
and these will be briefly considered.
?2SS.
UNIFORM ESCAPEMENTS.
If, in ordinary running ratchet, Fig. 768, we have the wheel a,
FIG. 768.
impelled by a weight or other force, and suppose the pawl b,
lifted and dropped quickly, as by the arm bv the wheel will
move one space, and an escapement will have occurred. In
this case the range will be one pitch. If, after a definite time,
this operation is again and again repeated, we shall have a
uniform escapement. In mechanism the releasing and checking
action is produced mechanically and not by hand, the impulse
being obtained from the movement of the wheel.
» The ancient and modern Egyptian locks, also those of ancient Greece,
Rome, India and China, contain the principle of running ratchets with flat
pawls, actuated by a key pushed directly into the lock. The Egyptian lock,
with pin precision pawls, is quite similar to the Yale lock in principle, although
very different in construction. Ancient Roman locks, found in
Pompeii, are similar in principle. Wooden locks are still in use iu China,
Persia, Bulgaria, Russia and Southern Italy, also in the Farue Islands and
Iceland. At the suggestion of the author, Professor Wagner, of Tokio, succeeded
in inducing some Japanese lockmakers to make a very complete and
intelligible collection of native locks for the kinematic cabinet of the Royal
Technical High School at Berlin.
FIG. 769.
Example 1.—The Free Chronometer Escapement (Jullien le Roy, Earnshaw,
Arnold, Jiirgensen), Fig. 769. The running ratchet gearing a, b, c, is
similar to Fig. 768. The pawl b is provided with a flat spring 3. The impelling
device is the balance wheel d, which acts as a pendulum. The releasing
device is at 4 . 5, and is attached to d, and when it swings to the left,
impelled by the movement of the watch, it releases the pawl by means of a
second running ratchet at 5. At c' is a stop for the pawl b. At 5' is the accelerator
which, for each tooth of the escape wheel a, swings from 5' to 5".
As it returns, the pawl b engages with the tooth which has just left the point
5". The spring £'permits the releasing tooth 5 to pass back dnring the
return oscillation. The balance wheel can swing freely beyond 5" and back
without engaging with the escape wheel, hence the name " free " escapement.*
Example 2.—The Duplex escapement, Fig. 770, is derived from the ratchet
of Fig. 699. The escape wheel is upon the same axis as the checking pawl
FIG. 770. FIG. 771.
* This beautiful movement is apparently the first form which was applied
as a pendulum escapement, having been used by Galileo in 1641.

96 ENGINEERING MECHANICS. [April, 1892.
b ; the accelerator is at 4, acting upon the impelling pawl at every vibration
between 4 . 4'.
The so-called " verge " escapement is similar in construction, except that
the arm b' is longer and curved. The simplicity of this form as compared
with the preceding is due to the fact that the impelling and checking pawls
are made iu one member It will be noticed that the entrance of the tooth
of the escape wheel into the space, causes a slight reverse movement at a,
due to the fact that b is really a tumbling ratchet gear. This escapement has
been called duplex by its English inventor, although some contend that it is
properly a double wheel escapement, although the two wheels are combined
in one.
Example3,— Another method by which the checking and impelling pawls
may be combined is shown in the Hipp escapement, Fig. 771. This consists
of a simple running ratchet a, b, c. The pawl h is a plate spring, which is
lifted and dropped by the passage ofthe teeth. The acceleration is given by
the deflection of the spring. If the impelling force upou the wheel a is
great, two teeth will pass, but this can be detected by the note emitted by
the spring, which will then be one octave higher than before.
B. Compound Escapements.
Example ./.—Lamb's escapement. Those escapements which have two
escape wheels are properly classed as compound, and to this class belongs
Lamb's escapement. This consists of a running ratchet gear, similar to
Example i( and the same form of impelling device, but between these is an
FIG. 772.
internal wheel with pitch ratchet gearing, similar to Fig. 686, which is impelled
with each direction of vibration. Another double-wheel escapement
is Enderlein's, based on Fig. 702, also one devised by the author, like Fig. 686.
Example 5.— Mudge's Escapement (also invented by Tiede), Fig. 772. This
is a double ratchet gear system, with one pawl in compression and one in
FIG. 773. FIG. 774.
tension, b, and b». At 2'and 2" is a "dead" pawl action for checking, and
at //* and //" a running pawl action for impelling. (See Cases 5 and 7, \ 237).
The pawls are lifted by the pendulum d. The releasing arms 3'. 5' and 3". 5"
are moved alternately by the pendulum; for example, the arm blt being
moved into the dotted position, lifts the pawl out of gear, and the weight of
the pawl and arm (sometimes assisted by a spring), gives an impulse to the
return vibration of the pendulum, the acceleration being provided by the
escape wheel acting on the portion IF. A similar action takes place on the
other side.
Example 6.—Bloxam's or Dennison's so called " gravity'' escapement, Fig.
773. The escapement is controlled by a pendulum suspended by a spring at
4. The escape wheel is made in two parts, as Fig. 686. The accelerating
surfaces II' and II" are much better arranged than in the preceding example,
the friction being reduced. A fan is used also, as shown at e, for the
purpose of preventing great acceleration of the escape wheel, which might
otherwise occur in the large angle (6o°) of escape. The fan is not fast to the
axis of the escape wheel, but connected by ruuning ratchet so that its momentum
is not checked as the escape wheel is stopped.
Example 7.—Free Anchor Escapement, Fig. 774. The two pawls are combined
into one anchor, as in Fig. 682, and the action is much the same as
Fig. 772. The escape is controlled by a balance wheel at d. The pawls 2'
and 2" are operated through the arm b3, and at the same time the impulses
are given by the action of the escape wheel upon the incliued surfaces//'
FIG. 775.
and //" The pawls are technically known as pallets. The tooth action at
5 is a continuous ratchet gear similar to Fig. 754. The arm fo is limited in
travel by pins at 3' and 3", or in some forms by a fork at 4 Since there is a
ratchet at 5 and also at 2, this forms a system of the second order.*
I
FIG. 776.
* A watch escapement of the third order has recently been designed by A.
E-Muller, of Passau This is made with a cylindei ratchet, as Fig. 609*
between the arm and the escape wheel. "»V".

April, 1892.] ENGINEERING MECHANICS. 97
Example &—Graham's Escapement, Fig. 775. The construction is very
similar to the preceding. The connection 5 betweeu the anchor-arm A, and
pendulum d, is different, and the arm b, does not come to rest, but both it
and the pallets 2' and 2" slide upon the teeth while the escape wheel is
stopped. An earlier form of pallets for this escapement is showu at b\ and
b'2 (called Clement's Anchor, from Clement, 1680 ; but described by Dr. Hooke
in 1666). This form produces a brief reverse movement to the escape wheel
at each oscillation.
Example 9.—The form of ratchet of Fig. 684 is used in Lepaute's escapement,
which was really invented by the watchmaker Caron, afterwards
Marquis Beaumarchais.
Example /o.—Cylinder Escapement, Fig. 776. This is made from the
cylinder ratchet of Fig. 700, the impelling surfaces being divided between
the anchor and the teeth of the escape wheel. The cylinder b is attached to
the axis ofthe balance wheel, and the wide spacing of the teeth ofthe escape
wheel permits a correspondingly wide amplitude of oscillation. If we imagine
the pallets of Graham's anchor to be formed between two concentric
circles (as, indeed, most watchmakers construct them), the " cylinder'' will
be seen to be a similar anchor.
Example rr.—Crown Wheel Escapement, Fig. 777. Escapements constructed
with crown ratchet wheels _(§ 241) are the oldest forms used iu
FIG. 777- FIG. 778.
ratchets.* The form of the pallets causes a reverse movement, and in the
old watches using a balance with its centre of gravity in the axis of oscillation,
without any assisting spring action, this reverse movement was a
necessity, which accounts for the long and extended use of this form of
escapement. Toward the end of the fifteenth century the hair spring was
introduced by Hele, in the form of a hog's bristle, and in 1665 Hayghens
made the steel hair spring, which made the construction of the modern
chronometer possible. The crown escapement is easily modified so as to
remove the reverse action, as was done by the author in 1864. We then have
a "dead " tooth action, as Fig. 699. The modified escapement is shown in
Fig 1 - 77S; the pawls are practically hyperboloidal in form f
C. Power Escapements.
In the case of watch escapements the impelling force is only
used to overcome the resistance of the watch mechanism.
Escapements can also be used to regulate greater forces, such
as are intended to perform useful work, and these may be
FIG. 779-
called power escapements. Alarm and striking clocks are of
this class, and there are numerous other forms. The following
example will serve to illustrate :
* This has been used since the tenth century, having been invented by
Pishop Gerbert, afterwards Pope Sylvester II, about 990 ; al.so by Heinrich
von Wyck about 1370, and applied to a pendulum by Huyghens. The oldest
tower clock in Nuremberg, built about 1400, has such an escapement.
-f In the Kinematic cabinet of the Royal Technical High School there is a
schematic series of models of clock and watch escapements.
Example 12.—Power Escapement for a Reciprocating Movement, Fig. 779.
At a bi Ci and a b» c> are ordinary running ratchets, the pawls b\ and f>., of
which can be released and engaged by suitable auxiliary mechanism. This
mechanism is either a substitute for or identical with the legulating device
(balance wheel, peinluhin, etc.) of a watch escapement. The escapement is
intended to control the motion of the swinging arm C by means of the lever
c\ and the descending arm A}. This is accomplished by a double acting
ratchet system dx d-> 5 (as Fig. 671), by means of the slide e, driven from 8 by
the arm Cv>
The actiou is as follows: When the parts are in the position shown in the
figure, the motion of the wheel a to the right moves tlie arm c-, by means of
the pawl b\ until the trigger 10" trips the pawl , falls into gear, and the pawl be, is disengaged, leaving the wheel
a free for another forward movement.
The preceding escapement can be readily converted into a
double acting one by introducing a second ratchet wheel toothed
in the opposite direction, with proper pawl on cl and trigger
connections to d,,; the other portions would remain the same.
This escapement appears to be new, and many important applications
will suggest themselves.
PERIODICAL ESCAPEMENTS.
3258.
A great variety of periodical escapements are to be found
the striking mechanism of clocks and repeating watches. The
entire period is the revolution of the hour hand, and if the half
hours are struck the order will be
1, 1, 1, 2, 1, 5, 1, 4, 1, 12,
making iu all 90 strokes in the twelve hours. A fan regulator
is used to cause the strokes to follow each other uniformly.
There are two systems of escapement in use for this purpose,
the German and the English, the latter also used for repeaters.
An essential piece of the latter, the so-called " snail," has been
shown in Fig. 688 ; its function is to control the number of
strokes. Further subdivisions cannot be here discussed, but it
must be remembered that the striking arm is itself a ratchet
mechanism.*
Important applications of periodical escapements are found
in the self-acting spinning mule, and both these and the clock
striking mechanism are examples of power escapements.
The mechanism in Piatt's mule is here briefly shown. Fig.
7S0, a and 6. The shaft 1 is required to make rapid turns
FIG. 780.
through 90 0 at intervals of different lengths of time. The wheel
a is an escape wheel with teeth in four concentric rings, I, II,
III, IV (compare Fig. 686), each ring having one tooth. The
other side of the wheel a is shown in Fig. b, where is the ratchet
chain ade. When a is released, the pressure of d at 5'
moves it slightly and brings the running friction wheel e into
contact, thus driving a through a quarter revolution, toward the
close of which the pawl d again enters into engagement.
(To be continued?)
* See Ruhlmann, Redtenbacher, Denison.

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MDOO COSJ-O OOS] 00-sls]s]s) Os]s] O- OO-Ln'-nLO H-OMLnLo H VO OLn Lo M>JD 0-4- 10 M^SJ4- to M C0O4- 10 O OO'JI Lo MMDSlLnOJ M C004- iO OS]LALO MMP COLnLO MMDSILn to H
0 tO tO si 4 tO COCOCOOsi CO O OO MMP 04-00 COLnLn H \| Lo 4 M OtOOJ tO O COLn W OJ (0 M COO1 O C00004-OJ MS] OLA COOOOJ MVOS)LA4- too OOOLAO M-^OLA M M O OOO
;;
4
y.
ID
t- — o |
10
w
4
CS
G(C
o
-J^ | Heat ofthe Liquid.
Internal Latent
Heat.
, External Latent
Heat.
C^ I Heat ofthe Stear,
1 | Heatofl 'aporization
.V I Total I feat.
I Specific I Witn
1 Weight, in Pounds.
I of one Cubic Foot.
Pressure. Pound
i>er Squa re Inch.
Temperature.
I 1 emperature.
I Degrees Fahr
-G j Heat ofthe Liquid.
Internal Latent
Heat.
«^, j Heat ofthe Stea
-a I Heat of Vaporization
V t Total Heat.
°> | Specific Volume.
1 Weight, in Pounds,
I of one Cubic Foot.

April, 1892.] ENGINEERING MECHANICS. 99
I 12. Determination of the Moisture Contained in Steam.
1. In order to determine the evaporative
Object. power and efficiency of a boiler or the consumption
of steam of an engine it is important
to know the amount of moisture contained in the steam as
it leaves the boiler. A great number of methods have been
proposed and carried out to this end, not one of which, how
ever, can lay claim to scientific accuracy, although the results
obtained are in most cases sufficiently close for practical purposes,
and have furnished much valuable information.
2. The methods followed in the determi
Classification. nation of the quality of steam are in their
nature either :—
I. Physical, comprising
a. determination by calorimeter,
b. by weighing,
c. by superheating;
II. Chemical, comprising
d. the method followed ordiuarily,
e. the method due to Escher,
f. the method due to Brauer ;
III. Mechanical methods, under which may be instanced
g. the method due to Moeller.
3. I. The physical methods are all based
Physical methods. upon the mechanical theory of heat. Of
these the calorimetric method is the simplest
and the one in most extended use : it is also the oldest, having
been developed by Him thirty years ago.
4. a. The calorimetric method proceeds on
Manner of conduct- the supposition that particles of water carried
ing the test. over by the steam are commingled with the
latter iu the form of minute globules or bubbles,
the resulting mixture being a homogeneous one. Steam
is taken from the "main steam pipe through a branch pipe
with stop valve, terminating in a spiral coil and provided
with a rose. The steam issues through this into a vessel containing
cold water, by which it is condensed. If now the increase
in weight and temperature of the water is known, the
quantity of heat given off by the steam may be calculated and
the percentage of moisture contained in it determined.
Calculation 5 * For calculatin g the quantity of moisture
contained in the steani, let
M -\- m be the weight of steam under test, M being the
weight of dry saturated steam, m that of the
entrained water ;
I be the temperature ofthe steam ;
4*\ T the weight of water in the vessel before making the test;
/, and A, the temperature of this water before, and after admission
of steam ;
method under discussion is subject to the error of all methods
based ou tbe test of a sample, namely that a small quantity
only can be subjected to test, of which it is uncertain whether
the quality is that of the bulk of the sleam. Kxperiments by
Hirn and Hallauer placed the percentage of moisture found in
the steam at from 2 to 5 per cent. Another authority, making
tests under identical conditions, found these percentages to
vary from o to 5, so the calorimetric method of test was abandoned
in this instance, not being considered sufficiently accurate.
Loring and Emery, experimenting on the boiler of the
steamer Gallatin, using pressures of from 60 to 70 lbs., found percentages
varying from .05 to 4.8. In another set of experiments,
conducted in Germany, the steam tested was condensed continuously
by a small surface condenser, and tbe steam found
to be nearly dry, while calculations and tests on the performance
of the engines using the steam showed the presence of
from 7 to 8 per cent, of moisture. The calorimetric method
may, therefore, fail to give account of all the water present in
the steam.
Manner of conduct- 7. b. The method of iveighing is of a
ing the test. strictly physical character. It was originated
by Guzzi and Knight. Both make use of a
copper ball for measuring.
This ball is inserted in a vessel connected with the main
steam pipe, is filled with steam, taken out and weighed. Guzzi
places his receiving vessel on a branch from the main steam
pipe, and blows through before using. Knight introduces the
receiver into the maiu steani pipe, and arranges so that the ball
may be opened and filled and drained while in the receiver. A
later process is that due to Carlo, but is even less to be recommended
than the older methods described above.
8. For calculating the percentage of moist-
Calcu/ation. ure adhere to the notation adopted in par. 5,
and, in addition, let
Tbe the volume of (M-\- "0 lbs. of the mixture in cubic
feet ;
y the specific .1/ weight of dry saturated steam of the pressure
of the test ;
-/ui the specific (M+ weight m) of — Vy water.
We shall have
(51)
y
1 — ,
Neglecting, as is customary, / w the volume of the entrained water,
M= Vy
m = (M + m) — Vy (51 a)
The weight of water, 111, is therefore found by subtracting
from the weight of the mixture (M-\- m), the weight of an
equal volume of dry saturated steam. We must know, therefore,
in addition to the weight (M + '"), the cubic contents of
let 1, q, and r have the signification assigned in jj 10. The heat
the measuring vessel and the pressure or the temperature of the
contained in the steam and water before and after mixture
steam. The percentage of water is, as before,
being the same, we have the equation,
in
Mlt + mq + Nq1 = (M-\- m + N)gi;
y J/AAi M+m
from this we obtain after a simple transformation, and substituting
for A—q its equivalent from (51), r,
In the absence of experimental data it is impossible to judge of
(M+m)(?—q2)-N(q2-th)
As the temperatures concerned in this formula are low, Hirn
the applicability of this method in practical research.
substitutes for q, and q.L the temperatures /, and f2, so that
9. c. The Method of Superheating pro-
Manner of conduct- ceeds as follows : a certain weight of moist
(MJ-m) (1081.4 4- .3051 — *2) — N{t2 —'

IOO ENGINEERING MECHANICS. [April, 1892.
Copyrighted.]
GRAPHICAL STATICS and Its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
This case is, for example, the one of a right beam resting on
three level supports. The beam, in consequence of these sub­
jections, cau only take a single movement, viz. : a gliding
according to the horizontal of the supports ; but two supports
suffice to impose on it this obligation ; hence the third is geo­
metrically superfluous aud materially it hinders the free change
of form of the piece, since it requires three of its points to rest
always in a right line. It is then fully in conformity to the rule
of \ 50 that Statics leaves, in this case, the reactions ofthe sup­
ports indetermined.
I 57-
GRAPHICAL DECOMPOSITION OF A SYSTEM OF FORCES ACCOR­
DING TO ANY THREE LINES SITUATED IN THE PLANE OF THESE
FORCES ; CASE OF EXCEPTION.—The problems of research of
the reactions which form the subject ofthe two preceding para­
graphs are equal to this, that it is advantageous to treat of it
directly because of the numerous applications of which it is
susceptible: To find three forces having lines of action given
through the other a line x parallel to / m, then, through the
extremities of x, to draw parallels 1 and 2 to XX' and Y Y'.
If the three lines XX', Y Y', Z Z' were concurrent, the
problem would evidently be possible only if the force F passed
to their meeting point, and then it would be possible in an in­
and causing equilibrium to a system of given forces or, what finity of ways ; one of the components could be taken at random ;
amounts to the same thing, to the flow near the forces (

April, 1892.] ENGINEERING MECHANICS. 101
It is required to decompose the resultant according to the
three Iii es of action
xx', yy, zz',
which we shall designate by tbe figures
5, 6, 7.
Let us draw the funicular polygon of the four given forces aud to the sides which represent them on the force polygon the
relative to a pole O, by starting from a point 7 taken on one of corresponding numbers
these three lines, and let us form the contour 7. 1. 2. 3. 4. .">
', 2,-3, 4.
by prolonging the last side to its intersection 5 with the line
designated by this figure.
Give the three following numbers
The resultant F of the four given forces passes through the
point of meeting 5 of the two extreme sides of this polygon, is
parallel to a b, and is represented by this last line ; its intersection
with Z Z' is at /.
Let m be the meeting point of the two other lines XX', Y V.
We shall have, accordiug to the rule above, to decompose F
according to Z Z' and I m and this latter component according
by, parallels 5 and 6 to the lines 5 and 6 which cut each other
at x. The three lines a y,y x, x b are the components sought
according to Z Z', Y Y>', X X'.
But another process more convenient and, in general, more
exact in the graphical point of view, can be employed.
Let us undertake to find the three forces directed according
to 5, 6, 7 aud causing equilibrium to the given forces. These
forces will be equal and opposed to those which are sought.
Let us suppose the problems solved, and let 5, 6, 7 be the
magnitudes of the forces sought.
Starting from a point 7 of the line Z Z', let us conceive that
the funicular polygon be drawn relative to the pole O of all the
forces both known and unknown.
Let 7. 1. 2. 3. 4. 5. 6. 7 be this polygon, which is closed
just as the force polygon, since the system is, by hypothesis, in
equilibrium.
On the force polygon we know the contour formed by the
lines 1, 2, 3, 4, as well as the portion of the indefinite lines 5
and 7, the first of which passes through the extremity b of the
polygon of the given forces and is parallel to S or X X', and
the second of which passes through the origin a of the same
polygon and is parallel to 7 or Z Z'. That which it is necessary
to determine, is the position of the side 6 or x y which is parallel
to 6. This line will determine the magnitudes 5, 6, 7 ofthe
three unknown forces.
Of the funicular polygon we know the portion 7.1. 2. 3. 4. 5
whose sides are parallel to the radii 7.1, 1.2, 2.5, 3.4, 4.5.
Let us prolong, on the force polygon, the lines 5 and 7 to
their meeting at u and let us join O u.
On the funicular polygon let us prolong two of the given
lines, for example the ones XX' and Y Y', to their meeting at
m ; through this point let us draw m n parallel to Z Z', and let
us prolong 6.7 to its meeting with m n at n ; finally let us join
5 n.
Let us consider the six lines which join the four points
5, 6, ni, 11
of the funicular polygon, and the six lines which join the four
points
O, x, y, u
respond, in the second, the concurrent lines. Therefore, in
virtue of Corollary II of (S lift, the lines 5 ;/ and O 11 are parallel.
Hence the following construction :
Give to the lines of action ofthe given forces the consecutive
numbers
r 2 Q 1
A > —.9 -*, *j
5, 6, 7
to the lines of action of the three unknown forces.
Starting from any point 7 of the last of these lines, construct
the funicular polygon relative to any pole O of the given forces.
Let 7. 1.2. 3. 4. 5 be this polygon. Prolong the given lines
to XX' and Y Y', which requires, through the point b, to draw
5 and 6 to their meeting at m, and draw m n parallel to 7.
a parallel to I m ; through the point a, a parallel -jioZZ',
On the other hand, through the origin of the force polygon,
which determines the point y ; then, through the extremities of draw a parallel to 7 ; through its extremity, a parallel to 5, and
prolong the radius let fall from the pole and extending to the
point of intersection 11 of these two lines.
From the extremity 5 of the funicular polygon draw a parallel
to this radius; this parallel will cut m 11 at a poiut tl. Join
11 7, which you will prolong to its meeting with }' Y' at 6, and
join 6, ; then, on the force polygon, draw O x parallel to £>,
6 and Oy parallel to (J, 7; join xy. The three forces sought
will have for magnitudes and for flow b x, x y and x a.
Remark.—If the three given lines XX', Y Y', Z Z' meet at
one and the sime point m, the line ZZA coincides with m n, the
point 7 with it. The problem is then generally impossible; for
the line *"> n, coinciding in this case with 5, 7 which closes the
funicular polygon, will not be, in general, parallel to O n. If it
is, the two points 7 and •• which determine the line 6, 7 coinciding,
this line is indetermined. Hence, in this case, the problem
is either impossible or indetermined. A thing which is easy to
foresee ; for, if the resultant of the given forces does not pass
through the meeting point ofthe three lines XX', Y Y', Z Z',
we would not know how to balance it by three forces directed
according to these lines, and, if it does pass through it, we can
do so in an infinity of ways.
of the force polygon ; by construction, the five lines
The Fig. 34 and 34 (Plate IX) solve the same problem in the
case where the given forces 1, 2, 3, 4 are parallel to one
5 m, m n, ni 6, 5.6, 6 n
another, so that their force polygon whose origin is a aud extremity
b is reduced to a single right line. The given lines are
are respectively parallel to the ones
XX', YY', Z ZA', or ,*>, 6, 7. The solution is the same as in
x u, y u, x y, Ox, O y,
the preceding paragraph, and the numbering also, so that the
figure will be explaiued by taking the statement of the rule
and we see that to the two triangles which the first form cor­ which has just beeu proven,

102 ENGINEERING
§58-
BODIES HAVING TWO FIXED POINTS, OR RESTING ON FOUR
CURVES THROUGH FOUR POINTS. INDETERMINATION OF THE
REACTIONS OF THE SUPPORTS.—When a body, as those considered
(fi 51), has (Fig. 39, Plate IX) two fixed points O and
O' situated in the plane containing all the forces, its position is
not only determined, but it cannot be dilated freely, since the
distance O O' of two of its points is subject to remain invaria­
ble, whatever be the forces or -the calorific effects which would
tend to modify them.
Therefore, the equilibrium ought to take place, whatever be
the forces acting ; furthermore (\ 50) the reactions ought not
to be able to be determined by Statics. It is this which we
prove, iu fact, at once. Let R be the resultant of the forces
directly applied. We can take, on its line of action, any point
/ and decompose the force R into two, according to the lines
IO and 10'. These two forces represent the pressures exercised
on the two fixed points O and O'; the point / being arbitrary,
we see that these pressures are indetermined.
The same thing would take place if the body, instead of
having two fixed points O and O', was subject to be supported
on four curves A, B, C, D. There would then necessarily be
equilibrium between the reactions of these curves and the force
R. Let A O, B O be the normals to the curves A and B at
their points of support.
To subject the body to be supported at A and B on these two
curves is equal (\ 54) to subjecting it to turn arouud the point
of intersection O of the normals A O and B O.
Likewise, to subject it to be supported on the lines Cand D
is equal to subjecting it to turn around the point O', the intersection
of the normals C O' and D W to these lines. Then the
problem is the same as if the body had two fixed points O and O'.
By taking a point /on the resultant R of the forces directly
applied to the body and decomposing this force into two according
to I O and / O', then decomposing the one according to
/ O into two others accordiug to O A and O B, then the one
according to 10' into two others according to O' Cand O' D,
we shall have the pressures on the four curves ; and, as the
/is taken at random these pressures are indetermiued.*
MECHANICS. [April, 1892.
3 59.
THRUST OF AN ARCH SIMPLY SUPPORTED.—It is important to
state precisely the mode of indetermination which is spoken of
in the preceding paragraph.
FIG. 4.
Let us suppose (Fig. 4) any body whatever, for example an
arch of a bridge whose two extremities A and B are fixed.
Let R be the resultant of the forces, whatever they be, which
are directly applied to it (ordinarily, the weights are vertical
and the cord A B is horizontal).
Let us take a point / on this force, let us draw / A and / /3 /
and let us designate by ;- and r', not the components of R according
to IA and IB, but forces equal and opposed to these
components, i. e., equal to the reactions of the supports A and
B. On a force polygon (Fig. 4), let a b — R ; let us draw through
a and b parallels to A /and B / we form the triangle a O b, and,
since the three forces A', r, >' are to balance one another, 1. e.,
since the triangle of these forces is to be closed, we shall have
b O = r', aud O a = r in magnitude and flow.
Let us draw, through the point O, the line O u parallel to the
right line A B. We can decompose the force b 0 = r' into two,
represeuted iu magnitude and flow by b to and u O, the one parallel
to the resultant R which we call r'a (it is the vertical component
of the reaction, if the resultant R of the forces acting is
vertical), the other/' according to the cord 4-1? /.
Likewise O a = r is decomposed into O a or/equal and opposed
to fi according to the cord B A, the other is a parallel to
R aud which we call r0.
We see then that the arch supposed to be free is in equilibrium
under the actiou : i° of the three parallel forces.
(1) r0, R, ;-'„;
20 of the two forces
(2) /,/',
these last equal, directed according to the same line A B and of
opposed flow.
(The arch being in equilibrium, the forces which incite it satisfy
((J 46) the conditions of equilibrium relative to the invariable
systems ; but the last two satisfy it of themselves. It is
necessary therefore that it be the same with the first three.
Hence, when a body has two fixed points and when we decompose
each of the reactions into two : the one parallel to the resultant
of the forces directly applied, the other according to the
right line which joins the two fixed points, the components
parallel to the resultant of the forces directly applied are determined;
the components according to the right line which joins
the two fixed points are equal and of opposed flow ; but their
common value can not be determined by Statics.
In the arches of bridges, the first are generally vertical and
are called the vertical reactions ; the second are generally horizontal
and their common value is called the thrust of the arch,
* It is well sometimes to observe that the indeterniination is here a little
because in fact the arch exercising, on its supports (abutments),
less great than if the points O and O were actually fixed. For then the
point /can occupy any position whatever on the indefinite line according to pressures equal and opposed to the reactions ;- aud r', the verti­
which the force R acts, while here it can occupy only a portion of this line cal components of these pressure are equal and opposed to ra and
so that the line / O falls in the angle A O B and the line / O' in the angle rf and, consequently, known ; they tend to support the abut­
C Cf D. Otherwise, among the definitive components of R according to the
ments on their foundations ; while their horizontal components
four normals 0 A, OB, tl' Cand O' D, there are some which would not tend
to cause the body to be carried on its supports, and the corresponding reac­ equal and opposed to/and/-* tend to overthrow them by making
tions, i e., equal and opposed, could no longer exist,'the reaction of each sur­ them turn arouud their bases.
face A being able to be directed only in the flow A O.
(To be continued.)

April, 1892.] ENGINEERING MECHANICS. 103
ELECTROTECHNICS.
A Compilation of Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
3d Method.—r is left out. R is a bridge wire, 1 meter long,
of Nickelin (a german silver high in nickel). The contact on
R is moved about until the galv. needle remains at rest. If the
part / included in circuit = 152.5 mm., X 0.1525 R. R should
be adjusted to either 0.1 or 0.01 ohm.
FIG. 55-
5~^vwv|ti
R.
If r is included in one of the branches and =

104 ENGINEERING MECHANICS. [April, 1892.
If A 1 is a variable resistance (box) the range of measurement G galvanometer, C commutator, TV shunt, B battery, and S
is increased. By this arrangement from 0.01 R to 100 R may be battery switch. The entire arrangement, including the ends of
measured. the cable core, must be carefully insulated.
Varley's method is a modification of the above (Fig. 60).
FIG. 60.
n -j- 0,01m
100 —7t —0,01m'
Here the bridge wire is replaced by a series of 101 resistance
coils upon whicli slide two contacts which are so separated that
two coils lie between them. From these contacts lead two wires
to the series e fi oi 100 coils, whose resistances are equal to each
other, and whose total resistance is equal to that of 2 coils in
the first series.
The total resistance between the contacts d c on the first
series is consequently equal to that of one coil of the same series.
The fall of potential in one coil of the second series is equal to
TJ„th part of that in the resistance of the first series.
Practically, this arrangement is equivalent to having 100 coils,
each of which is divided into 100 parts.
The equation for determining the resistance x in question is
11 4- 0.01 111 „
x — ! R
IOO ll O.OI 111
In the laboratories of Clark Muirhead & Co. the 101 coils
have each a resistance of 10 ohms, the 100 coils each 0.2 ohm.
With this arrangement, from 0.0001 R to 10,000 R may be
measured. Fig. 61 shows the method of connections used by
the above firm (for insulation resistances of cable).
FIG. 61.
-43 V V W VA v
These bridges are also made with resistances 100 times as
great, and are then adapted to the measurement of insulation
resistances of longer cables.
B
FIG. 62.
rt). For the measurement of high resistances (e.g., the insula­ Other things equal, the resistances are inversely proportional
tion of cables) the method of direct deflections (h) is especiall}- to the respective throws of the galvanometer needle.
adapted, with the disposition in p'ig. 62.
(To be continued.)
g —
J-TTILJ .-
I 1
CZJ
In the first place the cable is replaced by a carbon resistance
aud tbe resistance of the circuit is determined, which is required
to reduce the reading of the galvanometer to one scale division,
without shunt, with the given battery. Let this resistance,
which is called the figure of merit, be R ; also let 11 be the reading
one minute after putting cable in circuit. Then is the insulation
resistance
R
x = —
11
1^, or the value of the leakage due to deficient insulation should
be subtracted from 11.
The measurements are made with a negative current, and repeated
an hour later with positive current. During the meantime
the cable core is grounded.
/). The method of Bright and Clarke is used to determine the
insulation resistance of joints in cables, and employs a condenser.
The joint to be tested is placed in a salt water bath in
a thoroughly insulated trough (Fig. 63), one end of the cable
FIG. 63.
being free and the other connected to earth through battery of
100-300 Daniell cells. A copper plate in the trough is connected
to one binding post of the condenser, the other terminal being
grounded. An astatic galvanometer of high resistance is placed
in shunt around the condenser.
The leakage from the joiut to the copper plate is allowed to
charge the condenser (for a certain time, say %, minute), which
is then discharged through the galvanometer. The absolute resistance
is not obtained by this method, but simply a comparison
of the joint and a certain length of good cable, which
necessitates a second measurement.

April, 1892.] ENGINEERING MECHANICS. TO5
PUMPS AND PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
(Continued from page yd.)
THE WORTHINGTON FIRE PUMP.—In fire pumps, the valve
areas and water passages should be larger than in ordinary
pumps, to insure the complete filling of the pump cylinders with
water wheu the machine is running at its greatest speed.
The superiority of the Worthington valve
motion is especially promineut iu steam pumps
applied to this service, for it enables them to run
without jar, or danger of derangement, at the
very high rate of speed that is sometimes re­
quired. With all forms of single cylinder pumps
under such circumstances, the concussion of the
water valves at each reciprocation of the plung­
er, and the blow upon the valve rod tappets, are
dangerously severe, aud render the machine aud
water pipes liable to fracture. To obviate this
difficulty as far as possible, the length of stroke
is ofteu unduly iucreased to reduce the number
of these concussions in a given length of piston
travel. It fixes, however, at a poiut that can
be greatly exceeded by the Worthington, the
practical limit of speed at which single pumps can be driven.
Worthington Fire Pumps, fitted with water pistons instead of
plungers, are furnished wheu desired. Such modification of the
regular pattern is recommended only in cases where, on account
of frost, no foot valve to keep the pump charged with water cau
be used on the suction pipe.
The stated capacities of the pumps of ten inch stroke giveu
below are based upon a piston speed of about 83 and 125 feet
per minute.
U
to
•a
a
*"-. 0
a
cfi
IM
O
J-
It
OJ
a
a
S
VA
9
9
IO
IO
12
12
14
14
16
16
i8'A
x8'A7
20
20
20
m
u
A
5
1 "i
2M
2
2f<
2,"'2
2 ' 2
4
4
3
4
4
3
3
3
5
6
0.
U)
C5
^:
v.
K
3 4
, 3 4
•^
'/2
»>i
3
3
3
2
3
3
3
A2
3
7
2
3
2 >2
3'
3
3
5
5
A A
6
6
3 l A
4
4
8
9
6
0.
s
0
in
A
1A
*A
2%
*A
1
1
1
2
Ai
*A2
*A
2 A
4
4
4
4
4
4
5
5
2^
4
4
5
5
5
5
5
6
8
be
u
ca
"o
15
; s
1
'X
«X
'^
X
34
/ 3 4
'X
2
2
2
2
2^
4
2K
2/*^
2j4
2 /'<
4
4
2
4
4
4
4
4
3
4
5
6
In addition to the sizes given in the above list, a large number
of other sizes aud combinations can be supplied to meet the re­
quirements of any particular service.
In this pump the ordinary interior double-acting plunger is
replaced by two plungers, or rams having external adjustable
packings readily renewed, which work iuto each end of a cylin-

io6 ENGINEERING MECHANICS. [April, 1892.
der having a central partition. The plungers are connected to­
gether by yokes and exterior rods in such a manner as to cause
them to move together as one plunger, so that while the one is
drawing the other is forcing the fluid, thus making the pump
double acting. The valve boxes are also modified for the purpose
of sub-dividing
them into separate JC^A.IM
small chambers, easily
accessible and capable
of resisting very heavy
pressures. The general
arrangement shown in
the engraving is sub­
ject to numerous alter­
ations to adapt the
pump to different requirements.
The gene­
ral characteristic of
independent plungers
with exterior packing
is, however, in all cases
preserved, as being not
011I3- more accessible
in case of leakage, but
also as allowing the use of different forms aud material of packing.
The severe pressure to which these pumps are often ap­
plied, not less in some cases than S,ooo pounds to the square
inch, demands the most thorough construction and the use of
the very best material.
Compound cylinders are often used to great advantage on this
form of pump.
THE WORTHINGTON MINE PUMPS.—It is difficult to design
and construct a steam pump that will satisfactorily meet the
exacting requirements of mine pumping. The service is gener­
ally rough, severe aud continuous. Great care must be exercised
both in the selection and adaptation ofthe material used in construction,
as the water to be pumped is often of a kind that will
attack and quickly destroy it. The location of the mine is usually
remote from supplies, and any necessity for renewals or
repairs, unless they can be made with unskilled labor and with
little delay, must be attended with serious consequences.
These considerations, therefore, demand that a mine pump
should be extraordinarily durable, simple and efficient. The cut
stuffing boxes, into four separate and distinct water cylinders.
The valve areas and water ways are unusually large in propor­
tion to the displacements of the plunger, so that the velocity
and consequent destructive action of the water currents is de­
creased. The plungers, piston rods and stuffing boxes are usu-
FIG. 43-—WORTHINGTON MINE PUMP, " LEHIGH PATTERN."
ally made of a metallic composition that has been found best
adapted to resist the action of sulphurous water.
The pumps are designed to safely withstand a working pressure
of 300 pounds to the square inch, and all their attachments
are especially strengthened with a view of meeting the rough
usage and hard work to which, in this service, they are liable to
be subjected.
The regular sizes have steam cylinders 14 to 29 inches in diameter,
water plungers 7 to io'+ iuches and stroke 10 to 18
inches. Capacity 350 to 1200 gallons per minute.
Another style of the Worthington mine pump is known as
the "Lehigh Pattern," which is recommended in preference to
the packed plunger and Scranton Pattern Mine Pump, in all
cases where a working pressure greater than 300 pounds to the
square inch is encountered.
This pattern of pump (Fig. 43) is identical with that of the
pressure pump shown in Fig. 41, but with such modifications in
the detail of construction as have been deemed expedient to
meet the demands of mine usage.
Parts exposed to pressure should be subdivided as much as
possible, in order to overcome the objection of having to replace
the entire water end in case of rupture through accident or
negligence.
In this pump the water valves are arranged in a series of valve
boxes or pot chambers, each chamber containing a number of
small valves having a low lift, and which are easily accessible
by screwing back the nuts on the eye bolts, and removing the
valve box covers. Sizes, steam capacity 25 and 29 inches stroke,
water plunger -jyi, 10 and 12 inches, stroke 24 inches. Capacity
400 to 1100 gallons per minute.
For other patterns of Worthington pumps reference must be
made to the general catalogue published by the firm of Henry
R. Worthington, New York.
FIG.42.—WORTHINGTON MINE PUMP, "SCRANTON PATTERN."
COMPARISON OF DUPLEX WITH SINGLE CYLINDER PUMPS.
The following table is arranged for the purpose of readily comparing
the capacity ofthe Worthington duplex with that of any
single cylinder steam pump. In making this comparison, it
should be remembered that the duplex pump, being in fact, two
double acting steam pumps working together, side by side, has
double the capacity per minute of any single cylinder steam
pump of the same diameter of plunger ; and that a single cylin­
shows one pattern of the Worthington pump for miuing derpurpump, must have a plunger or water piston twice the area of
poses, known as the Scranton Pattern (Fig. 42).
one of the plungers of the duplex pump, iu order to equal it in
The plungers of this pump work through central, exterior capacity.

April, 1892.] ENGINEERING MECHANICS. 107
Sizes of Duplex Pumps.
Diameter
of Steam
Cylinders
in inches.
3
nA
\A*
S'A
5X
6
7A
6
7K
9
4.
tf
O
Tj* OJ
3ffl
sa
'i- a
1*9
p -j
rt'O
>g
Diameter
of Water
Plungers
in inches.
2
234-
3^
3'A
4A
4
5
sx AA
SA
6
7
8^
9A
xoA
12
14
10
11
12
15
16
Length of
Stroke
iu inches.
3
4
4
5
5
6
6
6
10
10
IO
IO
IO
IO
IO
IO
IO
•5
15
'5
15
18
Diameter of
Plunger and
length of stroke 1
required in
Single Cylinder
Steam Pump
to do the
same work.
2A
4
sA
5
63/
5%
7
S/s
6i/s
7A
&A
9 7 A
12
13
HX
17
«9 A
H
>5'<
'7
21
6
7
7
10
IO
IO
IO
IO
16
16
16
16
16
16
16
16
16
24
24
24
24
36
Gallons delivered
per minute at a
speed that cau be
taken as a basis of
comparison.
The number of strokes given 22 in A the tables is limited to that
IS
50
5o
5°
5o
5o
5°
50
5o
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
IOO
o
'5
30
55
50
90
65
IOO
135
'65
225
295
400
59°
700
855
"75
1600
815
990
1175
i»35
2085
which insures ease of performance under all usual conditions,
but in auy emergency the speed can be considerably increased.
OTHER DUPLEX STEAM PUMPS.—Since the foundation patents
in the Worthington duplex pumps have expired, the duplex
principle has been adopted by nearly all of the leading manufacturers
that make the single cylinder pumps. Some modifica­
tions in design have been made by some of these manufacturers,
but they all agree in using a plain slide valve for the steam
cylinders, the valve of oue cylinder being driven from the piston
rod of the other. The duplex type has apparently taken a per­
manent form, its very simplicity allowing of but slight variations
and there is, therefore, none of that great variety which is found
in the valve motion of the single cylinder direct acting pumps.
The sizes, capacities and general arrangement of the duplex
pumps as made by the other manufacturers are almost the same
as the Worthington, and they need not be further described.
The following are the leading makers referred to, and full de­
scriptions of their pumps may be fouud in their catalogues :
Knowles Steam Pump Works, Warren, Mass.
Smith & Vaile Co., Dayton, O.
Deane Steam Pump Co., Holyoke, Mass.
Dean Brothers Steam Pump Works, Indianapolis, Ind.
Geo. F. Blake Manufacturing Co., New York and Boston.
The Gordon Steam Pump Co., Hamilton, O.
The Barr Pumping Engine Co., Philadelphia, Pa.
The Buffalo Steam Pump Co., Buffalo, N. Y.
The John H. McGowan Pump Co., Cincinnati, O.
The Barr Pumping Engine Co.'s catalogue contains the follow­
ing useful observations concerning the length of stroke and the
speed of piston of direct acting pumps :—In ordinary short-stroke
pumps the capacity of the water-end is limited not so much to
the piston speed in feet, per minute, as by the number of times
a valve can safely and noiselessly open and close in a given time.
To assume ioo feet per minute as an ordinary speed for pumps
has been a time-honored practice; it is obvious, however, that
for short strokes it imposes an injurious rate of speed, to which
a pump should not, in regular service, be subjected. For ex­
ample, a pump having
3-iuches stroke must make 400 strokes per minute.
4
5
6
7
8
10
12
300
240
200
171
150
120
I cu >
As the above list of strokes represents lengths commonly in
use, it needs no argument to show the absurdity of the ioo-feet
basis of comparison ; for pumps having a stroke of six inches
and less, the number of strokes as given above is too great for
continuous service.
Table showing the Number of Strokes Required to Attain a
OJ v
0J44
50
55
60
65
70
75
80
«5
90
95
100
105
no
i'5
120
125
Piston Speed from 50 to 125 Feet per Minute for Pumps
having Strokes from 3 to 18 inches in Length.
200
220
240
260
280
300
520
340
560
5S0
400
420
440
460
480
500
LENGTH OF STROKE IN INCHES.

io8 ENGINEERING MECHANICS. [April, 1892.
EMINENT AMERICAN ENGINEERS.
Mr. Elmer Lawrence Corthell was born in South Abington,
Mass., iu 1840. He was two years in Brown University, Provi­
dence, R. I., before the Civil War ; was then in the Civil War,
Union army, in light artillery service, from private to captain
of a light battery, four years and three months. After the war
he returned to Brown University, and was graduated in 1S67.
He immediately entered a general engineering office in Providence,
engaged on railroad, hydraulic and city work. In 1868,
Assistant Engineer in charge of construction of the Hannibal
and Naples Railroad, Illinois. In 1869, in charge of location
and construction, as Division Engineer, of 45 miles ofthe Hannibal
aud Central Missouri Railroad, Missouri. In 1S70-71,
Chief Assistant Engineer constructing the bridge over the Mississippi
River at Hannibal, Missouri. In 1871-74, Chief Engineer
of the Sny Island Levee, 51 miles in length, on the east
bank of the Mississippi
River. In 1873-74, Chief
Engineer ofthe construction
of the bridge over
the Mississippi River at
Louisiana, Missouri, for
the Chicago and Alton
Railway. In 1876-1880,
Resident Engineer associated
with the late James
B. Eads in charge of construction
of jetties at the
mouth of the Mississippi
River. In 1879-S0, wrote
and published an illustrated
History of the Mississippi
Jetties. 1880, on
the Isthmus of Tehuantepec,
Mexico, making surveys
for the Ship Railway,
associated with Mr. Eads.
Examined and surveyed
the mouth of the Coatzacoalcos
River, Gulf of
Mexico and Pacific Coast
for harbors for Ship Railway.
1881-84, Chief Engineer
construction ofthe
New York, West Shore
and Buffalo, New York,
Ontario & Western Railway,
and terminal at New
York City being in charge
of the work on the line. From 1S85 to 18S7 he was associated
with Mr. Eads as Chief Engineer of the Atlantic and
Pacific Ship Railway, and other works also. 1887-88, in an eugineeriug
partnership engaged in the construction of railroads,
bridges, harbor and water works. During this time there were
constructed the Cairo bridge over the Ohio River, for the Illinois
Central ; Nebraska City bridge, over the Missouri River, for the
Chicago, Burlington and Quincy Railway, the Sioux City bridge
over the Missouri River for the Chicago and Northwestern ;
two bridges in Oregon ; water works at Bismark, Dakota ; also
Consulting Engineer, Elgin, Joliet and Eastern Railroad, designing
and erecting bridges, shops, etc. Mr. Corthell has made
several expert examinations of railroad properties for bankers
in Loudon and New York ; made examinations and report for
the Florida Coast Line Canal and Navigation Company from St.
Augustine to Biscayne Bay, Fla., 320 miles.
Since the termination of the partnership, Mr. Corthell has
continued in professional work as a consulting and constructing
engiueer, with headquarters iu Chicago, and an office in New
York City. He was Chief Engineer of the construction of the
St. Louis Merchants' Bridge over the Mississippi River, recently
completed ; Chief Engineer of the improvements at the mouth of
the Brazos River, Texas, consisting of jetties into the Gulf of Mexico
; in charge, as Consulting Engineer, of a four-track entrance
railroad into Chicago, for the Illinois Central and Atchison,
Topeka and Santa Fe Railroads ; in 1889 Consulting Engineer
for the six railroads entering at New Orleans for a Belt Railroad,
Union passenger station and bridge over the Mississippi River.
Engaged on examinations of Elevated Railroads and properties.
1S89, made examinations, plaus and report on the improvement
of the harbor at Tampico, Mexico, for the Mexican Central Rail­
road, and now has charge of the construction of the jetties as
Chief Engineer. Chief Engineer of the Union Belt Railroad
of Memphis, now under construction. Chief Engineer of proposed
harbor works at Aransas Pass, Texas. Chief Engineer of
the harbor works at the mouth of the Coatzacoalcos River,
Isthmus of Tehuantepec, Mexico, and is now engaged on the
completion of the National
Railroad of Tehuantepec,
which with the
two good harbors to be
provided, one on the Atlantic,
and the other on
the Pacific, will open up
the best Interoeeanic
Route. This railroad is
the precursor only ofthe
Ship Railway, to which
Captain Eads devoted his
energies for many years
until his untimely death.
President of the Southern
Bridge and Railway Company,
formed to build a
railroad bridge over the
Mississippi River at New
Orleans. Provisional Director
ofthe Ontario Ship
Railway Company,organ­
ized to build a ship railway
for the largest class
of lake vessels betweeu
Georgian Bay, on Lake
Huron, and Toronto, on
Lake Ontario. Many minor
works have been constructed
by him, and quite
a uumber of examinations
and reports made on
railway projects.
It is estimated that the works of various kinds constructed
under the supervision of Mr. Corthell have cost over $90,000,000.
Mr. Corthell is a member of the following societies : American
Society of Civil Engineers, American Society of Mechanical
Engineers, American Institute of Mining Engineers, Institution
of Civil Engineers of Great Britain, Member of the
Society of Arts of Great Britain, French Society of Civil Engineers,
Boston Society of Civil Engineers, Philadelphia Society
of Civil Engineers, The Eugineering Association of the South,
Western Society of Engineers, Honorary Member of the Mexican
Association of Civil Engineers and Architects ; Corresponding
Member for Chicago and, the Northwest for the French
Society of Engineers, Fellow of the American Association for
the Advancement of Science, Vice-President American Society
Civil Eugineers in 1888, President Western Society of Engineers
in 1889.
Mr. Corthell is Chairman of the Executive Committee of the
Engineering Societies of the United States and Canada to
arrange for an International Congress at the World's Exposition
iu Chicago in 1893. He is also Vice-President of the Interna
tional Navigation Congress to be held at the same time.

April, 1892.J ENGINEERING MECHANICS. 109
UTILIZATION OF NIAGARA FALLS SCHEME.
BY MR. BELA SzuTS, of Budapest.
Messrs. Ganz & Co., Budapest, having been invited by the
Cataract Construction Company to participate in the Niagara
competition, submitted a scheme, the details of which accom­
pany this article. Figs. 1 to 10 represent a turbine aud dynamo
of 5000 horse-power ; Figs. 11 and 12, the mode of suspending
the vertical turbine shaft; Figs. 13 to 15 show the relation of
the various turbine shafts in the installation of 5000 horse-power.
In preparing these plans the first and important point was to
find the most convenient arrangement and size of turbines ca­
pable of developing the effective power of 125,000 horse-power
under the stipulated special conditions. Messrs. Ganz & Co.
deemed turbines of iooo to 2000 horse-power impracticable, be­
cause such turbines, in order to produce the aggregate efficiency
required, necessitated more appliances, thus adding to cost, because
the relative efficiency of several small turbines is less thau
of one large turbine of equal power. It was necessary in the
first place to find out the greatest efficiency possible for which a
turbine might practically and with perfect reliability be constructed,
and after much experiment and calculation on this
point, Messrs. Ganz & Co. decided to design twenty-five turbines,
each of 5000 horse-power for driving the dynamos.
As it seemed to be certain that the dynamo-room could not
be made underground in the water-wheel room, the next point
of solution was the conducting of the 5000 horse-power from
the turbines to the dynamo-room erected above grouud. Were
the power to be transmitted by ropes or belting, the rock shaft
would require to be so large that the cost would be excessive in
view of the hardness of the rock to be bored ; and owing to the use
of vertically superposed pulleys of such dimensions without guide
pulleys light would be greatly diminished. Messrs. Ganz & Co.,
therefore, decided to transmit the power from the turbine wheels
to the dynamo-room by a vertical steel shaft as shown iu Figs.
1 and 2. A magnet wheel is fixed ou this shaft, which considerably
augments the vertical load to be carried. But a special
patented type of bearing which Messrs. Ganz & Co. have adopted
completely meets this difficulty.
The head race A, Fig. 3, is provided with an inlet sluice B,
having wood gates 9 ft. in height and 9 ft. in width, operated by
handwheel from the platform. Behind the sluices there is a
basin with coucrete walls D with a cylindrical sluice E. This
consists of a cylinder of /-in. plate iron, the bottom part of cast
iron being slightly turned inwards to fit on to the bell mouth of
the funnel F1 bedded in the concrete liner of the supply shaft
F. The circular sluice E is, owing to its special shape, free of
pressure from the water and may be hoisted by chains passing
over guide pulleys to any convenient point ofthe engine-room.
A load on the end of the chain counterbalances the cylindrical
sluice. The sluices B serve to cut off the water supply when
the apparatus is standing idle for a long time, but they are not
intended to open or close suddenly. An arrangement for this
purpose would have been too heavy and impractical, and the
result is attained in a better and easier way by the air cylindrical
sluice E. The supply shaft is a vertical rockshaft lined with
concrete. The lower part of the shaft turns to the turbine in a
curve, as shown in Fig. 1, ending in a tube of /-in. plate iron,
stiffened with angle irons fixed in the concrete. The lower
flange is screwed to the turbine chamber F. The mean velocity
of water in the supply shaft is supposed to be 7 ft., accordingly
the diameter equals 9 ft., and the quantity of water equals 414
cubic feet per second.
The turbine pit has in its entire length an oval section (Fig.
9), ending below, however, in a circular opening (Fig. 5) of
larger diameter, in order to obtain more room for operating
near the turbine. The turbine pits are connected one with the
other by horizontal culverts (Fig. 13), permitting passage from
one turbine to the other. These culverts, besides, would be ser­
viceable during the boring of the shafts, enabling operations to
be started cither from above or from below, and for the removal
of material. The dimensions of the pit have been minimized as
far as consistent with the necessity for allowing sufficient room
for raising the motor in pieces in the event of repairs being re­
quired. Although a turbine of 5000 horse-power may run in the
pit, its greatest diameter is only 12 ft., and there is nothing in
the pit which could not be taken apart.
The turbine wheels. The driving wheel (G, Fig. 1) is keyed
ou to the shaft, aud is supported by a conical ring of two pieces.
The buckets of this wheel are made in such a way that the wheel
may run even in the backed-up water of the tail-race without
great loss of efficiency. The guiding wheel

April, 1892.] ENGINEERING MECHANICS. in
HEHESEEI^^ JjsJII IIATO fjaUHl i fiMI IJIA]
and 15), they are fed by the pumps D by means of the dynamo
B and the countershaft C. Means are provided to collect and
clean the oil from all shaft bearings. Details of this arrangement
are shown in Fig. II. All the oil descends to the vessel
M3 (Fig. 1), divided into two sections by a vertical partition
wall. The oil enters at the bottom of one of these parts, and
flows over the partition into the stcond, leaving behind any impurities.
A special suction pump Ni (Fig. 1), driven by a hy-
dromotor, pumps the oil into the filter x1 (Fig. 3), where the oil
is cleaned by two layers of cotton and used again.
As shown in Fig. 13, the level of tail-race of the various turbines
is intended to have a slope of 7 to iooo, according to the
slope of the main tunnel. A similar slope is given to the tailrace
of all and each turbine into the main tunnel.
Under the bucket wheels space must be provided for examin­
ing and cleaning the buckets of the wheels. To admit of the
shutting off of the water, this space is fitted with the sluice O,
Figs. 1, 4, and 5. The gates are of wood and guided by slots
formed of channel iron on edge, and secured in the wall. The
hoisting gear of each gate consists of two hydraulic cylinders
secured in the concrete, and fed by the accumulators already
mentioned. Au apparatus fixed in the turbine chamber serves
to govern the gate. After lowering the gate, the water may be
pumped out by an ejector. The exciting current is taken from
a separate continuous current exciter Q (Fig. 1) driven by bevel
wheels P from the turbine shaft, developing 100 horse-power
while running at 300 revolutious.
In Fig. 5 is shown the ground plan of the guide wheel; the
channels are divided into four groups, forming on their upper
end a saddle, as shown in Fig. 1, the sides of which inclose a
right angle. On this saddle is located a valve R, keyed on to
the protecting tube T by four brass bolts and adjustable by
screws in vertical direction. These screws permit the regulating
at will ofthe distance between the guidiug wheel and valve
R. The protecting tube may be turned on a brass spur ring.

112 ENGINEERING MECHANICS. [April, 1892.
Near the stuffing-box H, the tube has a funnel-shaped prolongment,
in order to counterbalance somewhat the great pressure
the water exerts on the valve. By turning the tube as well as
the valve the buckets of the guiding wheel may be opened or
closed from nil to full. The tube is guided above by the box S,
supporting the toothed section Sn operated by the single-acting
cylinder S2, Fig. 6, and its rack. The cylinders are connected
oue with the other by strong horizontal frames resting backward
on the liner ofthe pit. These cylinders receive their feed
water from the same accumulators that feed also the tail-race
pistou.
The governing of these cylinders is operated by an apparatus
receiving its motion from the centrifugal governor. The governor
T. is driven by bevel wheels from the shaft of the exciter.
The distributor T,, Fig. io, is operated by reversing levers U6
from the goveruor T, aud is connected by pipes with the cylinders
S2. The regulator has to move only the distributor T„ Fig.
io, which permits the water of the accumulator to enter either
into the one or the other cylinder, driving thus the rack and
the protecting tube. The shaft U is connected with the connecting
tube by two toothed segments U,, being at the same
time geared with the bevel wheels U2, shaft U:l, gear U,,, and
the rack U5. This mode of connection permits the centrifugal
governor to remain in a certain position, without oscillating
until the moment when its velocity is altered.—Engineering,
London.
THE Baltimore and Ohio Railroad will re-equip its afternoon
express from Baltimore and Washington for Cincinnati. This
train will be known as the "Southwestern Limited," aud will
be equipped jointly by the B. & O- and B. & O. S. W., and will
be the safest, fastest, and finest train which ever ran from Baltimore
and Washington to Cincinnati. At Baltimore or Washington
close connection is made with the Royal Blue Line to
and from New York. The cars composing the Royal Blue Line
and "Southwestern Limited" are constructed upon the same
models by the Pullman Co., being vestibuled from end to end,
lighted by gas, heated by steam, and protected by Pullman's
latest anti-telescoping device. This is but one of the mauy
steps the B. & O. has taken recently for the improvement of its
equipment. So perfect is its road-bed, so stauuch are its bridges,
so solid are its locomotives, so efficient are its employes, and so
perfect is its general equipment, that the " B. & O." is coming
to the front as the model railway of America.
B. H. CRAMP & Co., of Philadelphia, have issued a neat circular
containing an "extract from Report of Bureau of Steam
Engineering U- S. N. for 1890," which gives a descrijition of tests
made at the New York Navy Yard in May, 1890, of Manganese
Bronze. The test specimen was cut from the pouring gate for
the hub ofthe propeller for the United States Steamer "Maine."
The transverse tests were made by placing the specimens on
supports on the bed of the testing machine aud applying the
load at the centre. For nearly the whole range of load the supports
were ten inches apart, but when near the breaking point
higher supports were used and placed nine iuches apart, ou account
of the bending of the specimens. The first specimen,
marked A, had the loads applied as shown in the table, the deflection
in each case being measured after the load had remained
on for two minutes ; the load was then removed aud the deflection
again measured to discover the amount of "permanent
set." This operation was repeated for each load up to 3,750
pounds, after which no measurements for permanent set were
SPECIMEN A.
(Placed in position specimen measured 10.562 inches.
1.009 by U013 inches.)
Total.
500
700
Soo
900
I,O0O
L300
1,400
1,600
I,80O
2,000
2,200
2,500
2,750
3,000
3.500
3.750
6,300
Specimen measured.
On.
Inches.
IO.527
IO.520
IO.517
IO.509
IO.507
IO.484
IO.480
IO.460
10.437
IO.378
IO.358
IO.256
IO.140
9.810
9.2S6
8.689
8.540
LOAD.
Off.
Inches.
IO.562
IO.562
IO.562
10.562
10.555
io-545
10.540
10.532
10.517
10.485
10.47*8
10.382
10.290
9-995
9-485
Broke.
SPECIMEN B.
Section
Specimen deflected.
On.
Inches.
0.035
0.042
0.045
0.053
o-o55
0.07S
0.082
0.102
0.125
0.184
0.204
0.306
0.422
0.752
1.276
1.873 \
2.022 J
Off.
Inches.
None.
None.
None.
None.
*o.oo7
0,017
0.022
0.030
0.045
0.077
0.084
0.180
0.272
0.567
1.077
(t)
(Placed in position specimen measured 10.562 inches. Section,
1.007 by 1.0115 inches.)
',150
2,000
2,500
3,000
3,5°o
6,450
V
6
u
ft
m
A
B
10.507
10.404
10.247
9.918
9-59 s
8.079
10.556
10.523
10.400
10.083
Broke.
0.055
0.158
0.315
0.644
0.9641
2.483 J
* Permanent set. f Nine inches between supports.
Applied load.
1 Max.
Total. fibre
strain.
6,300 82,150
6,450 §4,530
1 .
Deflec- «£
tion in -5

April, 1892.] ENGINEERING MECHANICS. JI 3
The metal will roll or forge hot which greatly increases its
strength.
We have made some beautiful forgings, some of which can
be seen at the Franklin Institute, where Mr. F. Lynwood Gar­
rison, lectured on that and other alloys, a copy of whicli lecture
can be had upon application to us.
We have also furnished castings for parts of the engines of
our new cruisers requiring great strength ; and many thousands
of pounds of forgings and rods of various diameters aud shapes.
We respectfully submit, that our rods are the best and strong­
est in the market, and solicit a trial of them. We are always
anxious to give prices for any style of castings, of not only our
Manganese Bronze, but also from auy other Bronze or Brass
manufactured ; and from our extensive experience, we are es­
pecially prepared to make castings from compositions known
only to ourselves, intended for many special purposes. If you
do not now get what you want, explain to us the peculiar quali­
ties you require and we will guarantee to meet them.
DYNAMO MACHINES.
IF there are any apparatus that have particularly exercised
the imagination of inventors, they are assuredly lamps, commutators,
and dynamo machines. These latter, especially,
have become very numerous in recent years. It is easy, however,
to establish a classification between the different models.
Every dynamo comprises two principal parts, viz., the armature
and the inductor. The various kinds of continuous curreut
armatures mav- all be referred to three well-known types of
winding—the Gramme, the Siemens, and the Edison. Besides
these there are still other types that we must consider, aud, in
particular, the Deroziers winding. We shall not dwell upon
the details nor upon all the advantages and disadvantages of
these various armatures, as they have already been presented
to our readers.
As for the inductors, the same is not the case. It is but a
few years ago that the labors of electricians indicated the con­
ditions that these parts of the dynamo must satisfy. Among
such conditions we may mention one in particular ; it is necessary
to reduce as much as possible the magnetic resistance of
the current, or the resistance offered to the flux of force through
the iron of the electros, and the air between the iron of the
electros and the iron of the ring. The flux of force, as we
know, is the product of the iutensity of the magnetic field
created by the surface embraced. Moreover, it must not be
forgotten that a wire surrounding a piece of iron, and being
itself traversed by a current, magnetizes such iron and creates
in the interior a magnetic field of a certain intensity. If we
take the product of such intensity by the surface of the piece
of iron, we obtain the flux of force, the consideration of which
is a most important matter in the construction of dynamos.
These few remarks suffice to show that, in a good dynamo, the
flux of force should have a maximum value ; it is well, then, for
a given number of windings of wire, to be careful as to the na­
ture ofthe metal of the inductors, to employ iron of very great
magnetic permeability, and to reduce as much as possible the
resistance of the air necessarily interposed between the in­
ductor poles and the armature. The latter condition imposes
the obligation of placing the inductors as near as possible to
the armature, leaving just the space necessary for the motion
of the armature, and afterward of making the latter embrace the
widest surface possible.
The second part of a dynamo machine, the inductor, gives
rise, as may be seen, to more numerous inventions than the
armature. In fact, there has been no want of models. One of
our most learned electricians has conceived the happy and original
idea of bringing together, in one plate, the various types
of inductors of continuous current machines, which we reproduce
in the accompanying eugraving.
No, I represents the well-known Gramme machine, No. 2 the
Edison-IIopkinson, and No. 3 shows us the arrangement ofthe
Siemens dynamo, with drum armature and horizontal inductors.
This machine bears also the name of Hefner von Alteneck,
the engineer-in-chief of the Siemens establishinent. In No. 4
we find the Schuckert type, with disc armature, and in No. 5
the form of the Western machines with drum armature, ofthe
Burgiu ring machines, and of the Crompton, Paterson, and
Cooper machines. No. 6 shows the large Edison machine of
1880, which was adopted by all the American central stations
and by tbe Milan station. No. 7 represents a third type ofthe
Edison dynamo of four or five bobbins. To this type is referred
the English Machine Phcenix. No. 8 gives the aspect of one of
the first types of the Gramme machine. Messrs. Burgin aud
Crompton devised a dynamo, which is represented by No. 9,
but wliich is now abandoned. In this we find the first principles
of the Meritens and Jackson machines. Fig. 10 gives a
diagram of the Kummer and Co.'s machine, which is similar to
the Jones dynamo and the Gramme motor. In No. n is found
represented one of the first models of the Gramme machine
with several poles—a model which has since been constructed
with more or less modification by the Oerlikon and Allgemeine
Gesellschaft Companies, of Berlin. In all tbese machines we
find a large external polygonal ring, to which, according to the
radii, are adapted iron arms which, in the centre, leave between
them an annular space, in which the bobbin revolves. No. 12
PRINCIPAL FORMS OF THE INDUCTORS OF DYNAMOS.
shows a motor devised by Silvanus Thompson. No. 13 is a
modification ofthe inductors ofthe dynamo No. 9, proposed by
Mr. Kapp for the reduction of the magnetic resistance of the
circuit. No. 14 is a section of the well-known Griscom motor.
No. 14 is a new form of motor for electric railways, constructed
by the Thomson-Houston Co. In No. 16 is figured a section of
the Eddy and Mather American machine. No. 17 shows a
Furgersen dynamo. No 18 shows one ofthe commonest forms
of the Gooldeu and Trotter dynamos. The dynamo of the Telephone
Company of Zurich is represented in No. 19, the Guzzi-
Ravizza and Ironsides in No. 20, and the Tyne dynamo, of
Scott and Moutain, in No. 21. No. 22 gives a section and profile
of a superior type of Gramme dynamo, devised by Kapp,
and since imitated by a number of manufacturers. No. 23 rep­
resents the Hochausen dynamo, No. 24 the Elwell-Parker and
Crompton dynamos, and No. 25 the Manchester type, due to
Hopkinson. It is to this latter type that belong the Brown of
Oerlikon, Mather aud Piatt, Sautter and Lemonnier, Tighe,
Joel, Clark-Muirhead, Blakey, Emmot aud Immisch, aud
Sprague machines. Nos. 26, 27, 28, 29, 30, aud 31 show respectively
the Lahmeyer, Thomson-Houston, Wenstrom, Eickmeyer,
Continental, and Mordey and Jones machines. No. 32 represents

ii4 ENGINEERING MECHANICS. [April, 1892.
a form common to several American motors, notably to the
Patten and United States and Jenny motors. Silvanus Thomp­
son devised the dynamo showu in No. 33, and Mr. Fein the
dynamo showu in No. 34. No. 35 gives the form of Kennedy's
iron-clad dynamo machine. Finally, the Alioth Helvetia,
Elwell, Siemens—with interior poles—Thury, Kester, Brush or
Schuckert-Mordey or Victoria dynamo machines are represented
in Nos. 36, 37, 3S, 39, 40, and 41. The enumeration
comprises but a few of the principal types of continuous current
machines, now no longer new. Doubtless among all these
dynamos there are several that are superior to the rest, but still,
the same qualities are sometimes reached by various means aud
different forms, and it is often difficult to fix one's choice betweeu
several models. The question of cost alone intervenes.
The short history that precedes shows the path that the dynamo
machine has traveled since its invention, and it proves that the
mind of inventors has not remained inactive.
EXTRACT FROM PROCEEDINGS OF MEETING OF ENGINEERS'
CLUB, HELD AT PHILADELPHIA, MARCH 5.
Mr. Carl Heriug gave some items of cost of transmission of
power from Niagara Falls to Buffalo. The units intended to be
used are 5,000 horse-power. The dynamos are to be coupled
directly to the turbine by vertical shafts. 600 to 700 volts at the
dynamo is to be transformed to 25,000 volts ou the line. Three
phase dynamos are to be used, making 250 revolutions and supplying
2,000 amperes. The cost of the whole plant per uuit of
5,000 horse-power is to be f iSo,ooo, or $36 perhorse-power. This
estimate includes generator, line aud transformers at each end,
line cost alone being $20,000. At present the cost of dynamos
varies from #50 to $75 per horse-power. The total efficiency of
the plant is to be 84 per cent, from the shaft of the turbine to
the secondary terminals at Buffalo, the dynamo alone giving an
efficiency of 96 per cent.
Mr. Wilfred Lewis introduced Mr. J. Bogart, Engineer of the
Construction Company, who stated that the Oerlikon Company's
bid is about as Mr. Hering has given it, but the problem
that interests us is rather what will steam power cost under the
most favorable conditions, with coal of a given price, or for how
much could a company put in a steam plant and sell to customers
power ? He also stated that he had received two estimates
as to the cost of power under these conditions, and that the
problem is by no means an easy one is shown by the fact that
the larger of these estimates is about two and one-half times the
smaller. The solution must not be complicated by other questions,
such as the use of steam for heating, or other purposes,
and this makes it a particularly difficult oue to handle.
Mr. Murphy stated that his recollection was that the cost of
pumping water at the eight steam stations in Philadelphia was
in the neighborhood of $8 per million gallons, pumped 100 feet,
while at Fairmount the cost was $2.
Mr. Smith—The marine engine seems to be about the nearest
to the solution of the problem.
Mr. Hering—I would like to ask Mr. Bogart what the cost of
power will be at Niagara.
Mr. Bogart—We cannot tell, because the work is not done.
The tunnel must be lined with brick and the shafts for the turbine
are not finished. We propose carrying a notch instead of
several shafts for our power, but we are ready to sell power in
large quantities at $10 per horse-power per annum at Niagara.
Mr. Salom—At Lockport Mr. E. H. Cowles told me that their
power did not cost $3 per annum, and I would like to ask Mr.
Bogart what they propose to do with the power that they develop,
as five persons per horse-power is about the maximum in
the most thickly-settled manufacturing districts.
Mr. Bogart—The plant, as now under way, is capable of developing
100,000 horse-power. It is proposed to use this first at
Niagara Falls, or at the present station by giving power to
manufacturers for coming there. Many manufacturing indus­
tries take much more horse-power than that stated by Mr. Salom—wood-pulp
mills, for instance—and a 3,000 horse-power
plant is beiug put in by one company, and a second plant is
under consideration. It is in the miuds of the Company, also,
to transmit power to Buffalo, which is a city of a large number
of small power establishmeuts. The turbiues are to be about
120 feet below the surface, leaving 20 feet to spare. The water
that can be taken by the tunnel will take a film of 1 % inches
off the Falls, the average depth being about 6 feet, as near as
we can judge.
Dr. Chance—Has any arrangement been made to put in im­
pact wheels ?
Mr. Bogart—Careful study has been made of this subject with
the Pelton Company, but the conditions do not seem to be
favorable.
Mr. Lesley—The location of Buffalo makes it one of the greatest
inland shipping ports in the United States, and the transmission
of power in large quantities at cheap rates should make
it one of the largest manufacturing centres also.
Mr. Bogart—The Corujjany has bought the right of way for
another tunnel ofthe same size.
Mr. Roney—I should like to ask Mr. Bogart as to the probabilities
of trouble from ice.
Mr. Bogart—We do not anticipate any trouble in the tunnel,
and any- ice that may form above will be carried down indepen­
dently in a shaft put in purposely for an ice-shaft.
Mr. Salom—I have no fear but that there will be users for the
power. It requires 24 horse-power per day to produce one
pound of aluminum, and a few tons will utilize the entire plant
as at present under way.
Mr. Murphy—Will Mr. Bogart give us an idea of a section of
the tunnel?
Mr. Bogart—The area is that of a circle of twenty-five feet in
diameter. It has, however, a circular top and a very shallow
invert It is through rock and lined with brick masonry.
W. R. ECKART, C. E. of the Technical Society of the Pacific
Coast, with a committee of citizens of which he is chairman are
making all necessary preparations for the coming convention of
the American Society of Mechanical Engineers, to be held in
San Francisco in May. Mr. John Richards, so well known as
an engineer and journalist, is president ofthe Techical Society
of the Pacific Coast.
IT is stated that the American Bell Telephone Company, of
Boston, has under way fifty lines of long-distance telephone
construction from Chicago to New York. Each of these fifty
lines takes two lines of wire, and as the distance from New
York to Chicago is about 980 miles, the length of wire used in
connecting these two points would be 98,000 miles. The size of
the copper wire used in construction of the long-distance telephone
weighs 174 pounds to the mile, making the total weight
of copper turned into wire for this one undertaking 17,052,000
pouuds, or 8,526 net tous.
IT is stated that the Bethlehem Irou Company, of Bethlehem,
Pa., will erect at Chicago, for the Columbian Exposition, a fullsized
model of its famous 125-tou steam hammer, the largest in
the world. It will be to all appearances a perfect duplicate iu
every respect. At the last Paris Exposition great attention was
attracted by a similar model shown by the Creusot Works, but
representing only a 100-ton hammer.
L. S. STARRETT'S Catalogue and Price List of Fine Tools
should be in a pigeon hole in the desk of every engineer and
draughtsman. New and improved tools are being constantly
brought out. Address, Athol, Mass.

April, 1892.] ENGINEERING MECHANICS. i J 5
M\
//
•fr-ii
B
ANOTHFR VIEW OF THE
PARABOLIC ROOF TRUSS.
NATIONAL TUBE WORK Co.,
McKeesport, Pa„ Feb. ro, lSt/s.
Editor Engineering Median ies :
Your letter of tbe 1st inst. to
General Manager Converse, in
reference to " Parabolic Trusses,"
has been assigned to the writer. In
answer to the same, I find by close
investigation that the "Parabolic
Truss" is not, as claimed, "a perfectly
rigid structure." I find from
the point of contact of the chord to
the apex of rafter there is not a point
but what is flexible, as shown by my
sketch herewith.
The same amount of pipe of different
sizes and dimensions that is used in the
"Parabolic Truss" can, if properly put
together, be made a much stronger truss,
and oue that will not deflect except by expansion.
With all due respect to the designer, I
must say that I find the " Parabolic Truss,"
as shown in MECHANICS, to be nothing but
an elliptic circle oue half turned over. I
have built elliptic circle bridges both of wood
and iron some years ago ; but tbe mechanics
of to-day condemn them for the very be.st of
reasons, as we can take the same materials
and construct a truss for roofs or railroad
bridges with much less labor and expense,
by intersections of points attaiued to, and
by obtuse and acute angles, and by chords,
struts and connecting bars, much more
simple and far more beautiful, and from 50
to 75 per cent, stronger.
With this letter I will send you a sketch
of the " Parabolic Truss," the dotted lines
showing the form it would take when under
pressure. This demonstration is not from
theory, but from actual practice, and I know
this to be true.
I have connected with suspension links all
the vertical points in the " Parabolic Truss,"
and which, I think, makes a superior truss
with but little extra cost. Tbe point of contact
ou the '' Parabolic Truss " shows that it
has a tendency to drive the top chord out of
place. The top and bottom rafters, formed
of a parabola turned upside down, causes an
extremely weak point. I trust you will not
contradict my statement until first having a
practical test of the points I have submitted.
I am of opinion tbat there can be a
strong truss made of pipe for roofs or
wagon bridges, very strong and durable,
but not on the parabolic system ; that
style of truss has long since been discarded
by mechanics for a much cheaper,
much more simple, and more durable
kind of truss, whether it be of
wood or metals. There is no arch as
weak as an elliptic. If you so desire,
I will send you a sketch of a truss
made of pipe for a span of 50 feet,
and warrant that it will not deflect
\' if properly constructed, and that it
will hold 75 per cent, more than
a " Parabolic Truss." This criticism,
let me say, does not need
any mathematical formula to
\ prove.the merits or demerits of
the " Parabolic Truss."
Yours, with great respect,
JOSEPH PLATTENUURG.
^jmHH
THE following is a diagram of the course of a Sims-Edison
Electrical Torpedo at a trial run at Spithead, England, Feb. 3d :
ATOB. TRACK OF DRUDGE
BWHERC TORPEDO IVA5 LAUNCHED
8 TOCSUBSEQUENT TRAC10E DRUOCE
C-WHERE SHIPCABLE WAS SLIPPED
B T 0 TRACK OC TORPEDO
0.1VHCRC TORPEDO WAS PICKED UP
THE Babcock & Wilcox Co. have recently put in five of their
boilers iu the Regents Park Station, London, which have called
out some favorable comment abroad. E)ach were 23 feet long
and five feet wide between the walls, with one steam drum 3 ft.
6 iu. diameter. Each boiler has a heating surface of 1619 square
feet, and a grate area of 30 square feet, and is capable of evapo­
rating over 5000 lbs. of water per hour, the working pressure
being 170 lbs. per square inch. The contract included a guar­
antee that 1 lb. of best Welsh steam coal should evaporate 10
lbs. of water from and at 212 deg. Fah. The diagram here
given and the following figures show the result of the official
trial that was made by Professor Robinson on Nov. i6tb, 1S91 :
g
^
'.
! >•
i
" ;
Iu
'*n -2 *
*. J
•0
li- ,
MUj
UOflO
....
moo
* ~ .
'
.^
0 u t>
AA
0
ct...,,
AAAA,
\
/^
0 1 1
0
i
y
•"
/
^ _
j
J 0 « a
T,mt
4 it
Heating surface
l6l 9 sq.ft.
Grate area 3°
Ratio of heating to grate surface
Kind of fuel—Nixon's navigation steam coal.
• • 5^-9 to I
Duration of test 5 hours
Average steam pressure '73-5 lbs.
Average temperature of feed-water 4S deg. Fah.
Pouuds of coal fired 2 352
Pounds of refuse 5"
Pounds of combustible 2296
Per cent, of ashes
2 -3°
Coal consumed per square foot of grate per hour . 15.6
Total water evaporated 22 925 lbs.
Average evaporation per hour 45*5 lbs.
Maximum evaporation per hour • • • • 5160 lbs.
Water evaporated per square foot of heating surface
per hour
2 -^3 lbs-
Water evaporated per lb. of coal 9-747 lbs.

n6 ENGINEERING MECHANICS. LApril, 1892.
Water evaporated per lb. of coal, assuming feedwater
at 212 deg. Fah. and at atmospheric
pressure 11.906
Temperature of boiler room 61 deg. Fah.
Temperature of flue gases . . 1S5 deg. Fah.
Force of draught in inches of water 0.391
DIRECT-CONNECTED CENTRIFUGAL PUMP.
The above illustration shows a Contractor's Pump, consisting
of a Standard Westinghouse Engine and a Morris Machine
Works Centrifugal Pump coupled together.
Before tbe advent of the above-named high-speed Engine, it
was found necessary to run this style of Pump by belt, except
"'"IIIIIIIIIIIIIN 1,1
t 1 1 1 1111 1 lillllllllllilllim 1 illlllllll milium mm in miiiiiiimiiiiiiinii iiiiiiiintiiwiiiif
in some cases, where the lift was but a few feet. Now, Pumps
of auy size can be had as above shown, with a capacity of from
400 to 50,000 gallons per minute, for almost any lift.
The outfit shown is considered superior to any other for the
following reasons :—
ist. It is very compact.
2d. Considering capacity, it is very light
3d. By using this style of Engine it is very efficient, giving a
greater quantity of water for a given amount of steam than any
other.
4th. The construction ofthe Pump is such that the passage of
solid matter found in water is allowed, as the Pump contains no
valves or moving parts that will give trouble or be liable to wear.
This style of outfit has found favor in tanneries, where a composition
Pump is used to resist the ravages of the tan liquor ;
for circulating purposes ou ship board, and circulating brine in
freezing tanks of ice machinery ; for raising sand and gravel
from river beds, and conveying it ashore by means of a discbarge
pipe; for dredging and filling at one operation ; for itrigation
and drainage purposes , and iu fact, for thousands of places
where the maximum quantity of water is to be moved at the
minimum of expense.
The Pump is manufactured by the Morris Machine Works, of
Baldwinsville, N. Y., while the Engine is made by the Westinghouse
Machine Co., of Pittsburgh, Penna.
Two facts have been established in connection with tbe manufacture
of American armor plate, especially to tbe satisfaction
of Naval engiueers and officials and armor plate manufacturers,
viz , that American plates are superior to foreign forged plates,
and that superior plates cau be produced by the rolling process
over the forging process. These conclusions have been arrived
at as a result of severe tests made with six 10^ inches thick
plates, three of which were furnished by Carnegie, Phipps &
Co. and three by the Bethlehem Iron Co. Four shots were fired
at each plate from a 6-inch gun with an impact velocity of 2075
feet per second, and an energy of 2988 foot tons, using the Holtzer
projectile of 100 pounds. One shot was then fired at the
center of each plate from an S-iuch gun, with an impact energy
of 4988 tons, using Firminy and Carpenter projectiles of 210 and
250 pounds weight, respectively. The plates were placed normal
to the Hue of fire.
The two Bethlehem nickel plates proved to be superior to the
third all Harveyed plate, and the
Carnegie rolled nickel plate showed
a 10 per cent, greater resistance to
perforation over the best French
all-steel plate. These tests remove
the uncertainty as to the safety of
rolling plates instead of forging, and
alters the economical aspect altogether
of their production, as well
as making it possible to expedite
tbe armoring of war vessels. The
Secretary of the Navy in noting
these experiments says :
" It may be assumed that the
principle of supercarburizing steel
to a considerable depth has passed
beyond the experimental stage. The
question of tempering or chilling
the carburized armor plate needs,
however, further experimental development,
and the lack of uniformity
in results, indicated in the Indian
Head armor trials, may probably be
ascribed to this want of experience.
The assurance of success, however,
is so great as to warrant the Department
in making further experiment
in this direction with every reason
for anticipating a completely satisfactory
result."
ALUMINIUM COINS.
Sir Henry Bessemer has written
to the London Times suggesting
the use, instead of £1 notes, of aluminium
token coins, bearing a promise
to pay just as a banker's note
does. The first impression, says Sir
Henry, produced on the minds of
many persons by this proposal will
naturally be the door which it apparently
opens to fraud by the casting
of such coins in plaster of Paris
moulds and the coating of them by
the electrotype process, just as base silver coins are made. Ten
years ago such fears would have been well founded, but the science
of metallurgy has given us a new metal which effectually bars the
way to this mode of forgery, while its distinctive character is
so clearly defined that a child could tell even in the dark a
genuine coin from a spurious one. The new metal—aluminium
—may be slightly alloyed so as to harden aud increase its durability,
and at the same time raise its fusing point, and thus
render the casting of it in plaster moulds quite impossible.
The specific gravity of aluminium is 2.56, while that of silver is
10.47, so that an aluminium coin ofthe exact size and thickness
of a common florin would weigh a minute fraction less thau a
silver sixpence, hence, as I before observed, if taken from the
pocket in the dark it would be instantly recognized by its extreme
lightness, aud could never be mistaken for any coin made
of gold or silver, while the great weight of all lead or pewter
alloys, which are capable of beiug cast in plaster moulds, could
never be passed off as aluminium coins, however their external .
surface might be coated or colored in imitation of that metal.
There are some other important details giving great security
against the forgery of aluminium coin, which, in the interest of
the public, it is undesirable to mention at this moment.
THE Laidlaw & Dunn Co., of Cincinnati, O., are fast pushing
to the front. In addition to the increased size of their works,
lately added, they have opened up a branch house in Chicago, at
199 South Canal St., where they will carry a large stock of Steam
Pumps, including Duplex, Single Direct Acting, Crank and Fly
Wheel, aud Deep or Artesian Well Pumps and Railway Supplies.

May, 1892.] ENGINEERING MECHANICS. 117
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering,
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
London Office, 270 Strand, D. NUTT, Agent.
Entered at the Post-ojffice in Philadelphia as Second- Class Mail Ma tier.
SUBSCRIPTION RATES.
Subscription,
Subscription, per year, foreign countries
PHILADELPHIA, MAV, 1892.
$2
2 50
THE Post-Office Department has contracted for the delivery
of 100 electrical machiues, each of which will legibly stamp
28,000 letters per hour.
FRENCH railway fares have been reduced from 9 to 22 per
cent, and freight from 36 to 44 per cent., beginning April 1.
The State Company will lose twenty million dollars reveuue,
but thetraveliug and shipping public will be the gainers.
THE Harveyizing of the wearing surface of steel rails now
being experimentally used will probably solve a question that
has given metallurgists a good deal of trouble as to the best
composition of rails, and will introduce a valuable economical
factor through the greater durability of rails.
THE Siberian railroad, now under construction, is considered
by many engineers familiar with the work as the most im­
portant railroad engineering enterprise in progress anywhere in
the world. Some of the bridges will rank among the great en­
gineering works of the world. The total length is 4900 miles,
of which one third is covered by river navigation.
THE brittle condition of the condenser tubes of the cruiser
" Baltimore," which broke like pipe stems when removed for
cleaning, at Mare Island, baffles the mechanical engineers to
explain. It is probably due to electrical action, though at
present the conditions for the existence of a circuit are not
apparent, The trouble has some connection with the use of
copper pipes.
AIR seeks a vacuum at a speed of 1300 miles an hour, and
exerts a pressure of 2.116 pounds to the square foot, is the way
of expressing the existence of a power not yet understood. The
weight ofthe air is one factor of speed, but not the only one to
be considered. Investigators seem content to infer that speed
or motion is a condition of matter, whereas it is but one result
of a cause whose action and nature are too little known.
CIVILIZATION is making an onslaught on Africa with rail­
road construction, the establishment of ship lines, the construction
of public works and the opening up of much territory to
agriculture and future commerce. .Six railroads are to be constructed
in North Africa, all of which will traverse districts
said to be very rich in possibilities. Besides the railroads and
steamship lines there are 17,000 miles of submarine cables sur­
rounding the continent.
SEVERAL British dependencies either have or are getting
ready to tax British coal imports, in order to raise money to
meet the increased demand by the parent country for contributions
to military aud naval expenditure. Besides this Sunday
labor in colonial ports is being put under costly restrictions.
The shipping interests are somewhat alarmed at this course,
and are anxious that no such severe financial demands be made
upon the colonies as to force them into retaliatory measures.
THERE are five miles of tunnel under the city of Baltimore.
Ventilation has been defective, especially in the Pennsylvania
tunnel. Electricity is to be used as a motive power to operate
a huge fan, to be erected at the foot of a ventilating stack. A
standing subway will be built eight feet wide by sixteen feet
high from the side ofthe tuuuel, near its top, to the foot ofthe
ventilating stack. The stack will be 100 feet high and 18 feet
square. The vacuum created at the middle of the tuuuel will
cause the smoke and gas to be drawn from the ends of the tunnel
to its middle, and out of the top of the stack.
PROF. ALFRED CHATTERION, B. Sc, of the Madras Engineer­
ing College, has a very suggestive paper in the Indian Engineer
upon the possibility of utilizing the immense water power of
India for the electric production of aluminum. Prof. Chatterton
enters very fully into the practical details and financial
aspect of the proposed scheme for the use of 125,000 h. p. He
suggests the investment of ,£"1,000,000, and shows figures,
which, though rough, are, he maintains, under rather than
overestimated, resulting in a profit capable of returning 75 per
cent., with aluminum at ^200 a ton. Meanwhile it is suggested
that a syndicate secure from government the right to use water
power of the Periyer project.
THERE is an earnest desire among leading political economists
and manufacturers, as well as among writers and thinkers, on
industrial problems, to have the statistical work, covering the
wages of labor (as contained in Vol. XX of the Tenth Census),
throughout the United States, continued. The struggle for higher
wages, and the contests of labor and capital are by no means over.
Many of these bitter and costly contests in the past have been
due more to the ignorance of those who blindly precipitated
them, than to any actual injustice on the part of employers.
One purpose to be subserved by the continued collection of
the statistics of wages, extra earnings, regularity of employment,
methods of payment, labor costs and influence of machinery,
is, that labor itself may be properly and fully informed as to the
whole vast question, that it may be able to intelligently discuss
and, if it must be so, to intelligently strike for just compensa­
tion. Strikes by the hundred could be averted or more readily
settled or adjusted, if there were some acceptable authority on
the subject, covering the whole field, such as a carefully and
conscientiously compiled Census Report. It is for this reason,
to say nothing of other reasons which readily suggest themselves,
that it is most desirable that the work be continued, and that the
legislation to this end now under consideration, receive favor­
able consideration.
The "Statistics of Wages," of the Tenth Census, was pre­
pared by Mr. Jos. D Weeks, of Pittsburgh, Pa., and his work
has received the cordial endorsement of the ablest political
economists on both sides of the water, as well as by leading
men in the Senate and House of Representatives. This work
ought io be continued; there are too many and too vital inter­
ests at stake to allow it to rest. No better qualified, more thor­
ough and painstaking statistician than Jos. D. Weeks can be
found for this important work, and it is to be hoped the needed
legislation will be enacted to allow ofthe prosecution of it. No
other man, either in the United States or Great Britain is as
capable as Mr. Weeks to handle this question in all its multi­
tudinous bearings; he can be relied upon to secure the facts
without prejudice, and the wage workers of the country owe
him a debt of gratitude for the work he has already done. Their
voice should be raised for the continuance of such work, and for
the continuance of his services in the execution of it.

n8 ENGINEERING MECHANICS. [May, 1892.
THE increase of carbon in steel affects the differences in the
hardening temperature. Each steel has its own temperature.
Silver steel, 900 degrees ; Wigston, 920. When quenched at
the temperature which gives greatest permanent magnetism,
a magnet is no more liable to lose its magnetism from rough
usage than when it has beeu hardened at a higher temperature.
THE descendants of the Philadelphian who, fifty years ago,
petitioned councils to not lay gas pipes lest the gas would burn
the town, or destroy the health of the people, recently had a
reunion in the shape of a meeting to protest against the introduction
of the trolley system. The city councils of Chicago
recently passed ordinances granting the right to use the overhead
trolley wires ou several streets. The feeder wires from the
power houses are to be carried in underground conduits. The
wires will be suspended l8}4 feet above the rails, aud the poles
and supports shall be placed 115 feet apart except at the intersection
of streets and avenues.
THE use of circular saws with diamond teeth is coming into
use in England for sawing stone, marble, granite, etc., which
have a sawing speed from 20 to 50 times quicker than by any
other method, and blocks cau be cut into slabs, etc. (from A
in. thick and upwards), almost with the same facility as timber
with an ordinary circular saw. The machine will "rebate,"
"notch," and "bevel," "chamfer," and cut, etc., at an angle,
and the sawn surfaces are perfectly straigut and square.
No abrasive material is required, such as sand, steel shot,
diamond grit, etc. , waste in cutting is reduced to the lowest
possible minimum—10 per cent, of material is saved. The depreciation
aud repair is about 10 per cent. The diamonds are
not tin soldered, but inserted red-hot iu an opening in the periphery
ofthe blade also red-hot, and welded together.
THE De La Vergne Refrigerating Machine Co. of New York
has made a 175 ton machine for a brewing firm in St. Louis,
Mo., capacity equal to the work of cooling accomplished by
the melting of 500 tons of ice in 24 hours, when making 40
revolutions per minute. The Corliss engine is 600 h. p., two flywheels
30,000 pounds each, crank shaft 15)2 inches diameter,
weight 20,S2o pouuds. Gas cylinders are double acting, 24
inches diameter aud 4S inch stroke. Steam cylinders, 48x64
X48 inches. The compressor connecting rods weigh 3,400
pouuds, the steam connecting rods 3,800 pounds. The machine
is 2SJ-2 feet high and covers a floor space of 37x22 feet.
A TRIPLE expansion locomotive has been designed for an
East Indian road. The barrel has three separate cylinders 24,
21 and 21 inches, respectively, in diameter, 52 tubes in each of
the lower cylinders and 26 in the upper one, each i;V inches in
diameter. A special pipe and valve are provided admitting
steam at high or low pressure, or both high pressure and inter­
mediate cylinders at once, to start the train, The cylinders are
14, 20 and 2S inches diameter,"and 26 inches stroke.
ONE ofthe boldest pieces of engineering work undertaken of
recent years is the construction of the " Transandine Railway,"
of South America. The hardest work occurs on the mountain
line, which is 149 miles long, 109 on the Argeutiue and 40 on
the Chilian side. The mountains are covered with perpetual
snows and have to be pierced by tunnels at a height of 10,450
feet above the sea. The only approach to these points is by
mule tracks for six months in the year. The line is a continuous
ascent from its commencement on the Argentine side to the
summit, where it immediately begins to descend on the Chilian
side. On account of the steep gradients over which the line
has to go, it has been fouud necessary to use tbe " Abt's Rack "
system, sections of which are distributed over the line, amounting
in all to a distauce of fourteen miles. The principal tunnels
begin at about two-thirds the whole length of the line-and
vary from 755 to 5540 yards in length, nearly all having 8 per
cent, gradients ; and as the rock is very hard, drilling machines
were used to expedite the work.
THE growth of railroad traffic in the mountainous districts of
the southwest has led to the devising of a locomotive especially
fitted for service on the Mexican Central. It has two boilers,
placed end to end, and resembles, in some features, the Fairlie
engine, except that the cylinders are secured to the boilers and
to the main engine frame. Each of the truck frames carries
three pairs of coupled driving wheels. The high pressure cyl­
inder is placed inside the low pressure cylinder. The boilers
are 52 inches in diameter, and have 201 tubes 2 inches in di­
ameter and 15 feet 9 inches long, fire boxes 56x56 inches,
placed between trucks; driving wheels 48 inches, truck wheels
28 inches ; high pressure cylinders, 13 inches outside diameter ;
low pressure, 28 inches. Valve motion outside, no eccentrics
used. Tank capacity, 3,000 gallons, coal bunkers, 5 tons
weight of engine 230,000 pounds, of which 200,000 is carried on
driving wheels,
A GERMAN firm has introduced a practical electric drilling
machine, 110 volt, A n - P- motor, by which belting and shafting
is dispensed with. The makers claim that the uotiou that electric
motors are chiefly suitable for transmission of power over
long distances is incorrect, and that it will pay to use copper
conductors iu small factories instead of belting. The electric
motor avoids the shaking and jarring due to belting. Speed
cones are unnecessary. Direct currents can be fed under different
pressures. If alternating motors are used, circuits of
varying frequencies can be employed, and if multiple current
motors are employed uo commutators are necessary.
THE disadvantages^ coating iron and steel with molten zinc
are well known, but supposed to be unavoidable. A cold galvanizing
process has been introduced which showed in the case
of hard steel wire as follows :
Tensile Strength.
Steel wire uncoated 165 tons per square inch.
Steel wire galvanized by ordinary
process 150 tons per square inch.
Steel wire coated by new process 165 " "
The results of tests to find torsional strength would be of interest,
in view of the rather surprising advantage developed by
the cold coating process.
ONE of the practical difficulties staring English naval engineers
in the face is how to get the desired speed in war ships
with the necessarily limited space for engines and boilers. War
ships cannot afford as much space for that purpose as in the
mercantile marine. For instance, to give the ship " Edgar " a
speed of 20J2 knots a horse-power of 13,000 would be necessary,
and the boilers to give this power, if similar in construction to
merchant ship boilers, would weigh 800 tons. It is now recognized
that the marine boilers are too light, and an increase of
20 per cent, in weight is now allowed, which will give greater
size. The naval engineers have continuous trouble with leaky
boilers, even with natural draught, and they have desired permission
to use a new form of boiler, which they argued would
give a power of S500 horse, with boilers weighing 196 ".tons, as
against existing boilers, which give only 5000 horse-power, and
weigh 24S tons. Notwithstanding all the alleged improvements
in boiler making, a forced draught sets the tubes to leaking,
and heuce the return in some instances of recent war ship
building, to the old double-ended boiler, which is so much

May, 1892.] ENGINEERING MECHANICS. 119
lighter in proportion to the heating surface than the two singleended
boilers with the same surface. A committee has the
whole subject of boilers under consideration.
THE new Masonic Temple iu Chicago will have 24 cars (elevators
built in a circular shaft, liaving a 250 foot rise. The
fastest elevators in New York have a speed of 600 feet per min­
ute, but the average speed is 300 feet. Three elevators of ten
tons each, capable of carrying 135 passengers at a speed of 200
feet per minute are being constructed to transfer passengers
from the Hudson River to the top of the Palisades. Each ele­
vator will be worked by 200 h. p.
SOMETHING new and revolutionary has lately come to light
in metallurgical chemistry by the discovery that compounds of
nickel and irou with the gas, carbon monoxide can be obtained
by merely passiug carbon monoxide, produced by the incomplete
combustion of coke or charcoal, over the finely divided
metal, and condensing the resulting vapor in a tube surrounded
with ice and salt. Its properties have been very fully investigated
by its discoverers, Messrs. Mond, Langer, and Quincke,
and also by- M. Berthelot, who published his results in a recent
number of the Comptes Rend us.
It is a liquid of high refractive power, with a relative density
of L31S5 at 62 0 F., which solidifies at 13 0 F., aud boils at 109 F.
At 358° F. the vapor returns to its original constituents.
Bodies can be plated by heating them to this temperature aud
suspending them in a vessel filled with this gas. The new process
possesses a great advantage over electro-plating, as not
only metallic surfaces, but any substance, however intricate in
design or fragile in structure, can be coated with a brilliant
superstratum of nickel by its means, without the tedium and
risk of first covering it with blacklead. Real flowers can be
plated with gold or silver by it, and the film is less liable to
flake off than when deposited by the electric current. The
liquid nickel-carbonyl is highly poisonous, but under proper
precautions could be used for medicinal purposes. A more important
possible utility is the extraction of metal from ores.
Commercial nickel contains about 60 per cent, of the metal,
the rest is cobalt, iron, carbon and other impurities, but pure
nickel can be obtained by passing carbon monoxide, ob­
tained from coke or charcoal, over the crushed mineral, then
condensing the liquid nickel carbonyl in artificially cooled
tubes, and finally heating this product to 35S 0 F., when the
pure nickel will be deposited.
PROF. THOMSON, in writing on High Potential Transmission
admits the possibility of carrying energy equivalent to 130,000
horse power or 100,000,000 Watts. The laying of pipe lines for
the conveyance of electric energy is now the problem 011 hand
Very high potentials are quite probable with conductors sep­
arated in a pipe filled with oil, by a net of dry cotton, Proper
oil insulation and proper regard for self-induction, with a
size to provide sufficient capacity to offset induction will give
us the conditions for transmission of high potentials. The
number of conductors in a single phase system can be reduced
to one central conductor surrounded by a tube or by several
conductors, all enclosed and insulated from a surrounding pipe.
The normal phase in transmission can be maintained by carefully
distributing the capacities and self-inductions, as con­
denser action accelerates the phase at the dynamo and selfinduction
retards. Good insulating oil one inch thick within
metal surfaces possesses a resistance equivalent to 500,000 volts.
Increasing the oil in solution to ten inches, covering every inch
of the high pressure conductors, keeping the rate of alteration
lower, a working power of 500,000 volts is quite possible. Allowing
a 10 per cent, loss with a double conductor conveying
20o amperes each conductor having about one-twelfth of a
square inch section, a 130,000 horse power energy might be
practically and can be theoretically conveyed 240 miles.
The most serious difficulty to bo met with is the condenser
action of the line.
THE new Peyton-Jordan pavement is claimed to be, in important
respects, superior to any yet tried. Its foundation is
steel plates laid in sand. These plates are three feet long by A
inch thick, and strong enough to withstand a tensile strain of
50,000 lbs. to the inch. They are flanged ou the sides and laid
from curb to curb across the street. The flanges are pinned together
and the plates perforated for drainage. The pine blocks
are interchangeable and grooved to straddle the plate rib se­
curing tbe rib joint. Repairs aud openings can be replaced
without damage to the pavement, and old and worn blocks can
be exchanged for new. All swelling is provided for, aud it can
belaid rapidly, presenting when complete a smooth, unbroken
appearance. It will last sixteen years, when the whole surface
can then be recovered without disturbing the foundation.
Sections of this pavement will be laid in Chicago and St. Louis.
It has already been tested in other localities.
THE bridge which Austin Corbiu desires to build across the
East River to give tbe Long Island Railroad an entrance into
New York has not yet been authorized by the Federal and State
Governments, but steps to secure this authorization have been
taken, and meanwhile tbe eugineers are making plans of the
structure. It will cost about $12,000,000, aud will be in connection
with the approaches about 12,500 feet long, orover two
miles. The New York terminus will be in Park Avenue, between
Thirty-fourth and Forty-second Streets. There will be
sixteen tracks in the shed. The bridge proper will be made of
cantilevers. There will be two granite piers in the river, but
there will be one span of iooo feet on the New York side, and
another of 1100 ou the Brooklyn side, and the whole structure
will be 135 feet above high water.
INFORMATION has been received of the completion of a very
important railroad in the Republic of Peru, by which the inhabited
provinces of that country are brought in direct communication
with the head of navigation of the Amazon River,
and thus to the Atlantic Ocean. The new railroad is an extension
of the famous Oroya Railroad, which was constructed by
Henry Meiggs, and has been considered a great triumph of en-
o-ineering, aud oue of the wonders of the world. The Oroya
road runs from Callao, Peru, to the town of Oroya, from which
the new line extends to Port Tucker ou the Pichis River, with a
branch of the Amazon. A commission appointed by the
Congress of Peru, in October last, has recently made a journey
over the line, and make a very favorable report.
THE future supply of electricity iu a large city for all purposes,
at any desired voltage of continuous or alternating cur­
rent, would seem to involve a system about as follows :
A generating station conveniently located for obtaining water
for condensing, cheap fuel delivery and ready disposal of ashes,
containing huge triple compound condensing engines driving
large dynamos, delivering either directly or through transformation
upward high potential three-phase currents ; a system
of high potential mains for three-phase currents, probably con­
sisting of sets of three conductors with a heavy opeu braid or
network covering, tightly woven on, and drawu iuto an iron
pipe filled with insulating oil placed underground to avoid atmospheric
disturbances ; sub-stations containing compounded
three-phase motors, generators feeding into the street mains
at the desired potential for lights and continuous current
motors ; motor generators feeding currents of suitable poten­
tial for street car propulsion ; alternating current transform­
ers delivering currents of alternating character at desired
voltage for lighting aud for driving commutatorless three-
phase motors.

i2o THK CONSTRUCTOR. [May, 1892.
Translated by Henry Harrison Suplee.
The recesses in a permit the friction wheel to run free when
a is at rest. This is evidently a form of ratchet gearing in itself.
The order of escapements at 2 is as follows :
I II, II III, III IV, IV I.
This is controlled by a second escapement, shown in Fig. 781.
FIG. 781.
The pawl b of Fig. 7S0 is connected by the rod/"to the beam a.
as shown. This mechanism is a step ratchet of four steps. The
steps are the pawls bv b.,,

May, 1892.] ENGINEERING MECHANICS. 121
Example.—Fig. 783 shows such an automatic brake device as applied to column,* we have undoubtedly a physical ratchet train in which
the pontoon bridge at Cologne. At a is a friction cone combined with a spur the particles of vapor are considered as a physical aggregate,
gear a', driven by the shatt and pinion a" iu the direction to wind up the which from the higher temperature, an- under higher stress.
cord 011 the drum c'. The drum is fast to the chaft c, but the cone a is loose Another example of a physical ratchet train is the apparatus for
on the shaft. The wheel a is connected firmly to the shaft c, when the cone operation by liquid carbonic acid which has been recently used.
b, which slides on a feather, is forced into engagement with it, and this en­ Electrical accumulators are also instances of physical ratchet
gagement is effected by the differential screw ./ and hand wheel d'. The use trains, as well as some applications of galvanic batteries, the
of the differential screw enables the requisite pressure to be obtained, and
action taking place by make and break of electrical contact.
also causes the motion of a" to be in the same direction as c' when lifting.
The dynamo-electric machine also becomes a physical running
The friction of the cones binds the parts firmly together, so that a is practi­
ratchet aud the electric motor a physical escapement, the whole
cally secured to the shaft until d' is revolved backwards, when c' follows by
forming a physical running gear train.
the action of the weight (.', the cones slipping upon each other and the
Again we may consider a "chemical" ratchet train, such as
pressure being automatically regulated, and the motion at once checked
coal or any fuel, which, during combustion, releases the energy
when o" is stopped.
which is stored in it. This may be utilized iu numerous ways,
Other and most important applications of adjustable escape­
but for our present considerations, mainly iu the production of
ments will be given hereafter. It may, however, be here noted
motion. Chemical action is also included in hot-air engines,
that by means of such mechanism tbe most powerful combinations
may be controlled with the exercise of a minimum effort.
and iu the operation of telegraph apparatus in a similar sense.
i 260.
We may consider the principal factors in a steam motor plant
as portions of a ratchet chain, somewhat as follows:
GENERAL REMARKS UPON RATCHET MECHANISM.
Ratchet mechanism, as already discussed, is applicable Chemical to a ratchet = combustion of fuel,
most extensive range of uses ; in this respect far excelling every Physical " = steam generator, etc.,
other form of mechanism. This is plainly due tothe fact that Mechanical escapement steam cylinder aud attachments,
ratchets are suited either to produce the effect of relative motion
and relative rest. Considered in this light tbe six preceding
Mechanical running gear = crank shaft and wheel,
classes may be grouped as follows : Common ratchets, checking these four uniting to convert the released energy iuto mechani­
ratchets, and locking ratchets are those which act to hinder cal motion. If we consider a locomotive engine, we have added
motion, while releasing and continuous ratchets, as well as to this another running gear in the shape of the driving wheels
escapements, act to produce definite motion. The motion pro­ aud rails, while the train and wheels and journal bearings unite
duced by ratchets is intermittent while that produced by the to form a combination of the sixth order.
forms of mechauism previously considered, such as cranks, Another chemical train may be formed by the use of explo­
friction, or toothed gearing, etc., is continuous. Mechanism for sives, which are released either mechanically, as by percussion
continuous motion may be called "running gearing,"* and or friction, or chemically, by combustion of some auxiliary
practically merges iuto ratchet gearing. The general province material. Again, we may have releasing gear of the first, second,
of ratchet gearing has only beeu partially covered in the preceding
pages, where such forms as may strictly be considered
machine elements have been included. An exception might be
made as to the allied forms of springs, some of which, indeed,
were referred to. There is, however, a large number of machine
elements of a different kind, whicli usually involve the continuous
action of the operative forces iu one direction ; these include
tension organs, such as ropes, belts, chains, etc., compression
organs, fluid connections, and many others, all of which
are considered in the following chapters. It will be seen that
these may all be so arranged as to be fairly considered ratchet
devices also ; as belts or chains may become friction or toothed
ratchet gears, aud even the valves of fluid connections are really
pawls.J
The pawl mechanism must also be extended to include tbese
classes of machine elements, and their limits thus greatlywidened,
especially in the case of pressure organs. Examples
of this will be found in the pistons and valves of pumps, both
for liquids and gases, which may act as checking or locking
ratchets, or in hydraulic motors and steani engines as escape-
•neuts, and in gas engines, as escapements and continuous
ratchets combined. Similar comparisons may be made of tlie
ratchet principle in the use of accumulators for hydraulic cranes,
presses, riveting machines, and the like, and in the cataract for
single acting steani engines we find a complete analogy to the
ratchet. In these cases we have ratchet systems of the higher
orders. The history of the development of these machines is
really that of their pawl membeis.
A very interesting example is that of Fig. 779, in which, if we
substitute a flow of steani for the ratchet wheel, we have the
arrangement of the single acting high pressure steam engine
with Farey's valve gear. The numerous modifications of escapement
gear, which are included in the steam engine, have occupied
the activity of designers down to the present time. A
number of the more recent valve gears have been shown i : ''/, 252,
and similar devices are used on engines for steani steering gear,
called by the French " moteurs asservis," and such gear also
plays an important part in the mechanism of some of the socalled
"fish " torpedoes.
or higher orders.
In the case of most firearms the release is of the second order,
since the mechanism of the lock acts upon a fulminate by percussion,
aud the heat of the latter releases the powder.
If we examine and classify all mechanism of transmission in
the above manner, it will be apparent that all forms are included
iu one or the other of the following classes, viz.: mechanical,
physical, or chemical ; these also entering into combinations of
the higher orders with each other.
The steam engine itself, as we have already seen, consists of a
driving train of the fourth order. Trains of still higher orders
are of frequent occurrence.
In the recording telegraph, with relay, we have a physical
ratchet train of the second order, releasing a mechanical running
train and operating a recording train, both physical trains
actuated by chemical trains, the whole forming a combination
of the fifth order. The ordinary signal mechanism of a railway
station, when mechanically operated, is a system of the fourth
order.
The Westinghouse air brake, not considering the boiler, is a
train of the fifth order, consisting of an escapement (steani
cylinder), driving ratchet (air cylinder), intermittent ratchet (air
vessel), escapement (piston and valve connections), friction
checking ratchet (brake gear). If we include furnace and
boiler, this becomes a train of the seventh order, and may be
still further extended.
A still more noteworthy example is found in the application
of compressed air for the purpose of operating pumping machinery
at the bottom of deep mine shafts. In this case we
have :
1. Furnace = chemical ratchet train.
2. Boiler physical
"j. Steani engine mechanical escapement train.
4 Shafting and transmission to running
5. Air compressor, driving ratchet.
6. Air chamber, " intermittent"
7. Air cylinder in mine, escapement train.
f8. Water cylinder in mine, driv'g ratchet "
Iu this manner the applications of pawl ratchets may be ex­
The preceding discussion and illustrations of the relationship
tended before our eyes and yet the limitations are not reached,
existing between mechanical, physical and chemical trains shows
and the further researches are carried the broader and more
the necessity of combining mechanical and technical research,
general does the scope of this division of mechanism become.
and a complete mechanical training therefore includes these three
Not only does it include fluid pressure organs, both liquid and
branches,, and also the later science of electro-mechanics.
gaseous in a strictly mechanical sense, as iu the case of pumps,
Modern methods of invention require research into all of these
etc., but also when these are considered in a physical sense with
lilies of science, and the constantly widening field of mechani­
regard to their internal stresses. This gives a branch which
cal engineering is thus extending its work, while at the same
may be called "physical" ratchet trains, of wliich the steam
time gathering into systematic form the many branches of
boiler is the most important example. In this, when taken in
couuection with a pipe full of steani, aud suitable valves for
applied mechanical science.
opening and closing, forming what has been termed a steam
* See Theoretical Kinematics, p 493- r , ,
* See the author's Theoretical Kinematics, p. 486, in which this classifica­ t The system of clocks operated by pneumatic pressure from a central
tion was originally made.
station, designed by Mayrhofer, at Vienna, forms a combination ot 33 dis­
f See Theoretical Kinematics, p. 458 ct set/.
tinct systems.

122 ENGINEERING MECHANICS. [May, 1892.
CHAPTER XIX.
TENSION 1 IRCANS CONSIDERED AS MACHINE ELEMENTS.
I 2 6l.
VARIOUS KINDS OF TENSION ORGANS.
The various forms of machine elements which have already
beeu discussed, have been those which offered resistance to
forces acting in any giveu direction, forming more or less rigid
constructions. We now have a series of elements which are
only adapted to resist tension, and which are very yielding
under the actiou of bending, twisting or thrusting forces. These
include a great variety of rope, belt wire, chain belt and similar
transmission devices, all of which may be included under the
general term of Tension Organs. Their usefulness is limited
by reason of the fact that they have only the single method of
resisting force, but at the same time the element of flexibility
permits the use of one aud the same organ to transmit power in
changing directions, aud hence gives rise to many useful combinations.
An especially valuable feature of teusion organs in
practice lies in the fact that many materials are excellently
adapted for such use, and cau be more economically applied.
FIG. 262.
METHODS OF APPLICATION.
A distinction is to be made between " standing and running'
tension organs. The first are those used to suspend weights,
support bridges, also in the construction of many machine details.
Examples of such use are found in suspension bridges,
pontoon bridges, hawsers, guy ropes, standing tackle, etc.
Running tension organs are used in machine design in connection
with other machine elements principally for the trausmission
of motion.
Running teusion organs may again be divided iuto three
classes according to their action iu connection with other
machine elements.
According as they are used :
I. For guiding.
2. For winding (hoisting or lowering).
3. For driving, this also being possible by winding and unwinding.
Combinations of these applications may be made, either with
or without the use of standing tension organs. In order to
understand the various applications it is desirable to consider
some of the most important combinations, hence these will be
briefly examined.
Q
FIG. 784.
1. Guiding.—Fig. 784 shows several combinations, adapted
solely for guiding. At a is the so-called stationary pulley, in
which a cord, led off at any angle, is used to raise aud lower a
load Q. The dotted lines show the position of guides, or in the
absence of these the direction of motion is governed by the
action of gravity. At b we have the so-called movable pulley,
the pulley being combined with the moving piece ; the weight O
is here supported on two parts of rope. Form e is a combination
of a and b, and is the well known tackle block. Form d
consists of four sets of form a, and the actiou of the cords compels
the piece Q to maintain a parallel motion. This is practically
applied in Bergner's drawing board.
In like manner four pulleys of form b may be combined as in
form e. This is the old parallel motion for spinning mules, also
used as a squaring device for traveling cranes*
The use of pulleys and bearings is to reduce friction at the
point of bending, and roller bearings, as Fig. 566, are also used,
but when the bending surface is well rounded the pulleys may­
arc of contact. This action, which here opposes tbe motion of
the cord, is in other instances made of great utility. Cord-
In Fig. 788 are shown several lowering devices. At a is a
lowering drum for warehouse use ; the unwinding coil at W,
be dispensed with. Pig. 7S5, at a, b, c, shows such arrangements, lowers the load Q, while the cord of the upward moving coun­
the action being the same as before, but with greater friction. terweight Q., is wound ou the drum at W.,; a brake can be ap­
The arrangement at d is a six-fold cord, aod in sail making eyeplied at B, and when necessary, guide pulleys used as at L /,.
lets are often used in similar manner, as at e. The friction is Form b is a lowering apparatus for coal trucks, consisting of a
great in all such devices, because the cord presses hard upon
the point of curvature ; its magnitude increases rapidly with the
combination of two winding coils, with a brake at B. The
* Form d is a kinematic inversion of the older form e.
FIG. 7S5-
frlction, which is to be considered as a particular case of sliding
friction, plays a very important part in constructions, involving
tension organs, and will be more fully considered hereafter.
FIG. 786.
In Fig. 7S6 is shown Riggenbach's rope haulage system for
use on inclined trackways, or so-called "ramps." Iu this
arrangement, the descending car is loaded at the top of the
ramp with sufficient water to enable it to draw up the ascending
car by the power of its descent. The speed can be controlled
by the descending weight, aud also a weight acting upon wheels
gearing into a rack ~.f
2. Winding.—The most important forms of winding gear are
FIG. 7S7.
shown in Fig. 787. At a is the common windlass, also known
as a winding barrel or drum, extensively used in many forms of
hoisting machinery ; b is a drum for spiral winding of a flat belt,
the belt being wound upon itself, and side discs being provided
as guides for the belt; c is a spirally grooved drum for winding
chain ; d is a conical drum, with spiral groove, used in clocks
(there called a fusee), also for hoisting machinery with heavy
rope ; and e is a rope "snail " used on the self-acting mule, to
produce the varied speed of the carriage. Many combinations
of winding and guiding devices are made, also of winding devices
with each other.
FIG. 7SS.
t Numerous illustrations arc in use in Switzerland and elsewhere w
clines varying from 25 to 57 per cent.

May, 1892.] ENGINEERING MECHANICS.
counterweight 0, is in the form of Poncelet's chain, the action
being to vary the rate of descent of the load U'„. This apparatus,
which is called a " Drop," is much used in the coal
mining districts in England. Form c is Althan's furnace hoist,
and consists of two drums with steel bands. The load of water
at fin by its descent, raises tlie charge Q., to the top of the furnace,
after which the water is drawn off, aud the empty car descends
and the water vessel is raised to the top again. The
speed is controlled by a brake at B.
FIG. 7S9.
Wrapping connections have been used from early times in
connection with beams and levers, as shown in Fig. 7S911, and
the form b is especially applicable to scroll-sawing machines.
Form c is a combination made with very fine steel bands, and
used iu the Emery weighing machine.
Combination windlasses are frequently used for lifting weights,
some forms beiug shown in Fig. 790, and other combinations
also in complete machines for hoisting, as in Fig. 791.
FIG. 790.
In Fig. 790, a is the so-called Chinese, or Differential Windlass,
consisting of two windlasses aud oue sustaining combination
; b is another differential combination used in a traveling
crane designed by Brown, of Wiuterthur, the arrangement
being intended to obviate the lateral motion of the load.
Another arrangement for the same purpose is showu at c (devised
by the author in 1S62) ; it consists of two drums united in
one. The signal arms and automatic safety gates, now so much
used on railways, are operated by a combination of winding and
guiding members, chains being used on the winding barrels and
wire connections on the straight lines.
Winding and guiding members are much used in cranes and
hoisting machinery, several combinations being given in Fig.
FIG. 791.
791. A crane with boom of variable radius is shown at a ; b is
a pair of shears operated by three windlasses, /*/", and lis, for
moving and holding the shear legs, W3 for hoisting and lower-
in parallel direction and uniform speed, trolley travel is effected,
hoisting or lowering by unequal wind motion.
In Fig. 792 a, three drums and one guide sheave are used ; b is
made with four drums and two guide sheaves, a combination
used in steering machinery for operating the tiller ; and c consists
of two drums and two guide sheaves so arranged that one
load is raised as the other is lowered, this being used in mine
hoists. This is also used for inclines or "ramps." When the load
is always to be lowered, the descending load does away with the
necessity of auy motive power, aud the speed is controlled by a
brake. Examples of this form are found in some mines and
stone quarries, and in apparatus for loading vessels, etc. (See
Chap. XXII.) Power-driven cable railways for passenger service
on inclines are sometimes made with two cables, one for
driving, and a second for guiding and as an additional security,
an example being tbe old road up the Kahlenberg at Vienna.
When round ropes are used it is desirable to have the drums
made with spiral grooves, in order to reduce the wear on the
FIG. 793-
rope. The travel on the drum causes the angle of the rope between
W and L to vary, and to prevent this the device shown
in Fig. 793 has been used by Riggenbach on the cable incline at
Lucerne ; two forms being given. The guide sheaves are traversed
by screw motion, the rope being led off in a plane parallel
to the axis of the drum, and in the second form two guide
sheaves are used for a double cable.
3. Driving.—This application of tension organs is most extensive.
The principal forms are given in Fig. 794. The cap­
stan a consists of a hollowed drum, the surface of which is
composed of numerous ribs and the rope is given several turns
about it. The axial travel produced by the spiral path causes
the rope to climb upon the larger diameter, from which it is
easily forced back to the middle from time to time by hand.
At A is a sprocket wheel with Y-shaped sprockets, much used in
many modifications ; c is Powder's drum, a form of grip drum
which grasps the rope automatically, and which is discussed
more fully hereafter. At d is a simple rope pulley, partly encircled
by a tension organ under such load as will produce sufficient
friction to prevent slippage ; 1' is a chain wheel with
teeth to prevent the slipping of the links. In all five cases the
wheel may drive or be driven by the tension organ.
By combination of driving and guidiug devices many useful
transmissions are made.
FIG. 795-
FIG. 792.
.Several forms are given in Fig. 795 : a is David's Capstan,
with conical windlass, with a ring-shaped guide roller which
constantly leads the rope from its travel toward the base of the
cone. At b is a counter-sheave device, the main sheave /"being
made with two grooves and the counter-sheave set at a corresponding
angle. This gives increased rope contact, which maybe
multiplied still more by increasing the number of grooves.
The counter-sheave may also form the second -pulley of the
ing the load ; c is a form of bridge c'rane, nsing a trolley combination, in
as at c; this is used in rope transmission devices.
combination with two winches. If both winches are operated Driving tension devices are often capable of being used to

i24 ENGINEERING MECHANICS. [May, 1892.
greater advantage than winding devices, since the direction of
motion need not be changed and is not limited. For these
reasons driving combinations are frequently used instead of
drums, as in hoisting machinery. Chain sheaves with pockets
to receive the ordinary oval link chain are here applied (see
i 2 75), or with flat link chain the sheave engages with the pins
of the chain.
FIG. 796.
Other driving systems are shown in Fig. 796. At 17 is a double-
lift with water counter-weight. Tis a pulley for round or flat
belt; the weights O, and Q.t are nearly equal, so that a semicircle
of contact is sufficient to prevent slipping at 7] and the
friction of contact is sufficient.
A reference to the Riggenbach cable road gear, Fig. 786, will
show a similarity to this device, but in Fig. 786 a braking de­
vice is provided at Q1 aud 0-. to protect from accident in case of
breakage of the cable. A similar device, using straius at T, has
been applied by Green for operating the sluices of the Great
Western Canal. At b is shown the grip-wheel, which has also
been used for cable driving. In this form the loads may be
quite unequal without apprehension of a deep groove cutting
in tbe drum. Koppen's system is shown at c: this uses a round
or flat belt with tightening pulleys L, L, so that sufficient friction
can be obtained for any given difference of loads; this
avoids the uuequal action upon the heavily-loaded side of the
belt, by producing tension upon the otherwise slack side, and
might be applied with advantage to the driving system of Fig.
795 c, requiring but a single tightening pulley, aud subjecting
the rope to only one kind of bending.
At d is showu a bucket gear, which combines driving and
guiding, and is much used for conveying in mills, grain elevators,
etc. If the difference in weight between the sides is slight,
the tension organ may be a leather belt, but for heavy service a
chain is used. This device has been in use from a very earlyperiod
for well buckets, aud in modern times in mud dredging
machines. At e is the Weston differential pulley block, a modifiiation
ofthe Chinese windlass, Fig. 790a. I\ and 7"2are chain
sheaves fast to each other, producing a differential action due
to their difference in diameter, the whole forming a substitute
for tbe older tackle block gear, Fig. 7841-.
The form shown at Fig. 796 d demands further consideration,
as it cau be given a series of most important applications.
If the tension organ is made a band and placed in a horizontal
or nearly horizontal position, it can be used to convey finelydivided
material simply poured upon its upper surface. Examples
of this are found in the transportation of grain, also in the
movement of paper pulp, and many other such purposes ; also
for conveying straw upon chain lattice conveyors, etc. In all of
these cases the material is kept on the conveyor simply by
gravity. This condition may be avoided and tbe capacity extended
by using a pair of belts, the material to be conveyed
being carried between them. A very important application of this
principle is found in power printing presses, the delivery of the
sheets being effected by systems of tapes and bands with great
speed and accuracy. Band conveyors are also used iu needle
machinery and in match making machines, and many similar
situations.
An important application of driving gear is found in the construction
of inclined haulage systems for mine ramps.
FIG. 797.
In Fig. 797 is shown tbe inclined cable system ofthe Rhenish
Railway. The driving wind TL, operated by a steam engine,
works the descending cable on one track aud the ascending
cable on the other. At L' is a tension pulley to take up tbe
slack cable and maintain a proper tension. The trains Q, and
Qv are connected to the brake cars B, and Bt, which are extra
heavy and control the rate of descent by proper brakes.
In the anthracite coal region of Pennsylvania haulage systems
are in extensive use for the transportation of coal, some being
constructed with irou bands, but most of them using ropes.
The arrangement will be understood from the diagrams iu Fig.
798 and 799, which, with the accompanying data, have beeu obtained
by the author from their engineer and constructor, the
late Mr. W. Lorenz.
FIG. 798.
The car in which the coal is hauled is not attached directly to
the cable, but is driven by a dummy D, which is permanently
connected to the cable. This dummy runs ou a narrow gauge
track, and at the foot of the incline the narrow track continues
on, so that the dummy D can go below the main track, as shown
in Fig. 799, and on the ascent it cau thus be drawu up behind
FIG. 799.
the cars which have been placed by the shifting locomotive.
The steam engine and drawing gear is placed at the head ofthe
incline, as shown in Fig. 79S, and the cable is led, as shown by
tbe arrows, that it passes twice over the driving wheel T, each
time covering about A of its circumference. The dummy cars
/}, aud D.l are connected by a secondary cable passing over the
tension sheave IA ; this secondary cable maintains the proper
tension on the main cable, whether the load is at the head or
foot of the incline, or ou the horizontal. The tension car is
given a play of 75 feet to provide for the necessary variation.
A different form of cable haulage is found in the system in
use betweeu Liittich and Ans, and sketched in Fig. Soo.*
FIG. Soo.
In this case the incline is divided into two sections, which
make an angle with each other as showu on the plan, and between
which is a short level space. On this space is placed the
steani engine and driving wheels Tj, T.„ T%, 7\, each wheel
haying its own engine, two engines alw'ays driving and two
being at rest; IA are the tension sheaves.
In this, as in tbe preceding case, it wiil be noticed that the
cable runs continuously in the same direction, differing in this
respect from the previously described winding and reversing
system. The cable is brought to rest iu transferring the cars
from one plane to the other in order that this may be readily
and conveniently done, but should this be avoided by running
them over the connection, by momentum or otherwise, the advantage
and usefulness of the system would be greatly increased.
This has been done in the cable tramways of Halliday aud
Eppelsheimer, first used iu San Francisco, aud shown in dia-
* See Weber's " Portfolio John Cockerill."

May, 1892.] ENGINEERING MECHANICS. 125
gram in Fig. So 1. This is most effectively applied on the trolley counter-sheave, as in Fig. 7057., to obtain increased tractive
streets of the city, for which it is admirably adapted. power.
Fig. S04 shows a plan view of a double system.
_ L, L'
FIG. So 1.
The endless cable runs in au iron way between and beneath
the tracks, the power being at T and guide sheaves at I, L,
with suitable driving and tension mechanism. The cars grasp
the cable by a gripping device through a narrow slot in the
trackway. The guide sheaves at the bases of the inclines aud
sides of the curves permit the grip to pass, aud when the foot
ofthe hill at the end ofthe road is reached, the grip is released
and the car transferred to the other track as at \l\, and in similar
manner shifted at the other end, IV,. The weight of tbe
cars ou the dowu grades counterbalances those on the up
grades, and so the motive power has only to overcome the frictional
resistance. The cable system of tramways has been extended
to Chicago and many other American cities ; also in
London, and a cable system of canal towage has beeu projected
by Schmick for the proposed Strasburg-Germersheiui Canal.
When it is practicable to propel the cars by a suspended cable
from overhead a different arrangement may be adopted.
FIG. S02.
Fig. 802 is a diagram of a system operated by a suspended
chain. The descending cars Ql are loaded aud the ascending
ones Q, are empty, and the speed is controlled by a brake at B.
If the action is in the reverse direction, a driving engine must
be applied at 7. A similar arrangement is much used in coal
mines which are entered by inclines. The chain is attached to
a fork on the cars.
The system of overhead cable tramway, which has been
brought to a high state of efficiency by Bleichert, is based ou
the same principle as the preceding, but for much lighter loads.
The system consists of a cable tramway in which a stationary
cable is substituted for the trackway. The running cable is
commonly called the pulling rope, and runs underneath the
stationary rope. The cars consist of a combination of grooved
sheaves, from which the bucket or other receptacle is suspended
by curved arms. The stationary cable is supported upon round
poles, and the arrangement of the stations is shown in the diagrams
of Figs. 803a and 803/).
•'/., . ':-' "/^LS'.SSS. ..it ,.^S. S. S. SSSsSS, , '• S'SS^SSSSSSSS:', SS >,/. ./> ^
FIG. 803a.
The stationary cable connects with the suspended tramway at
SI SH and SHI S rv . At So is the anchor of the stationary
FIG. S04.
At A\ is the motive power for systems I aud 77, and at A"2 the
motor for system III. The driving sheaves are at 7] the counter-sheaves
at G, and the tension sheaves at L'.
The supporting columns for the stationary cable must be
stiff, aud often quite high.
a b.
FIG. S05.
Fig. S05 shows the forms used by Bleichert, a being used up
to 24 feet high, b for heights between 24 and 80 feet.*
In Fig. S06 is shown a combination of driving and guiding
systems in which the guiding and driving sheaves are combined
upon the car Q, and the tension organ is fastened at two points
So So on the path of the car Q.
the current keeping the cables taut. The equilibrium of these
forces enables this to act in the same manner as the stationary
cable of the Bleichert system, the difference only being that the
load, instead of being suspended from the cable, exerts a lateral
stress. The driving cable is similar to Fig. 806 b, and is beneath
the surface of the water.
S/SS/S..,SSS':.. . ' ,
If we imagine, in the combination of Fig. 806, that the
FIG. S03/3.
traveling vehicle O may be longer than the distance .S0 Sa,
which is the full length ofthe tension organ, the principle will
not be altered, but the action will be modified, since the rela­
cable, with a teusion weight at LT The driving sheave is at T, tions of the traveling vehicle and the tension organ are now
driven by connections to the engine at K, and at L' is the ten­ inverted. The ends of the tension organ can now be joined
sion device for the pulling cable. If the service is heavy the
cable is carried twice around [the driving sheave 7, using a * On the tramway at Liker-Vashegy, poles of 140 feet high are used.
' . ' • ' . '
IE
FIG. 806.
; (KJT
The motive power is on the car and operates the sheave 7.
In the form shown at a, a Fowler grip sheave is used at T, this
form being suitable for a rope system, while the form shown at
b is better adapted to be used with chain.
The system shown in Fig. 806/) is. also adapted for hauling
boats, and has been used by Harturch for operating the railway
ferry across the Rhine at Rhinehausen. The ferry boat in this
case is guided by a stationary cable securely anchored, as in
Fig. 807, the anchorage being up the stream, and the force of
FIG. 807.
So

126 ENGINEERING MECHANICS. [May, 1892.
together, or in other words it can be made endless, and if heavy
enough, its weight can be caused to produce enough friction on
the bed of the stream to furnish the necessary resistance. This
is the construction of Heuberger's chain propeller, Fig. 80S, as
improved by Zede.
.. T
L L /TV-.. TJ IJ I, t.
FIG. 808.
T is the driving sheave for the chain, L, L, L are guidesheaves,
7,j is a movable sheave to' take up a portion of the
slack chain when passing into shallow water. The system is
made double, being placed on each side of the boat, and each
side is driven independently, so that sharp curves can be turned.*
If, in the case of a tension organ driven by a revolving pulley,
there is not sufficient tension given, the friction becomes insufficient
to overcome the resistance of the load ; if the necessarytension
is externally supplied and removed periodically, a continuously
revolving pulley can be caused to produce a lifting
and dropping action of a given load. This plan has been
adopted in some forms of drop-hammers, of which Fig. 809 is
the arrangement. T is a pulley
running continuously in
the direction of the arrow, Q
is the drop weight, 77a handle
by which the operator applies
and releases the tension which
causes the pulley to drive or
slip.
The applications of running
tension organs which have been
thus far considered, are those
in'which the device has been
used either to lift weights or to
transport the same from place
to place. One of the most
important applications, however,
is that of transmitting
FIG. 809. FIG. SIO.
rotative motion from pulley to
pulley, an operation which can
be almost indefinitely repeated.
This combination includes all numerous forms of belt, rope and
chain transmission, Fig. 810. The necessary tension for this
purpose is sustained by the journals and bearings of the pulleys,
also being modified by supporting or by tightening pulleys.
The two portions of the teusion organ are distinguished as the
tight and slack sides respectively, and many modifications of
this form of transmission are discussed more fully hereafter
(see Chap. XX to XXII).
There is one application, however, wliich is appropriatelydiscussed
in this place, namely, that in whicli rotative trans-,
mission between pulleys upon stationary axes is combined with
pulleys upon a movable member, thus enabling motion to be
transmitted from a stationary source to a moving body, Fig. 8i 1.
FIG. 811.
In case a, one of the driven pulleys is mounted upon a carriage,
saddle, trolley, or the like, and may be shifted in position
upon its ways or track ; the tension is sustained by the
three guide sheaves. Applications of this form, using belting,
are used upon planing machines by Sellers, Ducommun & Dubied
and others. With rope driving gear it is used to operate
the spindles upon the carriage of the self-acting mule, also for
operating traveling cranes by Ramsbottom, by Tangye, and by
Towne ; being combined by the latter with the squaring device
as shown in Fig. 784,?, and effecting all the functions of the
crane, including bridge and trolley travel, as well as the hoisting
and lowering of the load.
The form of Fig. Su b differs from a in that both sides ofthe
belt or rope are used to transmit power. The stationary pulleys
7] and 7", here drive the movable pulleys 7"2 and Tt. These
driven axes can be utilized in various manners, as, for example,
to operate a windlass device for the propulsion of the carriage
Q ; an example of which is found in Agudio's cable locomotive f
In this device the pulleys T, and Tt drove a friction train which
operated a drum connected with a stationary cable as in Fig. S06.
A more recent device is shown in a modification of Fig. 811 a,
as shown in Fig. 812.%
FIG. 812.
This construction, which is in use at the Soperga-Rampe at
Turin, consists of a double rack, placed between the rails as
shown at b, which also shows the gearing by which car is
driven. The motive power is placed at the foot of the incline
at T, G, the 500-horse power engine running continuously in
one direction. The cable is carried upon the overhead guide
sheaves A, and passes around the pulley A2, and through the
sheave system T T' of the locomotive, and is supported also on
guide sheaves under the track, a tension pulley being placed at
L'. The velocity of the driving cable is four times that of the
cars, and the descent is effected by gravity alone under control
of a brake. During the descent the bevel gears ou the shaft of
the driving pulley are released by friction clutches at K, thus
rendering the car independent of the cable.
The foregoing condensed description is nevertheless fully
sufficient to indicate the extreme service of which tension organs
arc capable in machine design. No less than seven systems
have been shown for railway use, and four for boats. This is
the more significant since it will be remembered that cable propulsion
had been abandoned for railway use, but yet appears to
now be revived with increasing success.
Our division into Guiding, Winding, and Driving systems
enables different devices to be placed in corresponding classes.
There yet remains to be considered the co-existing action of
many of the devices, such as pulleys, windlasses, cranes, etc.,
in which a negative motion may be given to the tension organ
by the descent of the load Q under the action of gravity, j!
This action can be fully determined by reversing the previouslyconsidered
movement for the backward motion. In the couimon
belt transmission, Fig. 810, the action is reversible, as is
also the case with the simple pulley, Fig. 794 d.
The case is different, however, with the rope tackle Fig. 7847and
the differential block Fig. 796c, which are therefore here
considered in the more general form of Fig. 813.
n 1, If in these forms the
cord Z is pulled in either
direction the lower
sheave will be also
moved up or down proportionally.
At the present
time systems using
endless cords are under
consideration, but fre-
2 quently choice is to be
made as to which portion
is best used. It will
be seen that the system
of Fig. 806, which is
made with both ends of
the cable secured, can
also be considered as a
portion of an endless
r~A
system similar to Fig.
808, aud other endless
systems are found in
A Tj Fig- 784 d and e; also
FlG - 8l 3- Fig. S13 b, which differs
r ., , from a only in the running
of the rope, the united ends being marked by a cross.
* The followingdata of performance are given bv Zede : Capacitv t tee 500 BunSlf tons H• length overall, 230 ft. ; breadth, 21-4 ft.; depth, 6"4 ft ; midship draught 3154
in. The chains were of cast iron, weighing 275 pounds per yard; two engines
of 150 I. H. P. gave a speed of 3.72 miles (!) per hour.
g Y d L°' I \ I . e , nloiresur la Locomotive funiculaire, Turin, 186
J See Bulletin de la Soc. d'Encouragement, Vol. XVI., 1869 P 48
K.«maUc a s,'P %T C ' OSUre ' First bussed in the Author's Theoretical
(To be continued.)

May, 1892.J ENGINEERING MECHANICS 127
THE LAST GUN,
FR. SCHMEMANN'S reply to Mr. Wm. H. Burr's criticism,
published iu the March number, of 1892, of ENGINEERING
MECHANICS, ofthe former's theory of his parabolic truss, in the
December number of 1891 of MECHANICS :
Mr. Burr, in acknowledging the correctness of the four main
formulas I, II, m, and Iv> m a k e s the fundameutal mistake in
author ofthe criticism shows no understanding whatever of the
real nature ofthe moment of resistance for a truss exposed to
the forces acting in the direction ofthe centre of gravity, as iu
the case of a loaded roof truss, in remarking : " These errors
are repeated constantly," etc. He proves by his whole criti­
cism a sophistic tendency in acknowledging the correctness of
the four/ormulas, I, II, III and IV, and denying the correctness
of the strains arrived at by the application of the same. In
stating, " As a matter of fact, neither of the stresses considered
can exist in consequence of the absence of all requisite truss
bracing " he shows quite a defect of knowledge in regard to the
formulas about the parallelogram of forces. A vertical strain
V (as the load on a roof) is acting on a truss system of two
chords and a post; it will produce in the directiou of the post
a strain of V cos. a and in the chords at top and bottom
ofthe post a strain V sin. a each, which later are acting iu an
opposite direction. These later forces produce, therefore, on
the post, a bending strain according lo the theory ofi the strains
in a girder, notwithstanding the author's denial without proof.
His bracing theory is only guess-work ; he does not show
any valid claim for it. My truss, as stated in the begin­
ning of my former article, is a hollow base truss, whose
moment of resistance is accordingly calculated to the load act­
ing on it, and this truss is sufficiently strong to resist all the
vertical (load) and even side forces, which is all that is required,
and all outside of this is bombast.
Mr. Burr is misleading himself, mainly by his mistaken idea
about the moment of resistance of a truss, and especially of a
hollow base truss.
My theory of the truss is correct. In finding the strains for
the horizontal lower chord and not considering the parabolic
intermediate pipe in the centre ofthe truss ; this has been done
for the sake of simplicity, as its influence on these strains is
of minor importance, as the moment of resistance of the
truss gets only a few per cent, increased in taking it in con­
sideration, where located in the neighborhood of the axis of
centre of gravity of the cross section of the truss, it being of
small influence in increasing the strength of the same. The
above omission, and taking it in consideration at a point be­
tween 2 and 3, it will only increase the strength of the truss,
and this point shows no fallacy of my theory, but only a
simplification. So far my reply to Mr. Burr
In regard to the details applied for my truss, I wish to
state that these pipes have shown, by actual test, a com­
pression and tension far superior over solid shape iron. My
roofs, carried out of pipes, have beeu quite satisfactory
already in regard to strength and economy.
Philadelphia, March 2S, 1892.
FR. SCHMEMANN.
inches long and two inches wide, were subjected to strain. The
results were us follows :
No. 3, cut from lower part of centre, broke at 2,490 pounds strain
No. 4, " ' upper part of centre," 2,000
No. 5, " " lower part of shoulder
No. 6. " " upper part of shoulder
1.390
1.130
As many belts arc- sold most indiscriminately from any part
applying the stresses given by these formulas to a section nor­ of the hide, it is evident that the strengtli of belt is equal to the
mal to the pipes ofthe upper aud lower chord, and not to a strain on the weakest piece. A belt made from two centre
section taken in the direction of the centre of gravity or nor­ pieces will sustain a strain of 26,940 pounds, while a belt made
mal section to the horizontal line, as these formulas give only from shoulders would not stand a strain of over 15,120 pounds.
the horizontal stresses, and in order to get the stresses in the in­ These facts were presented very correctly aud ably by Mr.
clined upper and lower chord the same have to be divided by Schierin at a recent meeting of the Polytechnic Section of
the cos. ofthe angle of inclinations ofthe different chord mem­ the American Institute of New York.
bers, and not multiplied with the cos. of these angles. The
MAKING good belting does not consist iu sewing together
pieces of leather, since pieces cut from different portions of
the hide have different degrees of strength. In a re­
cent test conducted by Mr. Charles A. Shieren under the
Fairbanks Scale Company of New York, four pieces each 18
ALL maiu driving belts over forty inches in width have to be
made iu sections, consisting of two or more pieces of leather
cemented together. The average hide for belting does not con­
tain more than forty inches in width of solid leather suited for
belting, very rarely over that; therefore, wide main belts are
made in sections. Ordinarily the pieces are not lapped parallel,
but simply butted. For example: A sixty-inch double
belt receives two thirty-inch pieces for the first layer, laid side
by side, and a thirty-inch piece over the centre ofthe two lower
pieces to break the joint, two fifteen-inch pieces on top of
each edge of the lower layer to complete the width ; thus the
belt is cemented together. However, for electric light plants
where belts ate run at high speed and with variable power
(which produces sudden strain), the seams of these butted
joint belts, iu several instances, broke, doubled up and destroyed
the belts completely. To guard against such a calamity it is
considered advisable to make wide main driving belts with
parallel joints. For example : A sixty-inch double belt will be
made of two thirty-three inch pieces, joined parallel, with a
three inch lap, making oue solid piece sixty inches in width,
and on the upper part put a thirty-three inch piece int he centre ;
and two eighteen-inch pieces on the edges, all joined with parallel
laps ; this cemented together will make a sixty-inch double belt
with unbroken surface, and as one solid piece of leather having
u niform teusion and able to withstand an equal strain over the
belt transversely as well as well as parallel, and thus will prevent
such large, heavy driving belts from collapsing at the
parallel joints. The cost of such a belt is considerable, however.
Leather being by nature an absorber of moisture, belts
must be guarded against exposure to oil. The oil is absorbed
by the belt, and in a short time will rot or destroy the fibre of
the leather. To prevent this, a compound that will close
the pores of the leather is used, but is not so effective with
perforated belts. An erroneous idea seems to prevail among
engineers that belting should be made of pieces only four feet
in length, as if all hides were of the same length and texture ;
it will surprise these men to learn that there are no two hides
alike, they vary iu some particular point. Hides exist which
make almost six feet of sound solid leather below the shoulder,
and again some hides will not make four feet of solid length ;
the only safeguard is to specify belting made of leather cut be­
low the shoulders of the hide, irrespective of length.
GEO. MILLER & Co., 1028 Filbert St., Phila., Pa., have had a
Reagan Shaking Grate under a 100 h. p. boiler for a year,
using buckwheat instead of stove coal, and pronounce it the
best grate in the market. The Globe Printing House, 112 N.
12th St., Phila., used 28 to 32 tons of coal under a 100 horse
boiler, but with the Reagan Grate used 22 tons per month and
had better fires. The Reagan Grate saves the Philadelphia
Times 1 5 tons of coal per month, and the Star reduced its coal
from four tn two tons per day. J. G. Brill, car builder, says
they have saved a great deal in the cost of fuel in eighteen
months' experience with this grate.

128 ENGINEERING MECHANICS. [May, 1892.
ALUMINUM: ITS MANUFACTURE AND USES FROM AN EN­
GINEERING STANDPOINT.
BV ALFRED E. HUNT, CE.
President of the Pittsburgh Reduction Company.
inum, as practiced by the Pittsburgh Reduction Company,
[Extracts from Lecture delivered before the', Franklin Institute there Feb., is practically 1802.] no waste whatever, and the waste problem
Aluminum is now being made throughout the world upon a
commercial scale only by processes of electro-deposition from
fused electrolytes. In this country, the Pittsburgh Reduction
Company and the Cowles Electric Smelting and Aluminum
Company are the only concerns manufacturing commercially
and furnishing the American market with aluminum. In Great
Britain, the Metal Reduction Syndicate, Limited, a branch of
the Pittsburgh Reduction Company, and in Switzerland, the
Aluminium Industrie Actien Gesellschaft, manufacturing at
Neuhausen, using the water power of the Falls of the Rhine;
and in France, the firm of Bernard Brothers, now building a
works at St. Michaels, aud operating the Minet process, are, so
far as the writer's knowledge goes, the only manufacturers now
whose metal is met in competition of the word's rapidly grow­
ing market for aluminum.
I am confident that the aluminum problem of quality, as de­
termined by the purity of tbe metal, has beeu solved, and that
upon a practical commercial scale, too, by several of the later
methods of manufacture. At the works of Pechiney & Co., in
Frauce, from a date at least as far back as 18S2, to my personal
knowledge, M. Heuri Brivet, their managing director, was en­
abled to manufacture regularly, by taking the utmost precautions,
and with carefulness and skill in manipulation, as well
as in all details of the Deville sodium process of production of
aluminum, metal of over ninety-nine per cent, purity, an
achievement which, with tbe knowledge and state of the art of
aluminum manufacturing then existing, and with the inherent
difficulties of manufacturing pure aluminum by tbe sodium
process, was worthy of the highest praise.
The impurities of the sodium-made metal are about one half
silicon and one-half iron. Both the Aluminium Company, Limited,
of Oldbury, and the Alliance Aluminium Company, of
New-Castle-011-Tyne, England, made metal aud placed it upon
the market in 1S87 and 1SS8, of over ninety-nine per cent.
purity; and Richards, in his work ou Aluminium, editiou of
1890, p. 246, refers to aluminum made by Grabau by a modifica­
tion ofthe sodium process, in iSSS, having 99.So per cent, pure
aluminum.
Both the Neuhausen concern and the Cowles, as well as the
Metal Reduction Syndicate, Limited, of Patricroft, Lancashire,
England, and the Pittsburgh Reduction Company, find no
trouble, by the electrolytic process, in producing regularlymetal
with less than one per cent, of impurity. Indeed, the
best results in quantity of output and regularity of working,
and therefore in economy of manufacture, are when producing
the purest aluminum, and it only requires further development
ofthe manufacture of the aluminum oxide used as the ore and
of the carbon anodes—matters wliich are perfectly practicable
and possible—to obtain, almost absolutely, chemically pure
aluminum by the electrolytic methods now in use. The Pittsburgh
Reduction Company have made a good many tons of
aluminum of over 99.90 per cent, purity; aud I take pleasure in
showing you and leaving for your museum a number of little
ingots of aluminum containing 110 iron, copper or lead, and
only eight-one-hundredtbs of one per cent, of silicon, having
99.92 per cent, pure aluminum, by the results of our chemist,
Mr. J. O. Handy. With these achievements accomplished, I
claim that the problem of quality ofthe metal, as evidenced by
its chemical composition, has beeu solved, and solved with
fully as much perfection as is the case in the metallurgy of any
of the other metals.
In the economical reduction of the ores of most metals, one
of the most difficult problems to be solved has been the wastage
due to oxidation, volatilization or tbe solvent action of slags,
or the impartial reduction or separation and collection of the
metal, and its consequent waste in the scoria or refuse product.
There are very few metals reduced to their pure state without a
wastage of at least ten per cent. In the manufacture of alum­
having beeu by the Hall process entirely solved.
Ingot metal will be made by the Hall process within the next
few years at a cost of betweeu eighteen and twenty cents per
pound ; the items of cost being about one-third for the ore, one-
sixth for the expenditure of other materials than ore, one-third
for the electrical current expended, one-twelfth for labor and
superintendence, aud one-twelfth for general expenses, interest
and repairs.
The expenditure for other reagents than the ore, for carbon
and for chemicals, is now less than five cents per pound, with
the Pittsburgh Reduction Company, and in the estimate can
fairly be reduced to three cents per pound for a large plant,
with most favorable arrangements made for its supplies. In
tbe item of electrical power, there certainly may be room for a
curtailment of cost; but even should this expenditure of elec­
trical power be lessened one-half, or entirely done away with,
heat alone being substituted as the energy for reduction of the
ore, it will be difficult to conceive of a method that would not
require a cost of at least one cent for this heat, which would be
a saving, perhaps, of four cents per pound upon this item of
electrical power. However, I feel confident that should such
processes be devised, the increased expenditure for chemicals
aud other reagents, besides the amount quoted as necessary for
the Hall electrolytic process, will nearly, if not quite, counter­
balance the saving in electrical energy expended in the Hall
process.
Iu the items of labor, superintendence and general expense,
interest and repairs, there may be a small saving made by a
process yielding metal more rapidly than by the comparatively
slow electrolytic process.
I would, however, here call attention to the fact that our
present experience leads me to believe that the items of labor
and superintendence will quite surely be reduced to between
two and three cents per pouud of metal produced, and the
amount required for general expenditure, interest and repairs
to uo larger than an equal expenditure, when the metal is made
upon a very large scale.
With the cost of manufacture beiug the ore at six cents per
pound of metal made, and subject to almost any possible
lowering of rate applicable to any other process, the power and
materials used at eight cents, and the labor and all remaining
expenses at between four and six cents per pound—cost items
that I believe will be obtained gradually within the next few
years by the electrolytic methods of production. I do not be
lieve that there will be other methods devised to successfully
compete with their totals of cost per pound. The average energy
per pound of metal produced by the Pittsburgh Reduction
Company is about twenty electric horse-power hours, or each
electric horse-power houi of energy exerted upon the electro­
lyte yielding about twenty-two and seven-tenths grams of metal.
Each month, by new experience, we are adding to this effi­
ciency, aud we confidently hope to make a gain of at least ten
per ceut. upon this record soon ; and I shall not be satisfied
until this gain in efficiency shall reach at least twenty-five per
cent, over present rates.
Aluminum is not much more acted upon thau is tin, copper
or silver by salt water, and even by such solutions in vinegar as
the metal is liable to be subjected to in ordinary culinary vessels.
Tbe salts of tin or copper thus dissolved are very poison­
ous ; but not only are the aluminum salts that are formed less
iu amount, but the acetate of aluminum formed resolves itself,
on boiling, into either an insoluble subacetate or into pure
alumina, neither salt having either taste or injurious toxic
action. For these reasons, quite surely aluminum will have a

May, 1892.] ENGINEERING MECHANICS. 129
large future for cooking utensils. Aluminum cooking utensils
have been used in my own home for the past two years, almost
altogether, being subjected to all the usual materials that
varied household uses subject them to.
The principal impurity of the commercially pure aluminum
of to-day is silicon, which exists in two forms, one seemingly
combined with the alumiuum, as combined carbon exists in
white pig iron, aud the other in au allotropic graphitoidal
modification. These two forms of silicon seem to exert somewhat
different effects by their presence in the aluminum ; the
combined form of the element rendering the metal much harder
than the graphitoidal variety. The combined silicon ordinarily
preponderates, being fifty-five per cent, to eighty per cent, of
the total silicon in the metal of ninety-nine per cent, purity
made by the Pittsburgh Reduction Company. The graphitoidal
silicon is separated on dissolving alumiuum in hydrochloric
acid as a black insoluble residue, aud appears like graphitoidal
carbon on similar treating gray cast iron. In fact, it has been
been mistaken for carbon by many superficial or ignorant ob­
servers. Carbou does not uuite with aluminum except at very
high temperatures, and its influence seems to be to make the
metal very brittle. Metal containing carbon can readily be
told by its abnormal crystalline aud peculiar colored fracture.
In the electrolytically made commercially pure aluminum of
to-day, the only other impurity is iron, which, if it exists in
larger quantity thau five, or, at most, ten, one-hundredths of
one per cent., is the result of carelessness in manufacture, or
the selection of needlessly impure alumina ore or carbou
anodes. The presence sometimes found of copper or lead iu
auy quantity in the metal, is the result of needless contamination
with these elements in the preparation of the ore or
the carbon anodes, or in tbe manipulation of the pots. By-
allowing the pots to ruu for a considerable time without ore,
and with a high current and very hot electrolyte, as sometimes
occurs in careless working of the pots, metallic sodium
has been alloyed with aluminum in noticeable percentages.
Upon placing such metal in hot water, the sodium will be
rapidly dissolved out with considerable effervescence, and
the pure metal left spongy, honey-combed and weak.
For many purposes the purest aluminum cannot be so advantageously
used as that containing three per cent., or even
four per cent., of impurity, as the pure metal is very soft,
and not so strong as the less pure. It is only where extreme
malleability, ductility, sonorousness, or non-corrodibility
is required that the purest metal should be chosen.
For most purposes a small percentage of other elements thau
silicon and iron are advantageously added iu producing
hardness, rigidity and strength. Titanium, chromium and
copper can readily and cheaply be added, and are constituents
that will not detract fsom the non-corrodibility of the
metal as much as do these natural impurities that come from
the ore and apparatus—additions that will give the aluminum
a better color and greater strength and hardness, with proportionately
less sacrifice of malleability, ductility, etc.
The properties of aluminum which will probably give it the
greatest availability- in the arts, are :
(1) Its relative lightness.
(2) Its non-tarnishing quality as compared with many other
metals ; aluminum not being acted upon by sulphur fumes at
all, and being very much more slowly oxidized by moist atmospheres
than most of the metals.
(3) Its extreme malleability.
(4) Its easy casting qualities.
(5) The influence of the metal in various alloys will give it
advantages, some of which I will try to enumerate and call to
your attention.
(6) Its high tensile strength and elast'city when weight for
weight of the metal is compared with other metals, and especially
when alloyed with a small percentage of titanium, silver
or copper, and properly worked by being rolled or hammered
or otherwise drawn down.
(7) Us high specific heat and electrical and heat conductivity.
Unfortunately, aluminum is not, section for section, as has
been widely claimed, comparatively a very strong metal. It is
only about as strong under tensile strain, section for section, as
cast iron, and has less than one-half the strength of wrought
iron under ordinary conditions. Under compression the metal,
unfortunately, has a very low elastic limit, although its extreme
ductility allows the metal to flow on itself so freely as to make
it for special purposes a very safe metal to use in compression.
I show a series of cylinders of one and one-half inch diameter,
which have each had a compressive strain of 200,000 pouuds
applied to them, together with the result of a compression
strain of 180,000 pounds upon similar cylinders of cast iron.
The same remark applies to transverse tests on alumiuum.
It is not a rigid metal at all and bends under transverse straius
very- readily. I append a table of results which, from our experience,
I believe will show about the average tensile and
compressive tests of commercially pure aluminum, unannealed
:
Pounds.
Elastic limit per square inch in tension (castings) 5,ooo
(sheet) 12,000
(wire) . . 16,000 to 30.000
(bars) 10,000
Ultimate strength pr. sq. in. in tension (castings) . . . .15,000
(sheet) 24,000
(wire) . . 30,000 to 65,000
(bars) 28,000
Per Cent.
Perc'tage of reduction ofarea in tension (castings) 10
(sheet) 25
(wire) 40
(.bars) 20
Pounds.
Elastic limit per square inch under compression in
cylinders, with length twice the diameter . . . 3,500
Ultimate strength per square inch under compression
in cylinders, with length twice the diameter . . 12,000
The modulus of elasticity of cast aluminum is about 11,000,000
forged " " 15,000,000
" resilience of cast " " -1600
forged " " -22oo
L'nder torsional stress in Thurston's torsional machine, the
metal has much lower modulus of rigidity than iron or steel ;
its maximum shearing stress in castings beiug about 12,000,
and in forgings about 16,000, being about that of pure copper.
The angle of torsion is equal to about that of the softest steel.
(To be continued.)
THE Mayor of Nottingham, England, accompanied by several
members ofthe corporation and other leading men of the town,
attended divine service on Sunday morning, February 28, in a
novel fashion. The meeting house was the local exchange of
the National Telephone Company, but the service in which
they participated was conducted at Christ Church, Birmingham,
51 miles away, the communication being, of course, by telephone.
They sat on each side of a long table on which 30 receivers
were placed, while at the church end were eight trans­
mitters—two in the belfry, two in the choir, two in the reading
desk aud two in the pulpit, switched on aud off as exigencies
required—an arrangement which has beeu in operation for
some weeks for the edification of Birmingham subscribers. The
Nottingham congregation were able to hear the be'ls very distinctly,
and the service, the responses and other musical portions,
while the preacher, having a clear voice and deliberate
utterance, was very audible, aud his sermou was listened to
with close attention.

i3o ENGINEERING MECHANICS. [May, 1892.
Copyrighted.]
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
If, as in the figure, the arch is supported, i.

May, 1892.] ENGINEERING MECHANICS. J 3i
solve it. It is essentially within the province of the theory of
elasticity.
But Statics teaches us that, if the part (A) of the body is in
equilibrium, it will be so, much more, if we happen to render it
invariable.
It is therefore necessary that the forces which incite it (the
elastic forces which it uudergoes on its part from the part (77)
being comprised in them) satisfy the conditions of equilibrium
relative to the invariable systems, a result which can be stated
thus : if we unite the exterior forces which act on auy portion
(A) of a body as if these forces acted on an invariable system,
we shall obtain (in the hypothesis which we always assume, of
forces all iu one plane) a resultant or a resulting couple. The
resultant or this couple are forces purely imaginary which will
be able in no degree to replace those from whicli they arise.
If, likewise, we compose (combine) the elastic forces which
the part (A) of the body experiences ou the part of the part
(B), we obtain, in the hypothesis where everything is symmetri­
cal with respect to the plane containing all the exterior forces,
a force or a couple.* This force or this couple is equally- imaginary
aud could not supply the place of the elastic forces
themselves.
But Statics teaches : i° that if the exterior forces, composed
as has just been said, furnish a resultant, the elastic forces
necessarily furnish one also equal and opposed to the preceding ;
that likewise, if the exterior forces are composed into a couple,
the same thing necessarily takes place with the elastic forces
aud that, besides, this second couple is equal and opposed to the
on the plane of symmetry.
The resultant R of all the exterior forces acting on the part
(A) of the body situated on one side ofthe section is called the
total elastic force exercised by this part 011 the part (B). In
order to find this imaginary force, we have operated on the ex­
itself can be taken at any point of its direction, provided that
this point be supposed invariably bound to the part (A) of the
body regarded as invariable. Let us apply it to the point C
where it cuts the line X' X, this point being thus regarded as
belonging to the left portion (A) of the body. Its component
* The elastic forces are not all in the plane of symmetry ; but to each elastic
force situated on one side of this plane a symmetrical force corresponds, and
these two forces, composed as if they were acting on an invariable solid, give
a partial resultant sitnated in the plane of symmetry. It remains then only
to compose these partial resultants which are in the same plane as the ex­
terior forces.
7"according to X' X is called the tangential clastic force or
shearing force. Its component TV, according to the normal to the
section, is called the pressure or normal tension exercised by
first.
(A) and (77). Here this would be a pressure. In fact, R being
the resultant ofthe exterior forces which act on the part (A) of
the body, the resultant R' of those which act on the part (7?) is
necessarily equal and opposed to R, since the entire body is in
equilibrium, under the action of the two forces Ii and R''. This
Iu what precedes, we have considered the elastic forces exer­ force R' cau be considered as applied to the same geometric
cised by (77) on (A) ; those exercised by (A) ou (7?) are equal poiut Cas the force R, but this poiut being regarded this time
and opposed to them.
as belonging to the part (/?).
Therefore, we can say again that, if in a body in equilibrium The components normal and tangential of R' would be the
we make any section which divides it into two parts (A) and (B), forces N' and T' respectively equal and opposed to TV and T.
the resultant of the exterior forces having their points of appli­ The two forces equal and opposed Tand V, acting, the first
cation in one of these parts is equal in magnitude, direction and on tbe part (A), the second on the part (77) of the body, tend to
flow to the resultant ofi the elastic forces which this part exercause
these two parts to glide along the section, or to separate
cises on the other.
them by shearing. Hence the name shearing moment given to
In the particular case where the exterior forces having their these forces.
points of application in one of the parts are reduced to a couple, The two forces equal and opposed TV and N', acting, the first
the elastic forces which this part exercises on the other are re­ on (A), the second on (77), tend : i° in the case ofthe figure, to
duced to the same couple.
press the two parts of the body the one against the other or to
cause pressures to arise. 2° in the case where they would be
2 64.
directed in opposed flow, i. c., where the one which acts on one
of the two parts of the body would be directed toward that
CENTRE OF PRESSURE ; SHEARING MOMENT ; NORMAL PRES­
SURE.—This theorem is true, whether the section made in the same part, they would tend to separate the two parts (A) and
body be plane or curved, provided tbat it be symmetrical with
(77), and then TV would be a tension.
reference to the plane containing the exterior forces.
The point Cwhere the resultant R cuts the line X' A'is called
Let us suppose it to be plane and let (Fig. 7) X' A'be its trace
the centre of pressure or centre of the elastic forces.
CASE WHERE THE CENTRE OF PRESSURE PASSES TO INFIN­
ITY.—The centre of pressure C is not necessarily in the interior
of the body ; it may likewise pass to infinity on the line X' X
in two cases :
i° When the resultant R of the forces which act on the part
terior forces as if they acted ou invariable systems, i. c., we have
(A) of the body is found to be parallel to the section X' X.
displaced their points of application on their own directions.
This case is always presented in right horizontal beams, sub­
Likewise, the point of application of the imaginary force R
ject to forces all vertical, wheu the sections considered are themselves
vertical.
2° When the exterior forces acting on (A) admit of no result­
ant aud are reduced to a couple.
We know, in fact, that a couple may be regarded as a force
infinitely small, whose poiut of application is infinitely remote.
We can understand in a single statement these two cases
where the centre of pressure passes to infinity. In reality, let
7

132 ENGINEERING MECHANICS. [May, 1892.
FIG. 44-—SECTIONAL VIEW OF PUMPING ENGINE WITH WORTHINGTON HIGH DUTY ATTA CHMENT.
PUMPS T\J>7D PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
To the ordinary compound direct-acting steani pump as
usually built there is attached a plunger rod which projects
through the outer end ofthe pump chamber, and around which
there is the usual stuffing box for packing the same. On the
end of this plunger rod is fastened a cross h^ad which moves in
guides that are bolted ou the outer end of the pump. On this
cross head, and opposite to each other, are semicircular recesses.
On the guide plates are cast two journal boxes, one above and
the other below the plunger rod, both equidistant from it and at
a point equal to the half stroke of the cross head. In tbese
journal boxes are hung two short cylinders 011 trunnions which
permit the cylinders to swing backward aud forward, in unison
with the motion of the plunger rod. Within these swinging
cylinders are plungers, which pass through a stuffing box on the
end of the cylinder, and on their outer end they have a rounded
projection which fits in the semicircular recesses in the cross
head, and consequently, as the cross head moves in or out of
the pump, it carries with it these two plungers, which in turn
tilt the cylinders backward and forward.
These swinging cylinders are called " compensating cylinders,"
and they are filled with water, except when the pumping
engines are used on oil lines, when they are filled with oil.
The pressure on the plungers within the compensating cylinders
is produced by connecting the compensating cylinders
through their hollow trunnions with an accumulator, the ram
of whicli moves up and down as the plungers of the compensating
cylinders move in and out.
Suppose the pump about to begin its outward stroke. At this.
time the compensating cylinders will be turned so as to point
toward the outer end of the pump, with their plungers at the
extreme point of their outward stroke, and at an acute angle
with the pump plunger rod, and with the full pressure of The
accumulator load pushing them against the advance of the
pump plunger. As the pump plunger begins its outward stroke
each forward movement it makes changes the angle of the
compensating plungers, until at one-half stroke the two plungers
will stand exactly opposite each other and at right angles
with the pump plungers, and of course in a position where they
cau neither retard or advance the movement of the plunger.
Now, as the pump plunger passes the centre of its stroke, the
compensating plungers being as before said attached to the
cross-head of the pump plunger rod, begin to turn in an opposite
direction from which they- started, and by degrees, owing to
the increasing acuteness of the angle they make with the
plunger rod, they begin to exert a power to push the pump
plunger along, whereas, before and up to the half stroke, they
resisted the movement of the plunger. This pushing force increases
constantly, until at the extreme end of the outward
stroke, and when the accumulator plungers are, as at the beginning,
at their most acute angle, they exert their greatest force
in helping to aid the pump plunger in its outward movement.
Tbe return stroke of the pump is made under precisely the
same conditions as the previous stroke.
If we were to convert the movements of the compensating
plungers into a diagram which would illustrate the power they
receive, and give out, we would have a curved line having a
point at the half stroke in which there would be no power exerted,
while at one end would be shown a line of resistance
above that zero line, which would be the exact result of that
resistance at each point in the first half of the stroke • and it
would also show on the last half of the stroke the same curve
of power given out again. The peculiar shape of this curve is
the result of carefully calculated arrangement of the details of
construction, and it can be made to conform very closely to the
curve of the pressure line iu the steam cylinder at almost any
poiut of steam cut-off.
Having now considered the pump end of a direct-acting
steam pump to which there is attached this new device for obtaining
a high rate of fuel economy, we will now turn our
attention to the behavior of the steani in the steam end of such
a pump. We will assume that the pump is driven by compound
cylinders, in which the area of the expanding cylinder is four
times that of the high pressure cylinder.

May, 1892.] ENGINEERING MECHANICS. J 33
Fig. 45 represents an indicator card taken from the high pres­
sure cylinders of such a pumping engine as we have under
consideration. The admission line is straight, and perpendicu­
lar to the Hue of pressure : this is owing to the fact
that in the duplex pumping engine there is a slight
pause at the end of each stroke, which not only allows
the pump valves to seat themselves quietly, but it as
well fills up the clearances and steam ports to the full
steam pressure before the piston starts. The resulting
pressure in this cylinder will be the pressure above
tbe line V at each of the ordinates, less the back
pressure, at the same ordinate. If we take this resultant
pressure and apply it to the same number of
ordinates, all of which shall start from one common
base line, we will have a curved line which resembles
Fig. 46, iu whicli tbe line A' B' C I)' EJ F' G> IT
I' fi' K' will show the available steam pressure at
each part of the stroke of the piston.
In Fig. 47 we obtain by the same process the line of
pressure iu the expanding steam cylinder, on the same
number of ordinates, and from each ordiuate of which
we must, as before, subtract the back pressure above
zero pressure. Wheu we have done so, we will have 1 *the
total pressure line of the expanding steam cylinder
as shown in Fig. 4S. In order that we may make a
comparison of the pressure in the expanding cylinder,
with the high pressure card, we must multiply the total pressure
shown on each ordinate by the ratio of the areas of two cyliu-
FiG. 46.
rs H 1 J
ders, which in this case is four to oue. This will produce the
curved line shown on Fig. 49. Now that we have the line of
pressure of each steam cylinder brought to the same
basis, we can add them both together and find at once
what is the total pressure, or power, that both the
steam pistons exert during each stroke of the pump,
and also just what proportion of that power is exerted
at each particular part, of each stroke. This adding
together of all the forces of a steam compound condensing
engine, under the conditions previously described,
will produce a card, as shown in Fig. 50, a figure
which at first glance would seem to be the farthest pos- ">
sible curve from what is required to move a pump
FIG. 48.
A> B 1 C Z>' E' F' Q 1 H* I' J'
plunger, which in its effect on a water column is to show a card
" vertical at each end, and parallel on each side." It was for
the purpose of producing this much to be desired, although
seemingly impossible result, that the high duty attachment was
invented.
FIG. 45.
Iu order that I may the better explain how this is brought
about, we will draw a figure which shall represent the pressure
of water on the pump above the atmosphere line, as well as the
pressure, or as it is best known, the suction line below the atmosphere
line, the total of which will be shown on Fig. 51.
We see in Fig. 51 the result we wish to produce, aud in Fig. 50
the means we have of producing this result; aud, as it must be
remembered, by a piston which is connected directly to the
pump plunger, without the intervention of cranks, shafts, or
fly wheels. In order to make a graphic illustration of the difficulties
to be overcome, as well as the means employed to
overcome them, we will on top of this line of the water card
pressures, and on the same base line draw the power, or propulsion
line, so that we can see how they fit each other.
This is shown by Fig. 52, in which A W W K are the outline
of the water load or pressure on the pump ; or as we may
say, the resistance wliich is to be overcome and A A" K"
A' is the outline of the force exercised by the steam cylinders
during the same stroke as was shown by Fig. 50.
The intermediate letters show the steam power exercised
at each part of the stroke F" F, being the half stroke of
the pump. In looking on this arrangement of the two dia-
FIG. 47-
-Zero Pressure Line
grams, it will be seen that at the beginning of tbe stroke
of the pump the steani pressure is largely in excess of what
is required to move the water, while at the end of the
stroke, it is far below what will be lequired to do so; and
that it is only at the half stroke that the steam pressure
and water resistance are equal, and that under the conditions
as shown, that is the only point where they would
meet on equal terms.
(To be continued.)

T 34 ENGINEERING MECHANICS. [May, 1892.
[Copyrighted.]
THK MARINE ENGINE;
Its Construction, Mode of Action and Management.
BY CARL BUSLEY,
Professor at the Imperial Academy at Kiel.
Translated by Assistant-Engineer EMU THEISS, U. S. N.
some salt in solution (sulphate of barium in the case instanced),
then the salt contained in the water of condensation will be
d yi,
where j' is the percentage of moisture ; and
>'=T (53)
10. To make the calculation it is necessary
Calculation. to know the volume traversed by the piston.
Using the same notation as before, x, w and
11 having the signification assigned in 2 n, par. 2, we proceed
as follows:
Let the weight of moist steam admitted to tbe cylinder be
(M -\- 111) pounds, the percentage of dry steani contained in the
mixture being x, then the volume l\ of the mixture at the instant
when superheating begins will be
U, -(A7+ m)(w+u),
(w -{- it) being the specific volume of the steam, which at that
instant is dry saturated steam.
By (33) the initial volume is
V=(M+ m) (w + xu)
Subtracting the latter equation from tbe former, we obtaiu for
the percentage of moisture in the steam,
r. V
(M-\-m)u
V,
(M+m)u V '
V
I E
y u
(52)
In this equation c = —, the cut-off, and ; = ——, the
'1 ' 1
weight per unit volume of saturated steani of the observed initial
pressure ; u is taken from the steam tables. As w +
u, we may, neglecting w, place — = it, approximately ; hence
v=
y
V,— V
I — e = —- —
V
15 2 It is to be noted that experiments on boilers made at Diisseldoifi
111 1880, showed the presence of from .21 to 9 per cent, of
moisture in steam of 5 atmospheres escaping into the air, while
when passing to the engine the percentage was from .56 to I.I.
Experiments conducted on the German cruiser Albatross in
1882, the steam pressure being 28 5 lbs., gave as the most reliable
result a percentage of 1.65.
15. The errors involved are due to thediffi- Errors.
culty of obtaining a fair sample of the steam,
the quantity subjected to test being so small, and of obtaining
solid water from the boiler, without admixture of steam. To
accomplish this end the vessel for taking the sample of boiler
water should be screwed to a gauge cock or to a cock used for
this special purpose, and should be fitted with a stop cock. This
is closed when the vessel is filled, which latter is not disconnected
until after it has become cool. A still better way is to
arrange so that the water may circulate through the vessel for
a while before tbe sample is taken. It may be possible upon
occasions to use the gauge glass for the purpose of taking a
sample.
16. e. Escher's Method is based on the con- Manner of conductsideration
that at the beginning of the test ing the test.
the feed water and the water iu the boiler are
of identical composition. The continuous introduction of feed
to make up for the water evaporated will result in increasing
the saturation of the water in the boiler. The rate of increase
furnishes a means of calculating the percentage of water carried
off with the steam.
17. In order to calculate the percentage of Calculation.
moisture, let 5 and I; represent the weight in
lbs. of material held in solution by one pound of the feed and
the boiler water respectively, s may be assumed as constant,
but /' changes ; let it represent the saturation after a time / from
the beginning of the test. Let D be the weight of feed water
per hour, and 7Tthe weight of water contained in the boiler in
'
pounds. The assumption is made that the feed water supply is
uniform and continuous, as also the consumption of steam. The
weight of steam generated in a given time will therefore be
i. e., the percentage of moisture is directly proportional to the equal to the weight of feed water pumped into the boiler. The
increase of volume wheu the point is reached at which super­ quantity of material held in solution by the feed introduced in
heating begins.
the time d t will be
11. The errors ofthe method under discus-
mx - D dt s ;
l/alue of the meth- sion are due to the fact that it is difficult to
iu the mean time the steani, containing a percentage of moist­
od of super-heat- obtain a cylinder full of steam ofthe quality
ure, y, will carry off an amount equal to
ing. of the bulk of the steam, and to the fact that
it takes some time to perform the test. The
m., —- Dy dt lc.
piston must be moved very slowly, as steam is a poor conductor The iucrease of dissolved material iu the boiler for the time dl
of heat; meanwhile the temperature in the cylinder or in the will be, therefore,
casing may undergo change, and we have uo longer isothermal
change of state.
12. II. Chemical Methods. Thesehavethe
Chemical methods, advantage over the physical methods of
testing of not necessitating cumbersome or
complicated apparatus. They are based on the supposition
that dry steani is free from the impurities fouud in tbe water in
7/7, — m., -= D (s dt —y k dl) = K dk,
cl k being the increase for each pound of water iu the boiler. Let
K
D
a,
theu we obtain the differential equation,
the boiler, whereas any water contained in it will contain impurities
similar to those found near the water level of the boiler.
13. The ordinary method proceeds as fol-
Manner of conduct- lows: from 45 to 55 pounds of sulphate of
dh +-- hdl— — dt
a a
The general form of the integral is,
ing the test. soda are introduced into the boiler, the quantity
depending on the size of the boiler. In
the course of the experiments samples of the boiler water are
taken at intervals from the gauge cocks (about a pint at a time)
y y_t
and at the same time samples of steam are taken from the maiu
steam pipe. Tbe steam is best drawn off through a small tube
To determine the constant, C: for
introduced into the steani pipe at right angles to its axis, the
t - o,h=s = \- C;
steani entering through perforations extending over its entire
length and turned away from the current of steam. The sttam
is condensed and the same quantity of water of condensation
hence
y
retained as was drawn off through the gauge cocks. The sets of
samples taken from the steani pipe are then poured together, as
C=--(x-y),
are also those taken from tbe gauge cocks. The sulphuric acid
found in each set of samples is the means of arriving at the
and the complete integral will be
moisture in the steam. To this end equal amounts of barium
chloride are added to the water obtained from the steam pipe
aud to that from the boiler direct, and the precipitated barium
(54)
Calculation.
sulphate is weighed.
14. The calculation of the percentage of
It is apparent from this equation that the value of k approaches
moisture is a simple matter. If analysis shows
that each pound of water from the boiler contains k pounds of
I — ) as its maximum, which it reaches for I = co. y can be

May, 1892.] ENGINEERING MECHANICS. 135
calculated from the equation for k by a series of approximations.
t is the duration of the trial in hours; k is the saturation at the
end of that period ; s is known. Assume as a first trial value
Substitute from this the value of —, the first term in the parentheses,
aud calculate a second trial value ; etc.
18. The errors involved are found in the
Errors. impossibility of securing perfect uniformity
of feed and steani consumption. The method
also takes no account of any deposition of solid material upon
the heating surfaces, which is bound to occur.
19.7". By Brauer's AFcthod acertain amount
Manner of conduct of a soluble salt, ordinary salt, chloride of
ing the test. sodium, is well suited for the purpose, is
added to the water in the boiler; in this respect
this method is like the one followed ordinarily. For ma
rine boilers sea water may be used. The feed must be water
chemically pure. If water is carried off by the steam, the saturation
of the water iu tbe boiler will gradually decrease. This
decrease furnishes a means of calculating the percentage of
moisture ofthe steam. If, therefore, the saturation ofthe water
in the boiler is ascertained at tbe beginning of the trial, aud
aga'n from time to time in the course of the trial, the weight of
water pumped into the boiler in the mean time being known
and the height at which it is carried being the same, we maycalculate
the quality of the steam during the time elapsing between
making tbe tests.
Calculation. 20. Iu order to make the calculation, let
.f be the variable weight of salt held in solution
by a pouud of boiler water ; sx the initial value of S, s., the
final value ; G the weight of water contained in the boiler, /'. e.
of both the water aud the salt held in solution. This weight
may be taken as constant, the solution being a weak one, and
the weight of salt a small fraction of the total.
Then
S = G s
is the weight of salt contained in the solution, and
d S = G d s.
If j' is the weight of water contained in a pound ofthe steam,
then the salt contained will be s y lbs. If IV is the weight of
water evaporated during any period, and d IV the rate of evaporation,
then the quantity of boiler water carried off by the steam
during the time dt is y d IV, and the weight of salt sy d IV. We
therefore have
dS = syd IV.
Combining this equation with the preceding one,
G d s --- s y d U'
ds
= y. d iv
s C
> f indifference. This is important not only for the reason that tbe
molecular constitution of steam is a matter not subject to direct
observation, but also for the reason that it is still an open question
whether the water is carried over by the steam uniformly
or in occasional jets. The first application of Brunei's method,
the occasion being a competitive test of locomotive boilers, was
unsatisfactory iu its results. One per cent, of common salt was
added to the boiler water, and the successive tests showed the
decrease of saturation to be almost imperceptible, indicating almost
dry steani, a result not in accord with tbe known tendency
of this type to priming. Later results have, however, proved
the efficiency of the method as applied to boilers with a single
water space, in which the saturation may be assumed uniform
throughout.
23. III. The Mechanical Methods seek to Mechanical
effect the separation of the water from the Methods.
steani mechanically, by means of separators.
Judging from recent experiments it would seem as if this
method, presupposing efficient apparatus, woulil yield results
more satisfactory than those obtained by any other method.
24. g. Of mechanical methods Midler's
may be adduced as au example. His appa- Mce/ler's steam
ratus for drying tbe steani, /'. e., separating filter.
out the water, consists of a cylindrical casing
containing a number of perforated pendent tubes, closed at the
bottom and expanded above into a diaphragm separating the
receiving chamber from the discharge chamber. The perforated
tubes are lagged with some filtering material. The steam, entering
through a nozzle near the bottom, passes through these
filters into the discharge chainber, and thence into the steam
pipe to the engine, the water falling into the bottom of the receiving
chamber, from which it is blown at intervals.
25. The efficiency of Mceller's filter has
been placed beyond doubt by a number of Practical value of
experiments, the most important of which Mceller's filter.
was a series of tests of the evaporative efficiency
of boilers undertaken at the Imperial Dockyard at Wilhelmshaven.
The filter worked very satisfactorily even when
the boilers were purposely made to prime. It is unsuited for
use ou board ship, because, with the great quantities of steam
to be dried, its dimensions and its weight become enormous.
Neither is it suitable as a grease extractor, for though it separated
66 lbs. of greasy water from 990 lbs. of steam, yet it proved
a difficult matter to separate the grease from the water, and
blowing overboard the whole, amounting to 7 per cent, of the
feed, was out of the question.
26. In consideration of the high pressures Method best suited
of steam carried by modern marine boilers, for a ship's boilers.
the method that appears to be best suited for
their test is that of Brauer. All the boilers should be filled
from the sea at high tide, with the vessel iu port, in order to
have the same water in all, and all the feed should be water
chemically pure, i e., water of condensation and distilled water
for making up losses. For s., we should take the mean of the
saturation of all the boilers ; a salinometer is all that is required
for this purpose.
27. We may briefly mention here that
steam may be dried mechanically, by means
Drying moist
steam.
i d s
s.L
A iv
G
of separators, explained more in detail when
speaking of superheaters ; by throttling at the engine, a subject
that will be discussed when we come to speak of tubulous boilers
; and by means of superheating apparatus, which the steam
is made to traverse on its way to the engine.
1 s <
loge —
G
G 5,
• r = iv ]oSe A
(55)
Errors. 21. The errors inseparable from this method
are in general identical with those inherent
in the method last described. It has this advantage,
however, over Esher's method that, the saturation growing less
as the trial proceeds, there is less danger of vitiating the result
owing to the formation of boiler scale. The main advantage of
the method under discussion, however, is the possibility of introducing
once for all a considerable amount of a readily soluble
substance into the boiler. Great care must be taken to avoid
the presence of this substance in the feed water, so that, in the
event of common salt being used, the feed water is not to be
purified by means of chloride of barium.
Advantages ofthe 22. The advantages which the two methods
two last methods. last described have over all the others are to
be found in the fact that the tests are restricted
to the contents of the boiler, the condition of the steam
in the pipes not entering at all. The relative proportions of dry
steam and of water, either carried over from the boiler or due to
condensation of steam in the pipes, are therefore a matter of
jj 15. Superheated Steam.
1. 7. Characteristic Equations.—The char- Characteristic
acteristic equation of superheated steam (see equation.
§6, par. 19), i.e., tbe equation expressing
the relation existing between the absolute pressure, p, the specific
volume, v, aud the absolute temperature, T, is given by
Zeuner as:
In this equation
I?
p v + Cp "
R T ft. lbs. (5°)
R = 0.005093 j
for metric units ;
C= 0.1925 )
.~ " '7 - for English units.
«•— 1-333
(To be continued.)

i36 ENGINEERING MECHANICS. [May, 1892.
SPECIFIC HEAT OF SUPERHEATED STEAM.
IN superheatiug steani we naturally wish to know how much
heat is necessary to accomplish an elevation of say 1000 0 Fahr.
This involves the question of specific heats. What is the speci­
fic heat of superheated steam? Clark says 0.622, Regnault,
0.48 ; Rankine from 0.475 to 0.48 ; and Gray, 0.3S3. With au­
thorities differing to such a large exteut we are at a loss to know
what figure to adopt. Engineers have generally adopted Rankine's
figures for saturated steam, but will they apply to superheated
steam ? It has been found that steani superheated 20° F.,
or more, acts as a perfect gas, approximately. It is then no
longer a vapor, but a gas. Not a decomposed gas, but a com"
pound gas. Now air also approaches a perfect gas and has a
specific heat of 0.238 under constant pressure and 0.169 under a
constant volume. Tbe specific heats of the constituents of
steam are generally recognized to be :
Oxygen 0.21S for a constant pressure and 0.156 for a constant
volume.
Hydrogen 3.405 for a constant pressure and 2.410 for a con­
stant volume.
J. McFarlaue Gray gives the specific heat at a constant pres­
sure :
At o deg. Cent 39006
At 100 deg. Cent 4066S
At 200 deg. Cent 502S4
Between 100 deg. and 124 deg. Cent 4°494
Between 170 deg. and 2S1 deg. Cent 439 22
At 500 deg. Cent, there is no saturated steam, aud at iooo deg.
and 11,000 deg. Cent, we have to deal with dissociation.
Grove in England and Deville in France have clearly shown
dissociation is possible in limited quantities. In a practical
way, to accomplish such dissociation, an inoxydizable retort,
cast iron, porcelain, or platinum must be used for the containing
vessel. If cast iron is used a coating rapidly forms in the
inner surface, the oxygen uniting with the carbon and iron,
forming a carbide of iron. This coating assumes a mirror-like
polish, resembling ebony, and arrests further decomposition of
the retort. It is also a partial non-conductor of heat, so that
the retort is most efficient, as a heating surface, when new.
This non-conducting coating suggests the advisability of preparing
cylinders of steam engines in this way. Prof. Thurston
has shown that au advantage results by pickling the working
surface of a steam cylinder and treating it afterwards so as to
get a non conducting enamel.
The temperature of steani in the steam space of any boiler is
necessarily lower by several degrees than the temperature of
steaming water because in ebullition work is performed and that
involves cooling. Some experiments show that steam is never
superheated by compression in a closed vessel in contact with
water, as the following figures of a test with a small experimental
boiler show :
TEMPERATURES IN MODEL BOILER WORKING UP TO
10 LB- PRESSURE.
Water temperature, iA in. Steam temperature, ther- Pressure. Lbs.
below upper level. mometer in steani space. per square inch
100
120
11"
158
174
188
200
212
215
226
2 ;t>
239
239
2V>
»7
I06
126
'45
164
179
192
205
212
222
233
2 35
235
2 35
—
—
—
—
—
—
—
—
—
5l
93
10
10
10
An active circulation will go far to prevent supersaturation of
steam, and if provision is made whereby the water falls as steam
rises, a desired uniformity of temperature is secured. The use
of liquids of a higher boiling point than water to get hotter
steam is not feasible A recent newspaper writer, in dealing
with the question, says : "Regnault, Frost, Fairbairn, Tate and
others have shown that tbe rate of expansion of superheated
steam is almost identical with that of air and other permanent
gas, if calculated not too close to the temperature of maximum
saturation. In passing steani through pipes heated by the hot
gases from the furnace, the effect is not much, if any, better
thau using a trap to separate the water of condensation. It is
obvious that for steani to pass from a boiler into a superheater
the latter can only be at the same pressure as the boiler, or
somewhat lower, and the gasification iu transit is not attended
by increased density nor exalted tension ; hence the failure of
ordinary superheaters. Practical engineers—makers of highpressure
engines for the trade—discovered long since that compression
of steam at the end of each stroke, or steam cushioning,
notwithstanding certain theoretical disadvantages, yielded
an average efficiency greatly-iu excess of free discharge of steani
from the cylinder. In this case superheating, of course, occurs,
by compression, under circumstances of exalted tension ; hence
the economy.
NEXT!
We are enabled to present our readers with a few further
particulars of the electro-metallurgical process which, according
to the German experts who have tested the method, is
to revolutionize the metal industry. The Di'isseldorfier Zeitung,
a most reliable journal, has published a further long
article in which it refers to the incredulity with which its
previous statement has in many quarters been received, aud
remarks that doubts will in due time be dispelled. Not only
iron, but also other metals, such as gold, silver, copper, and
aluminum, can be extracted from their ores by the new and infinitely
cheaper method. When it is considered, it continues,
that the current generated by a dynamo driven by a small
gas or petroleum engine will be capable of extracting day for
day more metal thau the largest gas furnace is able to produce,
some idea may be formed of the radical changes
which are likely to be the result of the employment of the
new process.
The invention which is more rightly described as an electro-technical
discovery, was perfected three months ago. The
inventor has succeeded in devising a practical process which
has secured the ready support of a number of well-known
American and German capitalists, who purpose forming a
gigatic international syndicate. The statement as to the saving
of So per cent, on the present blast furnace method is
said to be no exaggeration. The name of the inventor and
his supporters are to be made known to the world as soon
as the letters patents have been granted !—German Exchange.
THE use of coal tar for water-proofing masonry is recommended
by a French technical journal. I'or surfaces exposed
to the air it is advised to apply from one to three coats boiling
hot. Its durability is increased by adding a small proportion
of India-rubber dissolved in benzine. If the color of the coating
is objectionable it may be dusted with plaster of Paris before
drying. Where surfaces are to be covered with earth a
single coating of tar made thick by blazing is preferable. A
small quantity, two or three gallons, is brought to a boiliug
temperature and lit at the surface. It is allowed to blaze and
kept constantly stirred at the same time uutil the volume is
considerably reduced and it becomes pasty on cooling. The
product is spread as rapidly as possible with a large flat brush,
which is dipped often to prevent cooling. A single coat applied
in this manner adheres firmly to even the smoothest surface.

May, 1892.] ENGINEERING MECHANICS. x 37
EMINENT AMERICAN ENGINEERS.
D. J. Whittemore, born in 1830, at Milton, Vermont, was edu­
cated in his father's office and at Bakersfield Academy, Vermont,
and at the age of seventeen entered the Engineering Corps of
the Vermont and Canada Railroad Company. At the age of
nineteen was appointed Assistant Engineer iu charge of the
construction of tbe portion of said railway betweeu Swanton.
Vermont, and Rouses Point, N.Y. Upon the completion of this
work he was appointed Assistant Engineer in charge of the construction
of a division ofthe Great Western Railway of Canada,
where he remained until 1S52. Theu became Contractor's Engineer
in building the Central Ohio Railroad between Zanesville,
Ohio, and Wheeling, Virginia, and remained in that positiou
until July, 1853, when he
was appointed Assistant
to the Chief Engineer of
the La Crosse and Milwaukee
Railroad Company,
which positiou he
resigned in 1857 to accept
the position of Chief Engineer
and Director of
the Southern Minnesota
(Land Grant) Railroad
Company, and, as such,
located about 250 miles
of that company's line.
L'pou suspension of tbat
work, in 1S59, and with
broken health, he accepted
position as Chief
Assistant Engineer upon
the Fero Caril Del Oeste
in Cuba, where he remained
nearly one year.
In 1S60 he was offered
and accepted his former
position as Chief Assistant
Engineer of the La
Crosse and Milwaukee
Railroad Company, which
office he held until 1864,
when that Company was
merged into and formed
the Chicago, Milwaukee
and St. Paul Railway-
Company (a corporation
that now owns over 6,000
miles of railway line), he
was appointed its Chief
Engineer, which position
he has held to the present
time (1892), aud •
during his administrator
of said office, he has had
charge of locating and
D. J. WHITTEMORE.
building about 2,700 miles
of railway, including three bridges across the Mississippi and
one across the Missouri River.
Through his researches and experimental inquiry the hy­
draulic features of a rock deposit at Milwaukee became known
in 1874, resulting in the formation of the Milwaukee Hydraulic
Cement Company, whose works now produce 750,000 barrels of
hydraulic cement yearly. He was a Director of this Company
until 1891, when he resigned and accepted the Vice-Presidency
of the Western Portland Cement Company, of Yankton,
Dakota.
The University of Vermont conferred upon him the degree of
Civil Engiueer, aud the University of Wisconsin that of Doctor
of Philosophy.
He was appointed Honorary Chairman of the delegation of
about 250 American Civil, Mechanical and Mining Engineers
that visited England, France and Germany in 1889. He is a
member of the American Society of Civil Engineers, the
American Society of Mechanical Engineers, the Western
Society of Engineers, the Institution of Civil Engineers of
England, the Milwaukee Electric Society, and the Milwaukee
Press Club. He is also the President of the Wisconsin Society
of the Sous of the American Revolution, and Vice Chairman
of the General Committee of the World's Congress Auxiliary
on Engineering Congresses of the World's Columbian Exposition
of 1893.
His contributions upon professional subjects have been
A COMPANY to be known
numerous, and, in many-
instances, of rare value.
as the American Alumi­
num Company has been
formed in Philadelphia
with a capitalization of
$2,000,000. It is said a
large plant will be erected
with a capacity of fifty (!)
tons of aluminum per day.
The officers are : Henry
Harper, President; John
A. Proud, Secretary, and
Robert McKnight, Treasurer.
The in veutor of the
process is Edward C.
Broadwell, who says of it:
'' The chemical method
will probably never meet
with success from an economical
standpoint, owing
to the fact that aluminum
has never been found free
in nature. The chemical
method takes advantage
of chemical affinities and
substances found in an
elemental state necessarily
have weak affinities.
The electrical current furnishes
us with a medium
whereby this metal can
be extracted from its ores
at any point desired, as
well as with any rapidity.
The advantage we claim
lies chiefly in two points :
F/rst, we claim to be able
to make one pound of
commercially pure alum­
inum with the expenditure
of but one electrical
horse power. Previous to this improvement 22 electrical horse
power has been necessary to accomplish the same purpose.
Secondly, we are able to take clay of ordinarily fair quality and
remove from it, efficiently and cheaply, all iron silicon.
" Of the two above improvements it appears that the mode of
application of the electrical current has gone the furthermost
toward the cheapening of this process. I have been working on
this process since 1885, and have tried experimentally every
patented invention and scientific suggestion that came under
my observation. What at present has been perfected I discovered
last summer, and my claims are based 011 a combination of
chemical and electrical methods. We expect to put aluminum
on the market at a price cheaper thau copper. It is a metal

I3S ENGINEERING MECHANICS. [May, 1892.
that can replace copper in almost every instance, aud, if it can
be produced for 25 cents a pound, it will be cheaper than copper
at 10 cents a pouud, because it is three and a half times lighter,
and consequently there is three and a half times more in bulk.
Our competition will come chiefly from Pittsburgh, Pa., and
Lockport, N. Y., but at close pushing we cau sell the metal at
a profit for 15 cents a pound."
THE recent appearances of German military balloons over
various parts of Poland, apparently under perfect control of the
occupants, despite strong opposing wind currents, has given the
Russians a great deal of auuoyauce. One more "revolution"
is threatened. The details of recent exploits in this direction
only, vaguely indicate the possibilities of future accomplishments.
The fact is especially emphasized by Russian military
authorities that these balloons are under perfect control, sailing
hither and thither at any desired speed, and ascending or descending
at pleasure. The motive power is not suspected. At
Knovo and Warsaw these strange ariel visitors were seen within
a few days, and later another balloon was seen over the Proushkorff
railway station. It remained stationary for a time, and
then started in the direction of the fort works near Relets,
where it hovered awhile, when it returned across the frontier.
Reports of similar occurrences have been received from Sosnovitzy
aud other places along the frontier. The balloons come
from Prussian Silesia in the night time and project the rays of
powerful search lights in every direction. The balloons, which
were at a great height, remained stationary sometimes for the
space of 40 minutes, and would then proceed in any desired direction.
There is no doubt that the steering apparatus, whatever
it is, is admirably adapted for its purposes, for tbe balloons
apparently answer to it as readily as does a vessel to her helm.
If these statements are true they are very important.
Russian officials hold that with manageable balloons the whole
system of warfare will be changed. It is self-evident that none
of the present fortifications would be able to withstand an attack
from above them. Shells could be dropped with almost
unerring certainty, aud no city could defend itself from an
enemy far up in the air beyond the reach of any- missile. Even
modern cannon, with their great range, could not at present be
used against balloons, for the reason that gun carriages have
not been made that will allow of a perpendicular elevation.
English ballooning is far in the rear. The best practice in
England is shown iu the 10,000 cubic feet captive balloons, in
which gas is carried in steel tubes, each of which weighs seventypounds
and about 120 cubic feet of oxygen is carried. F'our
wagons carry 140 tubes, which weigh with wagons, nine tons,
and each wagon has a tail drum ou which is wound 2500 feet of
wire rope, which is provided with pulley, ball and socket joint,
and a strong brake and handles. The gas tubes are S feet long, 53 s
inches in diameter and A °f an inch thick. Test pressure 2700
to 3000 pounds per square iuch. In peace the pressure in tubes
is 100 atmospheres, in time of war 120 atmospheres. The balloon
will lift 650 pounds. The rope is steel wire in seven strands,
each consisting of twelve wires and a strong core, weight one
ounce per foot, breaking strain one ton. A wire runs through
the ceutre for telephonic purposes. The French balloon has a
cubic capacity of 19,000 feet. The Germans use a traveling
generator which weighs three tons. The hydrogen gas is made
from zinc dust, mixed with hydrate of lime and formed into
cartridges, then placed in a furnace and the hydrogen driven
off. About 2i)< hundred weight of zinc aud 204 gallons of acid
are required to give 17,000 cubic feet of gas, the amount needed.
Iron is not as good as zinc. English engineers favor the plan
of carrying compressed gas rather than to make it on the spot,
for several reasons, one of which is that it requires four hours
to make gas, aud only fifteen to twenty minutes to prepare a
balloon for the ascent, if the gas is already made. The German
engineers may have solved the problem of aerial navigation, but
the fact cauuot be accepted on the slender testimony at baud
If, and when they do, the advance made will not be restricted to
military service, but will be applied to more humane purposes.
THE Loudon Engineer,ixx speaking of the possibilities of still
further improving the steam engine says : " In a sense we think
that the recent course of events iu connection with the steani
engine and other heat motors is disheartening and disappointing.
It is quite certain that the science of thermodynamics has
never before in the history of the world been so well understood.
It is a more or less familiar subject to hundreds of men with
inventive brains. Why is it that none of these brains seem able
to effect radical improvements in gas engines, or steani engines?
Is there no room or space left for anything of the kind? Are
we to take it for granted that the giants of old have turned over
the whole ground, aud left no space for the trained philosopher
with the wisdom of all the ages to aid him ? It would appear so,
and yet valuable improvements are made in heat engines, only
they are not produced by men saturated with the lore of thermo-dynamics.
Is a profound knowledge of science never accompanied
by the power of applying that science in practice?"
A Mr. H. P. DOWLING, of Cardiff, Wales, has devised an apparatus
for measuring distances at sea, based on the differing
velocities of sound through water and air. Sound is usually
reckoned to travel 1100 feet per second in air and 4400 feet in
water, subject to sHght variations for temperature. The difference
in time in traveling a mile is 3.6 between the two media.
The sounding apparatus may be one of the following forms :—
(1) Two bells struck simultaneously by two hammers worked
by one lever or haudle, one bell being in the water and the other
vertically over it in the air; or (2) two bells or discs, which can
be simultaneously- sounded by electric currents controlled by the
motion of one contact breaker, as in the ordinary electric bell;
or, (3) a double syren, one half in the sea and the other vertically
over the first, in the air, both portions to be simultaneouslysounded
by the motion of oue handle; or (4) a double whistle
to be worked similarly to No. 3. Forms 3 and 4 to be sounded
by means of steam, water, compressed air, or auy combination
of these. In all four forms the sounds would be sent simultaneously
through the air and water, and the duration and pitch
would be identical in the two parts of the same instrument. The
duplicate sounds may also be produced by the detonation of
gunpowder, gun-cotton, &c. The receiving apparatus should
consist of one or more pairs of similar vibrating plates or diaphragms,
one of each pair being situated in the sea, and the
other in the air vertically over the first. The vibrations of these
plates would be used to work an electric coutact-breaker, and
thus cause the sound-signals to automatically control the electric
current through wires fixed from these receiving instruments
to the registering instrument. The registering apparatus
should have a system of electro-magnets and armatures, in number
corresponding to the number of receiving instruments employed
iu any particular case. Each armature, when moved by
the attraction of its electro-magnet, should cause its motion to
be automatically registered by a pen or pencil, which it presses
against, or moves across the surface of a strip of paper—the
paper being at the same time moved at a regular rate by clockwork.
The pens or pencils, of which there would be one or
more pairs, should be placed in a straight line at right angles to
tbe directiou of motion of the paper; and the clock-work
should make marks or punctures at regular intervals, so that
the difference in time of arrival of any signal tlirough the water
and through the air at any instrument may- be at once seen.
CHIEF Engineer Melville receives congratulations from most
unexpected quarters for his able administration of the office
he fills.
Iu noticing the annual report of Chief Melville, London
Engineering says : "Our first impression is a feeling of ad-

May, 1892.] ENGINEERING MECHANICS. J 39
miration for a system which allows such a report to be made over, can be trodden on with inn.unity, and would almost stand
public, and we can only compare it with shame to our own hole .1 cart being driven over them, a load of 1,8 1 wt. on 1 in. of
aud-corner method of hiding up in official pigeon-holes every­
bearing surface being required to compress a i-in tube to an
thing that bears the stamp of originality, and retailing to the
oval section. The difficulties of manufacture have been con­
nation only couleitr de rose fictions, in which everything is
siderable, long flexible strips of a soft and uniform metal being
stated to be of the best in this best of all possible worlds.
required. Thus the J+'-in. tubes are made out of a strip 14
Whatever may be the evils of the American system of ad­
mm. wide and .6 mm. thick. At present such strips cannot be
ministration—with its "spoils to the victor" distributed by
obtained of a greater length than 6000 ft. to 7000 ft., and as 10
a new President—it cannot be worse than our " Parlianicu-
ft. of strip are required for each i-ft. length of tube, the greatest
tarianism ; " at any rate no such frankly outspoken docu­
continuous length that can be produced at the present time is
ment as that now before us would be possible in England
limited, but it is thought tbat by means of electric welding this
under the present system. It expresses surprise at the re­
difficulty will be overcome. 'Ihe whole of tlie operations of
sults accomplished with the moderate expenditure of ^"130,-
. 00. Speaking of what is said as to the need of more en­
forming the strip into the finished tube arc accomplished in one
gineer officers, it says: "With such a frank official dis­
continuous process by a single machine. The weight of the
closure of this shortcoming it is the fault of the whole Ameri­ various sizes of tubing now manufactured ranges from 2A oz.
can nation if disaster occur through the paucity of engineer per foot for the 5-in. tubing, which is the smallest size manu­
officers. The declaration contrasts favorably—or unfavorably factured, up to 17 oz. per foot for the lX-' n - tubing.
for us—with the optimist statements invariably put forward in
the House of Commons, and which form her own official utterance
of a like nature."
A RECENT foreign newspaper account says that a Swedish
inventor, Dr. Gustaf de Laval, has shown a five horse-power
rotary steam engine which rotates with a speed of 30,000 revo­
lutions per minute. One or more mouth-pieces, letting in the
steam, gradually widen towards the turbine, so as to let the
steam completely expand and thereby give it the great­
est possible vital power before it comes in contact with tbe
wheel. This wheel may be of steel or aluminum bronze, and
in this case is 10 cm. in outer diameter, and is attached to an
axis of 10 mm. diameter. Transmission is effected by cog­
wheel gearings, which rotate in oil. Only about five atmos­
pheres have been used, but the turbine works well under from"
thirty to forty.
The economical working of the invention necessitated an
unusual speed of rotation, and this again that the rotating sys­
tem be completely centred whilst in motion. Otherwise the-
turbine might be flung from its place, or its axis, in any case,
might bend and at once destroy the bearings. The problem
has been solved in the simplest possible manner. The in­
ventor has used the tendency of the turbine and its axis to ro­
tate round its own centre of gravity, a tendency which, of
course, increased the speed of rotation. He has simply made
the spindle ofthe turbine so thin that it will adjust itself in ac­
cordance with its centre-seeking tendency, without causing too
great a pressure in the bearings. Thus he overcame the great­
est obstacle in the way of obtaining great speed of rotation and
profitable working.
A special use ofthe steam turbine will, thinks Dr. de Laval,
be in connection with the working of dynamos and other rapidly
rotating machines. He also thinks it will be well adapted for
marine purposes on account of its even motion and small re­
quirements as to space.
A FLEXIBLE metallic tube has been devised made out of
strips of metal coiled together in such a way as to give a per­
fectly tight joint without the use of packing, under high or low
pressure. The greater the pressure the tighter the joint.
These tubes have been successfully used for conveying pe­
troleum oil gas at a pressure of 300 lb. per square inch, and a
small tube A ' n - i n diameter formed out of a strip 14 mm. wide
and 6 mm. thick, only yielded at a pressure of 2000 lb. per
square inch. The tubes, moreover, will stand a partial vacuum.
Their flexibility is such that a T% in. tube can be bent to a ra­
dius of 4 in., and a I in, tube to one of 6 in. The tubes, more­
AN English concern is about shipping a band saw to Tas­
mania which will saw through a depth of 75 inches at a speed
of 7250 lineal feet per minute. Its blades are 8 inches wide,
and S60 feet long, and pulleys are 8 feet in diameter, lined with
rubber. It stands 20 feet high from base plate to top of upper
pulley.
The upper pulley is fitted with a number of traversing gears,
by means of which its position in reference to the bottom screw
can be adjusted. In working it is found that the pulleys should
not be kept in the same plane, as the saw expands unequally
by the heat generated in sawing, and moreover by turning the
pulley shaft round in a horizontal direction, the back ofthe saw
can be kept from bearing on the pulley run which has a ten­
dency to crystallize it.
BARTLETT, HAYWARD & Co. of Baltimore are building for
the World's Fair, a gas holder with capacity of 4,500,000 cubic
feet; diameter at base, 203 feet; weight 230 feet; telescopic in
dhsign, with four sections, one inside the other. The brick
tank will occupy a space equivalent to 57,000 cubic yards, and
will hold 8,000,000 gallons. Total pressure on foundations,
41,000,000 pounds ; maximum pressure per square foot, 52,000.
pounds. The heavy strains from wind pressure will be trans­
ferred to and resisted by guide framing, which consists of heavy
bridge girders connected by struts of lattice girders and dia­
gonal braces. Maximum estimated wind pressure 800,000
pounds, or 52 lbs. to 89 ft. of vertical service. The guide fram­
ing will be connected by hot driven rivets, and some of the
suspended platforms will be over 200 feet above the ground.
It will require 150 cars to transport the ironwork from Balti­
more to Chicago.
PROF. WM. R. WISE, of Baltimore, states in a late newspaper
interview, that he is the inventor of the German balloon, and
that after having failed to interest the American Government
in it, he sent it to Germany on December 31 last. He describes
his balloon as follows :
"The balloon which I planned was cigar-shaped. The car
was about 150 feet long and about 30 feet wide. The bag was
made of silk and was to be filled with hydrogen gas. The car
was made of steel rods and was attached to the bag with steel
apparatus. The propelling force was electricity iu a storage battery,
for which provision was made on board the car. The
battery- operated a screw propeller at each end of the car. The
propellers had a lateral motion of 90 degrees on each side, so
that any steerage power could be obtained by operating the
propellers at the required angles. The propellers were different
in form from those used by steamers, and were so constructed
as to act powerfully in the attenuated medium ofthe air. They

i/jo ENGINEERING MECHANICS. [May, 1S92.
were controlled by a balloon man, who could direct their force
as thoroughly as the pilot of a steamboat. In steering against
the wind the propellers were used simultaneously, one pulling
and the other pushing, with the result that, by a lateral action,
the force of the wind could be counteracted.
"The speed calculated for was about 20 miles in a calm. My
idea was that, iu warfare, the balloon should always be kept
far euough above the enemy to be out of tbe range of projectiles.
Observations were to be made by electric search-lights
and telescopes. The balloon was also adapted for the dropping
of torpedoes on naval vessels from the air."
THE Southwark F'oundry and Machine Co. of Philadelphia
has completed a pumping engine for the Spring Garden Water
Works, Philadelphia, which has a capacity of 20,000,000 gallons
for 24 hours, delivered against a head of 250 feet above the water
in the forebay, through a rising main of 48 inches in diameter
and 14,000 feet in length. The weight of the entire pump is 500
tons. The fly wheel weighs fifty tons, bed-plate 40 tons ; the
pump will occupy a space of 40x30 feet, and is 35 feet high. It has
two high pressure steani cylinders, 3 ft. S iu. diameter, and two
low pressure, 7 ft. 4 iu. The flanges are each 37 inches iu diamter,
two in number. Power is transmitted to the pump by a
triangular walking beam and a 20 feet fly wheel is located on
the main shaft. The steam cylinders are unusually large to
meet special requirements, and are placed vertically to minimize
mean aud avoid frictional resistance. The water cylinders
are placed horizontally and the valves work vertically. Tbe
steam and water cylinders are bolted to sufficiently massive
bed plates to prevent a tendency to oscillation, and the bed
plates carry the bearings for the beam shaft-crank, shaft, fly
wheel and steam cylinders. The entire machinery has a complete
support independeut of the foundation.
QUEEN'S portable testing sets are meeting with much favor-
Their new galvanometer is not affected by mechanical vibrations
or by proximity to masses of irou. It can be used alongside
runniug dynamos. The coils in the rheostat and bridge
are wound with platinoid wire.
WHAT CONSTITUTES THE BEST PAINT.
In a paper recently read before the Northwestern Railroad
Club some very useful hints are given which users of paints
will regard with profit to themselves.
It was very clearly demonstrated that the paint that for the
longest time will put off tbe necessity of repainting is the paint
which must, iu the nature of things, commend itself to the
user as the most economical. This fact before a body of practical
men like the Northwestern Railroad Club was fully and
best illustrated by the following calculation :
Suppose a small depot along the line requires twenty gallons
of paint; if a cheap material is selected, at 75 cents per gallon,
the cost would be—
20 gals, paint at 75 cts per gal $15.00
Cost of application 25.00
Total cost of cheap mineral paint $40.00
Such a paint would last at most two years, or a cost of $20.00
per year.
Now suppose the material selected should be the best white
lead paint at $1.50 per gallon.
20 gals, of paint at $1.50 per gal $30.00
Cost of application 25.00
Total cost of white lead paint $55-oo
Suppose the life of the latter is but three years, we would
have a cost of $18.33 per annum for the good paint and $20.00
per annum for the cheap paint.
Now suppose again, that the material selected was Dixon's
Graphite Paint.
20 gals, would cost$i.40 per gal $28.00
Cost of application $25.00
Total cost of Dixon s Graphite Paint $53- 00
Probable length of life ten years, although roofs painted with
Dixon's Graphite Paint have not required repainting for 15
years. On a ten year basis the cost would be $5.30 per year, or
about one quarter of the cost of auy other paint.
This illustration shows that durability is the main factor in
the paint, especially as the principal motive of painting is to
preserve the wood, or tin or irou over which the paint is
spread.
Next in importance to the pigment itself is the vehicle used
in spreading it. Ask your manufacturer to guarantee beyond
the shadow of a doubt that the oil used is linseed oil, pure,
simple and unadulterated. Pure linseed oil cannot be supplanted
by fish oil, rosin oil, emulsions, soap mixtures and the
like.
Graphite is one of the forms of carbon, pure, sweet and harmless
as charcoal. It is not affected by acids, alkalies, heat, cold
or any known chemcal solvent. The oil used in Dixon's Graphite
Paint is guaranteed the best boiled linseed oil. Graphite
Paint, weight for weight, will cover two or three times more
surface thau any lead, mineral or metallic paint, and last
four times longer. All this has been demonstrated beyond
question, and the manufacturers have the evidence.
Graphite Paint is recommended for roofs, brickwork, iron
structures and all places where a dark paint can be used, and
also as a priming paint.
For prices, circulars, etc., address the manufacturers, Jos.
Dixon Crucible Co., Jersey City, N. J., who are also glad to answer
all inquiries.
The British navy has been increased during the past six years
as follows :
1SS6. 1S92.
Breech loading guns . . 499 1868
Quick firing guus ... 33 1715
Torpedoes 820 2874
Ships at home .... 15 21
Ships abroad 96 no
Ships afloat and building,
all classes except
torpedoes .... 57 140
Officers and men, active
list 61,400 74,ioo
Naval reserve officers
and men 18,300 23,500
The total number of guns completed during 1S91 was 396, as
compared with 240 in 1S90.
Nature of Gun. Numbers
Completed.
16-25 in. of 100 tons 1
13-5 in. of 67 tons 21
10 in. of 29 tons 10
9-2 in. of 22 tons 19
8 in. of 14 tons 1
6 in. of 5 tons 75
5 in. of 40 cwt 22
4 iu. of 26 cwt 8
6 in. quick-fire 8
4'7 quick-fire 225
Total 390
THE Pennsylvania Railroad engineers at Altoona are experimenting
near Pittsburgh with a semaphore which dispenses
with colored lights in signalling. The new contrivance throws
a ray of plain, white light at different angles, which forms the
signals.
A CONGRESSIONAL Committee is considering a proposition to
establish a unit of wages by which the compensation of labor is
to be determined. The proposed unit is 60 pounds of good flour.

May, 1892.] ENGINEERING MECHANICS. 141
THE EDISON TRIPLE EXPANSION ENGINE AND MULTIPOLAR
GENERATORS.
One of the most serious problems that to-day confronts the
management of Electric Illuminating Companies, in large
cities, is the cost of the land necessary to accommodate the
large station buildings. When land costs $1,000 and upward a
foot front, every square foot of ground space that can be saved
materially reduces the necessary investment of the Company.
Recognizing this fact, the Edison General Electric Company
have recently brought out a new line of central station units,
consisting of two multipolar dynamos coupled direct, one on
either side to a triple expansion engine, and ranging in capacity
from 100 to 1500 indicated horse-power. This combination
does away with all belting and counter shafting, and thus
secures an increase of efficiency and a great saving of floor
space, two most important factors in central station practice.
The important features of this type of generator are given in
the following description, which will undoubtedly prove of
interest to central station managers.
THE GENERATOR.
The saving of floor space being one of the chief objects, the
necessity of coupling the generator directly to the engine
naturally suggests itself; but as the armature of the bipolar
generator now in general use must, of necessity, be run at a
comparatively higher number of revolutions per minute, it is
evident that unless a special engine is employed, another design
of generator is called for.
The multipolar generator is peculiarly adapted to this purpose,
as it may be designed to generate any desired electrical
output, at an armature speed corresponding to that of a slow
speed engine. This type presents the additional advantages of
requiring but small floor space, of being able to withstand
sudden variations of the load and of carrying heavy loads continually
withou danger of overheating.
The armature is of the Gramme ring type, of very simple
construction ; it is built up of f/J shaped copper strips, whicli
are slipped (in a single layer) over the laminated wrought iron
core, the upper end of one being connected with the lower end
of the adjoining loop, by a copper bar of corresponding thickness,
these bars acting as the segments of the commutator.
The number of brushes correspond to the number of poles of
the generator, and it is found that the large current output can
be divided among these brushes much more conveniently than
if only one set of brushes were used to carry the whole current
generated. The mechanical device for controlling these brushes
allows of their being operated together, so that when once
adjusted, the whole can be handled as though but one set
were used.
The field coils are wound on separate spools, wliich are
slipped over the field magnets ; these field magnets are then
inserted in an annular or polygonal field frame, mounted on
the bed plate of the engine. The bed plate being heavy and
massive and of special design, perfect alignment and rigidity
ofthe field frame with relation to the engine is secured.
The increased diameter of the armature in the multipolar
type of machine, gives a very large beat radiating surface.
This point, in connection with the special construction outlined
above, allows the Edison generators to maintain heavy loads
for periods of any duration, a factor that will be admitted as
eminently desirable in Central .Stations where such conditions
exist.
The armatures are mounted directly on both ends of the
crank shaft, and act as the fly wheels of the engine.
THE ENGINE.
The engine is of the triple compound 3 crank inverted cylinder,
automatic condensing type, well proportioned throughout,
liaving large wearing surfaces which can be easily adjusted.
The bedplate to which the main bearing boxes of the crank

142 ENGINEERING MECHANICS. [May, 1892.
shaft are cast is strong and is firmly
bolted to a massive foundation box which
also carries the dynamo frames; thus
perfect rigidity between engine and
generator is ensured. The crank shaft
is of forged steel with cast iron balanced
discs to whicli tbe crank pins are fitted.
There are two bearings to each crank,
and an additional large bearing ou each
end of the shaft to carry the armature.
On the shaft arc three eccentrics each
operated by its own independent governor
so that tbe point of cut-off iu each
cylinder is changed equally with the
load, thus doing away- with any tendency
to face, iu case the total load is at anytime
thrown off, or any accident happen.
Strong cast iron columns carry the cylinders
which are bolted together, aud
the engine made strong, compact anil
well arranged ; indeed these engines are
almost fac-similes of the latest aud most
improved types at present in use 011 the
finest ocean steamships, with necessaryadditions
to render them as highly efficient
for electric generating purposes as
their prototypes are for Marine Work.
They are calculated for tbe maximum
efficiency point at about I2'2 per cent.
below the normal maximum capacity of
the generator, and have a range to a
maximum capacity of 20 per cent, above
the normal maximum output of the
generator at 160 lb. initial pressure and
vacuum of 24" ; thus allowing each engine,
in case of an accident to the condensing
apparatus, to operate the generator
satisfactorily- non-condensing. In addition
to the many advantages alreadymentioned
these engines when connected to a suitable condenser
will reduce the consumption of fuel considerably, 'this
is an item of vast importance in electric light stations, increasing
their storage, boiler and engine capacity. The compactness
of this arrangement, as shown in the following table,
proves the advantages to be gained by the use of the dynamos
and engine thus combined.
COMPARATIVE FLOOR SPACE REQUIRED BY TWO GENERA­
TORS AND ONE ENGINE.
Two Bipolar Generators belted to o>ic High Speed Engine.
Total Capacity two Generators
K. W. 16 c. Lamps.
5°
90
200
35°
200
1,620
3,600
6,300
Minimum Floor Space in Squar
Feet.
270
374
511
57i
Two Multipolar Generators Coupled Direct to One Edison
Triple Expansion Engine.
Total Capacity two Generators. Minimum Floor Space in Square
50
100
200
400
16 c. Lamps.
900
1, Sco
3,600
7,300
I i i t
56
I .'I
1 So
356
NEW EDISON 200 K. \V. BIPOLAR GENERATOR.
The elimination of objectionable features from electric lighting
and electric power apparatus, and the introduction of im-
provements, is the present aim ot all manufacturers of electrical
devices. We show in the accompanying cut an Edison 200
Kilowatt generator of the latest form illustrating this. It is of
the well-known bi-polar type, with the general features of
whicli every practical electrician is acquainted.
The series field is built up of sections, wound on spools which
are slipped over the cores and then properly connected up.
Should a fault manifest itself, it can be located, and the spool
in which it appears can be removed, repaired and replaced, or
another substituted at once without loss of time, and expenditure
for repairs is thus reduced to a minimum.
To adapt this generator to the demands of electrical railway
service, the field has been provided with a compound winding,
easily adjusted to meet tbe necessary requirements by means
of a shunt coil, conveniently placed in the back board of the
keeper. The bearings being located close to the base frame,
the centre of gravity of the structure is low and great stability
is secured. Self-oiling bearings and carbon brushes contribute
to diminish the attention necessary to the operation of the
generator to a minimum.
A considerable number of these high capacity generators
have already been installed by the Edison General Electric
Company, throughout the country, and the advantages offered
have been duly appreciated.
1 11 ]•; Pittsburgh Reduction Company have removed from Room
59, No. 95 Fifth Avenue, to No. 116 Water Street, where a store­
room of .Aluminum, sheet, wire and ingots, will hereafter be kept

May, 1892.J ENGINEERING MECHANICS. M3
THE BUFFALO "B" VOLUME BLOWERS.
The fan illustrated herewith is ofthe type known as "Buf­
falo 'B' Volume Blowers," especially designed and adapted
for blowing forge fires, for forced draught under boilers, and
similar uses requiring quite a volume of air at moderate pres­
sure. Though somewhat similar in appearance to the cupola
blowers, the fans are so constructed that a larger volume of air
is furnished in a given diameter, but not at so sharp a pressure
of blast at the same speed. In the Southern States, in Cuba,
and in South America, especially on sugar plantations, where
bagasse is the principal fuel, scarcely a battery of boilers will
be found without forced draught, and these types of blowers,
especially in the larger sizes, are widely used for the purpose.
When properly applied, they insure perfect combustion when
using fuel of this nature. They are usually from 4 to 7 ounce
pressure, according to the conditions and the fuel burned.
Where fans with direct connected engines are required, steel
plate blowers with double direct connected vertical enclosed
engines are very convenient, if not too great a pressure of blast
is needed. Work requiring heavier blast thau it is practicable
to obtain from the steel plate fans with direct connected engines,
owing to the speed required, and which would be injurious to
Ihe life of a direct connected engine, can be accomplished with
the -tyle of blower illustrated herewith ; and if it is desired to
have independent power, they are placed upon bed-plates, and
an engine is furnished on the same foundation connected direct
-to the countershaft, and by proper proportionmeut of pulleys,
the blower can be run to obtain a maximum pressure while the
engine is making moderate speed. By this arrangement the
speed of a blower can be instantly changed.
The Buffalo Forge Co., Buffalo, N. Y., makers of the blowers
known as the *'B" type, have recently materially improved
their construction, and the illustration shows their latest design.
The manufacturers state that the journals are long and
heavy, that the different parts of the fan are so well proportioned
aud fitted to each other that at the highest speed there
is no vibration. These blowers are made with a solid shell or
casing, and have a smaller number of parts than any other
form of construction, which, of course, is a valuable poiut in
all high-speed machinery.
PROPELLER bosses, which will minimize the churning of
water, have yet to be designed. With reference to the English
war ship " Edgar," the 4 ft. 6 in. bosses circumferentially revolve
649 ft. per minute less thau the ves­
sel is traveling at 20.97 knots ; 594 ft. at
18.836 ; 557 ft. at 16.512 ; 4S8 ft. at 14015 ;
467 ft. at 15 4; 411ft. at 11.87; and 341
ft. at 9.647.
The speed is greater than the circumferential
travel of the roots of the blade
by about:
38,940 ft. per hour at 20.97 knots
35. 6 54
18.836
33,420
16.512
29,280
28,020
24,660
14,015
134
11 87
20,460
9- 6 47
Would uot therefore bosses of 6 ft. 6
inches diameter conduce to greater speed
than the 4 ft. 6 inch ? The following
figures show what increased speed might
might be expected with bosses of 6 ft. 9
inches:
Speed on Revolutions Speed of Speed of Bosses.
Trial. I ou Trial. 1 Ship, i (6 ft. 9 in.)
knots.
20.97
18836
16.512
I4.OI5
13-4
11.87
9.647
104
93
79
66
f>3
56
46
ft pr min
2124
1908
1673
I420
1357
1202
977
ft. per min.
2204
1971
1674
1399
1335
1187
954
We would appreciate any facts and figures
ou the above question from our
naval engineering readers.
UNUSUALLY' large quantities of ore are
crowding the smelters at Denver and Pue­
blo, far beyond capacity. A number of
smelters are projected at Colorado.
THE Gunnison country in Colorado was much talked of
ten years ago, and interest gradually subsided. Prospectors
and investors are now returning, and wonderful developments
are expected. An exchange remarks : "It is not her gold and
silver mines alone tbat merit candid and careful investiga­
tion, but her illimitable deposits of iron, coal, marble, granite,
kaolin, sandstone, etc., etc., to say nothing of agriculture and
grazing. Until quite recently most of these advantages have
been neglected.
THERE is a novel motor in tbe Patent Office which operates
by the power given out in different expansions of metals under

144 ENGINEERING MECHANICS. [May, 1892.
varying conditions. It is said that it has beeu running for several
years without stopping.
TOBIN BRONZE.
This metal, when rolled hot, is remarkable for its high elastic
limit, tensile strength, toughness and uniform texture, and is
stronger than ordinary mild steel rods or plates. As a comparison
between the two metals, the following facts are noted :
The tensile strength of six Tobin Bronze one inch round
rolled rods, turned down to a diameter of 5-s of an inch, tested
by Fairbanks, averaged 79,600 lbs. per square inch, and the
elastic limit obtained on three specimens averaged 54,257 lbs.
per square inch.
Tests of opeu hearth mild steel plates from A inch to one inch
iu thickness, manufactured by the Steel Company of Scotland,
were made by Kirkaldy for the English Board of Trade.
Forty-eight (48) tests give an average mean tensile strength of
65,630111s. per square inch, and a mean elastic limit of 36,510
lbs. per square inch.
At a cherry red heat Tobin Bronze can be forged and stamped
as readily as steel. Bolls and Huts cau be- forged from it,
either by hand or by machinery, with a marked degree of
economy.
Another important feature in the working of this metal at a
cherry red heat is, that it can be drop-forged in the same manner
as steel, either from rods or sheets.
It has a specific gravity of 8,379, while the specific gravity of
rolled copper bolts of a tensile strength of 33,000 lbs. per square
inch is S.7.
GOVERNMENT CONTRACT FOR COLD ROLLED STEEL.
It is stated that The Wilmot and Hobbs Manufacturing
Co., of Bridgeport, Conn., makers of cold rolled steel and
strip steel, which is used largely for all difficult pressed
stamped and drawn work, have just received a large United
States government contract for the material for use in the
manufacture of the United States mail lock hardware. This
order was placed with them, it is said, after a trial of various
makes of cold rolled steel for this special work, extending
over quite a period of time, and that the government adopted
what The Wilmot & Hobbs Manufacturing Co. term their
"extra special" stamping aud drawing steel, as being the
best for the purpose.
This company has recently purchased the hot rolling mill
plant of the Bridgeport Rolling Mill Co., thus giving them
additional facilities for preparing their special billets for
their cold rolling mills. This brings their annual capacity
up to about 15,000 to 20,000 tons of hot and cold rolled strip
steel.
Mr. Albert N. Stanton, formerly principal owner and general
manager of the Bridgeport Rolling Mill Co., has been
engaged to manage this department of their works.
THE Rue Injector, manufactured by the Rue Manufacturing
Co., 116 North 9th St., have issued a catalogue of general
information and directions concerning their injector.
The company is maintaining its position in the injector
field.
THE Woodbury Steam Engine has been so long familiar to
the public that it would seem but little more can be said for it
Unsolicited testimonials, however, testify to the warm appreciation
in which they are held by users all over the country.
Curtis & Wheeler, of Rochester, write their 10x14 260 revolutions
has been in constant use for years without repairs. The
Bartholomew Brewing Co. have had the "Woodbury" in use
for twenty-five years Prof. Kirealy writes he likes tbe " Wood
bury " better than auy other high speed engine 011 the market.
The chief engineer of the largest summer hotel in the world—
Hotel del Coronado, Coronado Beach, Cal., writes, " Au 8x12
has run 300 light dynamos three years. The Rainer Power &
Railway Co., at Seatile, Washington Territory, writes that their
"Woodbury" runs 18 hours in 24, and is an ideal engine.
C. H. and F. H. Stott, of Stottville, Col., have been running five
of these engines from six to ten years, and find them close in
regulation, easily cared for and economical in fuel.
THE Buffalo Forge Co., Buffalo, N. Y., have just issued a new
catalogue of their Steel Plate Planing Mill Exhausters, which
recently have been very materially improved in construction. A
notable feature of this catalogue is the large number of good
diagrams and forms of connections for wood-working machinery
from actual measurements of successful plants which have been
installed by this company in some ofthe largest wood-working
establishments in this country. Doubtless more complete and
detailed information regarding the successful application of
Exhaust Fans for similar duty is embodied in this catalogue
than anything ofthe sort which has ever before appeared.
The catalogue is issued in convenient form for mailing, on Sopouud
coated paper, and printed in an art ink.
QUEEN & COMPANY, Philadelphia, are just placing on the
market a new portable tachometer which has peculiar advantages
that render it of great value for instantly determining the
speed of rotating shafts. Three spindles are geared to the rotating
parts inside ofthe case, each one of them having a separate
scale on the dial, so that the indications are direct reading
throughout. A detachable point, with slightly flexible end, to
fit any ofthe spindles, is supplied, the flexibility of which acts
as a safeguard, for, if made perfectly rigid there is danger of
breakage when not applied exactly at right angles to the shaft.
A scale to correspond with each spindle is graduated on the
dial, and the ranges covered are : 40 to 200, 120 to 600 and 600 to
3,000, which gives a maximum capacity of 40 to 3,000 turns per
minute. A conveniently shaped haudleis attached to the body
ot the instrument so that it can easily be held in the hand.
The apparatus is well made and presents a handsome appearance,
the different parts being nickel plated. A tachometer
like this is desirable for both expert and practical work, and
those interested in the subject should write to the makers for a
copy of circular No. 310.
AN interesting and amusing instance of the efficacy of the
London-Paris telephone occurred the other day which is worth
recording. The Salvation Army band were marching from the
Royal Exchange, London, playing the "Marseillaise" when an
idea struck the members present in the telephone room. The
windows and doors were thrown open and the attendant at the
Paris end was asked if he could hear anything. The response
(in French) was immediate. "Yes, I can hear a band playing
the 'Marseillaise.'" That a band of music playing in the
streets of London could be plainly distinguished iu Paris is a
sufficiently striking marvel of the nineteenth century science.
IN the Priestman Improved Oil Engine the oil is contained
in au air-tight chamber, into which air is forced by an air pump
worked by an eccentric. Under the pressure thus produced the
oil is forced out through a fine jet, but at its point of exit
meets with a rush of air from the top ofthe oil chamber which
issues from an annular jet completely surrounding the oil orifice.
By this means the jet of oil is converted into a fine spray
whicli passes into a vessel known as the vaporizer, where it is
heated by means of the exhaust gases, with an additional supply
of air before passing to the engine cylinder. The engine
works on the Otto cycle and the firing of the charge is effected
by au electric spark produced by an induction coil and battery.
The recent trials aud tests by expert authority places it high in
the test of economic engines of its class.

May, 1892.] ENGINEERING MECHANICS.
EL1XTRH AL.
THE Electro Dynamic Co., of Philadelphia, has improved on
its two horse portable electric drill motor, with flexible shaft and
universal joint and bell guard. One size will drill a hole up to
1 A, inches in diameter; the second size a hole up to 2 inches in
diameter. With the shaft taps and drills may be operated. It
has been successfully used for railroad work, and is especially
useful for drilling stay bolt holes for fire boxes in locomotives.
The motor complete, with 100 feet of duplex flexible cable,
together with the resistance box ready to attach to the shaft,
including the weight of the gears, which are of hardened steel,
accurately cut, will weigh 233 pounds.
The motor is provided with a hook over the centre so that it can
be suspended on a pulley, and raised or lowered as the work
may require. In all heavy drilling required in naval vessels,
the motors are particularly serviceable, and there will no doubt
be a large field for their use in drilling for side armor bolts of
armored ships. The present motor is similar in its geneial features
to that built for the New York Navy Yard in 1888. The
average labor saving by the machine is estimated to be 60 per
cent., and in many instances, with s'.raight, plain work, 70 per
cent. It is certainly a most useful tool in ship yards, boiler
shops and erecting shops of all kinds.
THE lightest type of batteries for electric lighting of cars have
lately been introduced on passenger cars in Switzerland. The
box for each car is 15x29x19 inches, and weight of battery 245
pounds. Each car has 3 lights of 10 candle power, 2 of 8 and
2 of 5 for each platform; total, 56, good for 13 hours without
renewal.
—The Consolidated Electric Storage Co. have obtained an injunction
against the Accumulator Co. of New Jersey, restraining
them from making, selling, preparing or using storage batteries
infringing the Brush patents. This is the fourth time the Brush
patents have been sustained.
A BELT to transmit Soo h. p in the Royal Electric Light
Company's plant at Montreal is 130 feet long, 53 inches wide,
weighs 2000 pounds, and is made without a rivet. It is a solid
mass of leather, three ply, cemented by a pressure of 30 tons
weight. The surface will be made proof against oil absorption
by a special process.
BETWEEN 5,500 and 6,000 electric lights will be required on
the World's fair grounds. The T. H. Co. will have 3,500 lights
the Standard Co., of Chicago, 1,000 and foreign companies the
rest. Price $20 per lamp. The T. H. contract will be subdivided
between the Brush, F^ort Wayne, Schuyler and Excelsior
Companies. Contracts for So,ooo incandescent lights will soon
be made.
THE Nicaragua Canal Enterprise has been strengthened by
the co-operation of John W. Mackey, Andrew Carnegie, Austin
Corbin and H. M. Flagler, of the Standard Oil Co. As soon as
the present financial depression subsides the bonds ofthe company
will be placed in the principal markets ofthe world. The
enterprise is cordially endorsed on the Pacific Slope.
THE field for electric welding has been vastly widened by
the discovery of a process by a French investigator for
utilizing the intense heat of an electric arc. The arc process
makes possible the longitudinal joining of large tubes, the
making of large pipe fittings, the filling of blow holes in
castings, etc.
Two railroad companies in Massachusetts are preparing to
run ordinary railroad cars by electricity. The legislature has
passed a bill which says that all steam railroads of that State
"are hereby authorized to operate their railroads by electricity."
Professor Thomson lemarked at the banquet given by the
Boston Society of Civil Engineers, that a curreut of electricity
could, under certain conditions, be made to alternate no less
than 500,000,000,000,000 a second.

146 ENGINEERING MECHANICS. [May, 1S92.
—Walker & Kepler, Electrical Contractors, have just com­
pleted a steam electric plant for the steamboat Chauncey Viv-
erd and are at work on another.
—The Fort Wayne Electric Light Co. have sold to the Read­
ing Electric Light & Power Co., 360 lighters, and 180 arc lights.
The Fort Wayne Co. have control of a new Wood cut out box,
the invention of James Wood. The main feature of the box
is that it has a double break, and is considered both incom­
bustible and water proof. 5,000 of the machines have recently
been sold to the Thompson & Houston Electric Co.
—Kelly Bros., Goshen, Ind., have placed on the market a
new grate bar. The heavy service required in an electric light
power plant, makes necessary a grate of unusual strength and
one that permits free and rapid combustion.
—The Union Railway Co., of Chester, are now in a po­
sition to begin work on the new Electric Railroad between Media
and Chester. The comp iny will use octagon-shaped wooden
poles. Box rails will be ised for paved streets and the T rails
where there was no paving Ihe line is five miles, and the run
will be made in twenty-five minutes.
—G. B. Manapenny and E. E. Weaver have invented an anti-
induction machine for telephone lines, for removing all induc­
tion from electric light The new machine has had several
satisfactory tests. The parties in interest have applied for a
patent and when granted they expect to put them on the market.
L. S. STARRET'S TOOLS.—THE BEST RULE.
DESK RULES FOR DRAUGHTSMEN, BOOK-KEEPERS, ETC., No.
70.—Anyone who has tried to do nice ruling with a pen and ink
has had more or less trouble from the ink sticking to the rule
LS.STARRETT,
AriHU.,Mj4SS,
3a
1
and smearing the fin­
gers or blotting the
paper. Another fault
\ of most rules now on
the market for this
I purpose is their thick-
. ness, bringing the
{working edge too
high from the paper.
Experiencing^ the need of a [satisfactory desk rule I made
some for use in my own office. These proved to be just what
are needed, and so superior to the ordinary rule that I conclu­
ded to list them and carry them in stock.
They are made from spring-tempered steel, about 1 inch wide
and three sixty-fourths of an inch thick. One edge is ground to
a fine bevel, raising it from the paper to admit of pen ruling
without blotting. They are nicely finished, nickel-plated, and
are either plain or graduated; the graduations being in i6ths or
finer to order. Price list: —12 inch plain $1.00, graduated$1.50; working at a constant pressure? If the full pressure were left
15 inch plain $1.10, grad. $1.75; 18 in. plain #1.25, grad. $2.00.
THE HYDRAULIC MACHINERY OF SWING BRIDGES*
BY PROF. T. CLAXTON FIDLER, M. Inst. C. E.,
University College, Dundee.
Previous to the employment of hydraulic machinery for trans­
mitting power, swing bridges were worked by hand. The op­
eration was, therefore, slow and laborious. The application of
the steam engine for the performance of this work was expen­
sive, owing to the large amount of fuel consumed between the
periods of opening the bridge. What was really wanted for
* Abstract of a lecture delivered to the Dundee Mechanical Society.
such work was a store of energy, laid up during the long inter­
vals of leisure, and held until wanted for developing a high
power for a short period of time. This was accomplished by
employing a small steam or gas engine for gradually charging
an hydraulic accumulator under a pressure of about 700 pounds
per square inch. The energy thus stored could then be ex­
pended in driving an hydraulic motor, working the bridge at
almost any rate of speed. The introduction of this method of
working has enabled us to move the heaviest swing bridges with
speed, and to handle them with perfect control.
The points under consideration are illustrated in the hydraulic
machinery for the Anglesea swing bridge at Cork.
The weight is carried upon a circle of conical rollers of cast
steel about 20 inches in diameter and 10 inches wide, traveling
between upper and lower paths of cast iron about 31^ feet in
diameter.
The bridge is turned by a 1 *s inch short link chain wrapped
round the circumference of the upper roller path and pulled al­
ternately in either direction by a pair of direct-acting hydraulic
rams, the cylinders being fixed, side by side, upon the masonry
abutment under the tail end of the bridge.
The rams were designed to be 13A inches in diameter, with
a full stroke of 8 feet 6 inches. When the bridge is closed the
rams are both at half stroke, or nearly so, and in turning the
bridge through 90 degrees, in either direction, one ram advances
4 feet 2 inches, while the other recedes the same amount. The
corresponding intake of the chain is 25 feet, the stroke of the
ram being reduced to one-sixth of this amount by three-fold
chain tackle.
The tail end of the bridge is unusually short, having an ex­
treme length of only 37 feet 6 inches from centre of pivot, while
the projecting arm is 84' long. The total weight of the bridge
is 400 tons, the short arm weighing about twice as much as the
long arm.
Now, in order to open the bridge quickly and safely, it was
desirable to lose as little time as possible in starting and stopping
and to work the bridge as nearly as practicable at a uniform
speed throughout. The whole stroke ofthe chain being 25 feet,
a maximum speed for the same of 1 foot per second was taken.
Allowing at the start a run of 5 feet for getting up speed, and a
space of 5 feet at the end for stopping, the journey would be
performed in 35 seconds ; 10 for starting, 15 for uniform velocity,
and 10 for stopping.
It was calculated that the force] necessary to overcome the
friction was but 15 hundred weight, while that required to over­
come the inertia of the mass was 90 hundred weight.
If the bridge was to be opened in the manner described, the
chain would have to start with a pull of 105 hundred weight,
and after traveling 5 feet, the pull must be reduced to 15 hun­
dred weight, which would be merely sufficient to overcome
friction and to keep the bridge moving at a uniform speed.
How could this be accomplished in an hydraulic cylinder
to act upon the ram, the bridge would, in a few seconds, attain
an excessive speed. This difficulty was overcome by taking ad­
vantage of the known laws of hydraulic resistance.
When water flows through a small orifice, the loss of head is
proportional to the square of the velocity ofthe issuing stream •
and if the orifice in question is tbe admission valve of the hy­
draulic cylinder, the velocity of the issuing stream must be
governed by the velocity of the ram, and, therefore, by the ve­
locity of the bridge itself. Thus, when the chain drum revolves
at the intended maximum speed of 1 foot per second, the ram
will advance 2 inches per second. Now, if we reduce the ori­
fice to about one-eighth or one-seventh of a square inch, we
shall get such a great velocity of issuing stream, that the \gss

June, 1S92.] ENGINEERING MECHANICS.
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering,
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
Londou Office, 270 Strand, D. NUTT, Agent.
Entered at the Post-office in Philadelphia as Second-Class Mail Matter.
SUBSCRIPTION RATES.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
PHILADELPHIA, JUNE. 1892.
IN measuring the light of such illuminants as arc or incan­
descent lamps it is usual to take the measurements in a horizontal
direction only. The light from a gas burner or from a
standard candle is also taken horizontally, and so it might at
first sight seem quite fair to compare the arc lamp and gas
burner by their horizontal candle-powers. There is, however,
a very important difference. If a gas or caudle flame is transparent
its light is the same in all directions; the horizontal
light is, therefore, equal to the mean spherical light. This is
by no means the case, however, in an arc or incandescent
lamp. The result is that a 16-candle gas burner lights a room
better than a 16-candle incandescent lamp. The error is often
exaggerated in the case of incandescent lamps by taking the
light so that the filament is arranged "flatways" towards the
photometer screen. What is measured then is not even the
mean horizontal light. The result is that most comparisons of
the light of gas and electricity are somewhat unfair togas, especially
in the case of incandescent lamps. With arc lamps,
however, though the photometric comparisons are unfair,
especially for indoor lighting, where light is almost equally
useful whatever its direction, the arc really utilizes its light
better. Arc lighting is chiefly employed out of doors, and
while a gas lamp sends a large proportion of its light into
space, an arc throws most of its useful illumination on the
ground, which is just where it is wanted.
Though candle-power means little in connection with gas
burners, on account of the vagaries of standards of light; it
means still less in electric lighting. In one case it means the
horizontal or the spherical light, because they are the same.
When, however, an electrical engineer refers to the candlepower
of an arc or incandescent lamp, no definite meaning
can be attached to his statements.
N E W economics are being rapidly discovered in the utilization
of electric power. An English electrician, Mr. Trotter,
recently showed that it is possible to double the light of an arc
lamp by keeping one point of the carbon out of the way of the
other, whicli gives practically all the light. Industries says
regarding it :
While engineers are engaged in wresting another 1 per cent.
from the losses in the dynamo, they may easily overlook simple
means of doubling the light from an arc lamp. Mr. Trotter
showed with great clearness that, considered as a source of
light, an arc lamp provides two points of carbon. One has a
small area or crater raised to white heat, and this gives nearly
all the light. The other merely- gets in the way and cuts off
most of it again. This points to the enormous advantage of
using some such arrangement as Jamin's. As far as we know
Jamin merely wanted to do away with.feeding mechanism,
but, as Mr. Trotter pointed out, his arrangement has an enormously
greater advantage in making the lamp efficient and
shadowless. .According to the author of the paper, the curious-
looking light curves or " characteristics " of arc lamps are due
solely to the radiation of the crater, with the lower carbon in
the way. The variation from the crater of course follows the
law of cosines.
147
Mr. Trotter regards the alternating arc as seldom worth
using, as it flickers, and two craters are, of course, formed. As
Mr. Mordey pointed out in the discussion, alternating arc
lamps are much easier to regulate, as the mechanism is kept
in a continuous tremble by the alternating current, so that the
clutches work more perfectly. In another respect an alter­
nating arc lamp is easier to deal with. In parallel lighting
from a direct-current circuit a series resistance is required to
make the lamp burn steadily; on au alternating circuit a
choking coil or a constant current transformer can be used, so
that there is not the same waste of power. It will astonish
many people to be told that the arc is not blue, but is practically
the same color as daylight. At night the eyes are accus­
tomed to a strongly yellow light, and the parts ofthe eye that see
yellow light get fatigued. An arc therefore looks blue, not
only by contrast, but also because the parts of the eye that see
blue are fresh and sensitive. Mr. Trotter explained that in
order to obtain artificial daylight, ordinary gaslight, for instance,
would have to be filtered through blue glass, or else
the various objects intended to look white should be tinted
blue.
MR. P. SALOM, in speaking in the Engineers' Club of Philadelphia
said : The storage battery suffers from the fact that
the experiments have been heretofore confined to a small
scale. As much as 6,000 car-miles have been run with one set
of batteries, and it has been found that under the worst possi­
ble conditions one car-mile is equivalent to I j-2 electric horsepower
hours, so that one set of 108 accumulators will furnish
9,000
9,000 horse-power-hours, showing that = 166 discharges
54
are necessary for this work. The cost for power may be assumed
at 2 cents per horse-power-hour, or 3 cents per car-mile.
The term "cost per car-mile " is, however, a very indeterminate
one, for that cost depends greatly upon the conditions
under which the road is working, as to grades, character of
track, amount of traffic, etc.
The West End Road, of Boston, the best trolley system we
have, reports about 20 to 21 cents per car-mile, but this embraces
many items not usually included in that cost. In the
trolley system the duty varies greatly and suddenly, while in
the storage battery system the duty is constant. A comparison
of results obtained at Birmingham, England, shows that
horse-cars were operated at about 15.7 cents per car-mile, and
a storage battery system at 14*4 cents per car-mile.
The difference of 4 cents per car-mile in favor of the trolley
system, as compared with the storage battery as at present
developed, makes a difference of $3,000,000 per year, on a system
operating 2,000 cars, averaging 100 miles per day each,
and the difference would be still greater with a complete system
in operation.
As compared with horse-power, the storage battery sy stem
shows a great reduction in the space required. Allowing 12
horses for each car, the space occupied for stabling would be
12 times that required for the accommodation of a storage
plant. The cost of the life of an accumulator is 4 cents per
car-mile.
THE Baltimore and Ohio Railroad management is rounding
out that great system not only in extensions and projected additions
to mileage, but in numerous minor details of engineering
work, including heavy- expenditures for terminal facilities, especially
at Staten Island. Its passenger service now equals the
very best, and equipments of cars of superb construction
and engines of highest efficiency are being added as fast as
shops can turn them out. Chas. I. Scull is the guiding management
of the passenger service.
A COPY' of MECHANICS for June 1890, (No. 222), is wanted, for
which twenty cents will be paid.

148 THE CONSTRUCTOR. [June, 1892.
'translated by Henry Harrison Suplee.
Translation Copyright, 1890.
If we bring the applications of Figs. 806 and 811 into a general
? 264.
form in which the path of travel shall return upon itself, we
have Fig. .814 a. If the guide sheaves are removed aud the
CORD FRICTION.
When a tension organ which is loaded at both ends is passed
over a curved surface, there is produced between the tension
organ aud the surface a very considerable sliding friction.
Since this friction will first be mathematically considered in
connection with the subject of cords, it will be given the general
name of cord friction. The curved surface over which the
cord is passed is the pulley, and the motion of the cord takes
place in the plane of the pulley. If the tension T on the
driving side of the cord is to overcome the cord friction E, as
well as the tension / of the driven side, we have for the value
of the friction, F=> T—t. It is dependent upon the magni­
FIG. 814.
tude of the angle of contact a and upon the coefficient of friction/,
but is independent of the radius 7\ of the pulley ; it is
also dependent upon the influence of centrifugal force. For
cord crossed, the simpler form of F'ig. 814 b is obtained. The these conditions 7"=7'7-/«(i we have •z) :
(237)
rotation of the pulley 7", causes travel around the stationarypulley
T.r The old form of Agudio's cable locomotive may be
F=t(ef°-l*-z)- 1) (238)
represented by a similar diagram, F'ig. S14 e. The shaded pulley In these

June, 1892.] ENGINEERING MECHANICS.
sion organ, aud hence may be called the stress modulus, and is
The superficial pressure/, of the tension
rgan upon tlie cir-
cumference of the pulley increases as
designated as r. The ratio , we may, iu like manner, call the
the belt or cord passes
If. m the slack to the tight side. It is equal to Q d u
modulus of cord friction, and indicate as p. A series of values
, in which
b' /,' d „
lor both are given in the following table.
b' is the breadth of the surface of contact of the belt Now for
fa
Moduli
T T
I' =
for Cont Friction and St 1 ess
fi' a
/'
T
" P
any cross section q, the force Q =. q S. Hence we have :
t = 9_
S ~ b'R (
1.n
2 40
from which it will be seen that the pressure p can easily be kept
with moderate limits.
l
Special applications of this formula, and ofthe diagram Fie
816, will be given hereafter. '
0.1
0.2
°-3
0.4
o-5
0.6
0.7
o.S
0.9
1.0
1.1
1,2
J-3
1.4
] -5
1.11
1.22
*-35
1.49
1.65
1.82
2.01
2.46
2.72
3.00
3-32
3-'>7
4.06
4.4S
10.41
5-^2
3.86
3-°3
2-54
2.22
1.99
1.86
1.69
1.5s
1.50
'•43
'•37
'-33
1.29
'•7
1.8
'•9
2.0
2.2
2-4
2.6
2.S
3-°
3-2
3-4
3-6
3-8
4.0
4-95
5-47
6.05
6.69
7-39
903
11.02
15.46
16.44
20.C9
24-53
29.96
36.60
447o
54.60
1.25
1.22
1.20
1.18
I.If.
'•'3
1.10
1.08
1.07
'•°5
1.04
1.03
'•°3
1.02
1.02
Example.—Arc of contact=>r; coefficient of friction/ -016 velocity^ = So
leet Ihe tension organ is a leather belt under stress of 4oolbs. per square iuch
\\ e have from the first table . - - = „.79,, hence/' a i 0.79, X 0.16 *= ,076
or nearly o 4. From the second table this gives p = 1.49 and T=IOI that is'
over three tunes the above stress on the belt would be required to overcome
the Inctional resistance. If?- 20 ft., the value 1— - =0087 and f a --
0.496 or about 0.5, and the modulus of stress T = 2.54.
In order to make these relations more apparent, they are
showu graphically iu the diagram, Fig. 816, in which' the scale
upon the upper horizontal line gives the values for both moduli,
while the vertical scale on the left gives corresponding values
of the product fi' ct.
ROPES OF ORGANIC FIBRES.
z 265.
149
Hemp Ropt-.—T\x

150 ENGINEERING MECHANICS. [Tune, 1892.
be applied, and this may be considered practical working
length of the rope. We have for the available practical work­
ing load : 7" 4 — 7. P= Tor P' = P (1 — L ].
3400 V 3410 J
A vertically suspended rope will break by its own weight
when its length reaches about 2000 feet, since the modulus of
rupture is about 8500 lbs. for loosely twisted rope, aud about
14,000 lbs. for tightly twisted rope. The above length (2000 ft.)
may be called the length of rupture. F'or a cord suspended
in the water, as for deep sea sounding, the length of rupture is
about twice as great. For very heavy stresses three simple
strands are insufficient, and the strands themselves are each
made of smaller strands, as in cable construction. Very heavycables
are also made of more than three strands.
Cotton Rope.—Cotton rope has been used of late for purposes
of transmission, and is usually made with three strands, very
loosely twisted. It opposes a resistance to rupture of about
7500 pounds, reckoning the full sectional area, and is operated
under stresses ranging from iooo to 2000 pounds. It is used for
d iving spindles in spinning frames and mules, and in the snail
d um movement, as in Fig. 787,* and is also used for operating
traveling cranes ou the Ramsbottom system.
Driving ropes are usually operated over grooved pulleys, the
radius of the semicircular groove being slightly greater than
tbat of the rope. In machine construction the sheaves are
usually of cast iron, and in ship's tackle they are made of
lignum vita;.
The sheaves revolve ou cylindrical journals, and recently.
roller bearings are being used, Fig. SiS.f
FIG. SIS. FIG. SI9.
When the pressure is moderate, the rollers may be made of
hard bronze, but for high pressures the rollers, ring and journal
should all be made of hardened steel. Iu case of extremely
high pressures bronze bearings with nietaliue may be used, the
metaliue being a solid lubricant imbedded in recesses in tbe
box, Fig. S194 Such bearings were used most successfully in
the construction of the East River Bridge at New York, operating
for an entire year without requiring lubrication.
I 266.
WIRE ROPE.
Wire rope is usually round, and made with 36 wires, since six
strands are used, each containing six wires. Each strand contains
a small hemp core, and the strands are twisted about a
central core of hemp. These hempen portions are of greatest
importance in the construction of wire rope for transmission
(see \ 26S), aud should be made of the best material. Vox sta-
FIG. S20.
tionary ropes the hempen strands may be replaced by wire
giving 42 or 49 wires, and proportionally increasing the strength
* In a spinning mule of 844 spindles, by J. J. Rieter Tri Co., of Winter- actual factor of safety of 'A^" _ , e
y b
thure, a rope 22 mm. (0.866 in.) operates under a stress of 1.6 kg. (2275 lb.),
65086 ' '
taking the full cross section.
t Martini's design, used in the Italian navy.
J John Wallace 8: Co., London ; Selig in Berlin.
of the rope. The strands of six wires may be combined to
make ropes of 48, 54, 60, 66, 72 wires, etc., and other combinations
are also used.
In F'ig. S20 is shown at

June, 1892.] ENGINEERING MECHANICS. x 5i
The relation of the
stresses in the various
parts of the rope are
shown in Fig. 821.
On the right, the
tension side, there is
the tension stress (-j- ^*)
and the bending stress
(+ *"), giving a total
of 5 + s. On the left
the tension stress (J- S)
is diminished by the
reverse bending stress
(— s). The neutral
axis is therefore shifted
from the middle at
-V, to a point toward
the concave side of Fio. S21.
the bent rope at TV 1 .
Wire rope may be made either of iron or steel wire.
fabrication has greatly advanced within recent years.
lowing data are applicable to the various grades : :; and its
The fol-
Material. Elastic Limit. Modulus ' of Rupture
jAnuealed Iron Wire . . 42,000
Bright Iron Wire . . . 56,000
Steel Wire 64,000
Steel Wire 7S,ooo
Steel Wire 99,000
Steel Wire 113,000
Steel Wire 142000
56,000
So,000
S5,ooo
142,000
170,000
213,000
256,000
It will be evident that no general rule can be given as to
material, but that definite figures should be obtained for the
material to be used iu each case. For high speed rope the wire
should be both smooth and strong, wdth a modulus of rupture
of about 170,000 lbs. If we then take a working stress' .V =
2S,ooo lbs., aud a bending stress 75 = 2S,ooo lbs., we have 5' -f s
= 56. 000 lbs., which gives about threefold security.f
For 7? = 28,000 we have R 14,220,000
d = 500 S. If R is
28,000
made less, the security will be reduced ; if greater, it increases, j
The durability of the rope for mining servtce is increased by
galvanizing the wire.
For standing rigging of vessels galvanized annealed iron wire
with a value K= 56,000 is used, while for running rigging steel
wire rope (7v'= 170,000) is being more extensively used, this
also being galvanized. The latter rope is also suitable for
cables. Hawsers are frequently made from irou wire, with a
modulus of rupture A" = 56,000 to 70,000. The cables for steani
plowing machinery should be made of the strongest steel wire
A'= 256,000.
Wire Cables for power transmission are discussed in Chapter
The cables for suspension bridges are not made from twisted
strands, but the wires are laid parallel and held in position hy
bands of wire every two or three feet. *i
* See the researches of J. W. Cloud on steel wire in connection with the
Emery Testing Machine at the Watertown Arsenal. Trans. Am Soc Meeh
P.ng'rs, Vol. V.
t The Prussian rule requires 75* = A", which gives about : , and A' =
375 5, which gives s — 38,000, hen
given above.
Prschibram has used with best results
e security is only about 4-;,, or le
.5 = 23,000, s = 27,000 : also .S' =
22,750, j = 36,0, hut finds that a value .. 27,000 to 28,005 lbs. is better Tor the
preservation ol the rope. (See i, 26S.) In considering the question of pullev
diameter, the ratio to the diameter S of the wire should be taken not that
to the diameter d of the rope.
t If 6 is made so small that 75 + s is greater than the elastic limit, the
rope will receive a permanent set.
This, however, is not always dangerous.
in Fig. 822 the curvature 1 . 1
may produce a stress upon the
concave side of the wires wliich.
wheu added to To, may not exceed
the elastic limit. If. however, a
reverse curvature be given, as at -
3. 3, there may result a set, as
3'. 3', and too frequent repetition
of this reversal may become dangerous.
This is shown iu the case
of hoisting drums, such as Fig.
792c, in which the rope Wu Ln,
2 3 3
which is subjected to reverse bending,
has been found to last only
about : '.i as long as the rope 11 \ Lx.
i; Among important suspension
bridges are those built by Roebling in America, notably the Niagara and
the East River bridges. b FIG. 822.
'
'i 267.
WEIGHT OF WIRE ROPE AND ITS INFLUENCE.
A rope of parallel iron or steel wires, exclusive of anybands,
will weigh, per foot, 0.28 Q2 1 , A , i„ whidl / ;s the num.
ber of wires and .1 the diameter of each wire. I'or twisted
rope, the twist and the hemp core increases this value from 1 \
lo 1 ',. as much, or an average of 11 „ times. This gives for the
running weight per foot
Go - 3.92 - i d 2 — 3.07 i
(247)
4
This is also true for flat ropes, tbe value of the coefficient for
cable ropes being increased as above from 1% to 1'4 usually
about I* 0 times. For deep mine hoists the weight Go exercises
a marked influence upon the section of the rope. If L k is the
length 111 leet of the vertical hanging rope carrying a load PaX.
its end we have : P + I, Go = S — i

152 ENGINEERING MECHANICS. [June, 1892.
The great weight of the twisting rope has led to the use of a may be of two kinds ; first: uniform compression ; second,
double lift, each half of the rope assisting to counterbalance when this has reached its limit, a flattening of cross section.
the other half, or another plan is to use a conical drum, to Both deformations are observed in practice. Ropes which are
equalize the power.* The spiral winding of flat ropes also very flexible are loosely twisted, and therefore readily com­
serves to equalize the leverage of the drum, and by a judicious pressed as they pass over pulleys. The general compression
selection of drum diameter, this may be very successfully done. due to the tension ofthe load in the straight portion causes the
Flat ropes are little used in France, but are common in Bel­ twisted strands to press firmly together towards the axis, so that
gium, and their use is increasing in England and America.f a heavily loaded rope is very hard. The compression is gener­
Ropes of copper wire are used for lightning conductors, and ally permanent, and not elastic, as may be deduced from the
these are also made of iron wire rope with a core of copper. permanent reduction in diameter of ropes after use, and is gen­
\ 26S.
erally due, in the case of wire ropes, to the compression of the
hempen core ; as is shown by the observations of Leloutre and
.STIFFNESS OF ROPES.
Zuber f
The resistance of stiffness of ropes must be considered both The preceding remarks have not considered those wire ropes
in hoisting and in driving ropes. The measure of this resistance with metallic cores, used for ruuning transmissions. Such ropes
is the force required to move a rope hanging over a very easy are always very stiff, and permit little or no compression.
ruuning pulley, both ends of the rope bearing the given load Q. (Accordiug to Ziegler's experiments, only 0.22 to 1.2 per
It will be observed that the winding-up side of the rope does cent.)
not hang as closely to the pulley as does the other side, and that It is really almost as important, so far as flexibility is con­
the lever arm of the two sides is constantly changing. Eytelcerned, that a rope should have a suitable soft core as that it
weiu's formula gives for the stiffness S of a hemp rope of diam- should be made of the best and most elastic and flexible mateter
d:
S
(252
''A
in wliich, when 7? and d are giveu in iuches, .5 0.463. Cou-
Ctli
lomb gives the very inconvenient formula .5" - --
A' + C, Q
rial. This is shown by the fact that even with ropes made entirely
of hemp or of cotton, aud used for transmission over
pulleys, the inner fibres, which are never iu contact with the
pulleys, show great wear. This wear is evidently due to the
friction of the fibres against each other, due to the flattening
and changes of cross section. F
Weisbach gives, from very limited data, for wire rope :
O
S = 1.07S -\- 0.093
R
(253)
Example i.—Giveu a hemp rope 1" diameter, with a load of 8S0 lbs., bent
over a pulley 4" radius, from Eytelweiu's formula we have :
880
S — 0.463 - — 101.8 lbs.
4
which seems very high. Coulomb's formula gives 66 lbs.
Example s.—A wire rope, composed of 36 wires, each 0.030/' diameter, with
a load of 550 lbs., is bent over .1 pulley 44 inches diameter. From Weisbach's
formula we get:
5 = 1.078 + 0.093 — = 3.403 lbs.
The utility of these formulas is doubtful, and a fuller investigation
of the subject is much to be desired. It will be seen
from formula (253) that for wire rope the value of R should be
taken still greater than already considered for bending stresses
(formula 246) ; this subject is also discussed in Chapter XXI.
The above rules are deficient in that they do not take into
account ths kind of mechauical work absorbed by the stiffness
of ropes. Tbe angle embraced by the rope is, in the investigations
of Amontons, Navier, Poncelet and. Morris, assumed to be
constant, while in practice it is constantly changing, and exerts
a very material influence upon the result.
The author's consideration of the subject is here given :
Referring to F'ig. S23, it will be seen tbat the fibres or wires
ou the concave side of
the rope which passes
over a pulley R, are
compressed, producing
a reduction in the
form of the convex
side, the compression
originating with the
load Q, being transmitted
along the
whole length of the
twisted strands. The
bent position of the
rope cau no longer
retain its original section,
of diameter d,
QiS but its volume must
be the same as that
FIG. 823.
of a corresponding
length of the straight portion. The alteration in cross-section
The details are as follows :
Depth.*-. Dia. of wire 5. Weight Co.
3936 0.1043 '-52
3280 o .^84 1.36
2624 0.0925 1.19
1968 0.0866 1,006
1312 00807 0.912
S.
23,210
22,910
22,820
3«,S6o
23,130
s.
27,260
25,710
24,170
22,640
2 1 ,- "J '
S + s.
50,47°
48,620
46,990
45,500
44,220
656 0.0748 0-785 23,690 •9.550 43.240
The twisting of the rope was commenced at the small end, and the diameter
of wires increased every 5 meters (16.4 ft.) after the first 200 metres (656
ft). These ropes are very satisfactory, and last 3 to 4 years.
* Conical drums are used ln the American anthracite coal mines.
t See Dwelshauvers-Dery in Cuyper's Revue des Mines, 1874 : also F. Krane
in Zeitschrilt der Berg u. Iliitteuwesen, 1864.
A or this reason tbe desirability,
or rather necessity, of lubricating the wires or fibres is evident,
and this reduces the friction of the inner-lying portions of the
rope. Rieteu & Co. state that in the case of cotton ropes, "the
rope always wears out by the internal friction of the strands
upon each other, and that a load-twisted rope becomes useless
in a shorter time thau a soft, loosely twisted one, although the
actual strength of the latter is the smaller."
In view of all these conditions the insufficiency of the existing
rules for stiffness will be evident. It is apparent that the
angle of contact must have a strong influence, aud an entrance
is found in cable roads where, when the cable is deflected
through a small angle, small guide rollers are satisfactory, while
much larger ones are necessary for greater angles. At a certain
angle a, the deformation of the rope begins, and at another
angle a maximum is reached, beyond which the resistance of
stiffness is no longer dependent upon o. These points are of
greatest importance with wire rope. It must be expected that
the value of .S" will depend upon two functions of a, one for
compression, and one for flattening. The first may be unimportant
with old anil compressed ropes, the latter will be much
dependent upou the lubrication aud upon the coefficieut of
friction.
I 269.
ROPE CONNECTIONS AND BUFFERS.
The connection of one rope with another, when a smooth
junction is required, must be effected by splicing. This may be
accomplished by the short or German splice ; or by the long, or
M
2'
FIG. 824.
Spanish splice. The latter is the form to be used for wire rope.
From the middle point M of the splice, Fig. S24, if, for example,
a six strand rope is in hand, strands I, 2 and 3 on the left
are unwound, and strands 6', 5', 4', ofthe other rope wound iu,
and the ends cut aud worked in. The same is done on the
other side, the whole length 1 — 6 being 30 to 50 feet.
To connect the end of a rope to another portion of the construction,
the so-called hangers are used ; three forms being
shown in Fig. S25. At a is tlie so-called "swan neck," whicli
is secured to the rope by through rivets ; b is made with a conical
socket, the wires being doubled up, aud soft metal melted
and run 111 ; 7- is Kortum's hanger, the rope being held by two
toothed wedges driven in, and secured by pins. Numerous
tests have shown this fastening to be as strong as the rone
itself. *
In Fig. S2677 is shown a buffer coupliug used iu the Zentrum
mme at P")schweiler, designed by the superintendent, Ostert
See Leloutre, Transmissions et courroies, cordes et cables. Paris Tignol
,4. /.'.egl.er, Erfahrungs-resultant fiber Betrieb and Instandhaltu.nl der
rthur, 1871.
to
.-*..,. ...44,.4., j... I..... uiigs-rcsuitai
Drantseiltnebe, Winterthur, 1871.

June, 1892.] ENGINEERING MECHANICS [ 53
kamp. The wrought iron thimble in the bight of the rope
is fitted with a wooden block. Fig. 826/9 shows the so-called
FIG. S25.
"friction hanger," both this and the previous form being
arranged to be built into the upper part of the hoist cage.
c.
« 70.
STATIONARY CHAINS.
Chains may be considered as jointed rods. Running chains
are composed of very short members, in order that they may
the easier pass over sheaves, while stationary chains, which are
used in bridge, and other numerous constructions, are made
with quite long links.
B —
Fig. S27 shows the Admiralty form of stationary chain. Tha
links are made A fathom long, not including the thickness of
metal, and are divided into 10 fathom lengths, each length cou-
FlG. 828.
sisting of 20 links. The lengths are joiue d by a pin con nec-
tion, shown ou the left, and the pin is made of steel, galvan ized.
Another form, known as the
Gemorsch chain, is showu in
Fig. 82S, aud is well known in
Germany.
Each long link is made 1.5
metres long, and these are connected
by short oval links. The
coupling link is secured by a
common, but heavy screw bolt.
The proportions in tbe illustrations
are given in terms of
the diameter of the rotl.
In order to enable such chains
to hang freely, the so-called
"swivel" is used. A heavyswivel,
for chains such as Fig.
.827, is chosen iu Fig. 829.
The swivel bolt has a ring
attached which can be readilyopened,
and is large enough
to receive two chain links,
while the upper ring can receive
three. The limit of dimensions
is the thickness of
FIG S29.
metal of the chain of Fig. 827.
I 271.
RUNNING CHAINS.
The most important forms of ruuning chains used in machine
construction are those shown in Fig. S30 ; 77 is an open link, and
b is a close link chain ; c is a stay link chain, and 7/ a flat link
chain. This latter is especially- suitable for a pitch chain, on
account ofthe parallel pins which are at uniform distance from
FIG. 826.
each other. The other three forms are made with a higher
order of linkage, viz. : tbe globoid form already discussed in
In Osterkamp's design the spring cage is built iuto the Fig. yoke 224. of
the frame, thus economizing room.
In the wide open link chain a the globoid action cau readily
2«;ia
LStftSd
-©'
in
i..jjjjj..j

154 ENGINEERING MECHANICS. L>" e , l8 9 2 *
be disarranged ; less so ill the close links of b, and hardly at all
in the stay-link chain c, which latter closely resembles the
globoid link of Fig. 77, p. 142.
The proportional dimensions of chain links are not very
closely determined. Those given in b and c are from the German
Admiralty. The British Admiralty gives both for open
and for stay-link chains, the pitch length 4 tl, and width of link
3.6 d; in France, for open chains the length is made 3.25 d, and
width 3.4 tl, and for stay-link chains, 3.S5 7 and 3.75 7/ respectively.*
In craue aud hoisting machine construction, a very important
feature is the calibrating or adjusting of tbe links of chain.!
This is also a matter of much importance in connection with
the chain propulsion of boats used in France and Germany.
The chain used on the Sweetwater canal at Suez was made with

June, 1S92.] ENGINEERING MECHANICS. x 55
7-7
Lz =
>pen Links
4672
S672
\ 274-
Close Links.
4577
8127
CHAIN COIIPLINGS.
Stay Links.
5458
8567
Chains which are used for transmission of motion (so called
" endless " chains) require devices for coupling, as do also those
constructions with which chains are to be connected, and hence
we have a variety of eyes, rings, coupling links, swivels, and
the like.
FIG. 83 FIG. S32.
A piece which is sometimes used with anchor chains is the
so-called "twin" link, Fig. 831. This may be made of cast
steel, aud because of limited space is formed with circular openings.
The ordinary coupling link is shown in Fig. 832 a. The
link is of wrought iron, the bolt and pin of steel, both galvanized.
The pin is shorter than the diameter of the eye, and is secured
on both sides by a plug of lead. The next link is made somewhat
longer than the other links of the chain, so that the
coupling link may be more readily introduced. This form is
used for joining pieces of chain to form greater lengths. The
German Admiralty anchor chain is made with stay links, in
seven lengths of 25 metres (82 feet) each, joined with coupling
links, two of which are swivels. A bow anchor chain is given
two more lengths of chain aud made of irou 3mm. (0.118")
thicker.*
The chains for the system of boat propulsion are fitted with a
coupling link with rounded edges, and two are used together,
as in Fig. 832 b, which shows the chain used on the Elbe. This
coupling might also be suitable for power transmission chain.
The swivel is used to permit the chain to have a rotation
about its axis of length without twisting the liuks together.
FIG. 833.
The form of swivel used in the German Navy is shown
83312, and at Fig. 833 b is shown the English swivel.
* The lengths in the Knglish Navy are i2'7, fathoms.
in Fig.
Chains must also be provided with hooks for attachments to
the load to be raised.
F'IG. 834.
A single hook is giveu in Fig. 83477, and a double hook at
Fig. 834 b. The construction of such hooks demands the greatest
care, and according to Glynn, more lives have been lost and
damage incurred by the breakage of hooks than by any other
part of a crane. The case is one of combined resistance and
leads to unexpectedly great dimensions.
The diameter T7, of the shank of the hook may be obtained
from formula (72), so that we have for a load P:
d, = 0.02 v P (257)
This is based upon a stress of 3500 pounds, but an angular
pull may increase this five-fold. Taking

156 ENGINEERING MECHANICS*. [June, 1892.
CHAIN DRUMS AND SHEAVES.
i 275.
Chain drums and sheaves are usually made of a radius A =
10 to 12 tl, measured to tbe middle of the chain. In sonic cases
a rim is made on the chain sheave, as in Fig. 835 ...
FIG. S35.
whence we get, for
: = 8 9 10 12 14 16
— = 1.3066 1.toio 1.618 1.952 2247 2.563
18
:.87i 3.106
This form of sheave brings a bending action upon the links as Guide sheaves for either kind of chain are made with 16 to
shown in Fig. 835 b. Sometimes the flanges are omitted and the 30 teeth.
edges of the sheaves bevelled as in the dotted lines, and in other For chain propelling cables ordinary smooth drums with
cases the links have a bearing as shown at Fig. S35 c, in which parallel axes are used, with a groove for the chain.
the bending action is somewhat reduced. The bending is en­ In F'ig. 838 (7 is shown a section
tirely avoided, however, by the use of a pocketefl sheave, as in
Fig. S36.
f D - j- •, F
...-.*-&i^_'S'>^vYA<
FIG. 836.
S
rn
i '
J :"
This form is useful both for chain transmission, and as a substitute
for winding drums in hoisting machinery, as it enables a
small pocketed sheave to serve instead of a large drum. When
such a sheave is made with only four pockets, they form a
square with a side /)' = I 4- d + 2(1—d) s/°-5- 2.414 /—
0.414 d; while the side of the square of the alternate links is
D" 1.414 I + 0.414 d. The first gives the minimum, and the
second the maximum, (double) lever arm with which the chain
acts upon the sheave. If the pockets, instead of 4 and 4 are :
6 and 6, we have D = 3-732 / — 0.264 d
SandS, " " 77 = 5.026/ — 0.19877
Chain sheaves of this form require accurately made pitch
chain.
When the load is heavy, the friction causes the chain to cling
to the sheave, aud a stripper S, Fig. 836, is required to lead the
chain off in the proper direction /-', while the entrance is properly
effected by a guide channel E.
For flat link chain, a toothed chain wheel is used, Fig. S37.
In this form a guide channel Tf, and stripper S, should also be
used. The tooth profile is a circular arc with its centre at the
link pin. If s, be the number of teeth, we have for the radius
y, of the pitch circle :
]= .-„ (259)
1800
The minimum number of teeth is S.
Neustadt uses the following :
; = S for /' 500 to 6,000 pounds.
9 for /' = 6000 to 50,000 pounds.
: 10 for P= over 50,000 pounds.
FiG. 83S.
of tbe rim of the drum on the chain propelling gear on the
river Elbe. This is made with steel flanges and channels on a
wrought-iron rim. The last channel is made slightly- larger in
diameter in order to give a higher velocity to the driving side of
the chain. The wear upon tbe chain is au important item. Fig.
838 b, shows a link of a chain as worn after long service. It
must not be overlooked that the winding around the drum produces
a twist iu the chain, giving as many half twistsin the chain
as there are half convolutions about the drums. This twisting
is not injurious if the chain is bent as frequentlv in one direction
as iu the opposite. In fact, however, the chain is usually
bent into more concave than convex bends. This causes a twisting
motion to the chain and as it drags upon the bottom and
banks of the stream it produces much wear, aud causes kinks to
be produced at the shallow places. The chain must therefore
frequently be raised at such points aud a link opened and the
twist taken out.
This twisting may be
prevented by using the
drum arrangement
shown in F'ig. S39. This
consists of simple
drums all lying in one
plane driven by gearing
so that the proper
relative motion is compelled.
276.
RATCHET TKNSION ORGANS.
Tension organs may be combined with pawls, which in the
case of cords are friction pawls, (

June, 1892.] ENGINEERING MECHANICS. 15;
OCTAVE CHANUTE.
PRESIDENT OF AMERICAN SOCIETY OF CIVIL ENGINEERS.
( With Portrait).
OCTAVE CHANUTE, the present Presidentof the American Society
of Civil Engineers, was born in Paris, France, Feb. 18,
1832 ; and came to the United States in the latter part of 183S.
He received his education chiefly in NewYork City, and began
the practice of his profession as a civil engineer in 1S49, on the
construction of the Hudson River Railroad, under JOHN B. JER­
VIS, Chief Engineer.
He was gradually promoted
as the work progressed
over the several
divisions of the road, and
when he left the service
of that company, in 1853,
he was Division Engineer
at Albany, in charge of
the completion of ter-
, minal facilities and maintenance
of way between
Hudson and Albany.
In 1853 he went to Illinois
with H. A. GARD­
NER, previously Chief
Engiueer of the Hudson
River R. R., and was
there engaged in building
what is now a part of
Chicago & Alton R. R ,
between Joliet and
Bloomington, in Illinois.
Mr. CHANUTE remained
upon this work until 1S54
when he was made Chief
Engineer of the Eastern
portion of what is now
the Toledo, Peoria &
Warsaw R. R. He built
this road from Peoria to
the Indiana State line, a
distauce of about 112
miles, aud remained in
charge of maintenance of
way until 1861. Iu the
latter year he became Division
Engineer, with
similar duties on the
Pittsburg, Fort Wayne &
Chicago R. R., between
Chicago and Fort Wayne.
In 1S62 he was for six
months Chief Engineer
of Maintenance of Way of
the Western Division of
the Ohio cc Mississippi
R. R., from St. Louis
to Vincenues. Iu 1S63 he became Chief Engineer of
Maintenance of Way and Construction of the reorganized
Chicago and Alton R. R., and remained upon that line until 1S67.
During this connection, having been invited to submit a design
for the proposed Union Stock Yards of Chicago his plan was selected,
iu competition with a number of others and he built these
yards as Chief Engiueer. He was also awarded a premium for a
competitive design for a bridge across the Missouri River at St.
Charles, Missouri. In 1S67 Mr. CHANUTE went to Kansas City,
Mo., as Chief Engineer of the bridge across the Missouri River at
that point. This was the pioneer bridge across the Missouri
River, and as the river pilots and riparian dwellers had given this
OCTAVE CHANUTE.
stream a bad reputation, the successful completion of this
bridge across it in 1 Sl.S attracted great attention and interest.
Meanwhile the building of railroads had begun in Kansas,
and while yet occupied in the completion of the bridge, Mr.
CHANUTE was placed in charge as Chief Engineer first of the
construction of the Kansas City, Fort Scott cc Gulf R. R , from
Kansas City to the north line of the Indian Territory, 160
miles ; next of a parallel line in the same interest, theu known
as tbe Leavenworth, Lawrence & Galveston R. R., from
Lawrence, Kan., to the Indian Territory; next of a connecting
line between the
two, known as the
Kansas City and Santa
F'e R. R., and lastly, of
the Atchison & Nebraska
R. R., from Atchison
northward.
While simultaneously
in charge of the construction
of these four railroads,
he also designed
an

i58 ENGINEERING MECHANICS. June, 1892.
his personal interests, and to open au office as Consulting
Engineer.
In this latter capacity he took charge of the construction
of the iron bridges during the building of the Chicago, Bur­
lington & Northern R. R., between Chicago and St. Paul in
18S5, and those of the extension of the Atchison, Topeka, and
Santa Fe R.R. from Kansas City to Chicago in 1887 and 1S88 ; the
latter involving, besides a number of minor streams, the Mis­
souri River Bridge at Sibley, and the Misssisippi River Bridge
at Fort Madison.
In 1S80 Mr. CHANUTE removed his office to Chicago, where
he is now principally engaged in promoting the preservation of
timber against decay by chemical methods ; he being of tbe
opinion that the time has now fully arrived when large economies
are to be attained in this country by employing the methods
which are in current use abroad.
Mr. CHANUTE became a member of the American Society of
Civil Engineers Feb. 19, 1S6S, aud has contributed a goodly
uumber of papers to its Transactions. Among these may be
mentioned, "The Elements of Cost of Railroad Freight Traffic,"
"Rapid Transit and Terminal Freight F'acilities," "The
Preservation of Timber," the latter .two being reports by committees
of which he was chairman, "Engineering Progress in
the United States," " Repairs of Masonry," and " Uniformity
in Railroad Rolling Stock ; " besides some contributions to
various other societies.
He was Vice-President in 18S0-S1, and President ofthe society
at the last election.—Engineering News, May 22, /Sgr.
A CORRESPONDENT in the slmerican Machinist says : If engineers,
machinists and millwrights in general, and pipe-fitters
in particular, knew of the good qualities of graphite, I dare
say there would be ten times the demand for it. Its lubricating
qualities are questioned only by the impractical, aud it is
this quality alone that sounds its key-note, so to speak. Let
me describe a few of what I consider its most important uses.
As above stated, its primary object is lubrication, and it is to
this fact we must credit good pipe-joints and cool bearings.
In making pipe cement (or as I would term it, pipe smear), it
is not necessary to use the best oil or grease, as it is the graphite
and not the body in which it is suspended that makes the
mixture valuable and the joint perfect. I use the drippings
from line shaft bearings, caught in the ordinary way, and mix
it with the best Ticonderoga flake graphite so that it can be
applied with an ordinary sash tool.
During the past three years I have used about fifteen or
twenty pouuds of dry Ticonderoga Hake graphite for pipe joints,
cylinder heads, piston rod packing, etc.
Bolts, smeared with graphite mixed as above, I have unscrewed
after having been in the dampest places for upward of
two years or more, proving the anti-rusting qualities of graphite.
To cool hot bearings, put it on as thick as it will mix
with oil.
Almost any oil or grease will answer, but don't use poor
graphite.
THE Brush Electric Company, of Cleveland, Ohio, have issued
a superb souvenir for 1892. It illustrates anil describes all the
direct incandescent machines made by that company. There are
also descriptions of six complete isolated incandescent electric
light plants installed in six of the largest and best equipped
office buildiugs. This company has made a grand record in the
electrical field and their work is found iu every considerable
country iu the world. The Commercial management is especially
deserving of commendation and is suggestive of western
energy and restlessness. Their works are now crowded with
contract requirements and their electricians, not content with
making excellent work are reaching iuto the realm of the unfathomed
for fresh secrets to employ in their devices.
THE ATCHESON. TOPEKA AND SANTA FE SYSTEMS
The financial management of the Atcheson, Topeka and
Santa Fe Railway system have formulated a plan of income
bond conversion providing for the issue of $ 100,000,000 of second
mortgage bonds which cannot but recommend itself in general
and in detail to investors in railway securities on both sides of
the water. Of these bonds f 80,000,000 bear graded interest from
2'2 to 4 per cent., and are to be exchanged par for par for $So,-
000,000 of income bonds and balance. $20,000,000 are to be
offered at 70 to holders of income bonds, which latter bonds,
Class B, will draw fixed interest at 4 per cent, payable semiannually.
The former, to be known as Class A, will bear graded
interest as above mentioned.
The excellent character of the investment is apparent from
these figures. In 1890 the average net earnings from all sources
to
June 30, fiscal year, were $11,195,919
June 30, 1S91 10,390,702
June 30, 1892 11,736,218
That investors may know exactly what character of securities
they are purchasing, the fixed charges (estimated) are given for
5 years, beginning July 1, 1S92, as follows:
July 1, 1892 #10,200,000
July 1, 1S95 10,700,000
July I, 1S74 11,500,000
July 1, 1S95 11,900,000
July 1, 1896 i2,oco,ooo
The company owns 6,960 miles of road, and operates 7,17s
miles. The gross and net earnings for four years ending June
30, from railroad lines proper, were:
Gross Earnings. Net Earnings.
June 30, 1SS9 #27,572,S78 $ 6,772,390
June 30, 1890 31,004,357 '0,083,970
June 30, 1891 .... 33,663,716 9,620,546
June 30, 1892 35,77°,7° 2 10,886,218
The eastern terminus of this greatest of Americal railway
systems is Chicago, aud its termini on the Pacific coast, San
Diego and Los Angeles. The territory covered by this net-work
of roads has a grander future in its steadily developing resources,
agricultural, mineral aud manufacturing, than any other system
ofthe United States. Its possibilities can not be measured. It
is attracting a sturdy and thrifty population from the east of
Mississippi States ; it is affording opportunities for capital and
enterprise, and it is destined to be one of the most productive
regions of the United States. The management of this system
has within it some of the ablest railroad and financial managers,
who know not only what is the present value of that vast
property, but what are its capabilities when the overflowing tide
of humanity from the eastward presses and is crowded westward
in the near future. This system is but in its infancy. Its work
will be rather to keep pace with future rapidly growing traffic
requirements. The Income Bond Conversion Plan ought to be,
and will be, quickly accepted by far-seeing investors ou both
sides of the water. The company has set forth its plans in
details in the daily press, and our readers are recommended to
acquaint themselves with it. The special attention of our readers
abroad, many of whom are large buyers and holders of American
railroad securities, is asked to this exceptional opportunity
of safe and permanent investment in a railroad property that
has an empire of its own to create traffic for it. The financial
managers, from J. W. Reinhart, of Boston, Second Vice-President,
to the managers, engineers, and passenger and freight
agents, headed by men like James Dun, A. A. Robinson and J.
P. Nicholson, are all men in whom the public, and especially
investors, have the fullest confidence to make the most and best
of their 13,000 miles of road now and for the future.

June, 1892.] ENGINEERING MECHANICS. i59
ELECTROTECHNICS.
A Compilation ofi Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
777). Siemen's Method.—-The ends of the conductor are con­
nected to the terminals of a condenser of the capacity Kcharged
with the potential /'. The potential difference V of the con
denser is measured by an electrometer. After the time I, the
potential /", of the condenser, after its partial discharge, is
measured. Then the resistance
R = ]_ L
K ' (log V — log \\)
(See also sections on Conductors, Faults in Conductors, etc.)
77). Resistance ofi Liquids (Ayrton & Perry's Method).
-s^icucjjaj 1 |||i]
FIG. 64. F'IG. 65.
I
Jg§
i
1
•sen-
Iu a cell filled to a certain point with the liquid are suspended
a row of four electrodes in glass tubes. The outer two are plates
of platinum, the inner are platinum wires, which do not project
from the bottom of the tubes. The current is kept constant by
observing the galvanometer, and the difference of potential 6
(Fig. 65) and A (Fig. 64) are measured with the electrometer E
R
G is a ballistic galvanometer, C a condenser, .S' a shunt (3 or
4 times the resistance of the battery to be measured), 7j and T,
are keys. First: 'fi is pressed and deflection a of galvanometer
noted, which is proportional to E. M. F. of the cell B.
Second: 7j and T, are both depressed, and ft is noted propor­
tional to E. M. F". A. The resistance of battery is the
* = -'-„-
a — ji
The condenser is used to oppose the polarization of battery,
which sets in through 6* a short time after 7*2 is closed, and
especially when S is of the value chosen above.
An aperiodic galvanometer may be substituted for G, and a
high resistance for C. If E and A are then measured
E — A
A
Good results, however, will only be obtained by making 6*
much larger than x (at least 10 x) and measuring very quickly.
s
— . 5.
If the battery polarizes very rapidly this method will give
values higher than the correct ones.
p. Mauee's Method.—The battery whose resistance is to be
measured is placed iu one ofthe four branches of a Wheatstone
Bridge (Fig. 67).
The galvanometer;'then exhibits FIG. 67.
a deflection. If this deflection is ,»
unaltered by depressing I) Ct ^A
If .7 is made equal to b, e is then
the resistance sought for. This
method has a disadvantage in that
a relatively strong current flows
tlirough galvanometer, and in case
of a minor galvanometer the needle must be brought back approximately
to zero by the controlling magnet. This objection
is done away with iu
./. Orth's Method (Fig. 6S).
FIG. 68.
Then is the resistance x between if and JVi — — 10000 ohms. An E. M. F. E' which is exactly equal to that between A and
B is inserted into the galvanometer branch of circuit, but op­
In case of liquids of better conductivity, a smaller resistance
posing the P*.. M. F. E. The resistance in galvanometer branch
than (0000 is used. A ballistic galvanometer may be substituted
may then be made as small as possible, and by a certain change
for the electrometer if not convenient for use.
of the potential difference between A and 7? bringing the cur­
o). Resistance ofi Batteries (Munro's Method, Fig. 66). rent variation in the galvanometer branch to its attainable
FIG. 66.
HKT}^-
maximum, provided that any of the disadvantages set forth
above do not arise. On opening CD no current flows through
the galvanometer branch, that is, the shunt through C D to the
wire A B cannot be considered to exist; the resistance in the
outer circuit will not be altered but will remain.
r = 77 A- b + 1
and the amount of resistance in the galvanometer branch be­
-iTU-***
comes entirely
In order now to create in the galvanometer branch a potential
difference equal and opposite to A B, the followiug changes are
made. A variable resistance A' B' is included in galvanometer
branch at whose terminals any constant generator of current E'
(e.g., an accumulator) is so conuected that it offers the sameelectrode
to the galvanometer as the cell undergoing measure­
ment.
A B is so chosen that no current passes through G, whicli
choice must uaturally be made anew before each measurement,
since the potential difference A B varies with the changes in the
cell under test.
The current generated by E' is kept constant
by altering resistance in circuit A' E' B' and
any tendency to vary is shown by galvanometer
G'. This method is appropriate for dura­
tion test of batteries.
r. Victor von Lang's Method (Fig. 69) consists
in measuring the resistance between the
points A aud B which are at equal potential
the cells being connected in series as shown.
FIG. 69.
A
B

160 ENGINEERING MECHANICS. [June, 1892.
s). Thomson's Method.—Connect battery in circuit with resistance
box R and galvanometers of resistance G, and place a
shunt of .v resistance arouud battery. Note the deflection d.
Remove shunt and increase R to Rl until tl is again the deflection.
Then ^ R.-R
'box~~ S R + G
I). Resistance of Insulating Substances.
Dry Measurement.—Insulating material in flat sheets or plates
is measured by being clamped between two brass discs, and the
resistance determined by the direct deflection method. Since
the resistance depends on the E. M. F., considerable battery
power is employed.
Pressure, temperature and moisture especially have great influence
on the resistance. The influence of temperature may be
determined by heating the material to a certain degree, whicli
may best be ascertained by means of a thermo element.
Insulations on wire maybe composed by coiling the wire into
a flat spiral and clamping between the discs. The inner end is
insulated, the outer free. The resistance is found between the
copper core and the discs.
dloist Measurement.—A circular disc of about io centimeters
(4 in.) is made of the substance to be tested. Around the edge
of this disc is cast a paraffin ring about 4 centimeters deep. The
disc is then immersed in a solution of zinc sulphate, the paraffin
ring fitting in the vessel tightly, and thereby separating the
liquid into two parts iu contact with the surfaces of the disc.
A zinc electrode is inserted iu each part of the liquid and the
measurement.
77). Insulation Resistance of Aerial Lines.—Connect battery
tangent galvanometer aud a standard resistance A\ in circuit
and note deflection dv Multiply A\ by dx, wliich gives the constant.
Substitute the line resistance to be tested for A', and not
the galvanometer reading dx. The insulation resistance then is
I- d > *> IP
A = - — (A,
iooo ohms generally]
The insulation resistance per mile = R-M, where l\ is the
total insulation resistance and J7 the number of miles, generally
expressed in megohms per mile.
This subject is developed in future sections.
v). The resistance of hot conductors (filaments of incandescent
lamps, rheostat wires, etc.) is found by substituting the
values of the current passing, and the potential difference be.
tween the ends of the resistance, in ohm's law, whence
R = ~C'
70). Conductivity.—The percentage conductivity of any conductor
may be obtained by- multiplying the resistance of a conductor
made of the same material in a pure state (of same
weight and length), at the same temperature by 100, and dividing
the product by the resistance of the conductor uudergoing
test.
Let Rt resistance of unit length-weight at the temperature 7.
/ length of conductor to be tested.
Then,
and
w weight of conductor to be tested.
/-, = calculated resistance at teuip. I for pure conductor.
r. = observed resistance at temp, /of conductor under test.
or percentage conductivity x
_ Rt t.
;-, = 100 : x
100 ;-,
RESISTANCE IN B. A. UNITS OF WIRE ONE FOOT LONG.
ONE GRAIN IN WEIGHT.
Temperature.
Cent.
O
5
10
15
20
25
3°
35
40
Fahr.
32
4'
5°
59
68
77
S6
95
104
Soft Copper.
O.2064
0.2IO2
0.2144
O.2186
O.222S
0.2271
0-23T3
0.2357
0.2400
Hard Copper.
0.2106
O.2147
0.2188
0.22JI
O.2272
O.23I7
O.2360
O.2405
O.2449
Platinum
German Silver.
Silver. Sp G.= 12.
Sp. G. =8.47.
(approx.)
2.652
2-657
2.661
2.666
2.670
2.675
2.68
2.684
2.689
.261 B. A. units.
95.9 per cent.
4.24
4.25
4.25
4.26
4-27
4.27
4.28
4.2S
4.29
To change to legal ohms multiply by 0.9889 or subtract 1.12 per cent.
Example.—The resistance of 100 feet, No. 14, B. & S. gauge,
soft copper wire in 0.272 B. A. units at 25 0 C, weight 1.241 lbs.
= 86S7 grains.
Substitute iu formula, taking Rt from table 0.2271 at 25° C. ;
then
_ 0.2271 x 100-
' 1 = S687
1007- 1 100 x 0.261
7'2
O.272
The conductivity at any other temperature than 0° f may be
be determined from Matthiesseu's formula,
Ct = Ca (1 — 0.00387 t -f- 0.000009009 V).
Construction of Resistance Boxes.
Coils for resistance boxes are generally made of German silver,
platinum silver (Pt. 1, .Vg. 2), platinoid (German silver with 1 —
2 per cent, tungsten), or uickelin (German silver with large percentage
of nickel).
Coils of German silver are mostly employed on account of
cheapness and adaptability. The wires used have a double
winding silk and range from M. 16 to 40 B & S. gauge. They
are wound so that in one half of the coil the current will circulate
in an opposite direction to the one in which it flows in the
other, thus preventing inductive effects which would influence
galvanometer needle, if in the vicinity. The coils are immersed
in melted paraffin, which fills up the spaces aud excludes all air.
The ends are soldered to heavy brass blocks secured to the
ebonite top of the box, and in cases where great accuracy is required,
account is taken of the resistance of blocks, connections,
etc. There is generally a hole wherein a thermometer may be
inserted. Boxes are generally calibrated and stated correct at
15 0 C.
Single standard resistance coils are generally enclosed in a
brass box, out of the ebonite top of whicli lead the terminals,
which are copper rods bent so that the ends point downward
and may dip into mercury cups. When used these coils are immersed
in water aud the temperature noted.
Inter-calibration of a Set of Resistances. (Fordewenther).
Let the resistances be, for example, i„, 1/,, 2 and 4.
The highest resistance is compared with the sum of those below
it, by any method of comparing resistances, and the following
equations result:
4 = (2 + ia+ n) .x
2 ---(L,+ Xl, ) y
'•' "•'•-- 4 + 2 + ifl -f ib = s
y
4 =s -A+< s (.v+A)(jyA)
I.r-r-i)(r4-i)(.~+ 1
(To be continued.)
" (-*"+!) (y+i) 0+1)

June, 1892 ] ENGINEERING MECHANICS. 161
Copyrighted )
GRAPHICAL STATICS and Its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
arrange the arches so that their stability is assured without the
presence ofthe mortar; we admit then that it is assured, all the
All the tangential components Ft give a resultant equal tothe
more, when the mortar exists.
shearing force 7"; all tbe normal components /'',, which can be
placed, the ones on one side of the plane A'' X, the others on
the other side, give either a resultant N or a resultant couple.
In the first case, the centre of pressure C is at a finite distance ;
it is at the point of intersection of the resultant N and the trace
A' A of the section on the plane of symmetry ; in the second,
it passes to infinity. Hence, in order that it pass to infinity, it
is necessary aud sufficient that the forces F„ form a couple, or,
what amounts to the same thing, it is necessary and sufficient
that the algebraic sum of the projectious of the exterior forces
jFon the normal to the section be zero, wliich embraces, in
reality, the two cases mentioned above.
Remark.—The theorem of the preceding paragraph, which
admits of deducing the resultant (or the resultant couple) of the
elastic forces acting in a section, from the single composition of
the exterior forces, is valuable ; but we cau understand also that
the composition of the elastic forces themselves may be made
directly.
To this effect, let us consider an element infinitely small 77 b
of the line X' A" aud the strip of the plane of the section projected
according to a b. The elastic forces applied to the various
points of this strip are two by two symmetrical with respect to
(7 b ; now, in composing two symmetrical forces, we obtain oue
situated in the plane of the figure and applied at a b. By composing,
together, all the forces thus applied at 17 b and arising
from the strip of which a b is the trace, we obtain a single force f
which we can decompose into its components tangential and
normal yi andy~«.
The shearing force T is the resultant of all the forces ft, i. e.,
their algebraic sum, since they are all directed accordiug to the perpendicular to this plane undergo perceptibly the same elastic
line X X'. The normal pressure N is the resultant of all the displacements, and consequently, the same pressures or ten­
normal forcesy,,. Hence :
sions, so that it is sufficient to find the elastic forces at the vari­
THEOREM I.— The shearing force in a plane section can be ous points of the trace D E (Fig. 7) of a section on the plane
defined indifferently, the sum ofi the projections on /his section of symmetry in order to have them at all the poiuts of the sec­
of the exterior forces which act on a suitable side ofi the section tion. Let us consider in particular the normal components,
or the sum of the elastic forces which are produced in the section and let us admit that at each point of I) E a perpendicular is
(and which are exercised by the part of the body situated on the raised equal to the value of the normal pressure (5, at this point
suitable side, of which it has just been spoken, on the part situ­ reduced to the unit of length of D E. The locus of the exated
on the other side). Likezvise, the normal pressure can be tremities of these perpendiculars will be a certain curve die
defined indifferently the sum ofi the projections on the normal wliich to is not known. Only (\ 64) the area of this curve is
the section

i62 ENGINEERING MECHANICS. [June, 1892.
of the resultant are strict, and depend in no wise ou the hypo­ plane or not, which we have adopted. F*or another system we
thetical law of the trapezium.
would have different partial resistances.
We have desired only to show that, always useful, the knowl­ We may also have to consider a finite number of sections and
edge of the resultant allows, of itself only, the finding of the the partial resulauts in infinite number of the forces acting on
distribution ofthe pressures if we are willing to adjoin to it this the parts of the body formed by two consecutive sections.
hypothesis.
g 66.
2 67.
CASE OF EXCEPTION.—We put aside in what follows the case
DEFINITIONS OF THE SYSTEMS OF BODIES AND OF THE
FORCES CONSIDERED IN THIS CHAPTER.—We shall consider
(Fig. S) a body, or more generally, a system of bodies symmetri­
where the centres of pressure, in the two extreme sections
A0 Bo, An Bn, would be at infinity.
cal with respect to a plane containing all the exterior forces,
2 68.
such as A0 B" p q, p q p, q,, />, q, p., q2, p.2 q, p, q3, />., q.t An B„ iu FUNDAMENTAL THEOREM.—1° If a system of bodies, as those
contact one with the other along the surfaces p q, />, q„ . . . which have just been defined, is submitted to a finite number ofi
symmetrical with respect to the plane of the forces and any forces, among the funicular polygons ofi these forces, there
elsewhere, whether on the whole extent of these surfaces, or in always exists one which possesses the properly thai the retultant
a limited number of poiuts, with or without adhesion ; the ex­ of the elastic forces exercised in no matter what section, plane
treme sections Ao B0, An B„, wliich are represented plane, but or cursed, made in the body, has for Hue of action one of the
which could likewise be curves, are free or more generally sup­ sides of this polygon, and for magnitude the corresponding
ported to fixed bodies by any number of points.
polar radius.
Fig. a.
Iu that which concerns the given forces, we know (l 62) that,
if we wish to study the pressures which they determine in the
bodies, it is necessary to maintain their true points of applica­
tion.
The points of application are uecessarily at the iuterior or at
the surface of the bodies on which the forces act; aud, as we
suppose that they act only- in the plane of symmetry,
they are at the iuterior or on the perimeter ofthe
figure which the body marks ou this plane.
Three cases may be presented :
i° There exists only a finite number of forces,
hence, a finite number of points of application.
2° The forces succeed one another in a continuous
manner, so that their points of application form a
line ;
3° They succeed one another in a continuous
manner so that their points of application cover au
area of this section.
Let us make, in the system, sections Ao 7?„, A,B\,
. . . ., succeeding one another iu a continuous manner
according to any law. We represent them plane ;
but, save when the contrary will be specified, the
properties which follow extend as well to curved
sections, for example, to sections made according
to the surfaces of separatiou p q, />, q„ . . • . of the
bodies; but, plane or curved, they are supposed symmetrical with
respect to the plane of the forces.
Let A B, A' B' be two sections infinitely close together. If
it is a questiou of forces whose points of application cover an
area, we shall be led to compose fictitiously into a single one
whose point of application it is not necessary to define, all those
which act thus on each portiou A B A' 7." of the body.
We shall call it a partial resultant. We see that the partial
resultants are essentially relative to the system of sections, (To be continued.)
The side under consideration is the one which joins the
two forces whose points of application are bordering on
the section.
2 0 If the acting forces succeed one another in a continuous
manner, so that their points ofi application form a
line, among the funicular curves of these forces, there
always exists one which possesses this properly, that the
resultant ofi the elastic fiorces, exercised in any section
plane or curved, has for line ofi action one ofi the tangents
to this curve, and for magnitude the corresponding polar
radius.
The tangent in question is the one drawn to the point
where the funicular curve is met by the line ofi action ofi
the force whose point of application is on the section considered.
3° If the forces acting are such that their points of appli­
cation occupy an area in the plane ofi the forces, in considering
a particular system of sections plane or curi'ed chosen
otherwise arbitrarily among the funicular curves of the partial
resultants (ft 66) corresponding to this system of sections, there is
one which possesses the properly that the resultant of the elastic
forces acting in any one of these sections has as line of action
the tangent lo this funicular curve at the point where it is met
fie 9.
by the partial resultant answering to this section, and as magnitude
the corresponding polar radius.
[If zee take the partial resultants of a finite number of these
sections, there exists a funicular polygon of these fiorces which
possesses, but only with respect to the sections in definite number
in question, properties stated above (1°)].

June, 1892.] ENGINEERING MECHANICS. 163
PUMPS AND PUMPING MACHINERY.
1SY WILLIAM KENT, M.E.
To put this high pressure of steam on the pump plunger
direct would at once and by a sudden jump raise the water
pressure far above the poiut showu, aud with a shock the result
FIG. 49.
of which it would be hard to estimate; while the fall of the
steam pressure, after it passes the centre of the stroke, would
soon bring the pump plunger to a stop, which by its suddenness
would produce a shock not unlike that at the beginning of
the stroke.
Leaving for the time being this somewhat puzzling
problem, we will again refer to the action of compensating
cylinders, of an area of plunger, and under a pressure
of water that would adapt them to a pump operating under
the pressure of steam and water resistance, as shown by
the previously given figures. This will be graphicallyshown
by Fig. 53, in which the line A 7? is a neutral or
no pressure line, and the ordinates a" b" c" d" e" f"
cr" h" i" j" k" are equal divisions of the stroke corresponding
with the ordinates shown on the steam pressure
cards,/"" being in both instances at the half stroke of the
pump. The figures shown below the pressure diagram
represent the position of the plunger cylinders at the beginning
of the stroke, at one-quarter, one-half, threequarters
and full stroke, and it also shows what is the
effect of the influence exerted by these cylinders at these
varying points on the stroke of the pump.
At the beginning of the stroke, a" I", and when the
accumulating plungers are at their stroke, it will take an
amount of power equal to 17" I", to push the plungers of
the compensating cylinders in, against the pressure that
is on the end of them ; as the plungers are driven iu, the
angle ofthe inclination of the plunger to the centre line
of motion increases, and it takes less power to push them
in, and, as a consequence, the line of the resistance is
less and less at each ordinate, until we arrive at the half
stroke, where the plungers, standing at ninety degrees,
each being opposite the other, they are at a neutral line,
where they exert no influence on the progress of the
pump plunger in any direction ; but, as the plunger
moves on, the compensating plungers, acted on by the
pressure of the accumulator, begin to press outward, and
as they leave the centre perpendicular line they begin to
exert an influence iu helping to push the pump plunger
along, which influence constantly increases until the plunger
arrives at the outer end of its stroke, when the plungers of the
compensating cylinders give out their greatest force, and which
is exactly the force put into them at the beginning of the stroke.
This line of resistance, and of impulse can be varied by changing
certain features of the construction, but, as shown in the
diagram, it is calculated to suit the steam pressure, and cut-off,
of the steam pump we have undertaken to describe.
Having constructed another, and new, line of curves, which
show a retarding as well as an advancing effect 011 the power
brought to bear on the pump, we will now trace its influence,
by placing this curve on the same water card as we did tbe
steam propulsiou curve. This brings us back to Fig. 52, iu
which the line A A" takes the place of the line A B, Fig. 53.
Above and below this base line we construct the same curved
line as is shown in Fig. 53, and which, crossing the same number
of ordinates as have the other cards, shows exactly on each
ordinate the influence it exerts on the pump at that particular
point of its stroke. With this diagram before us, in which is
seen, first, the amount of power required to move the
water column at a steady, uniform pressure through one
stroke of the pump, and in which we have the steam
pressure line which is to move it, and also the line of
useful effect of the compensating cylinder, we will now
examine what is the combined effect of all these forces.
We will assume that the left hand vertical line is the beginning
of an outward stroke of tbe pump. We see at the
start that the line A IV is the amount of power required
to move the water; but we have the line A IVA" as the
steam power we have put on the pump at this point, and
we see that the power inclosed within the lines IV A"
B" C" D" E" F" is just so much more power than we want.
Now if we look at the lower left hand corner, we will see that
the space inclosed between the lines A A' B" C D' E' F' aud
FED C B A represents the amount of steani it takes to push
iu the plungers of the accumulating cylinder, and it adds just
FIG. 50.
B C D E F G II I J K
that amount of resistance to the advance of the plunger. At
F' F" we have arrived at the half stroke, aud here we find the
steam pressure is just equal to the resistance of the load, or
head of water on the pump; but as we pass this point, on to

164 ENGINEERING MECHANICS. [June, 1892.
the end of the stroke, we find that the area inclosed within tbe
lines E" //' K" fi" /" II" G" represent the amount of power
which by reason of the expansion of the steam (which in the
pumping engine described is sixteen to one) falls below what is
required to do the work. It is at this poiut that the compensating
cylinders come to the rescue, and give out the power which,
by reason of the high steam used at the beginning of the stroke,
was stored up in them ; and the space inclosed within the lines
F G II If K aud A"' J' T II' G' F' represent the stored up
power they now give out.
As the diagram is now constructed, the space inclosed between
the two curved lines would represent the total net power
exerted by the steam direct, as well as through the compensating
cylinders, while the space inclosed within the parallelogram
represents the resistance to be overcome in moving the
water column. Now if you will measure the length of any one
of these ordinates between the curved lines, and which represents
the power exercised at that particular part of the stroke,
you will find that it exceeds but a very little the resistance of
the pump plunger at the same point; the excess of the power
beiug just what is required to keep up the speed ofthe pump.
X-
The regulating device is equally efficient for high and lowspeeds.
It will be seen from Fig. 44 that the cylinders are
steam-jacketed, and that the steam in passing to the large Y-
\ -AAVAA
A-A -. .AAsA
t-AAAA ''AAAAA^
ykAAA^A

June, 1892.] ENGINEERING MECHANICS. 165
from the steani. The engine is provided with a jet condenser The steam pistons cushion upon vapor entrapped in the ends
and a double-acting horizontal air pump.
of the cylinders by the pistons passing beyond tbe exhaust
The Worthington high duty engine is built in other forms ports, the inlet ports being closed by tbe slide valve. The
besides the one shown in Fig. 44. A vertical engine with tan­ cushion of the pistons is so effective tbat the whole load
dem cylinders, the high pressure cyliuder being uppermost, is a against which the pump is working may be suddenly thrown off
favorite form. A plant of three such engines was recently
erected in the water works at Memphis, Tenn. The reciprocating
parts of each engine are balanced by a plunger attached
directly to the engine cross-head, working in a cylinder tilled
with water. This cyliuder is connected by pipes with an air
tank which is kept filled with air under pressure. In the Mem
phis engines the steam cylinders are 30 aud 60 inches diameter,
aud the water plungers 27 inches. The nominal stroke of the
plungers is 4 feet, aud the actual stroke during trial was 4.1625
feet. With a steani pressure at the engine of 105 lbs., and a net
load on plungers of 124.1s lbs. per square inch, and a mean
piston speed of 133.7 ft. per min., one of these duplex compound
engines gave a duty of 117,325,000 foot pounds per 1000
lbs. of feed water, aud a capacity- as calculated from plunger
displacement of 11,202,000 gallons per 24 hours.
THE HAI.L DUPLEX STEAM PUMP— The Hall Steam Pump
Co., of Pittsburgh, Pa., make a duplex pump whicli is on a different
principle from the Worthington, in that the main steam
valves are moved by supplemental pistons instead of bv a
direct connection from the main piston rods. This pump is
shown in Fig. 54. Fig. 55 is a sectional view, and F'ig. 56 a dia
FIG. 54.—THE HALL DUPLEX STEAM PUMP.
gram of the steam valve motion and the steani cylinders. In
the operation of the pump the piston of one division acts to
operate the steam valve ofthe other, and vice versa. In the cut,
the steam valve—a plain flat slide—stands at the right of its
stroke, admitting steam to the left of the main piston, moving
it to the right. When the piston nearly- reaches the end of its
stroke, and passes by the port B—seen near the top of the
cvlinder—port A being closed by slide valve above, a sufficient
portion of the steam which is moving the main piston passes
through this port across to and shifts the valve of the other
engine, which then makes its stroke, and in a like manner admits
steam to reverse the valve of the former.
The location ofthe ports sl and 77, near the end ofthe stroke
ofthe pistons, causes each iu its turn to pause—while the other
is making its stroke—for a length of time sufficient to allow the
seating of the pump valves by gravity instead of by the action
of these return currents.
The valve mechanism of each engine consists of but two
moving pieces, a common P slide valve and a small steani
piston or valve driver by which the slide valve is moved.
FIG. 55.—SECTIONAL VIEW UF THE HAI.I, DUPLEX STEAM
PUMP.
while having on a full head of steani without danger of the
pistons striking the cylinder heads or in any other way injuring
the pump.
It will be seen that by the proper location of the ports corresponding
to ./ and B in each cylinder, each engine must, iu its
turn, make a full stroke before admitting steam to reverse the
valve of the other ; the admission of steam, however, being
timed so that each engine starts before the other stops, thus
securing a continuous and uniform delivery. This obviates the
difficulty of short strokes aud consequent waste of steani.
FIG. 56.—DIAGRAM OF THE STEAM VALVE MOTION AND THE
STEAM CYLINDERS OF THE HALL DUPLEX STEAM PUMP.
The cut shows a piston in the water end of the pump, both
suction and delivery valves being above the piston. Other
pumps are made by the company, however, in which a plunger
and ring, similar to that shown in tbe cuts of the Worthington
Pump, are used. The following is a list of regular sizes, made
in either the piston or the plunger pattern, for boiler feeding
and general service in whicli the water pressure does not exceed
150 pounds :
( To be continued.)

166 ENGINEERING MECHANICS. [June, 1892.
ALUMINUM: ITS MANUFACTURE AND USES FROM AN EN­
GINEERING STANDPOINT.
KY ALFRED E. HUNT, CE.
President of the Pittsburgh Reduction Company.
[Extracts from lecture delivered before the Franklin Institute Feb., iSos.] teen times that of the iron wire, pound for pound, then as the
The following tables of tests are results obtained since those section can be reduced the aluminum-titanium alloy will be the
published in the article on "The Properties of Aluminum," by- cheapest as well as the most advantageous for electrical con­
Alfred E. Hunt, John W. Langley and Charles M. Hall, pubductors.lished in the Transactions of the American Institute of Mining Two things, however, should always be borne in mind in con­
Engineers, vol. xiii.
sidering the applicability of aluminum for given purposes in
Cast aluminum rods '. inch diameter A
iti " B
U- •• C
A " D
'* mean of above
Forged aluminum rods ' - inch, diameter E
iA " F
6-10 " G
" " mean of above 7,983
Diawn aluminum wire, No. 16, B. & S. Gauge . . 19,340
No. 16 " . . 10,500
Aluminum casting hardened with 3 percent, copper 6,132
'* '* drop forged . . .
sheet, No. 20, B. & S. Gauge
No. 10,
Cast Aluminum 0751 inches diameter.
Forged
Cast
" o*75I
0-970
666 "49
Forged
Cast "
0-980
C625
M34'
Forged " 0-620
• 478"
Cast '' 0-700
- 1036"
Forged " 0760
• 3J9'
MOMENT OF TORSION.
INCH POUNDS.
Elastic
Limit.
Maximum
Strength.
III4- 76
1274-
2548-
2042.
478'
745'
iiiS*
1*94'
It will be noted that the tensile strength of aluminum wire
runs up very considerably over that of the rolled metal. This
is due to the peculiar property of aluminum to harden under
work. The metal requires frequent annealing in rolling; and
if it is to be drawn into wire with as little annealing as possible,
the tensile strength is increased very considerably. This pro­
perty of the metal fs increased, especially if the aluminum is al­
loyed with a small percentage of copper, titanium or silver.
It is perfectly feasible to produce a wire of aluminum alloyed
with a few per cent, of silver, titanium or copper, which will
have a tensile strength of So,ooo pounds to the square inch,
and which will have, weight for weight with copper wire, an
electrical conductivity of 170 to that of copper being 100. When
it is taken into consideration that the copper will only have a
tensile strength at maximum of (say) 30,000 pounds per square
inch, against the 80,000 pounds strength of the aluminum-tita­
nium alloy, and when the further fact that iron or soft steel
wire has only a conductivity of seventeen in the same scale,
and has a less, or at most only an equal tensile strength pet-
square inch with the aluminum-titanium alloy, a wide field for
TABLE I.— TENSION TESTS.
J= 0*
?, S
u A
&%
V C
~ 3
Sa,J=
H
15.334
11.849
11,870
12,820
13,011
26,901
17.705
20,400
21,270
65,320
32.3"°
15,640
18,310
23,5io
29,650
a
<
4- 4^
0 g
i«
u V
a.
47°
3*5°
040
10-30
4'4°
0'70
3'8o
io'oo
480
14-20
I 5*3°
8'66
5*3°
9.60
4-10
usefulness for electrical conductors seems opened for the metal,
even at present, when the price of the wire of aluminum-tita­
nium alloy will necessarily be considerably higher; but when
such an alloy can be produced in fine wire at a price of (say) fif­
3"9
2*25
3'5°
1-50
278
078
2-50
234
i'15
7"io
8.50
3 "50
i"8o
TABLE TIL—TORSION TESTS.
7\NI;LE OF TORSION.
DECREES.
Elastic
Limit.
1-56°
437"
218°
1-25°
RBMARKJ!
11,000,000
10,084,000,
8,532,631'
15,194,074
11,270,2681
i5.4 6 °.39 2
Granular Very pure soft metal annealed.
0"2I27 Granular
0*2005 Granular
0'072I Granular
0-1618 Granular!
'' "
0*2602 Granular "
9,400,764 o'i654 Granular
Granular
"
12,430.580 0'2I28 Granular "
19,700,000 Silky Cold drawn metal » I per cent. pure.
Silky
Granular
Granular'
" annealed.
Silky Metal of97% percent, pure, remainder
mostly silicon.
Granular Metal cold rolled 98 per cent pure.
EXTENSION OF OUTER FI­
BRE.
Maximum Elastic Maximum
Limit. Limit. Extension.
no"
260°
72'5°
I57'5°
1093 0
57*5°
3 6 '25°
16875
'OOOOj
-0003
-00024
•00007
-00002
•166
•733
•0753
317
-1601
•048
' OI 93
*359
Final
Extension.
•1660
'9120
'0735
'4490
-1601
•1490
'OI93
•6550
SHEARING STRESS.
Elastic
Limit.
'si63-
7802-
*°I33-
9025'
3757'
Maximum
Stress.
I3'473
15-285
l6'022
IO-I33
i 6 '593
13-149
14-089
Modulus of
Rigidity.
843-658
186-133
434*313
869-849
461594
Elastic
Resilience.
the arts. The first is that the properties of the metal are very con­
siderably changed as regards strength, tenacity, hardness, rigidity
and color, by alloying it with small percentages of other metals,
conditions that do not materially change the specific gravity of
the metal. The second is the relative weight of aluminum ; taking
the tensile strength of aluminum in relation to its weight, it is
in plates as strong as steel at 80,000 pounds per square inch
ultimate strength, and in cold drawn wire as strong as steel at
180,000 pounds ultimate.
The specific gravity of aluminum, of course, is one of its
most striking properties; it runs from 2-56 to 2-70. The
weight of a given bulk of aluminum being taken as one,
wrought iron is 2*90 times as heavy; structural steel is 2*95
times; copper, 3-60 times; ordinary high brass, 3-45 times;
nickel, 3-50 times; silver, four times; lead, 480 times; gold,
8'99
6234
18-15
1967
3'49
7-70 times; and platinum, 860 times as heavy. Most woods
that would be used for structural purposes, are about orie-third
as heavy as aluminum.
The specific gravity of aluminum is 2*56 in ingots and 2-64 in
forged bars.

June, 1892.] ENGINEERING MECHANICS. 167
A cubic inch of cast aluminum
sheet metal, -098 pound.
weighs -092 pound of rolled with the strength of thin sections of the metal as does iron or
steel; the thin film of oxide wliich covers the surfaces of the
„, . , . Length if Bar In Fret.
metal which have been long exposed to moist atmosphere seems
II one eight Cubic 111 Foot. Pounds Tensile Strength able to support its
Cast iron
/•er Square Inch.
on ll'eight. to prevent its being further acted upon. But it does give a sur­
444
l6,000
535 face tarnish to the metal which cannot be rubbed off" with the
Ordinary gun bronze . 525
36,000 9,893 usual metal polishing compounds without interfering with the sur­
Wrought-iron plates . 480
50,000
15,000 face ofthe soft metal. This, however, can be removed by rub­
Aluminum plates . . 165
26,000
23,000 bing with a flannel rag which has been immersed in a two per
(cold rolled) 168
(cast) . . . 160
(forged') . . 165
35,000
15,000
20,000
39-6'5
•3.23'
17,700
cent, solution of hydrofluoric acid, and then again rubbing up the
polish with a rag saturated with carbon oil. Special aluminum
polishes have been devised which work very efficiently. When
TABLE II.—CURVES OF EXTE1NS1ON OF SAMPLES MARKED A, B, C, D, E, F, G, OF
TABLE I.
properly cared for, polished surfaces can
be thus kept bright for a remarkably long
— T -J_j__4:lr_,.._4:|_ J- -_1_ 1 1 ____
time.
7\s compared with most metals, pure
-SfiflHi A
I _L _n 1 , i_ ._ _ Ayr A "
, , , , , _m_ _i.^^i ^+_ ' A x
--+----- + "= '-'- - --~ - X - - - --
:i:::::::::::::::;::::::—:;::*-:: ^:-

168 ENGINEERING MECHANICS. June, 1892.
sheets which are now in general use under heavy structures ol
metal resting on metal shims on masonry.
Aluminum sheets will make a much more durable and satis
factory roofing than sheet copper now generally used 111 valuable
buildings.
finder heat the co-efficient of linear expansion of three eighths
inch round aluminum rods of ninety eight and one-ball per
cent, purity gave results as follows :
•00002295 |
•00002289 , .
, per degree Centigrade,
•0000206
•0000230
between the freezing and boiling points of water; that of iron
being 0000122, tin -0000217, copper '00001718.
The coefficient being obtained in the usual way by dividing
the difference in length of the test bars at two given different
temperatures, by the product of the original length of the bars
times the difference in temperatures.
The specific heat of aluminum, according to tbe experiments
of Prof. J. W. Richards, is -02143, water being taken as one.
The co-efficient of thermal conductivity of aluminum, obtained
by the method of Wiederman and Franz, silver being
taken as 100 and copper as 73-6, is 3796 (unannealed aluminum);
annealed aluminum 3887.
Aluminum stands fourth, being preceded only by silver,
copper and gold, as a conductor of heat as well as electricity.
One yard of annealed aluminum wire of ninety-eight and onehalf
per cent, purity, -0325 inch diameter at 14° C, having
054S4 of an ohm resistance; a yard of pure copper wire having
a resistance of '0315 under like conditions. The electrical
conductivity of a standard section of pure silver being taken at
100, an equal section of copper also at 100, pure gold at 78 o,
an equal section of pure annealed aluminum has an electrical
conductivity of about 54'2o.
Pure zinc 29-90
High brass 2150
Pure tin '5 45
Soft 'io carbon open hearth steel 1200
Platinum 1063
Lead 8'88
Nickel 7°9
Antimony 3'°&
Authority, Lazare Wiler communication to the Societe Internationale
des Electriciens.
This relatively high electrical conductivity when equal
weights are taken will undoubtedly prove a factor of importance
in developing electrical uses for aluminum.
The electrical conductivity of aluminum is increased fully
five per cent, by careful annealing even the ordinary soft wire,
and with hard drawn wire the conductivity is increased by annealing
nearly ten per cent.
Pure aluminum has no polarity, and indeed the commercial
metal in the market is practically non-magnetic.
Pure aluminum is very sonorous, and its tone seems to be
improved by alloying with a few per cent, of silver or its titanium.
For the sounding boards of musical instruments, aluminum
has been proven to be well adapted.
Pure aluminum is, when properly treated, a very malleable
and ductile metal. It can readily be rolled into sheets '0005 of
an inch thick, or be beaten into a leaf nearly as thin as gold
leaf, or be drawn into the finest wire. Pure aluminum stands
third in the order of malleability, being exceeded only by gold
ami silver; and in the order of ductility, seventh, being exceeded
by gold, silver, platinum, iron, soft steel and copper.
lioth malleability and ductility are greatly impaired by the
presence of the two common impurities, silicon and iron.
Aluminum can lie rolled or hammered cold, but the metal is
most malleable at, and should be heated to, between 350° and
400° F., for rolling or breaking down from the ingot to the best
advantage. Like silver and gold, aluminum has to be frequently
annealed, as it hardens up remarkably upon working.
I hie to this phenomenon of" hardening during rolling, forging,
stamping or drawing, the metal may be turned out ligid in finished
shape, so that it will answer excellently well for purposes
where the annealed metal would be entirely too soft, or too
weak, or lacking in rigidity to answer. Especially is this true
with aluminum alloyed with a few per cent, of titanium, copper
or silicon. It can be safely stated that under similar conditions
the purer the aluminum the softer and less rigid it is.
Aluminum can be annealed by heating and allowing to
cool gradually ; tbe best temperature is just below the red
heat. Thin sections can be annealed liy heating in boiling
water.
Aluminum can be easily and readily welded by the apparatus
of the Thomson Electric Welding Company.
Until very lately the lack of methods for successfully soldering
aluminum was among the greatest drawbacks to its introduction
for many purposes. Thanks to your townsman, Mr.
Jos. Richards, we have a cheap solder that works satisfactorily.
Some castings of aluminum can be made in dry sand moulds
or in metal chills. As an evidence of this, I take pleasure in
exhibiting a tea-kettle cast from the metal by the Auburn Hollow
Wax Company of Auburn, N. V. It, however, requires
some experience and expertness on the part of the founder to
master the peculiarities of the metal before perfectly sound
castings can be uniformly made. The aluminum should not
be heated very much beyond the melting point; otherwise it
seems to absorb gases, which remain in the metal, preventing
sound castings. In small quantities the metal can be best
melted in plumbago crucibles; but in large quantities it can be
more economically melted in a reverberatory furnace with
alumina or magnesia brick sides and alumina bottom. The
furnace should have a tap-hole for drawing off the liquid metal
into carbon-lined ladles. In no case need the metal be covered
with a flux to assist in the fusion or to form a covering of
slag. In fact, owing to the metal's lightness, the presence of
any flux will tend to unsoundness, due to particles of it becoming
entangled in the castings, while impurities may perhaps be
added to tbe metal by the action ofthe flux on the lining ofthe
melting vessel. The shrinking of seventeen-sixty-fourths of an
inch per foot, which aluminum has, is considerably more than
that of brass, which is about three thirty-seconds of an in'ch per
foot.
Undoubtedly, one of the greatest uses for aluminum in the
arts will be in the form of alloys with other metals. Aluminum
in proportions of a few per cent, added to very many different
metals gives valuable properties. Among these alloys is, of
course, aluminum bronze. The alloys of from tw/o and a half
per cent, to twelve per cent, aluminum with copper have so far
achieved the greatest reputation. With the use of eight per
cent. to twelve per cent, aluminum in copper, we obtain one of
the mose dense, finest grained and strongest metals known,
having remarkable ductility as compared with its tensile
strength. A ten per cent, aluminum bronze can be made in
forged bars with 100,000 pounds tensile strength, 60,000
pounds elastic limit, and with at least ten per cent, elongation
in eight inches. An aluminum bronze can be made to fill
a specification of even 130,000 pounds tensile strength and five
per cent, elongation in eight inches. Such bronzes have a specific
gravity of about 7-50, and are of a light yellow color. For
cylinders to withstand high pressures, such bronze is probably
the best metal yet known.

June, 1892.] ENGINEERING MECHANICS. 169
The fi
live to seven per cent, aluminum bronzes have a specific
gravity of 8*30 to 8 and are of handsome yellow color, with ,1
tensile strength of from 70,000 to 80,000 pounds per square inch,
and .in clastic limit of 40,000 pounds per square inch, ll will
probablj be bronzes of this latter character thai will be mosl
used; and the fa. t that sU,-|, bronzes can be rolled and ham­
mered at a red he.it with proper precautions will add greatlj
to their use. Metal of this character can be worked in almost
every way that steel can, and has for its advantages its greater
strength ami ductility and greater power to withstand corrosion,
besides its fine color. With the price of aluminum reduced
only a very little from the present rates, there is a strong pro­
bability of aluminum bronze replacing brass very largely.
A small percentage of aluminum added to Babbitt metal
gives very superior results over the ordinary Babbitt metal. It
has been found that the influence of the aluminum upon the
ordinarv- tin-antimony-copper-Babbitt is to very considerably
increase the durability and wearing properties of the alloy.
Under compressive strain, aluminum-Babbitt shows to be a
little softer than the ordinary Babbitt. A sample one and
one-half inches diameter by one and one-half inches high
began to lose shape at a pressure of 12,000 pounds. A simi­
lar sample of the same Babbitt metal without the addition of
the aluminum (having a composition of 7-3 per cent, antimony,
37 per cent, copper and eighty-nine per cent, tin) did not begin
to lose its shape until a compressive strain of 16,000 pounds had
been applied. Both samples have stood about an equal strain
of 35,000 pounds. In comparative tests of the ordinary Bab­
bitt metal and the aluminum-Babbitt metal, the latter has given
very satisfactory results. At the works of A. W. Cadman &
Co., 63 Water Street, Pittsburgh, a crank-pin bearing of a thirty
horse-power engine with the ordinary Babbitt metal required
resetting ; bout ever)- three days; and after inserting in the
bearing aluminum-Babbitt strips of about a half-inch width
upon the face, dove-tailed in alternately in the brass bearing,
the same bearings ran under similar work for two months
without requiring any attention; and when examined at the end
of two months, the crank pin was found to have become very
much smoother than it was before the aluminum-Babbitt had
been inserted. Mr. Cadman recommends dove-tailing in the
strips of Babbitt, for the reason that it gives equal bearing
all over the surface. Another advantage of this Babbitt is
its extreme malleability. It can be hammered out to a thin
edge without cracking, whereas the ordinary Babbitt is not
at all malleable. An advantage of this is that for bearings,
with aluminum, the Babbitt tan be rolled into shape for in­
serting in the dove-tailed recesses, which can be cut and
drifted out at a very small expense, and the amount of Bab­
bitt required is reduced to a minimum.
.Aluminum is also being used very successfully in steel
castings, and has added very considerably to the progress
which has been made within the last two years in obtaining
sound steel castings. A large number of steel casting com­
panies are regularly using the metal aluminum in quantities
of from one-half pound to several pounds of aluminum to
the ton of steel. In the manufacture of ordinary steel ingots
by the open-hearth and Bessemer processes, it has lately been
shown in the article on "Aluminum in Steel Ingots," by
Prof. J. W. Langley, at the January, 1891, meeting of the
American Institute of Mining Engineers, that the use of al­
uminum in small proportions (from one-third to three-fourths
of a pound of aluminum to the ton of steel) has proved to
be an economical success, preventing blow-holes and unsound
tops of ingots.
Alloys of aluminum with copper in proportion of from two
per cent, to fifteen per cent, have been advantageously used
to harden aluminum in cases where a more rigid metal is
required than pure aluminum. Copper is one of the most
common metals used al present to harden aluminum A
tew per cent, of copper decreases the shrinkage ol ihe metal
and gives alloys that ao- especially adapted for art castings.
I he remainder ..I the range, fn.111 tilt.cn per .ent. copper up
to over eighty-five pel' cent., give crystalline and brittle al-
loys ol no use in the arts; which are of a grayish-white
color, up to eighty per cent copper, where the distinctly yel­
low color of the copper begins to show itself".
With the exception of lead, antimony and mercury, alu­
minum unites readily with all metals ; and many useful
alloys of aluminum with other metals have been discovered
within the last few years, and I prophesy that many more
will be found within the next few years. I consider this field
as one of the most promising for investigation of any of
"the aluminum problems." The useful alloys of aluminum
so far discovered are all in two groups, the one of aluminum
with not over fifteen per cent, of other metals, the other of
metals containing not over fifteen per rent, of aluminum; in
the one case, the other metals imparting hardness and other
useful qualities to the aluminum, and in the other the alum­
inum giving useful qualities to the other metals.
The alloy of a kw per cent, of silver with aluminum to
harden, whiten and strengthen the metal, gives a metal espe­
cially adaptable for many fine instruments, tools and for elec­
trical apparatus, where the work upon the product and its con­
venience are of more consequence than the increased price due
to the addition of the silver. The silver lowers the melting
point of aluminum and gives a metal susceptible of taking a
fine polish and making fine castings.
Titanium and chromium can be readily alloyed with aluminum
according to methods divised and patented by Prof. John W.
Langley. This will probably prove to be the most valuable
means of hardening aluminum; a few per cent, of titanium
rendering the metal, under work, very rigid ami yet elastic at
the same time. Chromium is the best metal for hardening alum­
inum castings; the triple alloy being best adapted where a
very hard and yet elastic material is required.
More or less useful alloys have been made of aluminum with
bismuth, nickel, cadmium, magnesium, manganese and tin,
these alloys all being harder than pure aluminum ; but it is by
combinations of these metals, with additions, perhaps, of cop­
per, lead and antimony, that alloys of most value have so far
been discovered. Some are additions of" only one per cent, to
two per cent, of aluminum. The modifications of pewter, britan-
nia, white metal, delta metal, and the like, with additions of
aluminum, have shown very useful qualities, and will add very
considerably to the demand for aluminum in the near future.
The foUowing alloys have recently been found useful:
Nickel-aluminum, composed of twenty parts nickel and eight
parts aluminum, used for decorative purposes. Rosine, com­
posed of forty parts nickel, ten parts silver, thirty parts alum­
inum, and twenty parts tin, for jewellers' work. Sun bronze,
composed of sixty parts cobalt (or forty parts cobalt), ten parts
aluminum, forty (or thirty) parts copper. Metalline, composed
of thirty-five parts cobalt, twenty-five parts aluminum, ten parts
iron and thirty parts copper.
Besides these, Prof Fmmens, the well-known inventor of
Emmensite explosives, has great hopes for an alloy of alum­
inum bronze and nickel for a gun metal.
Prof. Robert Austin has discovered a beautiful alloy, contain­
ing twenty-two per cent, aluminum and seventy eight per cent.
gold, having ,1 rich purple color with ruby tints.
The addition of from five per cent, to fifteen per cent, alum­
inum to type metal composed of twenty-five per cent, antimony
and seventy-five per cent, lead, makes a metal giving sharper
castings and a much more durable type.

170 ENGINEERING MECHANICS- [June, 1892.
To ordinary brass, the addition of aluminum gives superior
strength and better anti-corrosive qualities.
Some very marked and valuable qualities have been discov­
ered in the use of aluminum and zinc for various purposes.
A mixture of aluminum with zinc is made by the Delaware
Metal Refinery, of Philadelphia, which has proved very useful
in the galvanizing bath; adding one pound of the aluminized
zinc alloy to each ton of spelter contained in the bath, and one
pound of the alloy additional for each 1,000 pounds of new
spelter put into the bath. The effects are to make the spelter
more fluid, coating smoothly twenty per cent, more surface than
ordinary spelter, with a surface that is brighter, more malleable
and will double-seam much better than ordinary galvanized
iron. The use of " aluminized zinc " for this purpose is patented
by Jos. Richards, of Philadelphia.
The aluminized zinc has also been added to good advantage
as an addition to ordinary brass mixtures; about one per cent.
to the weight of the brass mixture of aluminized zinc being
used, plunged with a pair of tongs under the surface of the
metal, where it is stirred with a rod. The surface of the brass
mixture is then skimmed, and after waiting about half a minute,
until the bubbles of disengaged gas cease, poured as usual.
The effects are to make sounder castings, increase the strength
and give a finer color to the metal, which will resist oxidation
much longer than ordinary brass. Should the amount of iron
in the brass mixture be high, as large an amount as two per
cent, of aluminized zinc can be added to liquefy the iron. The
use of aluminized zinc for brass alloys gives a heavier yield of
metal than without its use; and the Delaware Metal Refinery
people claim that the increased yield and sounder castings pro­
duced will much more than pay the slightly increased cost of
the brass mixture by the addition ofthe aluminized zinc.
Aluminum has been successfully used to replace lithographic
stone.
Powdered aluminum mixed with chlorate of potash is used to
give a photographic flash-light, which gives much less smoke
than the magnesium compounds used.
The Tacony Iron Metal Company, another well-known
Philadelphia concern, has successfully produced an aluminum
coating for iron, which undoubtedly will have considerable use
in the future. Samples of their work 1 take pleasure in showing
you this evening.
To the inventors who shall produce good methods of nickel,
silver and gold-plating aluminum so that it can take the place
of German and nickel silver, a rich reward is in waiting.
I have endeavored in the latter portion of this lecture to in­
dicate a few of the uses that have already been established, and
the openings that seem most prominent to my own observation
for the use of aluminum. Undoubtedly there are many other
fields yet waiting for the metal which will yield rich returns to
the successful investigator; and I close this letter by again re­
iterating the prophecy that the financially most successful solu­
tion of the aluminum problems of the future "will be in the
ways of utilizing the metal in the arts, rather than in devising
more economical methods of manufacture."
CYLINDER CONDENSATION.
MR. G. R- BOOMER, in a recent issue of London Engineering
gives the results of his investigation of the experimental data
available on the subject of cylinder condensation in steam engines,
as follows :—
desirable in one cylinder, the ratio of expansion has no practical
influence upon the condensation of steam per stroke.
(3) The weight of steam condensed in the cylinder per stroke
is, for simple engines, fouud by the following rule :—
Multiply the difference between the mean admission and exhaust
temperatures by the clearance surface iu sq. ft. Divide
this product successively by the latent heat of steam at the mean
admission temperature, and by the cube root of the square of
the number of revolutions of the shaft per second. This quotient
will denote the weight of steam condensed if it is first multiplied
by a constant, which is
Eor high pressure non-jacketed engines, about o. 11
For condensing non-jacketed engines, about 0.085 to o. 11
For condensing jacketed engines, about 0.085 to 0.053
The constant for jacketed engines is for cylinders jacketed in
the usual way, and not at covers. The constant varies for different
engines of the same class, but not for any given engine.
(4) If there were no cylinder condensation, the steam required
would be the final total volume ofthe steam as the exhaust port
is about to be opened, divided by the product ofthe actual ratio
of expansion and the volume occupied by one pouud of steam
at the mean admission temperature.
(5) If the result obtained by rule (3) be divided by that in (4)
the quotient will denote the ratio of steani condensed to that
necessary, provided there is no condensation.
Of course the economy due to compressiou is here neglected.
It may be obtained by complicating the rule.
In this ratio we have the term—
Clearance surface -j- total final volume ofi the steam
which is evidently greater for small than for large engines, and
clearly shows why the percentage of cylinder condensation is
largest for small engines.
(6) The actual consumption of steam per indicated horsepower
per hour is 33,000 multiplied by 60, aud the product
divided by the work done by one pouud of steam as such, (under
the actual conditions as to pressure, expansion, etc.,) and this
quotient multiplied by one plus the ratio in (5) above.
In calculating the work done by one pouud of steam, as such,
due allowance must be made for the indicator errors.
(7) The condensation is not affected by the density of the
steam at admission, but rather by its temperature, though the
density of the exhaust steam may have some influence.
Iu a discussion of a paper on cylinder condensation at a recent
meeting of the Institute of Marine Engineers, the following
propositions were submitted : — (1) That range of temperature
does not cause hut permits condensation. (2) That the increased
initial condensation found with higher rates of expansion is due
to increased work, and not to increased range of temperature.
(3) That initial condensation may occur not only when steam
is used at full pressure throughout the stroke, but even when
no useful work is performed. (4) That the lessened initial condensation
generally found with stage expausion engines is largely
due to reduced range of temperature, but notwithstanding reduced
range of temperature a stage expansion engine may condeuse
as much steam as a single stage engine. (5) That conducting
cylinders do not of themselves cause initial condensation,
the actual cause being the disappearance of heat and consequent
liquefaction of steani in the performance of work. (6) That discordant
results are almost certain to arise when the condensive
surfaces are active to their full capacity. (7) That instead of it
being necessary to consider why initial condensation exists, it is
often necessary to inquire why it is not greater."
At a meeting of the English Mechanical Engineers Association
(1) The condensing surface in the cylinder is the surface
held May 5-6, the above subject was elaborately discussed, and
bounding the clearance volume, i. e., the cylinder cover, piston
the conclusion reached was that there were so many different
head, and surface of steam and exhaust port or ports. He finds
conditions that it was not possible to cover them by any formula.
that the bore of the cylinder has little, if any, effect on the con­
MK. A. G. BROOKS, who conducted the Machinery Exchange
densation in engines as used now-a-days.
for many years, at 261 N. Third St., Philadelphia, is now with
(2) Within the ordinary limits of expansion of steam, as
II. M. Sciple cS: Co., Third and Arch Streets, Philadelphia.

June, 1892.J ENGINEERING MECHANICS.
THE AMERICAN SOCIETY OF MECHANICAL
ENGINEERS.
San Francisco Meeting. May 16 20, 1892.
The papers presented at the San Francisco meeting are here given in
abstract :
Mr. John Richards, member of the Society and President of Ihe
Technical Society of the Pacific toast, presented
Notes on a Problem in Water Power,
This paper was not intended to be a scientific discussion, but was intended
to draw out diseussion ifpon the recent development and possibilities
of impulse wheels. Water wheels may he classed as gravity
wheels, including overshot, breast and Poncelet wheels ; pressure wheels,
including turbines and reaction wheels; and impulse wheels, driven by
spouting water.
Turbine wheels constitute, perhaps, four fifths of the whole number,
and until recently have been the only wheels with which an efficiency
ot over Oo per cent, was considered practicable.
When the lew possible sources of loss involved in the use of spouting
jets of water are considered, it is a matter of surprise that so much less
study and effort for improvement has been given to impulse wheels, and
the question arises. Why has not the evolution of water wheels followed
on this line instead of pressure lor all low heads ?
That the efficiency of tangential wheels driven by impulse is
as high as can be attained by pressure turbines has been proved by
numerous experiments at Holyoke, Mass., as well as on the Pacific
coast, where such wheels have been longest in use; and where no one
would expect, under ahead of 50 feet or more, to attain with any
known type of pressure water wheels a higher efficiency than is given
out by tangential impulse wheels.
It was suggested that the members should see some of the impulse
wheels operating under high heads, and so obtain ocular demonstration
of the simplicity and efficiency of these water wheels.
Mr. John II. Cooper, of Philadelphia, presented a paper on
A Self-Lubricating Fiber Graphite for Bearings.
This was a description of a bearing material composed of natural
graphite, which is mixed in a finely divided state with wood fiber in
water and solidified by pressure in molds. T he material is then saturated
with oil and dried at a sufficiently high temperature to harden the
mass and oxidize the oil. The material may be machined in the same
manner as metal, and, it was stated, has been used with great success.
It is the invention ol" P. Holmes, of Gardiner, Maine.
Mr. Harris Tabor, of Elizabeth, N. J., presented a paper on
Machine Molding.
After presenting the general subject of making molds by hand, in
which due consideration was given to the necessity of skill and judgment
on the part of the molder, especially in ramming molds of different
depths, and for various classes of work, the writer proceeded to describe
the molding machine of his own invention, which is shown in the illustration
(Fig. 1).
The floor is shown broken open in order to exhibit the steam cylinder
by which the pressure is produced, the cylinder being single-acting and
the piston returning by gravity.
To the piston rod is attached the principal part of the mechanism,
consis ing of a table with lugs projecting upward, and supporting the
pattern frame upon which rest the patterns; the stripping-plate directly
over the pattern frame, and resting on it, to which the stripping-plate is
attached; the stool plate suspended to the stripping-plate frame, and
moving with it; side levers and tumbling shaft for tripping after the pattern
is drawn. 'The pattern frame has an annular passage which is
connected to the cylinder by a small pipe, the object of this being to
admit some steam to the pattern plate at each movement of the piston,
this steam serving to keep the patterns moderately warm, preventing
"sweating" or accumulation of moisture from the atmosphere, and
making them draw from the sand more freely and smoothly. The
stripping-plate frame is guided by two bored sockets, one at the front,
and the other at the back of the machine, there being air-holes below
the pistons, by which any desired amount of cushion can be obtainedfor
the drop of the stripping-plate frame. The stool plate is really part of
the stripping-plate frame placed below the pattern frame, and its object
is to support stools or internal parts of the stripping-plate used in holding
green sand cores, or heavy bodies of hanging sand, while the pattern
is being drawn. The side levers are pivoted at one end to the table, and
are connected at the middle, by links, to the stripping-plate frame, the outer
end being free. The tumbling or tripping shaft is in front of the machine,
near the floor, and has arms projecting upward along the line of travel
followed by the free ends of the side lev#s; on these arms are stops
which engage with the free ends of the levers on the downward motion,
to draw the pattern.
The ramming head is carried by the wrought rods seen at either side
of the machine, these being attached to a horizontal shaft at the bottom of
the cylinder, which allows them to be swung forward and back as shown,
a spiral spring being used to counterbalance tin- weight. Tin- ramming
head is usually of vv I, roughly cut out over the pattern, lo avoid loo
hard ramming mi the high places. This block may, of course, be readily
changed lo suit any flask within the capacity of the machine. The stops
on the stripping plate can be also changed to suit any pattern within tinrange
of the machine. The steam pipe enters the cylinder at ihe bottom.
and from the throttle valve lo the cylinder serves also as an exhaust pipe,
tin- throttle valve being a two-way cock by which sleam is either admitted
or exhausted from the cylinder.
The operation of the machine is very simple. Tlie half flask is put
on the stripping plate, with the sand-box to hold the sand which is lobe
compressed, and both are filled with sand. The ramming head is then
swung forward over the flask against stops which define its position,and
the throttle valve opened. The upward motion of the piston and attached
FIG. 1.
parts carries the flask and sand up to the ramming head, where it is
rammed instantly, anil upon the throttle-valve lever lieing moved again
steam is cut off, and at the same time exhausted, allowing the flask to
descend; the stops then engaging the free ends of side levers, and arresting
the downward motion of the stripping-plate at a point about midway ;
the pattern, continuing to descend, is drawn from the mold, and when
the piston has returned to its lowest position the sand is struck ofl" the
flask, which is then taken from the machine. As the man removes it he
presses the tripping treadle with his foot to release the stripping-plate
frame, which then falls to its proper position with respect to the pattern,
and the machine is then ready for another mold.
Mr. Chas. II. Manning, of Manchester, N. IL, presented a paper
entitled
A Novel Fly Wheel.
After describing the bursting of the fly wheel of the Corliss engines;
at the Amoskcag Mills, which occurred in October 1891, and which has
been discussed fully in the technical press since that time, the writer
proceeded to describe the wooden rim liy wheel which was made to
replace the broken one.
The wheel is shown in the illustration (Fig. 2).
As it was not desirable to remove either of the cranks, the hubs were
made in halves, and in erecting the wheel the design as shown was
departed from to the extent of placing the joints of the two hubs at right
angles to each other on the shaft. The bolting together of the half
hubs was made ample to hold the halves of the wheels together when
running at normal speed of 61 revolutions [.er minute, independent of

172 ENGINEERING MECHANICS. [June, 1892.
any other strength in the wheel. The ar.ns were so placed that the
inner end served as a butt-strap over the end of this joint. The arms
wen- so designed that each one would safely cany the belt strain coming
on its half the wheel, il" the other 11 arms were entirely relieved, and
the bolting to the hub is sufficient to carry its portion of the rim if cut
adrift from the remainder of the rim. Sharp angles and changes of
section in the arms were avoided as much as possible, as will be seen in
the arm section, both where it joins the hub and the rim. The circular
cross section was selected in preference to the elliptic on account of the
greater certainty of uniform distribution of metal.
The counterbalancing of cranks and connecting rods was obtained by
placing heavy cast-iron plugs in the hollows at the outer end of the
three arms directly opposite each crank, and these plugs were secured
in place by I-inch bolts running through the centre of the arms, and
large washers fitted to the inner ends of the arms. Though the total
weight in the wheel is not much less than that of the old one, the
weight in the rim is only about one-half, but it has shown itself to l.e
ample for a very steady speed.
As for safety, the speeds being the same in both cases the hoop tension
in the rim per unit of cross section would be directly as the weight
FIG. 2.
specia
Safety
wheel
per cubic unit, and its capacity to stand the strain directly as the tensile
strength per square unit, therefore the tensile strengths divided by the
weights will give relative values of different materials.
Cast-iron weighing 450 lbs. per cubic foot and wilh a tensile strengtli of
,440,000 I . per square foot would give a value of
whilst ash,
and with I,
1,440,000
= 3,200,
45°
f which the rim was made, weighing 34 lbs. per cubic foot,
52,000 lbs. tensile strength per square foot, gives a result
1,152,000
34 3. 2 °°
53.SS2
:33,SS2, and
10.5S, or the wood rimmed pulley is
ten times safer than the cast-iron when the castings are good.
This would allow the wood rimmed pully to increase its speed to
^10.58 = 3.25 times that of a sound cast-iron one with equal safety.
When completed this wheel was run up to a speed of 76.
The cost of this wheel complete was $7,000 nearly, which is less than
that of its sinful predecessor. In this cost is included all patterns and
Mr.
appliances, and it could be duplicated for much less money.
was the greatest consideration, and it is firmly believed that this
is as safe and durable as any in existence.
W. Wallace Christie, of New Vork, presented a paper on
An Experiment With Aluminum.
Thi was a description of tests of the following mixtures :
MIXTURE NO. I.
Wrought-iron Turnings 10 lbs.
Cast-iron 'Turnings 10 "
Steel Rail Chips 10 "
Ferro-Silicate of Iron and Aluminum 2 "
TEST NO. 2.
Wrought-iron Turnings 10 lbs.
Cast-iron Turnings 5 "
Steel Rail Chips 15 "
FeiTO-Silicate of Iron and Aluminum 2 "
These were melted in a brass furnace at a temperature
of about 3000° F. in about three hours time, the ferrosilicate
of iron and aluminum being added last. The
castings made were 1)4 inches diameter by 14 inches
long and in green sand without any charcoal facing, and
after the skin of sand had been removed they were found
to be smooth and clean.
Mixture No. I was very fluid when hot and white, but
had to be poured quickly, as it soon cooled.
Mixture No 2 was not as fluid nor as white as No. I.
Mixture No. 1 made a very homogeneous casting; No.
2 not nearly so much so, and its fracture duller than No.
I, which latter was very bright.
It may a so be said that pieces of both mixtures which
have been on my desk since April, 1890, when they were
cast, have retained their original brightness, whicli speaks
well for the small percentage of aluminum in them.
Mixture No. 1 could not be touched by a specially
tempered cold-chisel, but its edge was entirely destroyed.
The piece of mixture No. 2 shows where a tool maker
had used an hour's time cutting off but little, and during
that time the tool required many sharpenings; I believe,
five or six. When heated to a high red heat they both
crumble when struck with a hammer, but when heated to
a dull red heat No. I was placed under a steam hammer,
anil though quite resisting, allowed itself to be flattened to
about I "4 inches thick before crumbling, but gave better
results when annealed over one night.
No. 2, when heated in the forge to a dull red heat,
could be flattened to about -'4 inch thick.
Having in his possession a piece of No. I when doing
some laboratory work at Cornell University, the writer
had it remelted and cast into the usual shapie for tension
tests. This piece, though but S% inches long, was put in
a Fairbanks testing machine, but as it was uncertain as to
just how it would act, no extensometer was used for fear
of the test piece breaking suddenly. Breaking occurred
at a scale reading of 13,860 lbs. 1 he piece broke, however,
in the jaws of the machine, and in the larger section
of the piece, as there was a flaw in it (cinder flaw).
For fear of breaking the jaws of the machine the test
ended here. After breaking the smaller section in the
impact machine, the area was obtained by a planimeter as
.31 square inch, which makes the tensile strength per
square inch at the time of breaking 44,710 lbs. This
would have been higher, and probably considerably, but
for the flaw and untrue grip of the jaws, which caused a
combined transverse and torsional strain. The area of
smaller section was less than that of the sound portion of
larger section, hence its use. When placed on a I Ieisler impact machine,
between supports 6 inches apart, a weight of 25 lbs. falling 1 3+ inches
was required to break a circular section of.31 square inch. Two uses
for this metal have suggested themselves to me: one for floor plates in
a boiler or engine room where great strength is not required, but where
wear is. Also as bearings for pivots. Of course, it is not desirable to
use it for work requiring finishing, as it is too hard for that, except when
done on a grindstone.
The ferro-silicate of iron and aluminum used was an ordinary commercial
article, purchased in the open market, and whose composition the
writer was unable to learn.
No. 1 is much harder to grind than No. 2, and both present vei y smooth
surfaces, as can be seen by the inspection of the specimens.
Mr. W. S. Aldrich, of Baltimore, Md., presented a paper
On Compounding Centrifugal and Load Governing by a Rotary Piston
Halve.
The nature of the problem of close governing was outlined as follows :

June, 1892.] ENGINEERING MECHANICS.
(1) The speed regulation to be as nearly perfect as the operation of
the governing forces and of the legtilating'niechanism will permit.
(2) The steam supply to be as directly proportioned to the external
load as the mechanism of the steam-engine will allow, by varying the
mean effective pressure on the piston.
(3) Automatic regulation of the point of cut off alone, or of all tinevents
of the steam-stroke, if desired.
(4) The valve, valve mechanism and governor mechanism to be as
free as possible of any needless frictional resistance, requiring a minimum
power to alter their motions in sense, direction or magnitude.
(5) The governing forces to he brought int.. operation upon any
change of speed or of external load, or of both at the same time, by
compounding the centrifugal and Ihe load governing principles.
(6) The centrifugal governing forces to operate on the valve mechanism
at a minimum required variation of speed.
(7) The load, or dynamometric governing forces, to be indirectly
applied, and not through the intervention of mechanism by and through
which the power is transmitted from the engine to the dynamo.
(8) The instantaneous variations of the external load to be as immediately
and positively felt at the valve as the load governing mechanism
will permit.
(9) The variations, through any cause, of the driving effort on the
piston and internal friction of the engine, as distinct from the external
load variations, to be controlled by effective and sensitive centrifugal
governing.
I IO) The compounding of the centrifugal and the load governing
forces to be effected in such a way that they shall operate upon the valve
independently of each other, or more or less dependently.
It was the writer's opinion that a compound cut-off valve mechanism,
operated by centrifugal and load governing forces presents a somewhat
satisfactory solution of almost all of these questions. The two governing
forces may be introduced by makingthe valve of the piston type, and
giving it a variable movement of reciprocation, with a variable movement
of rotation or of oscillation, the movements being independent of each
other. The valve friction will be reduced to a minimum by combining
reciprocation with rotation. The centrifugal governing forces control the
variable reciprocation; the load governing forces, the variable rotary
movement, or vice versa. An electro magnetic mechanism under con
trol of the turning moment of the dynamo, or of its external electrical
circuit, introduces the load, or dynamometric principle. This electromagnetic
control of the point ol" cut off not only possesses great facility
of application, but differs from all other applications of the dynamometric
principle in not requiring intermediate Iransmissive mechanism, with
gear-wheel or pulley trains, nor weights, springs, or belt-tension devices
of ordinary transmission dynamometers. It also acts instantaneously
upon any change of load on the dynamo circuit; and, it is not possible
to anticipate further any load changes, because the slightest change of
load is instantly felt at the valve, through the electro-magnetic mechanism
controlling one of its movements.
The rotary piston valve, with a variable compound helical motion,
possesses all the advantages of a slide valve and a piston valve, and the
inherent disadvantages of neither. There is no scoring or grooving of
the valve face or its seat; hence minimum liability to leakage and a
maximum duration of normal working conditions. The structural advantages
of piston valves are all maintained. By giving a rotary motion to
a piston valve, or a sliding motion to a rotary valve, as is here done, the
governing forces are a minimum to effect any change in either motion of
the valve; for. the angular movement is more easily varied than it would
be with no sliding, and the travel of the valve is more easily changed
than with no rotation. These features make it very easy to control one
or the other movements by hand (in locomotive and marine engines), or
by sensitive governing mechanism for central station engines ; and in the
latter case this becomes a marked advantage, as it allows of dynamometric
governing by delicate adjustments of the electro-magnetic mechanism to
suit the external load conditions.
The advantages of governing central station and other engines in the
electrical service, by compounding the centrifugal and the load governing
forces by a rotary-piston valve, may be thus summed up :
(1) Best combination of conditions for uniform speed under no load or
extreme variations of load, and steam pressure constant or slightly
variable.
(2) Steam supply as directly and instantaneously proportioned to the
external load as it is possible to make it by electro-magnetically controlling
the point of cut-off.
(3) Valve friction reduced to a minimum.
(4) Load governing forces capable of the most sensitive and delicate
adjustment by electrical means.
(5) Independent governing against variations in the external load,
compared witth variations of driving effort and of the internal load of
the engine.
(6) Each governing principle regulates that which the other cannot,
and without interference.
(7) Rotary-piston valve, with helical ports, gives quick and sharp cutoff,
with increased port area.
(8) Failure of either governing device permits of the engine running
temporarily under control of the other.
(9) Dynamometric governing of a multiple-expansion engine driving
A3
several dynamos, any one of which may he thrown on or ..II at anytime.
Profs. J. E. Denton and 11. s. Jacobus, of Hoboken, N. J., presented a
Summary of Results of Principal Experimental Measurements of
Performance of Refrigerating Machines.
The tests discussed in this paper included air machines, ammonia
machines, both absorption and compression, sulphurous acid and earl ie
acid machines, 'the refrigerating eflect is given in pounds ol "ice melting
eflect" per pound of coal required to drive the steam engine.
The ice melting eflect of Ihe various types is as follows :
Air Machine.—3.4 pounds or 43.1 per cent, of the theoretical
effect.
Ammonia Absorption Machine.—20.1 lbs.=52.2 per cent.
Ammonia Compression JIIaehiue.--46.2tj, to 16.4 lbs. for
pressures of 45 to S pounds ; or 72 to 50 per cent.
Sulphurous Acid Machines.—26.24 to '7-47 'bs. or 65.4 to
57.S per cent.
No definite data are available for carbonic acid machines, but the high
pressures, (Soo pounds) and the fact that the efficiency is less than
ammonia machines renders their use improbable.
Mr. F. M. Rites, of Pittsburgh, Pa., presented a paperon
Tbe Sleam Distribution in a Form of Single-Acting Compound
Engine.
'This was an examination of the steam distribution in a well known
single-acting compound engine, and was intended as an economic study
of the type only, without reference to details of construction.
Numerous indicator cards were given, and especial stress laid upon
the manner in which the volume ofthe receiver could be predetermined
so that the variation of cut-off should control Ihe most desirable compression,
and secure a remarkably uniform efficiency under extreme
variations of conditions.
Mr. B. J. Dashiell, Jr., of Philadelphia, Pa., presented a paperon
The Electric Railway as Applied to Steam Roads.
The writer first discussed the question of high speed train resistances,
and then proceeded to describe an electric locomotive claimed to be the
hrst large freight locomotive displacing steam on a standard gauge
railroad. This machine is in operation over a road of I '4 miles in
length, carrying merchandise from the freight station at Whitinsville,
Mass., to the Whitinsville Machine Co.'s plant. The power is conveyed
to the locomotive by trolley. 'The motor is one of the " G " type
of the Thomson-Houston Electric Company ; the power is communicated
from the armature to the rear axle by means of double reduction
gearing, and from the rear axle to the forward one by the side rods.
The motor consists of wrought-iron field magnets bolted to a mitis-iro'n
yoke. One of these yokes carries the bearings which support that end ofthe
motor on the axle, while the other yoke is spring supported from the other
axle. This keeps (Fig. 3) the gears always in line and meshing correctly
with each other, and at the same time provides considerable spring
support for the motor, which in designing slow-speed locomotives should
be looked carefully into as well as in locomotives for extreme high speed.
The gearing consists of aluminum bronze pinions and mitis iron spingear
wheels. This gearing runs in gear eases, in which a plentiful supply
of grease is placed This decreases the noise and friction, thus
increasing the life of the gears very materially, fin the intermediate
shaft is heavily keyed a mitis-iron brake dram, which is covered with
wood lagging. It is embraced by two half bands of steel, tightened
upon it by means of the brake-drum lever, situated in the operating
stand or cab.
The wheels are 42 inches in diameter, and are heavily steel tired.
The frame consists of two heavy side-plates in which are located the
main axle-bearing Two heavy east-iron plates, in which are east the
cow-catchers, are bolted to the side-plates by means of heavy through
bolls, whicli are a driving lit in reamed holes. These end [dates carry
the heavy spring draw -bars, and bumpers.
'the operating platform or cab is located at one end of the main
platform, and is made of pipe frame-work and covered with protecting
roof. (In this platform are located the lever for operating the controlling
mechanism, the brake and the double-acting sand-boxes. The
universal trolley-bar also extends upward from the locomotive at this
point, as shown.
The controlling mechanism consists of two large rheostats of the
Thomson-Houston railway type. These are so arranged with their
contact shoes that no reversing switch is needed. The operator stands so
that he always faces the direction in whicli the locomotive is to go, and
being in this position, he pushes the controlling lever from him to make
the locomotive go forward, and pulls it toward him, past its vertical line,
to make it go backward. A positive centre notch or lock is provided, so
that in turning the current off there is no danger of passing the neutral
point on the rheostat, and so reversing the locomotive with the current
on. When the operator stands in the above-mentioned position he pushes

174 ENGINEERING MECHANICS. [Tune, 1892.
the brake lever from him in order to apply tlie brake. The steel bands
are so arranged on the brake drum that the friction tends to tighten them
up mure upon the wood bagging, and so assist the operator in braking
the train.
The following data gives the detail of construction of this locomotive,
tlie construction of which has been under the direct supervision of the
engineers at the works of the guilders :
Wheel base 6 feet 4 inches.
Diameter of wheels 42 inches.
Speed reduction between armature and axle . . 1 to 25.
Gauge 4feeet8$*2 inches standard.
Wheel base 6 feet 4 inches.
Measured height above rail platform ... 4 feet 4 inches.
Greatest length of locomotive at cowcatcher . 15 feet 91/ inches
Greatest length of platform 12 feet -jv^ inches.
Greatest width of platform 7 feet 1% inches.
Weight of complete locomotive, less trolley
P"le 42,5^5 lbs.
Approximate weight of motor 5,40 j lbs.
FIG.
As in street railway work, a combined main switch, lightning arrester
and fuse box is placed on the locomotive and within easy reach of the
engine driver, so that he can instantly shut the current off from the locomotive
by a slight movement of the hand.
The construction of the motor is of the most rigid and waterproof
character, the held spools having their wire enclosed entirely, sewed up
in canvas cases, which are covered with a heavy coating of waterproof
paint.
The locomotive, which weighs 42,525 lbs., or about 21 tons, was designed
to operate at 500 volts and to develop ioo II. 1', at the thaw-bar.
This enables it to pull a train of h to 12 heavily
loaded cars, or an aggregate load of 300 lo 500
tons, at a speed of 5 miles per hour on a level
with ease.
Mr. A. F. Nagle, of Chicago, 111., presented
a paper upon
The Density of Water at Different Temperatures.
After pointing out the discrepancies between
various authorities the writer plots a curve
which apparently reconciles closely the results
of different writers. The only reliable experiments
appear to be those of Kopp, but the
writer appears to place especial confidence in
the figures of D. K. Clark.
Mr. W. F. M. < loss, of Lafayette, Ind., pre­
sented a paper on
An Experimental Locomotive.
This was a general description of the Schenectady
locomotive which has been erected
for experimental testing at Purdue University,
and which is shown in the illustration (Fig. 4).
The arrangement includes Alden brakes on
the supporting wheels and every facility for
measuring all the data required. Steam may
be furnished either from a stationary boiler or
from the boiler ofthe locomotive, and the en­
tire outfit is very complete in every respect. The future results of the
experiments with this engine should be of permanent value.
Prof. C. II. Peabody, of Boston, Mass., presented a paperon
The Economy and Efficiency of the Steam Engine.
The writer urged the use of the British Thermal Unit in statements of
engine performance, instead of the usual statement of pounds of steam
per horse power. The advantages of the change were that the unit is
applicable to air and gas engines as well as steam engines, besides being
a more accurate method ol expression. Since one horse power is equivalent
to 33000 foot-pounds per minute we have
_33000_
— 42.42 B. T. U.
per minute, and this constant divided by the heal consumed per horse
power per minute will give the efficiency.
The method to be followed in determining the performance of an engine
in British thermal units is given in detail.
Mr. W. (>. Webber, of Erie, Pa., presented a paper on
Some Tests of a Portable Boiler.
The construction of ihe boiler tested is shown in illustration (Fig. 5).
The boiler might be described as of the simplest form of return tubular
type, occupying but little space, and combining with the safety ofthe
stationary return tubular boiler the convenience and portability of a
(FIG. 4

June, 1892.] ENGINEERING MECHANICS. 175
Portable (Fig. 5). The front end of the boiler is cylindrical in form,
and extends over the furnace, forming the crown sheet (Pig. 5). The
rear end is oval, the lower portion extending below the cylindrical portion
far enough to hold the short tubes leading from the lire-box to the
back connection (Pig. 5). The short tubes in this lower portion are
larger in diameter than the upper longer series of tubes, as will be seen
from the accompanying table, and are arranged in the proportions of
about 1 squarefoot to 2 square feet of heating surface, respectively. The
furnace is lined with lire brick, which can be detached when desirable,
these lire brick being held in place by vertical iron rods which are protected
from the fire and can be removed and replaced when necessary.
These iron rods are square in cross section, and are set at an angle to lit
the V-noleh in ends of lire brick, and the ends of the lire brick notched
so as not only to be held in place by the iron rods, but also to protect the
latter from the action of the fire. The recent improvement, above
alluded to, consisted in lining the back connection, or combustion cham­
ber, with brick 111 a similar manner to the lining of the furnace (Fig. 5)
This tire brick lining soon attains a high temperature, greatly increasing
the efficiency of the boiler by insuring complete combustion ofthe gases
passing through the lower series of tubes, and coming in contact with this
O77 the Elastic Curve and Treatment of Structural Steel.
This paper was a discussion of tests of structural steel used in the
Henderson Bridge across the Ohio River at Henderson, Ky. The point
emphasized was that tests should be made after rolling into shape, as
different shapes give very varying properties to steel, and that tests ofthe
billets cannot be depended upon. It was the writer's opinion that the
shapes should be annealed in the form in which they were to be used,
and that built up members, even with two or three webs, could be
annealed without injury or distortion.
Many tables and diagrams of tests are appended to the paper.
Mr. Thomas Gray, of Terre Haute, Ind., presented a paper on
The Measurement of Power.
This was principally devoted to a detailed description of a fluid transmitter
by means of which the movements either of a lever or a belt
dynamometer could be accurately and conveniently recorded.
Mr. Gray also presented a paper on an
Autographic Recording Apparatus
which was a description of a system of levers which were attached to a
Riehle testing machine for the purpose of producing a magnified record
of the behavior of the test piece during the operation of testing.
Mr. Albert W. Stahl, of San Francisco, presented a paper on
and vanes for the transmission of various phases of wave motion to the
shore in such a manner as to render the utilization of the power possible.
While none of the plans presented were in actual successful service, the
paper was a valuable contribution lo the literature ..I" a subject which is
doubtless destined lo attain a successful soluti. n.
Messrs. Samuel M. Green of Holyoke, Mass., and George I. Rock­
wood of Worcester, Mass., presented a paper on
Two-Cylinder vs. Multi-Cylinder Engine.
This paper was a report of tests to demonstrate that more than twocylinders
were unnecessary to secure the highest economy of steam.
They were made on a triple expansion engines., constructed as to permit
cutting the intermediate cylinder out of the circuit, and runningthe high
ami low pressure cylinders as a two-cylinder compound using the same
conditions of initial steani pressure and load, 'fists made with a steam
pressure of 142 pounds. 'The result showed an economy of 13 41 and 13. II
pounds of dry steam per I II. P. per hour for ihe two cylinder arrangement,
and 13.01, and 13,25 pounds, with the triple expansion arrangements;
thus giving practically the same results for both forms, and both
being remarkably high.
PHILADELPHIA, May 26, 1892.
KDITOR ENGINEERING "MECHANICS" :—
DEAR SIR :—I notice in your edition for May, an article in
which you mention our house iu connection with the Reagan
Water Circulating and Shaking Grate.
Being a machinist and engineer of over 35 years experience I
feel that I am capable of judging somewhat as to the merits of
an invention of this kind. It is so simple in every particular
that auy one, even though not a mechanic, should be able to
determine that it is a good thing, if iu no other way, by the'
higher temperature of the water, particularly when a man can
hold his hand on the feed pipe that enters the grate and dare
not touch it where it emerges from the grate and enters the
boiler. This is one point that no intelligeut man can deny.
The next positive proof is, that burning the same class of coal
as we used before the grate was put in, carrying the same load,
aud everything as near equal as possible, we had saved eight
tous of coal at the end of the month, with less ashes, less work
fire-brick lining. In the ordinary portable boiler the crown sheet is flat, and having much better power, with scarcely any variation in
and, although subject to the greatest heat, is the first part exposed by low- the steam pressure, holding it steady at So lbs., which we were
water. In the boiler tested the cylindrical crown sheet gives a large
effective heating surface, and is always protected by water. This boiler
unable to do before the grate was put in.
has no water sides to fill with sediment which are difficult to keep clean, How any man of ordinary intelligence can stand before a fur­
and liable to burn out; the fire-brick lining of the furnace and combustion nace door and pull out the hot coals and clinker, day after day,
chamber has none of these faults, and also insures a very high degree of roasting the brains out of his head, is more than I can compre­
temperature, and more complete combustion of the gases, and consequent
economy in fuel than any water lined furnace.
hend particularly when this grate is to be had, which does away
'The writer claims this type of boiler will give a very large and efficient with all of this hardship and reduces the work of firing a boiler
total horse power for the weight anil space occupied, and gives a fully- one half. I am aware that some people become so accustomed
tabulated report of tests.
to doing a thing in one way, that it becomes a fixture iu their
Mr. Gus. C. Henning presented a paper
mind, so deeply rooted that it is almost impossible to remove it.
I do hope for the sake of economy that other engineers will
take this subject up and thoroughly examine it, as it is a matter
of great importance, not only to them, but to their employers
as well, as every dollar saved by an engineer, in the faithful dis­
charge of his duty, is certainly appreciated by his employer.
BENJAMIN STOPPER,
Engineer.
A PIPE dome, 40 feet diameter, has been constructed for a
Jewish Synagogue, in Philadelphia, by F. Schmemann, C. E.
The cost was 50 per cent, of solid shaped iron structure.
THE Ball & Wood Company, of No. 15 Cortlandt Street, New
York, has just shipped the eighth 150 H. P. Engine within as
many months to the Edison Electric Illuminating Company of
Paterson, N. J. Iu addition to this average of oue engine per
month, they have also furnished to the same company one of
their Improved 300 H. P Compounds.
Visitors to the Ball & Wood Shops at Elizabeth will now see
over thirty engines under construction embracing types of their
The Utilization of the Power of Ocean Waves.
Improved Simple, Tandem Compouud aud Cross Compound
This paper contained a very full presentation of the theory of wave
motion and then proceeded to describe a number of suggestions of floats Engines all on contract and in preparation for early delivery.

176 ENGINEERING MECHANICS. [June, 1892.
THE MAGNOLIA ANTI-FRICTION METAL.
We are requested by the Magnolia Anti-Friction Metal Co. to
state that the analyses of anti-friction metals, among wliich is
one of the Magnolia Metal, made by Dr. C. B. Dudley, contain
gross errors, as regards the analysis of the Magnolia Metal.
Dr. II. G. Torrey, U. S. Assayer in United States Mint service,
New Vork, states that in the analysis of the Magnolia Metal Dr.
Dudley has overstated one constituent part and has omitted tin
(which it always contains), as well as other materials. Dr. Torrey
also states that the analysis of the autimouial lead which is
given by Dr. Dudley may be a correct analysis, but that not an
ounce of this is ever used in Magnolia Metal.
DANIEL KELLY, No. 51 North 7th St., Philadelphia, has oue
of the largest and best equipped machinery establishments in
the city. As a practical machinist and expert in mechanical
matters Mr. Kelly has a made reputation. He made his start in
one of the largest mechanical establishments of Rhode Island
and started on his own account in this city in 1S67. His stock
covers the best makes of improved pumps, lathes, bolt cutters,
planers, shapers and milling machines. Among the equipments
for machine shops, which have had special sale, is an engine
lathe having a 16 in. swing, 6 foot bed, back geared, screw
cutting, with plain gibbed carriage and turns 3 feet 3 in.
between centres, that cau be furnished with any variety of carriage
or length of bed required ; a large number are in use in
this city. It has independent rod aud friction bend ; bed screwis
made of steel with large bearings and has an open and shut
nut. The cone has four sections, the largest of which is 9 in.
diameter, and all have A ' n - drop, and are 2, 5 a iuches wide for
a 2 iu. belt. The spindles are made of a high grade hammered
steel, etc. ; change gears are furnished with this lathe to cut 2
to 24 threads to the in. and higher numbers desired. The
counter-shaft has patent friction pulleys, 9 in. diameter, 2*+' in.
face, and can make 140 turns per minute. Among the lathes to
wliich particular attention is drawn is a No. 1 square arbor
lathe ; hand lathes in variety ; wood turning lathes ; horizontal
boring machines; traverse drilling machines; pulley lathes;
turret lathes, etc. Complete bolt, nut, spike, washer aud rivet
machinery outfits are quickly furnished The size of the bolt
cutters cut all the way from ,'j to 1 in. to 6 inches. The National
double bolt cutter automatic opeuiug and pump, with internal
overflow, and several important improvements over their two
previous designs. The automatic now used he considers superior
to straight line and others which he has abandoned for it. The
adjustment of tension and working parts of this and pump are
all easily accessible. The cone is supported at both ends and is
out of the way. Mr. Kelly has also two important improvements
caveated, viz : an easily centering device for jaws of vise,
and adjustable ways or gibs on vise so it can be tight or loose,
as required. He has a large stock of power bolt cutters and nut
cutters, surface grinders, bolt binders ; a good strong machine,
well adapted for car builders and railroad work, upsetting brass
rods, etc. Another most important department is iroii planers,
both steam and hand power. A hand and power planer 10x10
in. x 2 feet, having two of the adjustable plates and square
tables. The cutting tool travels back and forth over the work,
which remains statiouary and pieces that would require large
and costly- planers or special tools may be planed without extra
cost or trouble on these machines. They are recommended for
smooth and accurate planing on the regular work as well as for
the difficult pieces. They are built in this form to plane from
20 to 25 iuches iu width and from 4 to 12 inches iu length. Parties
interested should see these planers at work, iu order to fully
understand their great range and adaptability.
The new traverse stroker of 15 in. stroke of cutter bar, 27
inches traverse of saddle pin, and will plane a piece on table 14
inches high, is another important piece of machinery, the finished
weight of which is 2,300 pounds. That the stroke can be
changed while the machine is in motion is one of the special
features recommending it.
Of milling machines, of which he has a large number in
stock, are designed to suit every branch requiring such
machinery intended for large or small work. They- are built of
substantial proportions well put together, and the severest tests
have only increased these machines over every other style. The
calm cutting fixture, a simple device that can be applied to any-
milling machine having an arm and a rack feed table is very
generally being adopted. The former pin is fixed in the yoke
in line with the spindle, and a weight, attached to the table,
keeps the former or model pressure up against the pin. The
former and work are rotated by boom and gear which may be
driven by hand power. The pump department contains a large
lot of these machines in various styles to cover a great variety
of purposes. Among the number is the Rider compression hot
air pumping machine, and for which pre-eminence is claimed as
a pumping machine, which is at once reliable, simple, durable,
and under all circumstances safe. In intrusting it to unskilled
labor no risk is incurred, and it may be properly attended bypersons
under whose care a delicate or complex machine would be
ruined. The Rider Compression Pumping Engine is especially
intended for domestic use in both city and country, and is
adapted to every situation where a supply is required of from
one thousand to two hundred thousand gallons of water per
day. No engine in the world is so simple, nor less liable to
derangement, and no engine is so free from small parts which
wear quickly and make much disagreeable noise. Then he has
the boiler feed pump and heater combined, adapted to feed any
boiler from 1 to 40 horse power. Improved artesian well pumps,
single and double oiling feed pumps, centrifugal pumping
machinery. The hoisting apparatus and tramways for warehouses,
factories, foundries, machine shops, freight depots,
etc., with capacity from 500 lbs. to 12,000; double and single
track, comprise not only the fastest but safest type of hoisting
machines made.
The catalogue which shows the machines iu their general character,
gives a very extended description of any tool or machine,
which may be had on application.
THE P.all & Wood Company ever since the shipment of their
first improved Ball High .Speed Engine in October last have
been running twenty-four hours each day to keep up with their
orders, and now have between twenty or thirty engiues on the
floor under construction, all contracted for. Important additions
to their works are under contemplation. Among their
recent shipments are the following :
Two 300 H. P. Cross Compound Engines for the Brush Electric
Co., Cleveland, Ohio ; two 125 H. P. engines for the Yonkers
Street Railway Co., Yonkers, N. Y.; one 100 H. P. eugine
for the Pennsylvania Railroad Co. of Baltimore, Md. ; one 150
H. P. engine for the Tide Water Oil Co., Bayonne, N. J.; two 300
Cross Compound Engines for the Sauquoit Silk Mfg. Co., Scranton,
Pa.; one 300 H. P. Cross Compound Engine for the Edison
Electric Illuminating Company, Paterson, N. J. ; three 150 H. P.
Standard engines for the Edison Electric Illuminating Company,
Paterson, N. J.; one 150 H. P. for the State House, Trenton,
N. J.; one 100 H. P. eugine for the Meriden Electric Light
Company, Meriden, Connecticut; two 80 H. P. engines for the
Four Seasons Hotel, Cumberland Gap, Tenn.; one 150 H. P. engine
for the Laconia Car Co., Laconia, N. H.; two 150 H. P. engines
for the Chicago Arc Light & Power Co., Chicago, Ills.; oue
100 H. P. engine for Sulzer Brothers, Winterthur, Switzerland;
one 60 H. p. engine for the U. S. Navy Yard, Brooklyn, N. Y.
PALLISER'S Specifications for Contractors, Engineers and
Architects are of use for ready and convenient reference. They
can be had through the trade. Office, 24 East 42d .St., N. Y.
THE Van Duzen & Lift Co. advertise a loose pulley oiler,
which is quite a favorite wherever tried.

June, 1892.] ' ENGINEERING MECHANICS. 111
THE NATIONAL PIPE BENDING COMPANY, of New Haven, of them have been sold in foreign countries. These Heaters
Conn., whose advertisement is faniilar to our readers, are hav­
arc made only by the National Pipe Bending Co., New Haven,
ing a large demand for their Special Horizontal Heater, of
Conn., and are made any size from 8 h. p. to 2,000, h. p.
which a cut is here given. This Heater is arranged specially
for plants where it is impossible to have an upright Heater aud
for use with coudensors, aud can be arranged with the exhaust
through both heads of the Heater, or the exhaust cau go in at
the side and out at the head. A great many of these Heaters are
being used in connection with condensing plants and pumping
stations, aud they are fouud very satisfactory. The feed water
going to the boiler passes through a brass cell, which entirely
preveutsauy leakage from contraction or expansion, as there is
never any trouble on that line. There is also a very free passage
through the Heater for the exhaust, so that it is not choked,
causing any back pressure. The Heater has now been in use
for fifteen years, and is found as reliable as any Heater that
has ever been put on the market, over 500,000 b. p. of them
having beeu sold, nearly all in the United States, although some
THE Jos. Dixon Crucible Co. have issued a neat and instruc­
tive catalogue of their products, whicli can be had on applica­
tion. Special attention is called to their Waterproof Graphite
Greases. Their Smoke Stack and Boiler Plant Joint is giving
excellent satisfaction, and their Traction belt dressing is an excellent
preventative.
FOR some time experiments have been conducted at Newport,
R. I., with a new and very effective submarine mine, whicli has
now been adopted by the Government. It consists of a castiron
box, 3 1 ,' feet long by lS inches square, filled with nitro­
glycerine, and weighing 380 pounds. Riveted to the top is a
malleable iron plate, which has a flange attached, with a screw
threadjon its inside. Screwing into this flange is a composition
head/diaving two ebonite binding posts, and attached to which
are two contact springs. A spherical rubber packing, having
two quarter-inch holes through it for the reception of wires, fits
into the head of this cap, making it perfectly water-tight.
P'itted to four lugs, which are placed diametrically opposite
one another on the cap, are four contact arms, having an ebon­
ite diaphragm secured to the lower end. On the bottom of the
mine proper is riveted a small box, containing a reel of wire
cable, held by means of a pawl whicli takes into teeth on a cog­
wheel. This pawl is in circuit with two electro-magnets, which
are controlled from shore or a station. On one end ofthe cable
is an anchor, by which the mine is held in place. The cable is
long enough to permit the mine to come within ten feet of the
surface. Inside the mine is a charge pan, containing six
pounds of dry gun-cotton and a small dry cell, the wires of
which lead to the binding posts in the cap, and thence down
to a detonator in the centre of the priming charge of guncotton.
SEPARATORS
FOR REMOVING WATER, OIL, GREASE AND IMPURITIES FROM
STEAM.
THE COCHRANE SEPARATORS, HORIZONTALOR VERTICAL
MANUFACTURED
ARE
BY
SOLD ON 30 DAYS TRIAL.
BEING INTRODUCED ON THEIR MERITS, VIZ.: EFFICIENCY AND PRICE.
HARRISON SAFETY BOILER WORKS,
G E R M A N T O W N JUNCTION, PHILADELPHIA, *f»A.
THE IMPROVED BALL ENGINE.
SIMPLE, COMPOUND AND TRIPLE, HORIZONTAL AND VERTICAL,
— AS BUILT BY
THE BALL & WOOD CO.,
Office, 15 Cortlandt St., New York,
Is superior in DESIGN, FINISH and WORKMANSHIP. In REGULA­
TION and ECONOMY it has no equal. Built with new tools, from
new patterns, and after long experience, it should and
DOES mark tbe latest step in steam engineering.
REPRESENTATIVES:
THOS. G. SMITH, Jr., No. 11 Hammond Building,. .CINCINNATI, OHIO.
W. B. PEARSON & CO., Home Ins. Building, .... CHICAGO, ILLS.
A. M. MORSE, & CO., Commercial Building, .... ST. LOUIS, MO.
W. A. DAY, No. 128 Oliver Street BOSTON, MASS.
HYDE BROS. & CO., Lewis Block PITTSBURGH, PA.

IV ENGINEERING MECHANICS. [June, 1892.
THE GARVIN MACHINE CO,
Milling Machines,
Both UNIVERSAL and PLAIN.
Screw Machines, Monitors, Gang Drills,
Profilers and Tapping Machines.
CATALOGUE ON APPLICATION.
DANIEL KELLY,
51 North 7th St., Philad'a, Pa.
No. I Universal Milling Machine.
THE NATIONAL ADTOMATIC BOLT CDTTER
For Cutting Bolts. Also Bolt
Headers and Pointers.
THE BEST MACHINE MADE.
The advantages of this machine are
/ convenience in handling and good workmanship.
Sole Specialist in Bolt and Nut Machinery.
DANIEL KELLY,
51 NORTH SEVENTH STREET, - - PHILADELPHIA, PA.
THE M. T. DAVIDSON
Improved j&e&m pump.
FOR SALE.
•Warranted to be the
simplest and most efficient
steam pump in the
market, whether
SINGLE OR DUPLEX.
A DANIEL KELLY,
S 51 North Seventh St., Phila.
One 21 in. x 13 ft. LODGE & DAVIS ENGINE LATHE, complete.
One 24 in. x 20 ft. FII-IELD ENGINE LATHE, complete.
fine No. 3 GARVIN UNIVERSAL MILLING MACHINE, complete.
The above-mentioned machines are new, never having been used,
but will be sold at a sacrifice to settle up an estate.
DANIEL KELLY,
51 North Seventh Street, Philadelphia, Pa.
THE NATIONAL FEED WATER HEATER.
A BRASS COIL HEATER delivering Water to the
Boilers at 212° Fahrenheit.
400,000 HORSE POWER NOW IN USE
PRICES LOW. SATISFACTION UNIVERSAL.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE.
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
OF HOLYOKE
STEAM PUMPS,
WATER WORKS ENGINES.
WRITE FOR ILLUSTRATED CATALOGUE.
f Deane Steam Pump Co.
IT5" HOLYOKE
HflT^*V*r>Tl"I=: . TOTAjSIrS MASS
72 Cortlandt St.,
NEW YORK.
49 N. 7th St.,
PHILADELPHIA.
9 S. 4th St.,
ST. LOUIS.
54 Oliver St.,
BOSTON.
226 Lake St.,
CHICAGO
1710 Blake St.,
DENVER

July, 1892.] ENGINEERING MECHANICS. 177
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, .Mechanical, and Mining Engineering.
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
London Office, J70 Strand, D. NUTT, Agent.
Entered at the Post-office in Philadelphia as Second-Class Mail Matter.
SUBSCRIPTION RATES.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
THE Mannesmann rail making process is to be improved by
making the rails hollow and filling them, while hot, with sand
or auy silicious powder, which, under heat and roll pressure,
will become a solid block of silica. Greater endurance is
claimed for rails so made.
THE Pullman Car Co. use electric lighting, which costs seven
cents per lamp per day. The plant includes a Brotherhood en­
gine and an Eickemeyer dynamo, at 50 pounds pressure, the
dynamo running at 900 revolutions per minute generates 80
amperes at 72 volts, when all the batteries and lamps are in circuit.
PROF. CROOKS latel}- used an induction coil giving 20 alterations
per second aud 467,000 volts to charge a battery of Leyden
jars. The vibrating current raised the number of alterations in
the final current to 1,000,000, while the volts were 116,000. He
and others are patiently following in the footsteps of Nikola
Tesla, who is now quietly preparing some new electrical surprises
for the scientific world.
REV. F. J. SMITH'S chronograph is a very delicate and practical
device, wliich measures time and distance to very minute
degrees, by graphical devices, by the breaking of electric circuits
and a tuning fork. He also can measure the modulus of
elasticity of metals and can take photographs in rapid succes­
sion by means of electric sparks of moving objects.
Captain Holden, R. A., has a chronograph which takes successive
records of short intervals of time on a revolving drum.
THE photograph of a flying bullet can be taken in one twohundred
thousandth of a second, as has been ascertained by
experiments. It is obtained by throwing the shadow of a bul­
let, obtained by au electric spark on to a sensitized plate. The
bullet completes a circuit between a lead and copper wire, and
discharges a small Leyden jar which gives the spark that produces
the photograph. In its passage it showed compressed
air in front and the effort of the air to fill the space in the rear.
THE breech loading mechanism known as the interrupted
screw system is likely to be supplanted by the Gerdom breech
mechanism. The other system used by Krupp has a motion of
translation only at right angles to' the axis of the piece. In the
improvement referred to the locking is done by an interrupted
screw, and the motions of the block are two, one of rotation
about the axis of the block and the second of revolution about
the vertical axis. The motion of translation is entirely dis­
pensed with.
PROF. J. B. JOHNSON, of Washington University, St. Louis,
Mo., a high authority, finds the elastic limit of Staybolt iron to
be 28.300 lbs. per square inch and breaking strength 49.200 lbs.
per square inch. He adds : " This is a remarkably fine specimen
of wrought iron for staybolt purposes. Its elongation, 34
per cent., is the greatest I have ever found for wrought iron,
aud this is of the utmost importance in staybolt iron. The
fracture shows a pure, fibrous, unlaniinated and uncrystalline
structure."
EXPERIMENTS with the light of arc lamps show that all
PHILADELPHIA, JULY, 1S92.
parts of the crater of the arc are at equal degrees of brilliancy.
The light thrown on any zone of ground beneath the lamp
THE Heilmann electric system is to be applied to a locomo­ varies with the cosine of the angle it makes with the arc, but
tive, and it is designed to develop 4S0 h. p.
calculations based ou this single rule are jeopardized by the
fact that the lower carbon eclipses partially the light thrown
THE inequality of temperatures in steani boilers, especially vertically. The light of any particular angle is proportional to
marine boilers, is giving engineers some trouble, because of the area of the crater seen from that angle. What inventors
the straining ofthe plates, due to the sudden transition from a have to do is to devise means to utilize the light now eclipsed
high temperature to a low one.
bv the lower carbon.
THE Fansa Dam, which forms the reservoir from which water
is supplied to Bombay, is the largest masonry dam in the world.
It is two miles long, 118 feet high, 100 feet thick at greatest
depth and top, isjz feet broad. The lake covers au area of 8
square miles. The supply area is 52 square miles, and the
reservoir capacity 100,000,000 gallons per day. There were
I 4,7 0 7.°°o feet of coarse rubble stone used. The quantity of
masonry was 11,000,000 cubic feet. The maiu to Bombay required
50,000 tons of cast iron pipe, 4S iuches diameter, laid
above ground. Each section weighed five tons.
FOUR Worthington Pumps, with a capacity of 40,000,000
gallons per day, will supply water for fire protection at Jackson
Park. An electric launch, 36 feet long, seating capacity 30,
will be used on the watering fair grounds. A Jenney four
horse-power motor, wound for 100 volts gives a speed of nine
miles per hour. The Union Switch and Signal Co. is erecting
mechanical interlocking machinery on several railroads at
points near where they enter Chicago. There will be fine interlocking
towers, and pneumatic signals are to be constructed
with all switches. The total amount of road covered is eight
miles.
IT has been within a comparatively short time that proper
attention has been given by engineers and capitalists to the
capabilities ofthe arid regions of the west. The irrigation engineers
have organized themselves into an association, and will
hereafter meet two or more times each year. No less than a
score of schemes of irrigation have been worked up and are in
a fair way of being pushed through. Among them is one deserving
of special notice. A large, artificial reservoir is to be
built on Salt River, Arizona, with au estimated capacity of
163,000 cubic feet. The dam will be 200 feet high and the water
will extend back 16 miles. Cost, #1,500,000.
ENGINEERS, working with high temperatures, will be pleased
to know of the introduction of a a new optical pyrometer by
which it is possible to read the temperature of a furnace or a
piece of glowing metal, by merely looking at it through a telescope.
This is the principle : The light of a naphtha lamp and
the light of the glowing body is allowed to reach the eye
through a piece of red glass, aud the aperture through whicli it
conies is expanded or contracted by means of sliding V-shaped
shutters until a uniform illumination of the two parts of the
field of vision is attained. The shutters have an arm that moves
over a scale graduated, either by meaus of platinum-rhodium,
or thermo-junction pyrometer.

i7S ENGINEERING MECHANICS. [July, 1892.
THE British Government will expend ,/,'20o,ooo in building
light-houses 'along the Red Sea. The Government of New
South Wales proposes to expend /, 3,000,000 in water aud sewerage
works, reservoirs and bridges. There is 15 per cent, less
shipping progress in the Scotland ship-yards than a year ago.
At the last meeting of the British Institution of Mechanical Engineers
300 members were present. The Institution is iu an
exceedingly vigorous condition It requires five tons of coal
per week to keep the electric plant of au ordinary English ship
going one week, and this coal space would hold candles enough
to last six mouths. Both French and American eugineers are
engaged on plans and inventions to work guns by electric
motors.
IN English engineering circles considerable interest is now
being excited over a process which has been discovered for enamelling
the iuterior of boilers, with a view to the prevention
of corrosion aud incrustation. Experiments have been proceeding
with the process for the last three years, and the results
are certified by local firms to be of a most successful character.
Further tests are being applied, and if what is claimed
for the process is definitely attained, the gain to engineering
generally will be great. During the past month a limited liability
company has beeu formed for the purchase of the patents
working the process in question. The first directorate will include
Mr. Richard Bttrnwell, head of the Fairfield Ship-budding
and Engineering Company ; Mr. Andrew Stewart, malleable
iron tube manufacturer ; Mr. Graham Hardie Thomsou, iron
merchant; Mr. Robert M'Lareu, pipe-founder; and Mr. John
Draper, chemist.
HERE is a suggestion to our railway presidents who have
long tunnels on their lines. The Batignolles tunnel, at Paris,
is to be lighted with 9CO incandescent lamps, but to run them
all the time would cost too much. So each train on entering
is to automatically light only those lamps opposite the train.
On the walls are to be printed, besides a limited number of advertisements,
reading matter which will be provided along each
side of the tunnel. By an automatic process, quotations ou the
Bourse, the latest news telegrams, winners of horse-races, and
other matters of interest will be displayed, aud as the train
slows down before entering the tunnel, it is easy for the passengers
to read what is exposed to their view. In this way
they would obtain information that otherwise would not be
available until some hours afterwards. The laying down of
this installation is beiug now actively proceeded with, and it
will be completed in the course of next month.
THE next sitting of the European Railroad Congress will be
held at St. Petersburg iu August, 1S92. The subjects for consideration
are —uniform technical terms, frogs and switches,
maintenance of track, limit of wear of tyres and rails ; relation
between track aud bridges aud track and rolling stock, track
for fast trains, control of speed of trains, breakage and wear of
steel rails, maintenance of track on metal and wooden sleepers,
durability and preservative treatment of wooden sleepers, track
aud rolling stock on curves, production of steam in locomotive
boilers, high pressure and the compound system, high pressure
and differential valve gears, rolling stock for lines with lioht
traffic, continuous heating for passenger trains, locomotive run­
ning, double screw system v. first-in-first-out system, locomotives,
fuel consumption, tubes, tyres, lubrication, crank axles,
fire-boxes, boilers, switch engines, lubrication of car axle journals,
etc. The first sitting of the congress was held at Brussels
in 18S5. The congress is now supported by 32 governments
and 244 railway administrations, representing 123,260 miles of
railway. The Chinese and Japanese Governments will be represented
at tbe St. Petersburg congress.
THE shallowness of water has a retarding effect on steamships.
In a recent trial a vessel made 17.S knots at high tide
and 16.9 at low tide with 2600 horse power. The " Edgar," in 12
fathomsof water, required 13,260 horse power to attain 20 1 , knots.
In 30 fathoms she reached 21 knots with 12,550 horsepower.
or a loss of A knot. The " Latona" made ^ knot in speed in
deeperwater atStokes' Bay. The " Blenheim," in 9 fathoms, with
15,750 horsepower, made 2oknots. Iu 22 to 36 fathoms the speed
rose to 21', knots. Depth of water gave increased speed of iA
knots. This is certainly a strange statement, but it is borne
out by facts. The eminent engineer who makes it offers no
explanation, nor does he intimate to what extent the speed of
ships might increase with increasing depth. The only explanation
given is, that the ship drags water, and that when the
water is not very deep the bottom offers greater resistance to
the dragging. It is now in place for naval engineers to explain
this phenomenon mathematically.
PlERE H E IS AGAIN !—An English engineer thus proclaims :
"I have done what no engineer in the world has done. . . .
I have found a means to reverse the engine without excentrics.
I have also found a means to balance the slide valves.
I have also found a means to cut off the steam at any part
of the stroke, thereby making two revolutions with only one
cyliuder full of steam. I have also found a means of making
all steam engines without a steam jacket or steam box.
This patent, I suppose, all mechanical engineers will tell you is
a downright lie ; but I am in a position to prove it. This
engine will save millions of money in coals alone, and hundreds
of thousands of money in the manufacturing of the
steam engines, and, I may sa}-, thousands of lives. This
engine has no exceutrics, no excentric rods, no excentric pulleys,
r.o connecting-rods ; it need not have a starting or stopping
valve—unless thought proper"—and so on, through half
a column or more, which even then does not exhaust the wonders
of this startling invention or the marvellous capabilities of
the inventor.
AN improvement iu telephoning has lately been introduced
in England in which a metallic return circuit is established between
all telephones, which avoids induction from near-by wires
or earth currents, and which prevents all cross talk. The receiver
is of the Graham-Bell type, but instead of a coil fixed
round the permanent magnet of that instrument, this magnet
has a horseshoe-shaped armature of soft iron, mounted on the
pole nearest the diaphragm of the instrument, aud a coil is
mounted on each side of the two legs of the shoe.
No call-bell is provided at the central station, but the attendant
sits constantly with a telephone to her ear, and is put into
communication with any subscriber by the latter depressing a
lever, fixed to the stand of his transmitter. Under his directions
the attendant connects both the main wires from his instrumeut
to the main wires from the instrument with which he
wishes to establish correspondence, and when this is done, the
call bell at this instrument can be ruug by turning a handle
fitted to that of the person desiring correspondence. A similar
bell is fitted to his own transmitter, which is rung by turning
the same handle, but only when the main wires from his instrument
are coupled up to a second telephone. The subscriber
therefore knows that he has been switched on as desired by his
own bell ringing on turning his call handle.
AN interesting paper on " Solar Heat " is giveu in a recently
issued volume of the " Transactions " of the Astronomical and
Physical Society of Toronto, by Dr. Joseph Morrison. Two
theories have been advanced to account for the source and
maintenance ofthe heat of the sun. One ascribes the heat to
the energy of meteoritic matter falling on the sun, the other
asserts that the supply of heat is kept up by the slow coutrac-

July, 1892.] ENGINEERING MECHANICS. 179
tion ofthe sun's bulk. Taking the " solar constant " as twentyfive
calories per square meter per minute, Dr. Morrison calculates
that the linear contraction of the radius of the sun which
is requisite to keep up the present rate of radiation, is 000000-
497 2 ft- iu one second, or 156 9 ft. in a year, or 29,716 miles in
a thousand years. " Now 450 miles of the sun's diameter sub­
tends at the earth an angle of 1 sec, and therefore it would require
7575 years for the sun's angular diameter to be reduced
by i sec. of arc, which is the smallest angle that can be accurately
measured on the solar disc." With regard to the meteoritic
theory of solar energy, a calculation shows that a quantity
of matter which weighs one pound falling freely from
infinity to the sun would develop by its kinetic energy 82,340-
000 units of heat. From this it can be found that the heat
radiated could be developed by the annual impact on the sun
of a quantity of meteoritic matter a trifle greater thau i-iooth
ofthe earth's mass, and having a velocity of 3S26 miles per second.
THERE is a stroug tendency in the United States to convert
raw material into more or less finished products. The
construction of the Nicaragua Canal will add a stimulus to
that teudency, because of the advantages in distance and freight
to Asiatic countries. That water-way will render the distance
from eastern manufacturing centres to Japan one-half, and enable
us to supply the Japanese and East Indian market with
our raw cotton. Coal averages $t.io per gross ton at the mines
and is sold at less than English coal at New Castle, while the
general average of English coal is $1.57 per gross ton. England
has already lost the advantage of cheaper coal, and trades
unionism is depriving her of much of the advantage of cheaper
labor. Freight rates have been steadily declining on raw and
finished products in our own countn-, and with the steady decentralization
of industries a turning point will be reached in
a comparatively brief time, when the manufactured products of
this couutry can compete in some of the great markets of the
world with those of England. There has beeu an increase between
two, and three-fold in the exports of locomotives, cars,
glass, locks, hinges, builders' hardware, saws, tools, stationary
engines aud boilers since 1890. This tendency towards the fab­
rication of raw material is receiving support through a number
of influences, and must, ere long, give evidence of its expansion
in a greater export trade to countries heretofore almost exclu­
sively dependent on British sources of supply.
LEAKING tubes in marine boilers are giving the engineers no
end of trouble. Mr. Yarrow suggests a thin tube plate. Doubtless
in the two matters of expansion and circulation, or the ne­
glect of them, has rested the secret of most boiler troubles.
The difference in temperature between saturated steam at the
very highest tension used, and the furnace gases is so great
that one cannot believe that water, which should be practically
the same temperature, can be in contact with the tubeplate and
tube ends. Experiments have been made, in order to determine
this point, by inserting a tube through a stuffing-box iu
the boiler shell, and drawing off the contents ofthe boiler from
any part by sliding the tube in or out. The experiments, how­
ever, are not likely to prove very instructive, carried out in the
way that was adopted iu making them. Water at any considerable
pressure of steam at that temperature, would not appear
as water on being released in the atmosphere. If only steam be
present in the neighborhood of the tube ends, it may be at
times superheated steam. One can conceive that the heat may
be transmitted so rapidly to the water in the boiler, owing to
the intensity of the flame, that water would be evaporated and
superheated before the steam could disentangle itself of a vessel,
and, although the circumstances are by no means parallel.
the fact may serve the purpose of illustration. In water tube
boilers the water sometimes gets ou the top of the steam—one
boiler of this class was designed specially ou this principle—
and the question arises whether, iu navy boilers crowded with
tubes only having an inch space between them, the same effect
is not produced. What probably happens is that steam aud
water alternate amongst the tubes, more especially at the tube
ends ; steam is formed, hangs to the surfaces at first and increases
in volume, until the water breaks through and the
steam finds its way upwards through the wilderness of tubes.
If the period of these alternations of steam anil water contact
is at all extended one cau understand how hard it must be on
the joints between the plate aud tube, aud there is quite enough
to account for the water pouring out at the furnace mouth
faster than it can be pumped through the feed valves.
The trouble from leaky tubes has led to the introduction of a
device for the protection of the tube ends from actual contact
with the hot gases. This is the application of a protecting ferrule
which has a trumpet-mouth end very much turned over.
The ferrule is of considerable leugth, so that it projects inwards
some way beyond the tubeplate. It also projects outward beyond
the tube, and the bell, or trumpet-mouth end, turning
back until its edge touches the tubeplate, thus forms a shield
to the contact joint betweeu the tubeplates.
The necessity for greater speed demands the highest possible
form of boiler. So after all the only way to stop the leaks is to
go slower, aud that means larger boilers.
WE are promised one more step forward in the metallurgical
field. The science of steel making has been neglected in the
higher experimental fields for twelve or fifteen years. Mr.
William Anderson, President of the British Association of Mechanical
Engineers, in his recent address, said, regarding the
sluggish progress in metallurgical arts, and especially with reference
to steel: " The problem indeed is excessively involved ;
it amounts, in fact, to a consideration of the number of permutations
or combinations possible among some ten variables,
the relations of which to each other are also dependent, not
only on actual temperature, but also on the rate of its changes
and on the uniformity of these changes throughout the mass.
In the first place it seems almost certain that pure irou, which
is the basis of steel, is allotropic, and can exist in at least two
forms, one of which is hard and the other soft. Carbon, again,
which is an essential ingredient, also exists in steel in two forms
—either in chemical union with the iron, or not merely in such
union, but at the same time also in the form of detached patticles
of carbon suspended in the mass. There are other ingredients
besides, even iu the purest steel, if theoretical purity be
considered a combination of iron and carbon only, as some
authorities hold that it is—which, it is well known, even in
very minute quantities exert a notable influence on the mechanical
properties of the material ; and these properties are
further dependent on the temperature to which it is heated, and
on the manner and rate of heating aud cooling. In consequence
ofthe changes through which iron, carbon, and possibly other
constituents pass during changes of temperature, the chemist
is impotent to pronounce from mere analysis what the quality
of steel may be ; and the ordinary mechanical tests are not of
much avail, because the specimens are not and cannot be in
the same condition of internal stress—ou which again the molecular
arrangemeut appears to depend—as the masses from
which they are cut. Moreover, specimens for mechanical testing
cannot always be taken from the central parts of the huge
forgings and castings now in use for many purposes. It certainly
appears to me that the mothod of noting the rate of cooling
by curves automatically traced, as now so well and so in­
geniously worked out by Professor Roberts-Austen, affords the
best promise of placing in the hands of the mechanic the meaus
of judging at auy rate of the uniformity iu composition of the
material, and even, perhaps, of its actual chemical nature, so
far as this affects his wants. It is, besides, uo small advantage
that the thermo-electric autographic apparatus is cheap, that it
occupies but little space, that it cau be employed in au ordinary
room, and that the results sought can be obtained iu a few minutes.

1S0 THE CONSTRUCTOR. [July, 1S92-
Translated by Henry Harrison Suplee.
CHAPTER XX.
1276.
BEL TING.
SELF-GUIDING BELTING.
Belt pidleys are indirect acting friction wheels (\ 101) and the
belt itself is a tension organ combining the functions of driving
and guiding (§ 261). Those belts which act without requiring
the use of special guiding devices may be called self-guiding
belts. This action is attained by the use of cylindrical pulleys
when the edge of the prismatic belt runs iu a plaue at right
angles to the axis of the pullev ; or in other words, when the
middle line ofthe advancing side ofthe belt lies iu the plane of
the middle of its pulleys.
When a belt runs upon a conical pulley in a direction normal
to its axis, its tendency will be to describe a conical spiral path
upon the pulley, as w'ill readily be seen upou the examination
of the development of the surface of the cone, Fig. S40.
If the pulley is made with a double cone face or a rounded
face, Fig. S41, the tendency will be for the belt to run at the
middle of the face even when the direction of the belt is not
exactlv correct.
For "leather belting, with a height of the crowning or curvature
of the face s = A of the width of face, the belt may deviate
from the plane of the pulley by 2y' a (tan = four per cent ),
while for cotton belting, on account of the lesser elasticity of
the material, the crowning 5 should not exceed r',,T of the face,
thus reducing very materially the permissible deviation. In
ordinary circumstances at least oue of a pair of pulleys should
be made with rounded force.
FIG. 842.
The simplest arrangement of self guiding belting is that for
parallel axes, Fig. S42 a and b, a being for open belt and b for
crossed belt, either arrangement beiug suitable to run iu either
direction.
F"or inclined and intersecting axes self-guiding belts are not
suitable, except in the case of inclined axes in which the trace
5 5, Fig 843, of the intersection of the planes of the two pulleys
passes through the poiuts at which the belt leaves the pulleys.
The leading line then falls in the middle plaue of each pulley,
but the following side of the belt does not, hence such systems
cau only be run in oue direction. The leaving poiuts in the
figures are at a and by The arrangement gives au opeu belt
wheu the angle 3 between the planes of the pulleys = 0°, aud a
crossed belt wheu 8 = 180°. In the intermediate positions a
partial crossing of the belt is produced. If ? = oo°, the belt is
half crossed (or as commonly called, quarter twist); if 3 = 45 0 FIG. 844.
In Fig. 844 examples are given of guide pulleys for parallel
axes, all three pulleys lying in the same plane.
At a is showu a belt trausmission with tightening pulley, b is
a device for transmitting motion when great difference of speed
is desired. Iu this case the guide pulley Cis as large as the
driver A, and if desired may also be arranged to act as a tightener.!
At c is Weaver's device for similar uses.*) In this case
two belts are used, and the device has been used for driving
circular saws. The pulleys should be fitted to run very smoothly
in such devices.
The cases in Fig. S45-S46 have parallel axes with two guide
pulleys. In the first case the guide pulleys are placed iu planes
, tangent to both operating pulleys, and hence driving may occur
it is quarter crossed.*
iu either direction. Usually, however, it is required to provide
- : The aoove geometrical construction is only approximate ; for an exact
solution see a paper by Prof. J. D. Webb, Trans. Am. Soc. Mech Eng'rs
Vol. IV., 1883, p. 165.
Translation Copyright, 1890.
The leading off angle may be made as much as 25°, which
occurs when the distance between the axes is equal to twice the
FIG. S43.
diameter of the largest pulley. Another rule for the minimum
distauce between shafts for quarter-twist belts is to make the
distauce uever less than v b D.
GUIDE PULLEYS FOR BELTING.
When a belt transmission is arranged with guide pulleys,
proper guiding action is obtained when each guide pulley is
placed at the point of departure of its plane with that of the
uext following pulley.t
t See also the paper of Prof. Webb, referred to in the preceding note.
t Eckert's patent (German) for driving the drum of a threshing machine.
\ See Cooper's Use of Belting. Phila., 1878, p. 171-

July, 1892.] ENGINEERING MECHANICS. 181
S, j s
FIG. 845. FIG. 846.
s, s
for motion in but one direction, iu which case the second form
is used as being simpler of installation. The pulley B may be
used as one of the guide pulleys,
in which case it may be placed
loose upon the same shaft as A,
and C ox D be made drivers or
driven.
By placing the guide pulleys
between the axes of A and B,
instead of beyond them, they
will revolve iu the same direction,
and may be made fast
upon one shaft, as in Fig. 847 ;
this arrangement admitting of
motion in only one direction.
In Fig. 84S is an arrangement
for inclined axes, which is a
modification of Fig. 846, as will
be seen by the dotted lines.
The guide pulleys run in opposite
directions, but may conveniently
be placed upon the
same shaft.
In Fig. 849 is shown an arrange- P o
ment of quarter-twist belts with
guide pulleys. One side of the belt is placed in the intersection
6" 5 of the planes of the two pulleys. From auy point c
FIG. 84
Fig. 851 shows the general case for inclined axes. Two
points c and i\ are chosen ou the line of intersection 55 of the
planes of the two pulleys, and the tangents c a, c b, r, a„ c, b,
FIG. 851. FIG. 852.
drawn, and iu the planes of these tangents the guide pulleys
C and C, are placed. Under these conditions the rotation may
be in either direction. The arrangement shown in Fig. 852
occurs when the line S S passes through the middle of one of
the pulleys.
FIG. 848.
A simplification of the general case occurs wheu, as in Fig.
on 5*5, the tangents c a and c b are drawn, aud in the plaue of
S53, the guide pulleys fall upon one and the same geometrical
these the guide pulley Cis placed. This arrangement permits axis which is parallel to the axes of both transmitting pulleys.
of rotation in either direction.
In this case the only inclination of the belt is that given to it
Another arrangement for the same purpose is shown in
by the guide pulleys. The rotation can be in but one direction,
Fig. 850. The side of the belt leading off from sl is inclined viz. ; that shown by the arrows ; if the reverse is desired, the
towards B, the other side passing over the guide pulley C, guide pulleys must be placed as showu in the dotted lines.
which is in the same plane as A and 55. This arrangement is If the inclination of the shafts is too great the belt will be
well adapted for driving a number of vertical spindles from one
liable to Urop off when the pulleys come to rest. The use of
horizontal shaft.*
guide pulleys involves special hangers, a practical form for
which is shown iu Fig. 854.!
' An example is Jacob's grinding mill with 40 sets of stones; see Uhland's
Praks. Masch. Konstr., 1868, p. 83, 1869, p. 242.
FIG. S53.
t Patented iu Germany by the Berlin-Anhaltischen Maschinenbau-Aktieu-
Gesellschaft.

182
The vertical axis is provided with an oil bole and is fitted
by a ball and socket bearing to tbe bracket D. The flange on
the lower edge of the pulley keeps the belt from falling off tbe
FIG. 854
pulley when at rest. The form in Fig. 855 was designed by the
author for the arrangement of Fig. 848, both pulleys being loose
upon the wrought iron shaft.
If the position of the shafts can be so chosen that the line
5 5 touches at least one of the pulleys, the very practical
arrangement showu in Fig. 856 can be applied. If the distance
FIG. 856.
ENGINEERING MECHANICS. [July, 1892.
FIG. 857.
r"
A Cis great in comparison with the width of bei':, the pulleys
C and Cj can be placed side by side instead of over each other,
Fig. 857, in which case round face pulleys should be used.
FIG. S5S.
By the use of a fifth pulley the preceding arrangement may
be so modified that two pulleys, B, and Bv can be driven from
one driver, A. This is shown in Fig. 858 as applied in a spinning
mill, in which the pulleys L\ and J?,,are on different floors
of the building, and are also provided with loose pulleys*
parallel shafts, one of which intersects its axis at right angles,
the other passing beneath.
FIG. 860.
Another arrangement, devised by the author is given in Fig.
860 In this case the following side of the belt is passed over
an 'idler pulley, Q or C.„ and a second time around the driver
(see also Fig. 795) hy which the angle of contact ais doubled,
and the modulus of friction eU (| 264) increased. This may be
called a double acting transmission. The cross section of belt
may be made ft of a single acting transmission, so that in spite
of the increase of length an economy of belting is obtained.
One of the guide pulleys may also be used for a tightener.
These devices will also "be considered in connection with rope
transmission (Chapter XXI.) to which they are especially applicable.
I 278.
FAST AND LOOSE PULLEVS.
Fast and loose, or tight and loose pulleys, as they are sometimes
called, are generally used in connection with another belt
transmission in order to throw the latter 111 and out of action
the belt being guided by a belt shifter, which by the means of
forks or finger-bars, enables the moving belt to be shifted.
These shifting devices mav properly be regarded as guide
pulleys, and are sometimes fitted with rollers, as shown dotted
iu Fig. 861, at e and r0.f
FIG. S61.
FIG. 862.
It is preferable to have the loose pulley upon the driven shaft,
since the belt then ean be shifted with a gradual spiral action
by the shifter E, Fig. S61. It is best for the driving pulley to
be made straight face, or if two fast pulleys are used side by
side on the driving shaft, these should have very slightly
rounded faces, if the belt is to be shifted promptly and readily,
and for the same object the shifter should be placed as close to
the driven pulleys as possible. The loose pulley should be kept
thoroughly lubricated, and for this purpose numerous oiling
devices have been made. The friction between the hub and
shaft acts as a driving force upon the loose pulley, and this has
been a source of numerous accidents. This action is avoided
in the arrangement in Fig. 862, in which the loose pulley is
carried ou a consecutive and stationary sleeve D.%
A variety of mechanical belt shifting devices have been
made, \ the desire being to prevent the action of the belt
from moving the shilter. A useful form is Zimmermann s
Shilter, Fig. 863.
FIG. 859.
t-Such roUers as especially necessary.for ^^?r ~*£» ^^ "J>*ch -re
liable to catch on the shilter fingers, ana e\cu .a.6c
In the arrangement of Fig. 859 the pulley --/ drives two cases. . This has been used by the
* See Fairbairn, Mills and Millwork, II., London, 1863, p. ,03.
X See
For
Berliner
the
Verhandluugen, 1669, P."
theoretical discussion of these various arrangements, see i 301.
7 '
Society for Prevention of Accidents, of Mul."°V S *| h Belt shiflers.
i See Berliner Verhandluugen, 1868, P- 17", =•"

July, 1892.] ENGINEERING MECHANICS. 183
The shifter bar F, to which the fork G can be clamped at any
desired point, is operated by the lever //, wliich turns upon an
axis at I, forming a-'dead " ratchet mechanism. The similarity to
the ratchet devices of Figs. 754 and 755 will be observed. The
movement of the bar is effected by connection at K or Kv
and also a sin B = R — Ru which gives
8 which can occur For any value of ft = C A M, draw M N
perpendicular to MA and make M N = the arc M C = a ft.
Drop the perpendicular HI P to A C, aud draw N O perpendicular
to MP. NO will then = a ft sin ft. Through N draw
FIG. S64.
Q N A'parallel to A B, and we have A Q — PQ 4- A P=a
(ft sin ft -f- cos ft). By takiug successively all the va'ues of ft
between o° and 90
Fig. S64 shows a shifter for quarter-twist belt. In this form,
devised by the author, the guide pulley, which is required to
support the belt, also serves as a shifter to move the belt to and
from the belt pulley B, and loo=e pulley B0. If these pulleys
are given greater width thau that of the belt, as shown ou the
right, a vertical adjustment cau be given to the upright shaft ;
a condition sometimes required in grinding mills and similar
machines.
I 279-
0 in this manner, we can determine the path
of the point N, which will be the evolute of a circle, C N D
IT
B D being equal to the length of the arc B M C = — a. If we
now draw D E parallel to B A, and take its middle point E, we
have D F' = E l

184 ENGINEERING MECHANICS. [July, 1892.
FIG. 868.
This has been done in the proportional diagram for cone
pulleys, Fig. 868.
The method of using the diagram is as follows :
The sides A B and D E of the rectangle represent the distance
a between the centres of the pulleys ; all radii are giveu
iu proportional parts ai a, for which reason A B is sub-divided,
the size of the diagram being selected so that A B = 18 to 20
inches. If, then, 1 a and \'
a are two giveu radii for a
pair of pulleys on a pair of
cones, we take the vertical
chord of the curve which
= l / a — 1 a, prolong the
chord downward until its
length = 1 a, and draw the
axis a b e d parallel to A E.
Theu for the other pairs ol
pulleys on the cones, we
1 ::2 have b 2 and b 2', c 3 and
c 3'', etc., which can be
taken directly from the diagram
with the dividers. If
the given pair of radii to
which the cones are to be
made equal, tbe chord R —
/i'i — o, aud the axis will
pass through A" at right
angles to C X.
off toward C, the corresponding radius X d, and
prolong the axial line dd' to its intersection d' with
BE. Then liy off the given geometric ratio on CX,
considering Xd as 1 (shown in the diagram by the
small circles for the ratios \, \, |, J, £), aud draw rays
from d' through the points of division, and these rays
will intersect the curve at the correspouding points
for the pulley radii I\\. We then have for the radii:
a 1 and a \' for the ratio 1 1 4
b 2 " b 2' " "2:4
c 3 " c 3' " "3:4
dX" dX'" " 4^4
c 5 "

July, 1892.] ENGINEERING MECHANICS. i«5
judgment, the value being governed to a great extent by the
quality of the material. Customary values are for:
Leather S — 4000 to 6000 lbs.
Cotton 5 = 3000 to 4000 lbs.
Rubber 5 —- 3500 to 5000 lbs.
Leather and cotton,_/"—-• 0.16 to 0.25*, p = 1.6 to 2.1
Rubber, / = 0.20 to 0.25, p =1.8 to 2.1
These give as approximate values for .
Leather and cotton, — or r = 2.5 to 1.9
Rubber,
T
A'
By using these values together with those giveu for 5, in (262)
we get for the specific capacity for belting :
Leather, cV0 = 0.0062 to 0.0098 ")
Cotton, Na = 0.0036 to o 006S V (265)
Rubber, N0 = 0.0050 to 0.00S2 J
These are based upon'low and moderate speeds ; say up to
3000 feet per minute, and the variations between tbe ltmits given
are those due to the differences in strength of various kiuds of
leather and canvas used.
The resistance to bendiug or stiffness of a belt must be taken
into account, aud the ratio of thickness 0 to pulley radius R,
must not be too great. Practical experience has shown that
— = — should not be exceeded to obtain best results.*
R 50
From the known stress and the thickness of the belt the
superficial pressure /, between belt and pulley may be calculated.
We have only to substitute in (241) for the width b'
of the surface of contact, the width b of the belt itself, and
since q - b S, we get the simple relation :
P_
5
TF
to
(264)
Example /.—Required a leather belt to transmit ioo H. P and the speeds
of pulleys to be n = 80 «j = 150 revolutions. Taking the specific capacity at
0.007 and the lineal velocity of belt at 3000 feet, we have q -—- = 4.8
3000 X 0.007
sq. in. cross section.
4.8
If we use a double belt 0.4" thick, the width should be - — = 12 inches.
0.4
2 TT K ll 3000 X 12
For the driving pulley we have: = v, and R = ~ =71.7
sav 72", or 154 inches. Forthe driven pulley we have K, = •— —- = 38.4''.
.. 33300 X 100
For the superficial pressure p, we have P = — — = 1100 lbs. Also
T = 2.5 P= 2750, hence S\= — -— = 573. We have also (=1.5^= 1650,
which gives S.. — 343, or a mean of 458 lbs., which in {264) gives a mean value
45-8 •' 0.4
2.5 lbs. on the large pulley, and/ -
72
nearly 5 pounds. This is verified since, if/= 0.16:
458
38.4
4.98, or
72 - 3 14 •' 12 2.5 X 0.16 = HOD,
which is the value of Pas above.
Example 2.—What horse power can be transmitted by a cotton belt 4 inches
wide and 0.25" thick, at a velocity of 2000 feet per minute ? Taking the specific
capacity at 0.006, which has been found satisfactory in practice, we have
from (262) N=qv Na = 4 X 0.25 X 2000 X 0.006 = 12 H. P.
Example3.—A rubberbelt is required to drive a centrifugal pump (rubber
being especially adapted for damp locations). N = 20, the pump vane to
make 300 revolutions, and the driving shaft So revolutions per minute, and
the belt speed 2000 feet. Taking the specific capacity at 0.007, we have 20 =
q X 2000 X 0.007, hence q = 1 43 sq in., and if we make 6 — 0.2 we have a
,, ,. r. 2G0 ° X 12
width b -= 7 1 . For the driven pulley we have R, = - - — = 12.71, say
lbs., whence />
id for Un* driver A*
the small pulley.
425 .1 2
47.8
.75 • -.,. 1.1
80
47.8". A mean value of .Sis 425
1.7S on the large pulley and 42s ' - ., - ,,,,
12 71
For extraordinary cases the fundamental formula should
always be applied. F01 double-acting belts, as in Fig. 860, in
The thickness 6 for single leather belts varies from ,\" to ffi'; which u = 2 TT instead of TT, the value fi a = 1, and the modulus
double, triple, quadruple, and even quintuple thicknesses beiug of stress is only 0.6 of the preceding value, hence q is reduced
sometimes used, the thicknesses being secured by cement, and in the same proportion. If the belt velocity v is very high, it
sewed or rivetted together. Cotton belts are usually from f," is no longer permissible to neglect the influence of centrifugal
to \y thick, while rubber belts are made of auy desired thickness,
a web of canvas being interlaid between the successive
thicknesses of rubber.
The stress modulus r depends upon a andy", and the latter coefficient
varies with the age of the belt, being greater with belts
which have beeu used some time thau with quite new belts. It
is advisable, however, to make all calculations as for new belts,
force. For a speed .. = 5000 feet and a stress 5 = 568 pounds
(see \ 264) the exponent in the friction modulus becomes 0.847""
instead of/" a, which for f'= 0.1O and a = tx, givesy"' a = 0.84
X 0.16 TT — 0.42. This gives r = 2.91 or about \ of the normal
value, wliich requires one-sixth greater cross section q for the
belt. The highest limit of belt speed in ordinary practice
appears to be about (>ooo feet per minute.f
iu which case we have for smooth iron pulleys, for:
\ 281.
* For cotton the thinner belts from 0.25" to 0.4" are preferable.
EXAMPLES OF BELT TRANSMISSION.
The table of existing examples of belt transmission on next
page will serve to furnish data for comparison with calculated
results.
The great variations in the values of S and N0, in the following
table are not surprising when the differences in the
quality of material, and the various conditions are considered.
Many leather belts are working under high stresses which arconly
practicable because of the excellence of the material.
Some such belting can be operated under stresses as high as
2000 pounds, which enables much lighter sections to be used.
Many belts which appear to have beeu excessively heavy have
simply been calculated to work at a moderate stress.
The plausible but erroneous idea that the pressure of the
atmosphere influences belt action cannot be admitted. It is
contradicted not only by the fact that the same coefficient of
friction exists for ropes as for belts, but also by the recent
and careful experiment made in a vacuum by Leloutre which
confirmed the theory of the modulus of friction.
jj 2S2.
BELT CONNECTIONS.
The various methods of connecting the ends of belts generally
give a greater stress at the point of connection than in the body
of the belt. The attempts to reduce this weakness and also
provide for the greatest facility in the making of the joint, has
caused a great variety of methods to be proposed ; some of the
best of these are here given :
.0 a a a
0 a a
n i • A
i* * • 1)
FIG. 870.
In Fig. 870, a is a lap joint sewed with hempen thread ; b, a
lap joiut secured with screw rivets ; c is a plate coupling, the
plate and prongs being made in oue malleable casting and the
prongs bent over and clinched after insertion in the belt, several
clamps being used for belts more than 4 inches in width. At d
is shown belt lacings for use with single or double belts. The
upper oue has the defect of giving intersections which make
the lacing cut itself, and the knot at the edge of the belt reduces
the strength of the joint.} These defects are both avoided in tbe
lower form, which is an American belt lacing.^
f In the construction of the Arlberg tunnel a hoisting machine was used
in which the belt had a velocity of 4700 feet per minute, which worked well
for fourteen mouths.
\ Leloutre has used the upper form of lacing for a belt of 26" wide, 0.66"
thick with excellent performance and durability.
?See Cooper, Use of Belting, p. 189.

186 ENGINEERING MECHANICS. [July, 1892.
Horse
""• Power N
1
2
3
4
5
6
7
8
9
IO
11
12
624
200
190
'75
•53
13°
9o
81
60
54
42
40
13 53°
14 497
15 47°
16
17
4»3
325
IS 134
19 60
20 35
21 66
n
40
100
52
182
AA
223
120
AA
120
160
R
108
-
111*
39-37
AA
22.6
_^6_ J28_
94 45-3
65
1S2
AA
137-5
100
IOO
EXAMPLES OF
V
2887
3749
2440
56-9
— — 35 6 *
3°
JA 3955
47-25
83.8
3°
39-37
59
59
1
45 98.4
125 354
60
90
66
102
70.8
47-25
49.2
38-9
60 144
262 27
__7°_ 99
144.4 48
62.5 96
'14 49-5
48 120
120 48
125 60
172.4 43-5
AL
133-3
4 S
45
AA AA
175 29.6
AA
99-3
165
243
3*
3'
37-S
2410
2S33
2833
1535
23.8
2224
2066
5'5&
3620
3*3°
3000
3915
3"3o
P
7114
'731
2528
1573
1256
'544
1034
928
631
660
614
630
3337
4457
4S77
4453
25«3
•39°
2706 722
I&33 704
4/63 45i
BELT
b
105
24
21
29
12.6
10
12
9.8
12.2
17-3
11.8
13-8
38
3°
32
3°
22
10
16.5
5
n.S
TRANSMISSION.
.5
0.67
0-47
0.24
°-35
0.52
0.40
o.35
0.52
o.47
0.24
0.20
0.24
0.72
0.72
0.72
0.72
0.72
0.72
0.47
0.72
052
S
5 12
3S8
1222
388
483
981
612
455
270
400
654
483
3'3
526
540
5*2
412
412
228
4 98
.85
No
.0062
.0046
•0147
.0046
.0059
.0121
.0075
.0056
•0033
.0092
.0082
.0059
.0036
.0065
.0065
.0105
.0049
.0049
.0049
.0062
.0023
REMARKS.
Leather, 2 belts side by
side.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Leather.
Cotton.
Cotton.
Cotton.
Cotton.
Cotton.
Cotton.
Cotton.
Cotton.
S-p]y Rubber.

July, 1892.] ENGINEERING MECHANICS. 187
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
i° Let (Fig. 9) Ao B0 A, Bx be the body or the bodies
considered. Let us conceive them to be subject to a definite
number of forces whose points of application are
whose lines of action are
cx |, oc 2, cx .„ cx t, ot;,,
1 « 1, 2 3- j, 3 * s. 4 ot 4, S cx 5
and whose magnitudes (Fig. 9) are
L 2, 3. 4, 5-
By reason of the restrictions made in \ 67, the reactions which
are exercised in the extreme section Ao Bo (Fig. 9) admit a resultant
; let To be the magnitude of this resultant and Co i'o its
line of action.
Through the origin a (Fig. 9) ofthe force polygon, let us draw
a O equal and parallel to r0 and of opposite flow, so that O a
running from O toward 1? represents the force r„ in magnitude,
direction and flow.
Let us construct the funicular polygon ofthe five given forces
having the point O as pole and let
C, i- 2. 3. 4- 5- Ci
be this polygon.
Let us cut the body or the system of bodies by any section,
plane or not, A B ; tbe poiuts of application bordering on this
section are a , and o s. I say that it follows from this that the line
of action of the total elastic force r exercised on the section A B
by the part Ao Bo A B is the side 2.3 of the funicular polygon
aud that this force r is represented in magnitude, direction and
flow by corresponding polar radius 2.3 or O (."reckoned from
the pole.
In effect, the part Ao B0 A B of the system should be in equilibrium
under the action :
1° Of the forces r0 1, 2.
2 0 Of the action exercised by Al Bl A B accordiug to the
surface A B and which we shall call — r.
The force — r being obliged to balance the ones ra, 1, 2, the
force 4- r is their resultant. Now the resultant of the forces r0
and 1. cx , is represented ou force polygon by the radius 1.2, and
has for line of action 1.2 according to the rule ofthe parallelogram
; by composing, iu like manner, this partial resultant with
the force 2, we obtain a new resultant represented, on the force
polygou, by O Cor 2.3, and having for line of action the side
2.3, which was to be proved.
Remark.—We see that it is essential to specify the position of
the points of application, otherwise we would not know what
the forces, acting on the part Aa Ba A B of the body, are. If,
applications of the forces may be, hence also at the boundary
when these points form a continuous curve. But, in this case.
the two bordering points cx 2 and cx „ placed on each side of the
section A IS become blended with the point where the section
cuts the curve the locus of the points of application, which furnishes
the statement of the second part of the theorem.
The third part is deduced immediately from the second and
first.
2 69-
POLYGON OR CURVE OF THE PRESSURES.—Among all the
funicular polygons of forces directly applied to a body or a system
of bodies as those defined in \ 66, the one defined by the
part 1° ofthe preceding theorem is the only one which furnishes
always the representation of the reactions of the supports, of
the total elastic forces which are exercised in each section, and
of the mutual actions of the bodies upon one another. For, in
order to have mutual actions, it is sufficient to apply the theorem
to sections/ q, />, ./,... (Fig. S) made according to the surfaces
of contact of the bodies.
This polygon gives, therefore, under the most simple and
striking form, all the indications that Statics can furnish on the
forces, whether exterior or interior, which act on the system.
We call it the polygon ofi the pressures or the cut vc of the pressures
in case 2°.
In the case 3°, the polygon or the curve of the pressures is a
funicular polygon or curve, no longer of the forces directlyapplied,
but of their partial resultants determined by a system
of sections. In this case, it furnishes the elastic forces only for
these sections.
The name polygon of the pressures conies from the fact that
this polygon was first employed to determine the pressures in
stone arches ; but, under the general form in which it is presented
here, it can, according to the cases, furnish pressures or
tensions, and, hence, can be called polygon (or curve) ofi the
clastic fiorces. We shall, however, retain, in general, the name
sanctioned, adding that it ought to be called also the polygon
(or curve) ofi Miry, the name of the Chief Engineer of Bridges
and Highways who, first, in 1S42, used it in the study of arches
and has thus become, after Varignon and Coulomb, oue of the
founders of Graphical Sialics.
for example, the point of application cx 3 is fouud at y '.., the force
3 ot '3 would act on this part of the body ; the theorem stated
would show it, since, in this case, the two points of application
bordering on the section A B would no longer be cx , and o- „
but c/. '.,, and y. 4.
2 0 prised between it aud a, b„ the line of action ofthe elastic force
which it undergoes is no longer directed according to the side
2.3 ofthe polygon of pressures, but according to the side 1.2.
Hence, the locus ofthe centres of pressure ofthe sections comprised
between a, b, and a, b., is the portion yf y2 of the indefinite
What precedes remains true, however close the poiuts of line 1.2, comprised betweeu the sections a, b, and a.,bv
\ 70.
POLYGON OR CURVE LOCUS OF THE CENTRES OF PRESSURES.
—Let us suppose now that the question is of plane sections.
Although the lines of action of the elastic forces are the sides
of the polygon of the pressures, and, accordingly, the traces of
these sides on the plane sections form the centres of pressures,
we should not confound the polygon or the curve of the pressures
with the locus of the centres of pressure.
Let us take the case of the isolated forces and the section A B
(Fig. 9) comprised betweeu the points of application cx 2 and ot 3,
in such manner that the elastic force which acts there has for
line of action 2.3, and the centre of pressure Cis the intersection
of this line with A B.
Let us consider a series of sections succeeding one another iu
a continued manner, according lo auy law, and let us trace, in
particular, the ones a,l\, a.zb2, a:.b„

188 ENGINEERING MECHANICS. [July, 1892.
Therefore, we see that it is necessary to take the two points
of intersection such as y, and yf of each of the sections a, l\
passing through the poiuts of application cx , of the forces, with
the two neighboring sides of the polygon of pressures, and theu
the locus of the centres of pressure is the line
n v v ' v v / -.- -. ' v v ' - v ' C
*-n /1 /1 12 /2 "3/3 iiii 1 :i ii. *-1.
which shows that the centres of pressure are indeed, as is evident,
on the directions of the sides of the polygon of the pressures
; but a section, such as A B, which cuts the side 3.4 of
this polygon has not its centre of pressure ou this side, but on
the side 2.3 prolonged. The centre of pressure changes
abruptly for two planes infinitely near placed ou each side of
one of the points of application of the acting forces.
In order that this sudden change may not take place, and in
order that the polygon of the pressures be at the same time the
locus of the centres of pressure, it is necessary and sufficient
that the two points y1 and yf, for example, both be blended at
the point 1 of the polygou of the pressures, which requires that
the section a, l\ passing through the poiut of applicatiou cx , of
the force cx , 1 coincide with the line of action of this force, and
that it be the same with the sections a.1

July, 1S92.J ENGINEERING MECHANICS. 189
ELECTROTECHNICS.
A Compilation of Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
Resistances for heavy cut rents.—Hospitalier proposes an
arrangement similar to Fig. 70, which consists of German silver
FIG. 70.
wires 1 meter long (40 in.) and 3mm. diameter (yi in. approx.,
No. S, B. & S.). Each wire will carry 6 amperes without au
appreciable rise in temperature. The ends ofthe wire are bent
so as to dip into mercury cups as showu, or better still, soldered
to copper bars. A wire 1 m. diameter (No. iS, B. cc S. approx.)
will carry one ampere. Uppenborn employs a resistance box in
which the coils are surrounded bv water, which takes up the
heat generated by the heavy currents, and permits a greater
current density in the wire than would otherwise be allowable.
RHEOSTATS.—Rheostats or resistance boxes for commercial
use are used either to reduce or to regulate the amount of cur­
rent passing in a given circuit, or to reduce or regulate the
E. M. F. between given points of that circuit.
They are in geueral constructed of coils of German silver,
tinned, galvanized or bare iron wire wound ou a suitable man­
dril and stretched sufficiently to separate the convolutions. The
ends are connected to brass terminals, which are segments of a
circle insulated from each other. Connections are made either
so that the coils are connected in series, or parallel by the
movement of a contact arm capable of turning about the centre
of the circle of contacts, aud whose outer pressure is ou the
segments.
It is best, if possible, to arrange the coils so that they are
horizontal, connection taking place more rapidly with such a
disposition. Wires in rheostats should never be subjected to
currents which will raise their temperatures much above the
points given in the tables presently referred to. No current
should be submitted to a wire which will affect its mechanical
strength or by successive heating aud cooling alter its structure.
The tables B—Nos. 11, 12 and 13 are the result of experiments.
In columns No. 1 of these tables the capacity iu amperes may
be used, regardless of the size of the box or the energy in watts
lost in the box, which is ordinarily constructed of dry wood.
With fair veutilation the heat limit is 39 0 C.
Column No. 2 gives amperes admissible wheu fire-proof construction,
using slate, porcelain, etc., for insulating, is employed.
Heat limit 4S 0 C, the temperature of surrounding air being
22° C.
Column No. 3 gives the current allowable for "starting"
rheostats which are used with shunt-wound motors, and which
is not kept in circuit more than one minute.
Iron wires under No. 22, B. & S., do not form sufficiently stiff
coil for practical use. When high resistances are required Ger­
man silver should be employed, expense not forbidding. The
ratio of cost of German silver, tinned and galvanized iron wire,
regarding their resistances and current carrying capacities, is
20 : 1.5 : 1.
Where economy in space is an object (as in electric car
rheostats) resistances are made by winding thin hoop iron ou
sheets of asbestos board, and between each sheet interposing
another insulating sheet. Another way is to employ discs of
sheet iron with a hole centrally punched. These discs are cut
radially at one place and sprung partly open, the end of one
being in contact with the beginning of the next. Insulating
discs of asbestos are interposed, and the whole bolted down,
forming a compact flat spiral whose flat side is perpendicular to
axis.
Prof. S. H. Short uses a rheostat which consists of a cyliuder
containing powdered carbon, in the bottom of which is a cop­
per contact plate. Through the top of cylinder turns a screw
rod whose lower end is provided with a contact plate. By turn­
ing this rod the resistance is increased or lessened according to
the direction Of rotation. Short circuiting is accomplished by
screwing down until the contact plates meet in a grinding contact.
Rheostats are variously employed in applications of electricity
—in stage regulators to "dim " the lamps by gradual steps, in
regulators for dynamos (where the regulation is effected by
altering the magnetization of the field) either in shunt or series,
in regulators for accumulators, pressure equalizers on circuits,
and starting boxes for shuut wound electric motors.
The last being the most general application, an example,
employing the tables above mentioned, is appended.
To start a shunt motor, a resistance must be inserted in cir­
cuit with the armature, and gradually cut out as speed is
attained. Were this resistance left out, the armature having
low resistance and generating no counter E. M. F. would short-
circuit the feeders and burn out. The resistance box or rheostat
should be so calculated that the maximum current allowed to
pass at time of starting is uo greater than the current required
for full load.
Example.—5 H. P. Motor, 220 volts, 90 per cent, efficiency.
This motor, therefore, requires
746 X 5 -*r 90 = 4144 watts.
4144 0 „ , . T, .,
— = 18 a amperes or maximum current. If coils are wound
220
from galvanized iron wire, the nearest size is No. 13 (see table
11 B) whose max. current is 17 amp., aud which is. sufficiently
close, the table including a safety factor. Neglecting the resist­
ance of the armature, tlie resistance between the feeders to
220
maintain iS.S amperes is 18.8
117 ohms. The number of
feet per ohm of No. 13 wire is given as 91.4. The number of
feet is, therefore, 914 X ii:7 = 1070 ft. If spirals are wound
ou 1'+" mandril, th^re will be about three turns per foot, or
3210 turns in all. No. 13 wire (W. & M. gauge) is .092, or about
11 turns per inch. Allow, after stretching, 4 turns per inch.
3210
Then = 802 inches of spiral, or 67 ft., sav 67.5 ft. If i8 //
4
is chosen as length of coil - f'7.5_X_i£
= 45 coils, which may be
18
arranged best in wire sections. Weight of wire = 24 lbs. If
tinned wire is euiployed, 800 ft. will be sufficient. No. 13 wire,
table 12 B, capacity, col. III., 18.3 amp., weight 11 lbs.
A discussion of the general arrangement of rheostats, connec­
tions, etc., is not within the scope of this work. The above cal­
culation is made on the supposition that the heaviest curreut
permissible through the armature is that employed 011 full rated
load. The operation of starting a motor from rest consumes,
however, less than one minute of time, and much larger cur­
rents may be employed, depending on the size of wire ou the
armature ofthe motor. This entails larger wire in rheostat, but
less resistance is required.
Rheostat coils may be connected either in series, parallel or
combination of these. The range of a set of coils in series may­
be increased by connecting to the switch segmeuts, so that when
only one coil is in circuit the next segment will throw two iu
parallel, the next three, and so on.
The tables referred to above are taken from an article by A.
B. Herrick in Elec. World, April 5, 1890.
5) CAPACITY.
a). Absolute Measurement.— A condenser is charged with a
known E. M. F. The quantity or charge is theu
Q = C. E.

i go ENGINEERING MECHANICS. [July, 1S92.
If the condenser is discharged through a ballistic galvanome­
ter (see 1). Quantity). Q = c—av K. Combining these equa­
tions we get
C--
t
AAas/K
t. TT
A second measurement is necessary to eliminate E aud c. A
very high resistance R is inserted in the circuit and the deflec-
E , c 1
tion a, : then the current 1 = -=- = c a. and -— = ———
R E R a,
From the above it is deduced that
C --T-T - >nt
TT R a,
If the galvanometer is not damped *v K== 1.
b). Comparison of two Capacities by a Single Deflection.—
The condenser or cable to be measured is connected as in Fig.
71, and the deflection ou depressing key /noted.
Iu the plan of the condenser Cis inserted a staudard condenser—1
microfarad for example,—whose deflection ft is noted.
The capacitv Cof condenser is then
C = 8 microfarad.
If the capacities widely differ a galvauometer shunt must be
employed. The deflection is then too small.
Let G be the galvanometer resistance, JV the resistance of its
shunt, At the deflection which the condenser would cause without
the shunt, and which measures the correct capacity, and A
the deflection with the shunt ; theu is
At- ^v. + cfA
The correction A" consequent on induction is determined in
the following manner :
Two condensers are procured whose capacities are in the
ratio of 1 : 2. The deflection a of the larger with a shunt N equal
to the galv. resistance is observed, as also is the deflection ft
caused by the smaller without shunt.
Then is A -«(£-
This method is used for short cables and condensers. Its
errors are : I. The deflections of galvanometer are not proportional
to the discharges on account of the air damping. 2. Induction
takes place among the windings. 3. The behavior is
different with cables of much length on account of I.
When condensers are defectively insulated, the leakage current
disturbs the measurement to a considerable degree.
Let a, be the first deflection which changes to a current reading
n.,; then according to Kempe the correct value is
a = Vrc (c 2 a,)
Auother method used in the laboratory consists in obtaining
a constant deflection by charging and discharging the condenser
through the galvanometer a certain number of times per
second, by means of an electro-magnetic tuning-fork.
b). Compensation Method.—The previous method is not applicable
to long cables ou account of the sluggishness of discharge.
The compensation method is shown iu Fig. 72.
The battery ft is discharged through the resistances r, and r2.
Along /•', r, slides a grounded contact t\, so that opposite potentials
may be given to a and tf in any desired ratio.
a is connected with c aud d with/".
After the charge c is connected to b and fi to e, unless the
charges happen to be equal there will be a resultant charge or
remainder, being the difference of the charges c\ and c2. This
is shown by connecting g and h. The contact e is then adjusted
until no deflection takes place in connecting g aud li when
c — c A
C, should be a condenser or set of condensers calculated in
microfarads.
c). Siemens Bros'. Methods.—The condensers to be compared
are successively charged from a battery and discharged through
a very high resistance. The time which the initial strength of
current /takes to fall to i is noted iu both cases. If/, and t are
these periods the capacities are in the following ratio.
c : cl = t : lv
Construction ofi Condensers.
Condensers are built up out of alternate layers of tinfoil and
plates of good insulating material.
The metallic layers are connected alternately to opposite
electrodes. Their capacity is adjusted to microfarads or fractions
of the same, by the addition or subtraction of layers. '/$
microfarad is a size much used in practice. Siemens & Halske
employ mica for the dielectric, Berthoud, Borel & Co. paper
saturated in resin varnish, aud Zellweger & Ehrenberg ebonite.
Clark's condensers are built up of tinfoil and mica coated with
paraffine or shellac varnish. Those of Willoughby Smith have
for the dielectric plate of gutta percha compound containing a
large proportion of shellac.
The capacity Cof a condenser is directly proportional to the
specific inductive capacity K of the dielectric, to the area S of
the opposed surfaces, and inversely proportional to the thickness
d of the insulating layer.
C = KS
2 TT d
A condenser of 1 microfarad capacity designed for ordinary
work is made of sheets of tinfoil and paraffined paper as follow :
37 leaves of tinfoil 1S4 X 152 mm. (43.35 sq. in.) are separated
from each other by two very thin sheets of paper saturated with
paraffin after being thoroughly dried. These are connected in
two series of 18 and 19 leaves respectively. The series of 19 is
grounded.
(To be continued.)

July. [892.J ENGINEERING MECHANICS. 191
VI
u
-a tu
*>.
u
e V
0
u
V
e
2
5
3
3
3
4
5
6
7
7
8
10
10
12
IO
12
•4
12
14
16
PUMPS AND PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
(Continued from page 165.)
MISCELLANEOUS NOTES, RULES AND FORMULA.
4.
to
n
E
rt
4.
V
O
aJ
s
5
*%
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2
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3
4
4
4/4
5
5
6
6
7
7
7
8
8
8
24
0
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t/j
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0
5
D
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4J
4
4
4
5
6
7
8
8
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10
10
12
12
12
12
15
'5
12
THE HALL STBAM PUMP.
Regular Sizes.
PISTON AND PLUNGER PATTERN.
u
4J
P,
U
tn C *40 LU
0 0
~ 41
rt TT
-So
I—
il
c 0
rt" 5 "
US
... p.
a
•°3
.04
.05
.10
.18
•37
•43
•55
• 85
•85
1.22
1.46
2.00
2.00
2.00
3.26
3-26
2.60
•**
0
1- •=
ft?
oj s aj
CD. in
'(/)
100 to 200
100 to 200
100 to 200
100 to 200
100 to 200
75 to 150
75 to 150
75 to 150
75 to 125
75 to 125
75 to 125
75 to 125
75 to 125
75 to 125
75 to 125
50 to IOO
50 to IOO
75 to 125
.g-g Sizes of Pipes for
Short Lengths.
.s-g To be increased as
Brt length increases.
X!
VSm
a* «J "H
> ^
"u 3*3
-d:T u>
ij
a
£
-
Cj= °
,/,'*•

192 ENGINEERING MECHANICS. [July, 1895
pumped, etc. With direct-acting and fly-wheel steam pumps a
piston speed of from 50 to 120 feet per minute will be found a
fair margin for various duties, although a continuous boiler
feeding pump, for instance, will sometimes run slower thau this,
a fire engine pump much faster.
Air Chambers, for heavy pressures especially, should be
arrauged so that they can be readily charged with air, to replace
that absorbed by the water. No arbitrary rules can be made as
regards the sizes or shape of air vessels, which vary according
to the pressure from four to fourteen times the capacity of the
barrel of pump. In the case of steani fire engines air chambers
are usually made of some twenty-five per cent, larger capacity
thau for ordinary pumps, and it may be taken as a rule that the
greater the pressure the greater in proportion should be the area
of the air vessel.
Efficiency of Pumps.—It must always be borne iu mind that
the theoretical efficiency of pumps is much greater than their
actual efficiency-, or in other words, given the size and speed of
a pump, it lifts theoretically a great deal more water than it
does in actual practice. The modulus of efficiency of pumps
working under ordinary conditions may be roughly stated as
follows : Common lift pumps, 50 ; centrifugal pumps, 50 ; ordi­
nary lift aud force pumps, 66 ; air pumps, 56 to 66 ; water works
pumps, So. Claudel gives the following per cent, of efficiency
as taken from actual tests : Fire-engines working with hose, 35-8 ;
pumps for drainage, 50 to 69 ; pumps for town water supply
(single acting), 70 to 75. These figures must not, however, be
considered as arbitrary, as the loss of efficiency will depend
largelv ou the construction of the pump., its speed, duty, leak­
or a little more, but as a pump cau rarely be said to be in perfect
order, a lift of say 15 feet, or even less, if it can be conveniently
arranged, will be found to give a much better effect, iu
fact, the shorter the lift the better the effect. This is particularly
the case with high speed pumps, or when a pump is used for
pumping thick or warm liquid. For hot liquids the suction
should be done away with entirely. Centrifugal pumps will lift
up to 20 feet, but about 7 or 8 feet will be found a much better
working lift, and these pumps also, the lower the lift the better
the effect. It ma)- be taken as a rule, that the faster the speed
of the pump so iu proportion should the length of the suction
be reduced.
Suction Pipes, etc.—Suction pipes should be of ample size, as
straight as possible, and perfectly air-tight; if beuds are necessary,
they should be of as large a radius as cau be conveniently
arrauged. In all cases of long suctions or heavy lifts, foot or
retaining valves should be fitted to the suction pipe, in fact, it
is better to fit them iu all cases, as they keep the pump read)'
charged with water. A rule sometimes employed for steam
pumps is to make the suction pipe one-half the area of the
pump chamber, with an increase iu diameter for high speed
purups or those pumping thick fluids. Strainers should always
be fitted, and the strainer holes be of ample area, say about
three times that of the suction pipe.
Speed ofi Waler through Pipes.—Although water can be made
to fly through water pipes up to a speed of 500 feet per minute,
the actual working speed attempted—except, perhaps, iu
steani fire pumps—should not exceed 250 feet per minute
and a speed of say 250 feet per minute is to be preferred. As
the fluid frictiou iu the pipe iucreases in the proportion of the
square of the velocity, it follows that if pumps are driven at a
verv high speed a considerable loss of power through friction
occurs.
RULES RELATING TO PIPES, ETC.—To find the pressure per
square iuch of a column of water ; multiply the height in feet
by 483-
A cubic foot of water at 62 0 F. weighs 62.36 lbs. 62.36 -•- 144
sq. in. -4= .433 lbs.
To find the quantity of water in a pipe.—The square of the
diameter in inches gives the weight of water iu pounds for
three feet in length nearly. For accuracy add 1.1 per cent.
To find the diameter of pipe required to discharge a given
quantity of water at a giveu speed per minute :
Rule.—Multiply the number of cubic feet of water per minute
by .144, divide by the velocity of flow in feet per minute, divide
hy -7-854, and take out square root, which will give diameter of
l lj pe-
. . . . /144 Xc. ft. permin. . /c. ft. per min.
Diam. iu inches V — = > •-
.7854 X vel. vel.
For a velocity of 200 feet per miuute, diameter^-- v c. ft. permin.
For a velocity of 1S3.3 ft. per minute, diam. = v c. ft. per min.
For American gallons, diam. 4.90
Is. per min.
velocity.
For a velocity of 200 ft. per minute, diam. = .35 1 v gals, permin.
To find the velocity of flow of water in a pipe required to discharge
a given volume of water in a given time :
Rule.—Multiply the number of cubic feet of water by 144,
and divide the product by the area of the pipe iu iuches.
Pump Formulas—To find the horse power necessary to elevate
water to a giveu height.—Multiply the total weight of the
column of water in pounds by the velocity per minute in feet,
and divide the product by 33000 (allowing at least 33 per cent.
for loss by slip, friction, etc.). (Bales.)
age of valves, imperfect filling of the water chamber, etc., and Formula to find horse power of Pumping engines.
will vary considerably iu different makes of pumps.
G = the number of gallons required per hour; C = the
Depth ofi Suction.—Theoretically-, a perfect pump will draw number of cubic feet required per hour ; F = the height in feet
water from a depth of 34 feet, but in practice this cau never be to which the water is to be raised : P=. pressure in square inches
done. If the pump is iu first-rate condition, it will lift 25 feet = F X -443-
G X F Cx F
Horse power = or
237.35 b 3'.73o
Horse power
102,857
£SAA_
13.75°
In these formuke no allowance has been made for friction, etc.
Another Rule.—To find the horse power necessary to elevate
water to a giveu height, multiply the total weight of the water
lifted per minute, in pouuds by the height in feet, and divide
the product by 33,000 (an allowance of 25 per cent, should be
added for water friction, and a further allowance of 25 per cent.
for loss in steam cyliuder).
The area of the steani piston, multiplied by the steam pressures,
gives the total amount of pressure that can be exerted.
The area of tbe water piston, multiplied by the pressure of water
per square iuch, gives the resistance. A margin must be made
between the power and the resistauce to move the pistons at the
required speed—say from 20 to 50 per cent., according to speed
and other conditions.
Theoretical Capacity of a Pump.—Let C = cubic feet of
water per hour, G = American gallons per hour.
D = diameter of pump cylinder in iuches.
4? = length of stroke in inches.
N = number of strokes per minute.
C = .02727 IT- S N.
G = . 204 TPSN.
D f _G
2045/V
G_
204 77 ; X = -—-
5
5
_G_
AOAD 1 N
( To be continued.)

July, 1892.] ENGINEERING MECHANICS. J 93
THE Nicaragua Canal boomers can find a good argument in
the latest figures of the increased traffic. The tonnage has
tripled in eleven years. Last year 4207 vessels passed through
the canal with over 12,000,000 gross tons. Tolls, $15,000,000.
STEATITE by itself, and in union wdth oils and varnishes,
promises to become a very valuable article to protect irou and
steel surfaces, as well as to cover buildings and walls. Experiments
are now being iudustriously made to ascertain its merits.
THE best frequency of alternating currents is a matter of
opinion. On the Continent they range from as low as 20 to 45
and 60 , in England, from 70 to 100; while in the United States
the average is 130, which is becoming recognized as the best,
considering all things.
SEARCH lights have beeu so improved that vertical beams
can be cast long distances. By the addition of a mirror a search
light beam can be directed perfectly vertical, or to any angle,
without shifting the projector, and to produce signals that cau
be read at cousiderable distances.
OMNIBUSES are now being lighted abroad with electricity.
The apparatus consists of a fine cell secondary battery, which
gives a current of one ampere at 10 volts for 15 to 20 hours.
Recharging takes 6 hours. A 5 candle-power Edison-Swan
lamp is used, backed by a white reflector.
MR. MAXIM says : "If I can rise from the coast of France,
sail through the air across the Channel, and drop half a
ton of nitro-glycerine upon an English city, I can revolu­
tionize the world. If I die some one will come after me
who will be successful if I fail. ... It can be done as sure
as fate."
THE punching of acid open hearth steel reduces its tensile
strength from 28 to 21 tons, or nearly 22 per cent., while that
made on basic lining is reduced from 27.6 to 24.6, or 11 per
cent., while a stronger specimen fell from 31 to 29 tons by
punching. This decided the use of basic steel by the admiralty
on the same terms as the acid lined furnace.
A PRIESTMAN launch is coming to this country to serve as a
sample of what the Priestmans can do in petroleum launches.
The boat will be 36 ft. long, 7 ft. 3 in. beam, 4 ft. 6 in. deep,
engine 10 h. p. two cylinders, 9 in. diameter, 9 in. stroke.
Ignition is effected electrically. Nominal speed, 240 revolu­
tions per minute. Speed, 9 miles an hour. Forty gallons oil
good for 6 days' run.
THE Haswell Electro-Browning Process is the product of a
Vienna chemist, by which metals can be better protected from
corrosion than by present methods. Lead peroxide is used as
a coating, and the peroxide deposit is effected in cold water iu
twenty minutes. Its advantage lies in the fact that it is a cold
water process, and does therefore not interfere with the temper
of articles immersed.
Six electric railroad schemes are being considered in London,
two of which propose to build lines from 18 to 30 feet below
the level of the Thames. The tubes will be from 11A feet to
16 feet diameter. The train seating capacity of all these lines
would be 336 persons, und provision would be made for trains
every three minutes on several of the lines. The schemes have
thus far been favorably considered.
ONE pound of solidified petroleum has been found to evapo­
rate 13 to 14 pounds of water, while one pound of best steani
coal evaporated 6 to 7 pounds water. The solidifying is done
by the Clenhall process. In a test a 6 h. p. tubular boiler con­
taining 80 gallons water, was heated by 62 lbs. of the Clenhall
fuel aud in 36 minutes the steam-gauge registered a pressure of
60 pouuds. Factories may be erected in the various oil regions
and the product in bricks shipped.
THE Oerlikon Secondary Battery has been improved by substituting
gelatinous silicic acid soaked with dilute sulphuric instead
of the usual dilute sulphuric acid, for electric car lighting.
The cells contain plates 5.9 ins. square, o. 1 iu. thick, placed
0.14 iu. apart. The weight of cells is 44 pounds, and when
packed in wooden boxes the weight is 97 pounds. Four such
boxes, with support and connections, weighs 530 pounds aud is
good for a 23 hour run. The battery is designed for 140 ampere
hours.
A SAND dredger, with hoppers capable of handling 3,000
tons of sand in 45 minutes is to be set to work soon on the
bar in the river Mersey, Englaud. The Birmingham, Eng.,
municipality want Parliamentary authority to raise $30,000,-
030 to establish a new source of water supply in Wales.
The construction of several great water ways is projected in
Europe. Among them one connecting the Danube with the
Rhine, one between the Elbe and the Danube, and one between
the Oder and the Danube.
A SCIENTIFIC design for screw propellers is a subject that
agitates the minds of scores of marine engineers. Much is written
and many apparently valuable suggestions aud correct formula
written out, but the propeller itself is not yet plowing the
water. Empirical rules prevail because of lack of reliable data.
Past Assistant Engineer H. Webster, U. S. Navy, has published
a table in the May number of the fournal ofi American Society
ofi Naval Engineers based upon trials of fifteen ships and
which will furnish tbe student with valuable material.
THE presence of peroxides in the electrolyte, whereby a proper
diffusion in accumulators is impossible, has given rise to
many theories. The changes in the strength of the acid in
secondary batteries manifests itself in variations of electromotive
force, but electricians differ as to causes. The general
principle is admitted that the stronger the acid the greater the
electromotive force. Yet, in an acid of strength corresponding
to a specific gravity of 1250, no action takes places with lead.
There is evidently a great deal to be learned of the connection
between the detention ofthe acid and the force evolved.
IN an article on Wood Pavement in Paris, contributed to the
Revue Pratique des Travaux Publics by Mr. Brown Vibert, the
author remarks that to insure durability this class of pavement
must be laid with considerable care. The concrete foundation
should be 6 in. thick, and made with 300 lb. to 440 lb. of Portland
cement to a mixture of 9 cubic feet of sand and 27 cubic
feet of gravel. As soon as it has set the concrete should be
covered with a , 7 ,T in. layer of mortar, consisting of 660 lb. of
Portland cement to every 35 cubic feet of sand and left to
harden two or three days. The blocks should then be set
in rows separated from each other by a space f in. wide.
These cracks are filled with cement mortar, and a layer of
broken porphyritic stone \% in. thick spread over the pave­
ment. This layer is soon driven into the wood by the action
of the wheels. Provision must be made for the expansion of
the wood, and for this reasou in wide roadways a space about 2
in. wide is left open along the side walk and afterward filled
with sand. In a roadway 131 ft. wide an expansion of no less
than 16 in. was observed to take place in fifteen days, the blocks
being very dry. In Paris these blocks are 6 in. high, 3 in.
thick, and SA in. long. The cost as laid is about 9s. 6d. per
square yard for Landes pine aud 14s. 3d. per square yard for
northern spruce blocks. The duration is said to be about seven
or eight years under heavy traffic and about fifteen under moderate.

194 ENGINEERING MECHANICS. [July, 1892.
IN the same journal is published a very interesting article ou
the "Transmission of Power " in war ships, being a translation
by Walter F. Worthington, Past Assistaut Engineer U. S. Navy,
also an article written by Nobre Soliani, Chief Engineer Italian
Navy. While asserting that steam must be used for most all
purposes ou war ships, the writer shows that compressed air
can be advisedly utilized for the operation of fire pumps, main
air pumps-, air compressor for torpedoes, hydraulic pumps,
steering engines, capstan engines, winches, dynamo engine for
electric light, blowers for fire room, blowers for ventilation, ash
engines, work shop engines, gun and turret turning engine and
ammunition hoists Steani should be used for air compressors
aud hydraulic system for loading guns. The electric system
has been found useful for working medium and light guns, and
for operating machinery designed to run at high speed. The
compressed air system has many recognized advantages in
dealing with the problem of veutilatiug the internal compartments
ofthe modern ship. Iu the case of au Italian war ship
of the first class, the weight of the machinery by the addition
of compressors is about 125 tons.
CANALIZATION, especially on the Continent, is likely to receive
much more skillful and determined engineering attetitiou
and consideration thau it ever has received, because ofthe rapid
growth of traffic of recent years. The International Convention,
to meet this month at Paris, will take up the whole ques
tion, and probably start influences to work that will, in a fewyears,
largely change and improve and cheapen existing
methods. This country will -be creditably represented by engineers,
who, though not going to teach, can learn a great deal
that they may be able to put to good use in this railroad-covered
country. On the Continent the volume of canal traffic is
rapidly increasing, and it is desired and intended to multiply
facilities for cheap water transportation throughout Europe.
Congresses have been held at Brussels, 1SS5 ', Vienna, 1886;
Frankfort, iSSS; and Manchester, 1S90. Among the questions
that will be considered at the Congress will be the means of
feeding the cauals, and several matters will be brought forward
that have not been discussed at any previous meeting. Atten
tion will also be giveu to the strengthening ofthe banks with a
view to allow of more rapid transport, aud to the storage of
water that can be used, not only for the canals, but also for irrigation
and for industrial purposes. It is also expected that
some definite decision will be come to with respect to the more
rapid towage of boats, as well as upon many other points, such
as the width and depth of canals, the best material for effecting
transport, and the administration ofthe waterways.
A NEW form of fan for ventilating collieries has been introduced
in England. It operates on the same principle that
a locomotive takes water when running. This fan is constructed
entirely of iron, is open running, and delivers its air
from every point of the circumference. The fan is 4 ft. 6
in. diameter, aud 3 ft. wide, with eight blades; the blades
being 4 ft. wide, and 9 in. from circumference towards the
centre—thus leaving 3 ft, or 2 5 of the diameter of the fan
for ingress, aud ', for egress—the aperture through which the
air enters being , 7 S of the whole disc. In trial tests the following
results were obtained : Area of passage, 5 ft. by 4 ft.
6 in., equal to 22 1 , square feet; velocity, 1130 ft. per minute ;
water gauge, 1 "4 in.; cubic feet per minute through the one
side, 25,425, and assumed cubic feet through both sides,
50,850, with fan running at 400 revolutions per minute. We
may add that the fan is to be erected at a neighbouring colliery,
when more definite results will be obtained from actual
working; but Mr. Hopton calculates that a fan of similar
construction, but 24 ft. iu diameter and 9 ft. wide, running
at the rate of 75 revolutions per minute, would extract 813,-
600 cubic feet per minute, aud that from the peculiar design
and construction of the fau, which enables the air to be
takeu hold of aud expelled with very little strain upon the
machine, a fan of this description would be very light in
comparison with others; and that au engine with a 17 in.
cylinder, 8 iu. stroke, aud steam at 55 lb. pressure, would
drive the latter fan without difficulty.
EXPERIMENTS have been recently exhaustively made by
Professor Roberts-Austin at the Royal School of Mines, to determine
whether sulphur can be eliminated from pig iron. It
was found that potassium cyanide, placed on the surface of
molten cast iron, almost completely removed the sulphur. Because
ofthe extreme volatility of the cyanide, a flux had to be
provided to hold this metal during desulphurizatiou, aud
sodium carbonates were tried. Experiments showed that
sodium carbonate alone would not do ; but with potassium cyanide
the results were more satisfactory. The results show that
under certain conditions any amount of sulphur can be readily
and almost completely removed from pig iron. Those conditions
are the contact of the molten metal with an alkaline or
basic slag, aud the necessity of having the metal and the surroundings
in a perfect state of deoxidization—a basic process in
direct contrast to the basic phosphorus process. Indeed, it
would not be beyond the bounds of possibility to find that, if
the conditions ofthe basic-lined converter were suddenly transformed
from highly oxidizing to thoroughly reducing ones, the
sulphur would be removed and not the phosphorus.
The sulphur was eliminated apparently by metallic sodium
with the formation of sodium sulphide, part of which volatilized
while part remained iu the slag. Since the sodium or potassium
is produced in situ, it is obvious that the sulphur will be
more easily removed from pig iron, which favors its production,
thau from blown metal or steel. It fact, it will always be found
easier to eliminate sulphur from cast iron than from steel,
whatever happens to be the means employed.
THE American Whaleback steamer, according to Marine
Engineer Goodall, is destined to supplant English sailing ships
and steam freight ships.
As compared with vessels of the ordinary cargo-carrying
type, the principal advantages of a whaleback steamer are :
Firstly, less surplus buoyancy is required ; or, in other words,
a vessel of a given tonnage will carry more dead-weight cargo.
Secondly, owing to the shape above the load line, together
with the circumstance of the engines being placed aft, the
whaleback is stronger than the ordinary tramp boat, presuming,
of course, that the scantlings are similar.
Thirdly, the reduced amount of superstructures gives a reduced
air and wave resistance.
On the other hand, there are apparent drawbacks in the
whaleback steamer. Some of these are :
Firstly, iu case of injury to the ship's hull, the reduced spare
buoyancy would increase in proportion the danger of sinking.
Secondly the absence of masts and sails, in case of a breakdown
of the machinery, would be a serious cause of helplessness
and danger. It would be practically impossible to have
masts iu a whaleback steamer of the American type, and to
work the sails with effect at sea from the narrow platform
which serves in the place of a deck. Therefore, if built without
sails, whaleback steamers should be fitted with twin-screws and
engines.
Thirdly, the comfort of the crew would be less than in a
steamer with a large and comfortable deck, where, in fine and
moderate weather, the crew can get about to work, and, at any
rate, breathe the fresh air. As a consequence, iu a whaleback
steamer running on the high seas, an improvement in the
accommodation and a perfect system of ventilation would
have to be arranged for the crew.

July, 1892.] ENGINEERING MECHANICS. T 95
ENGLISH engineering journals are giving unusual attention
to tbe "Balancing of Marine Engines and the Vibration of
Vessels." The higher speed with which vessels are being
driven is pushing this problem into greater prominence. A
good deal is to be learned on the question it seems. Mr. A. F.
Yarrow, a very high authority in England, has written much on
the subject and read some of bis conclusions to the Institution
of Naval Architects. While the subject is of special interest to
marine engineers it possesses many features of interest to all
other engineers who have charge of the construction aud erec­
tion of heavy machinery. The main cause of vibration is said
to be due to the unbalanced moving parts of the machinery,
such as the pistons, piston-rods, valves, gear, or by a screw, the
centre of gravity of which is out of the centre line of the shaft,
or it may be due to want of uniformity in the piston, area or
shape of the blades. In a torpedo boat the vibration is the
same, whether the screw is on—as when the boat is station­
ary and the engines are simply revolving. Of course there is
less vibration at faster speeds. The strengthening of hulls indirectly
prevent vibrations. The true cause of vibration is due
to machinery, and hence machinery should be so designed and
constructed that it may be steady within itself. During the
first half of the downstroke the upward pressure on the cylinder
cover is greater than the downward pressure on the bed plate
to the extent of what is needed to set the reciprocating parts iu
motion, and this excess of upward over downward pressure lifts
the engine bed aud that portion of the hull to which it is attached.
By a like train of reasoning it can be shown that during
the latter half of the downstroke aud the first half of the
upstroke the tendency is to lower the engine bed ; also that
during the second half of the upstroke the tendency is to raise
the engine bed. To sum this up in a few words, during the
upper half of the revolution the engine tends to lift the vessel,
and during the lower half to depress it. The main principle
which governs the whole matter may be thus summed up : As
no internal force can move the centre of gravity of a body, it
follows that any momentum generated by steani pressure iu
the moving parts, such as the piston, etc., must be attended by
an exactly equal momentum in the rest of the ship in the opposite
direction. The remedy for this is to produce an equal
momentum in an opposite direction. The use of bob weights
equal to the rotary weights, and having the same vertical mo­
tion aud the same relative position on the shaft, will effect this
result. The exact amount, position and stroke of the bob weight
can be calculated accurately if the data is carefully gathered.
Triple expansion engines balanced at rest are far from balanced
at work, and hence the rocking motion, in addition to
the vertical motion, due to difference in weight of different
parts ofthe three engines. A writer of evident ability suggests
that much ofthe vibration is due to the unbalanced pressure of
the three-bladed screw surfaces. The suggested remedy is, fourbladed
screws in place of the three-bladed. Experience has
shown that this removes much vibration at all speeds and at
all revolutions.
OUR English cousins are just a trifle nervous over the bare
possibility of the revival of ship building on this side. The En­
gineer handles the question in this way : The enormous devel­
opment ofthe iron and steel trade of America, and the circumstance
that their own high tariffs have, for reasons well understood,
prevented them from competing with other nations, have
not naturally driven Americans to build ships, and of late years
shipbuilding has advanced by leaps and bounds on American
waters. This is in large part due to the traffic on the inland
seas, called lakes by courtesy. As an example, we quote the
following passage from au American exchange : "Shipbuilding
goes on as if no dull season ever came. The work now under
construction at lake yards will cost over $5,000,000, and the
carrying capacity will aggregate 65,000 tons a trip. This is a
great increase, considering the condition of lake freights. Four-
fifths of the new tonnage is steel, the rest being irou and wood.
The 'Mahoning,' the new 'straight-back,' building at Detroit,
will carry 4000 tons, even on the present low stage of water,
and several others will have 3800 tons capacity. Ten of the
McDougall whalebacks are building, the smallest being 320 ft.
over all. Besides the freighters, five Government vessels—
lighthouse tenders anil lightships—are on the stocks, and five
passenger steamers, the largest being 210 ft. long and 35 ft.
beam, are building at Detroit for Lake Michigan traffic." Even
if we allow a little for the overblowing of the American trumpet,
it is clear that at no distant date the United States will become
a shipbuilding nation, and the fact is one with which the
trades unions of Great Britain will have to reckon.
Many persons in this country hold, we know, that it is impossible
for American shipbuilders to sell ships at English
prices. But there is more to be considered than price in this
matter. Thus it appears that the lnman ships would carry some
American mails and get about ^'21,000 a year from the Govern­
ment for doing it. These things are managed at the other side
ofthe Atlantic in ways not practised at this side. If an objection
chanced to be raised, the immediate answer would be that
the money was well spent in fostering American iudustry, and
the reply would be deemed conclusive by an overwhelming
majority. The question of price, under sueh circumstances,
might be regarded as of very secondary consideration. Again,
it is quite on the cards that the Pennsylvania Railway Company
would, directly or indirectly, supply all the iron and steel
needed for the new lnman ships practically at cost price. It
only remains, in a word, to be considered whether there are in
the States the talent, skill, and experience necessary to the
construction of such ships as it is proposed to build. It is
stated that the drawings for the new ships, which will be larger
than anything now ou the Atlantic, have been prepared for
more than a year. For ourselves, we have not the least doubt
that they can be constructed, but we are by no means certain
that the results in poiut of speed will be satisfactory. There is
no royal road to tbe attainment of twenty-one knots an hour,
and until this speed cau be reached, English boats will retain
their present proud position. We do not believe that any
shipbuilder or engineer can construct a twenty-knot vessel
suitable for the Atlantic passenger trade. There are men in
England, Ireland and Scotland who can do it ; aud if the proposed
ships attain the promised necessary speed, then it may
be takeu for granted that the work will be achieved by British
brains It is, of course, out of the questiou to talk of the
treachery to home interests involved. Every man has the right
to carry his talents to the best market ; and we cau only hope
that those who give their aid to America will make her pay
well for it. There is, however this much to be said. Even in
Great Britain and Ireland the men who possess the requisite
abi'ity can be counted on the fingers of oue hand, and it may
be found that Americans will have to rely on themselves for
the accomplishment of a task of the difficulty of which they
can scarcely lorm a conception, simply because they lack the
requisite experience ; and even when the ships are built, it is
not easy to see how they can be adequately manned.
THE Atchison, Topeka and Santa Fe system is taking a
grand financial step which will place it where it rightly belongs,
among the foremost railway systems of the United States. It
is the greatest artery of the great Sorihwest, and is the spinal
column, so to speak, of the mighty region tlirough which it
passes from Chicago to Los Angeles and San Diego. Investors
are accepting the liberal opportunity offered in the plan uow
before the public, for securing paying bonds, free from the uncertainties
that beset so many classes of railway securities. The
financial management of this system has from the first been
wise, energetic and comprehensive, and this, its final and grand
effort, cannot but command the confidence of the railway and
monetary world.

196 ENGINEERING MECHANICS. [July, 1892.
THE COCHRANE FEED-WATER HEATER AND PURIFIER.
THE illustration given herewith of the Cochrane Feed-Water
Heater and Purifier is a fair representation of that device as
now constructed by the Harrison Safety Boiler Works, German -
town [unction, Philadelphia, Pa.
The principle of utilizing exhaust steam for heating feed
water is not new, but the special equipment of this particular
heater combines several features not covered by any appliances
devoted to. similar objects. In this heater the water to be
heated is brought into direct contact with the incoming steam,
and thus applies by absorption more heat than is possible where
the contact is made through the metal of pipes.
The Cochrane Heater was the first in which an oil separator was
used iu connection with an exhaust heater, and also the first where
the separator was introduced within the body of the heater proper.
As will be seen from the accompanying cut, water enters at
the top of the heater, and passing over a series of trays, becomes
finely subdivided, and takes up the heat of the exhaust
steani, which has first beeu thoroughly purified, having entered
through the separator. When the water acquires the temperature
of the exhaust steani, those gases which are subject to the
action of the heat at 212 0 Fahr. are driven off, and the carbonates
of lime precipitated and retained on the trays, which may
be automatically cleaned through suitable hand holes.
Below the trays and but slightly above the regular water level
is a skimming attachment, which is operated by raising tin-
water level.
The principle of filtering by settlement is utilized in this
apparatus, and provision made by meaus of a hood under which
the water passes to the pump, to utilize the water which has
beeu iu the heater the greatest length of time.
The supply of cold water is automatically controlled by a selfregulating
valve through the medium of a float, having a hollowsteam
connection open to the outer air, to prevent the ball from
sinking by the accumulation of water sweated through the
copper, and also to give warning of any leak in the float by
letting the water escape iu a noticable manner.
The over-flow, drip and blow-off pipes are connected to a selfsealing
trap, and with the standard valves, gauge glasses and
fittings throughout make this a self-contained device of the first-
class. This heater can also be used as a condenser for supplying
large quantities of hot water. It is also specially built,
adapted and arranged for steam heating systems, using exhaust
steam aud returning by gravity, to act as oil separator, drip,
expansion tank, return tank, feed-water heater and purifier, and
pump governor.
A heater constructed of cast-iron is now recognized as being
easier to clean, more durable and less expensive in first cost
than those built of any other material, and the Cochrane, while
supplying hot water at a temperature of from 208 0 to 212°
Fahr. will give all the purification which can be obtained in
a heater where exhaust steam alone is used.
Separators for live and exhaust steani are now so well
known and their importance so generally appreciated for the
separation and removal of solid or fluid matter from gaseous
or vaporous currents that a short description of one of the
latest developments in appliances of this kind may be of
interest.
The Cochrane Separator for Horizontal Pipes as herewith
illustrated, consists of a cast-iron casing, having opposite
lateral openings near the top for the ingress and egress of
the steam.
The upper section is divided by a baffle plate, having
parallel corrugations or ribs extending vertically from top to
bottom, with two equal openings, one on each side next to
the casing, of a combined area 25 per cent, greater than the
area ofthe entering pipe.
Surrounding and guarding that portion of the baffle cut
away ou each side for the steam passage is a special deep rib
to prevent water from flowing or being driven through by
the current of steam. The inside of the casing is also provided
with vertical ribs.
Forming the bottom of the separator proper the sides pitch in
toward the centre from all directions and lead directly to the
receiving well or reservoir, the mouth of which is specially protected
from the curreut of steam to prevent any interference
with the contents, either during passage thereto, or after coming
to rest. A suitable gauge glass and valve in drip pipe completes
the equipment.
The Separator for Vertical Pipes as illustrated, differs from the
Horizontal form in having openings at the top and the bottom
for the ingress and egress of steam, and in using an angular
baffle plate, which plate is also provided with ribs to break up
and divert tbe eutrained water and oil from the current of steam,
on the same general principles as those employed for the
Horizontal Style.
The wall is formed by casting on the bottom piece of the
Separator a pipe projection, which rises to the lower edge of
the baffle plate.
The priuciples of action in both Separators embody all the
best points of approved methods for obtaining the most complete
separation, and give by a straight downward course, the

July, 1S92.] ENGINEERING MECHANICS.
most rapid flow to well. Release side openings for the purified
current to pass out, of sufficient area to prevent back pressure,
are so placed and protected that there is no possibility of any of­
the separated oil or water beiug picked up again and carried
past the separator.
These Separators in sizes from 1 )2" upwards are manufactured
by the Harrison Safety Boiler Works, Philadelphia, Pa , under
patents granted February 4, 1S90, and May 3, 1S92.
BURLINGTON ROUTE—NEW SERVICE.—A through Pullman
sleeping car, Chicago to San Francisco, is a feature ofthe Burliugton's
new service. This car leaves Chicago daily on the fast
train at 1:00 p. M., and runs via Denver, Colorado Springs,
Leadville, Glenwood Springs, Salt Lake City andOgden, arriving
in San Francisco at 11:45 A. M., less than four days en
route.
THE Missouri Pacific Railway has devoted much attention to
the subject of a proper steel for locomotive fireboxes, and in
some specifications recently made for new engines to be built
at the Baldwin Locomotive Works the tests specified for the
firebox steel are very difficult to meet. Tne Wellman Iron &
Steel Company undertook to meet the requirements, and as a
result the firebox steel was fouud to contain only from .00S to
.013 per cent, of phosphorus. The ultimate tensile strength
averaged 48,000 lbs. per sq. iu. The reduction of area in per
cent, of original area averaged 6S per cent. The final elongation
in per cent, of original length (which was 2 ins. betweeu
shoulders) was 4S per cent. This is a quality of steel that is
especially well adapted for fireboxes as it is soft and ductile and
low in phosphorus.
PROBABLY* a greater number of accurate observatious have
been made ofthe temperature of locomotive smokeboxes in the
last two years than for the ten years preceding. This is a good
sign, as it is one ofthe indications of a desire ou the part ofthe
railroad men to find out why locomotives are not more efficient-
The temperatures have been generally taken by a pyrometer.
This is by no means au accurate instrument, but its indications
are generally true within 50 degrees, and therefore the records
are accurate enough for preliminary investigations. It is now-
pretty clearly shown that with a short flue the temperature of
the smokebox is higher than with a long flue ; also that the
'9 /
greater the vacuum i„ the smokebox the higher the tempera­
ture. The range of temperature while an engine is working
varies from about 300 degrees F„ as the lowest, to 1,400 degrees
F., as the highest In some experiments the heat has been so
great as to soften the brass lube uf the pyrometer. In compar.
mg the records of pyrometers in locomotive smokeboxes, the
location ofthe several instruments must be carefully considered.
The results of different tests often are not comparable, as
the pyrometers have been located in different places. The
highest readings will always be obtained when the pyrometer
is put between the deflecting plate and the tube sheet', and the
lowest when it is placed near the front end ofthe smokebox.
What is sought is the temperature ofthe gases of combustion
just after they leave the tubes, as that is the final heating sur­
face over which those gases pass. After they have left the tubes
the products of combustion can generally do no more useful
work. In order that future observations may be of real value
there should be some agreement on this matter of locations.
It would seem for various reasons that the proper place is between
the deflecting plate and the tube sheet ; preferably somewhat
below the centre ofthe boiler in order to get au average
of the current of gas flowing from the tubes. The pyrometer
should be a long one aud extend practically across the boiler.
Speaking iu a general way, the results so far obtained show
that the temperature of locomotive smokeboxes is less in compound
engines thau in simple engines. Perhaps a fair average
ofthe difference is 300° F. A marked difference is to be expected,
as there is less vacuum iu the smokebox due to the less
powerful exhaust ofthe compound, and there is, in consequence,
less coal burned per square foot of grate per hour. The velocity
of the hot gases over the heatiug surfaces being generally less,
more heat is extracted from them and they pass into the smokebox
at a lower temperature.—R. R. Gazelle.
THE contract for 10 new passenger engines for the Baltimore
& Ohio Railroad has been given to the Baldwin Locomotive
Works, of Philadelphia. The engines are to be completed by
the middle of August. Three of them will be built according
to designs of the Baldwin Locomotive Works and seven ac­
cording to designs of Mr. Hazelhurst, General Superintendent
of Motive Power of the Baltimore & Ohio.
UP to the opening of the Chicago & South Side (Alley) elevated
road iu Chicago last week there was in some quarters
considerable doubt as to the adaptability of the Westinghouse
brake for elevated railroad service. It was thought that the
release would not be quick enough and the pump would be
overtaxed. Now, after one week's experience, the special
value of a compressed air brake for frequent stops is so fullyproved
that all doubt has been removed, aud all concerned
with the road are more than pleased with its operation.
THE passenger service of the Baltimore & Ohio Railwav
Company has made great strides of recent years, and it now
has reached a degree of excellence in all details which recom­
mends itself to the traveling public. A complete reorganization
has been brought about, and the facilities of this company
are now not excelled by any. Its block system is being ex­
tended, its passenger engines embody every improvement
known to the science of locomotive construction. Its passenger
cars are models of beauty, and the speed of its through
trains is equal to the fastest on competing systems. It is doiii"
much to deserve and secure the lion's share of World's Fair
travel, for tens of thousands from the East will want to go
West via. Baltimore and Washington. Chas. O. Scull, the
General Passenger Agent, though a young man, has shown ex­
traordinary ability in the management of his department.

198
ENGINEERING MECHANICS.
NO. 8 PLAIN MILLING MACHINE.
Brown & Sharpe Mfg. Co., Trovidence R. I., U.
DESCRIPTION OF NO. 8 PLAIN MILLING MACHINE
This machine is adapted for a larger aud heavier class of
milling than the No. 6, having wider cones for belts, larger
spindle, heavier table and saddle, and more powerful feed.
The spindle has a front bearing 33+' iuches diameter, 5',
inches in length, and a rear bearing, 2'i inches diameter, 5
inches long. In addition to the taper hole for receiving the
arbor, the spindle has a recess across the end and a cap nut, by
which an arbor liaving a clutch collar is positively locked for
driving the cutters.
The spindle boxes are bronze, tapered, and have means of
compensation for wear.
The table is heavy, 66 inches long, 16 iuches wide, having a
working surface 54 inches long and a bearing saddle 40 iuches
iu length. It has three T slots running the entire length between
the pans at end of same. It may be lowered 19', inches
below the centre of spindle, aud has an automatic feed of 48
inches, and au adjustment in line with spindle, of 934' inches.
Milling may be done 21 inches from face of column, aud cut­
ters 16 inches diameter may be used.
Tbe cone has 3 steps 'the largest 13V inches diameter) for 4',
inch belt. The back gearing is 8^ to I, thus giving, with the
two speeds provided ou countershaft, 12 speeds for spindle.
The feed cones have two steps, ami by transposing these aud
changing the feed gears, eight changes of feed from .02 inches
to .25 inches to one revolution of spindle may be obtained in
either direction.
The overhanging arm is of steel 4-V iuches diameter, aud
[July, 1892.
may be rigidly connected tothe knee
by an improved arm brace, which is
readily adjustable and has a bearing
for the outer end of arbor, thus allowing
the usual arbor support to be
used at any intermediate point near
the cutter to counteract the tendency
of the arbor to spring under heavy
cuts.
The vise has jaws 7's inches wide,
i**s inches deep and will open 4,2
inches.
The Overhead Works have two
sets of tight aud loose pulleys :6
inches and 20 inches in diameter for
5 inch belt, and the countershaft
should run 112 to 140 revolutions per
minute.
Weight of machine, boxed ready
for shipment, about 5,000 lbs.
Floor space, ii4!sx6S*2 inches.
Dimensions of the boxes in which
the machine is shipped, 67x42x67
iuches, 66x21x21 inches.
Each machine is furnished with 1
vise, 1 hand wheel, 1 knee crank, I
arm brace, 1 collet, 1 centre key, 1
support for cutter arbor, two stops
for table, rod for driving out arbors,
1 oil can and stand, 6 wrenches, complete
overhead works, aud 1 copy of
"Treatise on Milling Machines."
THE oldest and oue among the
ablest architects in the United States,
Stephen Decatur Button, of 430 Walnut
St., Philadelphia, celebrated his
Soth birthday recently and was the
recipient of an address from his
younger associates iu the architectural
profession. A catalogue of Mr.
Buttou'swork throughout the United
States would make a neat catalogue. He is still iu active
service.
P. BLAKISTON, SON & Co.'s Hand-Book of Electro-Chemical
Analysis, by Edgar F. Smith, has had a fair run.
COPIES of Engineering Mechanics are wanted for January,
April, May, June and November, 1S90 ; January aud February,
1S91 ; aud December, 1889.
T. O'CONNOR SLOANE'S small treatise ou Electricity Simplified,
published by Norman W. Henley & Co., 150 Nassau St.,
N. Y., is meeting with good sale.
PROF. J. B. JOHNSON has rendered a service to the engineering
profession in tbe publication of "Tables of Stadia aud Earth
Work" which are reprinted in convenient form from "Theory
and Practice of Surveying." The work is published by John
Wiley & Sons, 53 East 10th St., New York. Prof. Johnson's
work ou Surveying is meeting with a hearty recognition
from the profession, and deservedly stands high up among
works ou surveying.
THE Ohio Machine Tool Works of Cincinnati, O., have just
placed on the market a new machine tool intended for the rapid
production of machine work, such as boring and turning blank
gears, motor gears, cone, friction aud other pulleys, aud heavy
duplicate work for all classes of machinery, especially Corliss
and slide valve engine details. The speeds range from 25 ft.
per minute for cutting, up to 3 00 revolutions for scraping or
polishing ; swings 26 inches, is 7 ft- long and is geared 30 to I.

July, 1892.] ENGINEERING MECHANICS. 199
THE -American Society of Civil Engineers held the spring
meeting at Hygeia Hotel, Old Point Comfort, Va., June Sth to
12th. Papers were read bv J. Foster Crowell "On Uniform
Practice in Pile-driving;" by Mr. John B. Dunklee, "On the
Iron Wharf at Fort Monroe, Va ;" by Mr. Desmond Fitzgerald
on "Rainfall—Flow of Streams," and "Storage." President
Cohen delivered the annual address. The Norfolk Navy Yard
was visited. The Society took steps to raise $3,000 towards tbe
expense of the International Engineering Congress at the
World's Fair. Papers were read on "Hardening Structural
Steel," by A. C. Cunningham ; "Results Obtained from Fullsized
Steel Eye Bars," by Frederick H. Lewis; "How to Pro­
tect Iron Roof of R. R. Tunnel," by J. G. Dogron. Visits were
made to several places of note, among them the new dry dock
and the iron coal pier of the N. & W. R. E. Co. The banquet
took place Saturday evening.
THE paradise of the United States is Southern California.
The Hotel del Coronado, at Coronado Beach, ou the Pacific
Coast, at the water's edge, is the largest, finest and most sumptuously
equipped seaside hotel in the world. It attracts an increasing
throng of travelers to that section of orange groves
and tropical fruits. The ocean breezes maintain a temperature
of 65-75 the year round, and flowers are ever in bloom.
There is an increasing attendance of eastern people during the
summer months, and during the winter season this grand
hostelry is justly well crowded. It is owned practically by
Colonel Babcock, formerly of Cincinnati, aud J. D. Spreckles,
of San Francisco. There are 750 rooms, aud the grounds include
4,000 acres in all, covered, for the most part, with shrubbery,
flowers aud perfume producing vegetation.
THE Jersey City aud Bergen Railroad Company, of which
Mr. C. B. Thurston is President, has just closed au important
contract with the Ball & Wood Company of NewYork for three
of their Improved Cross Compound Engines of 300 h. p. each.
The engineers of the Pennsylvania Railroad have carefully investigated
all the leading makes of engines, something like
eight of which were in competition for this contract. The intention
of the company is to make the plant which will operate
its lines a model one, not only in respect to the latest and most
improved type of engines, but in its other equipment and arrangement.
THE Lake Roland electric road of Baltimore has awarded a
contract for the electrical equipment of its road to the Thomson-Houston
Electric Co., of Boston, and to the Duplex Railway
Co., of New York, for the track work. Work will be
commenced next week on Cedar avenue, Baltimore. The contract
for the elevated structure on North street will be let in a
few days.
MEXICAN NORTHERN PACIFIC.
The company recently organized in England to build this
line is reported to have secured all the funds necessary to complete
the road. Tracklaying will begin south of Deming, N.
M., as soon as the rails which are now being rolled in England
are delivered at that town. The surveys of the entire system
have been made, aud it is proposed to begin active construction
work near Deming at once, and rapidly push the work south
of that point into Northern Mexico. The general contract for
building the road and furnishing material has been let to Huss,
Townsend & Co., of The Rookery Building, Chicago, 111. The
firm is composed of George M. Huss and George Townsend.
The route is from Deming, N. M., southward to Guerrero, a
point about 150 miles west of the city of Chihuahua, Mex , and
thence eastward to Chihuahua and southwest to Topolobampo.
on the Pacific Coast, and northward to Guaymas, au approximate
distance of 1,200 miles. The line is designed to open up
the mining regions of the Sierra Madre, a large area of pine
and oak timber lands, aud the agricultural and grazing plains
and valleys now without transportation facilities. The general
character of the work is light, the line following the river valleys
with easy grades and good alignment, though there is a section
of about 100 miles where the Sierra Madre range is crossed
that will be heavy mountain work. The general maximum grades
will be one per cent, and the curves six degrees, though 111 the
mountaius a maximum of 3% per cent, grades and 15 degree
curves will be used. William Martineau is Resident Engineer.
THE MONIER SYSTEM OF IRON AND CEMENT CONSTRUCTION.
THE Monier system of iron and cement construction, of which
so much has been said and written ill the past year or two, is
made the subject of some interesting notes in a recent issue of
the Revue Industrielle. Mr. Monier's system, which is patented,
consists, as is now pretty well known, of a combination
of comparatively light iron rods, which form a sort of frame
work, and of cement mortar, whicli is poured around it, the
combination forming, it is claimed, a structure of great strength
and comparative lightness. The questions which have presented
themselves in connection with it have been these : Will
not the iron rust under the conditions of its use ? Will it adhere
well to the cement mortar ? What will be the influences
of changes of temperature 5 It is held that the iron in the
cement is protected against all outside corroding agents, and
can, therefore, not rust. Several years' experience with some
Monier work is said to have established this beyond doubt.
As to the adherence between the cement and the iron this also
has been found to be excellent, and a number of experiments
made to test this point are said to have given satisfactory results.
The answer to the third question concerning temperature
effects appears to be the most doubtful. It is naturally to
be feared that in submitting to varying temperatures a collection
of materials having such co-efficients of expansion as
cement and iron, a general breaking up would occur. Still, Mr.
Monier's experiments in this direction also are understood to
have giveu good results. The advantages of the Monier system
are summarized as follows : Solidity, lightness, low cost,
aud rapidity of construction. For all work where water tightness
is necessary the system is recommended. When it was
first proposed to follow the system in the building of the aque.
duct to supply the Vienna Neustadt with water an experimental
gallery, measuring 3X4 in., with walls 5.2 in. thick, was built
and tested to destruction, the results, as given, being in favor
ofthe system. In the construction of gas-holder tanks and gas
mains it may again be applied equally successfully. Its use in
bridge building, however, is one of the latest and most novel
applications. Test arches which have been built, and bridges
for regular traffic have all behaved well, and their performance
has added not a little to the general advertisement of the system.
The article iu the Revue Industrielle is accompanied by
16 illustrations, showing the various dispositions of iron framework
which may be adopted for different purposes.
^FOR SALE.—
One 21 in. x 13 ft. LODGE & DAVIS ENGINE LATHE, complete.
One 24 in. x 20 ft. FlFIELD ENGINE LATHE, complete.
One No. 3 GARVIN UNIVERSAL MILLING MACHINE, complete.
The above-mentioned machines are new, never having been used,
but will be sold at a sacrifice to settle up an estate.
DANIEL KELLY,
51 North Seventh Street, - - Philadelphia, Pa.

Ill ENGINEERING MECHANICS. [July, 1S92.
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W. A. DAY, No. 128 Oliver Street, BOSTON MASS
HYDE BROS. & CO., Lewis Block, PITTSBURGH PA.

August, 1892.] ENGINEERING MECHANICS. 199
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering.
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
London Office, 270 Strand, D. NUTT, Agent.
F.ntere.t at the Pnst-office in PJiitaaett"iia as -leconrt-l tass Malt Matter.
SUBSCRIPTION RATES
Subscription, per year . $2 00
Subscription, per year, foreign countries 2 50
PH1LA.DE1.PI I IA, AUGUST, 1892
Xo less than six projects for new cable or electric railroads
in London are before a Select Committee of Parliament. All
of the roads to be underground and one of them to pass under
the Thames. The diameter of the tube for one of the lines is
set down at 16 feet, of the others 11,14 feet. The tunnels to be
deep enough to pass under streets and houses. The roads to be
liable for any injury to property through vibration or other
causes.
THE demand for pure concentrated sulphuric acid by the
explosive and coal tar industries has become so great that manufacturers
are seeking to minimize the wear and tear of the platinum
vessels used in distilling over the acid. Gold is less corroded
than platinum in the process, and hence the stills were
lined with gold, the deposit being made by electrolysis. But
such deposit is more or less porous and the film of gold becomes
detached by the boiling acid and lost. This difficulty appears
to have been overcome by a process recently patented in Europe.
A plate of platinum is brought to a temperature above
the melting point of gold and the desired quantity of this
metal in the molten stile is passed on to the platinum. The
two metals appear to form an alloy at the plane of contact and
to become indissolubly united. Different thicknesses of gold
plating are used. That for the bottom of the still is from oneeighth
to one-fourth as thick as the platinum it covers. That
for the dome or capital, less than a sixteenth. Several of the
new stills have been in operation for more than a year during
whicli time from iooo tons to 2000 tons of acid, ranging from
93 to 9.6 per cent, have been distilled in them, leaving the gold
lining untouched. The first of the stills made under the patent
is of course greater, but already experience has shown, that
with stills running 2000 tons ofthe strongest acid annually, the
extra cost will be repaid in two years or even in less.
SINCE the channel ofthe Clyde was lighted with beacons and
buoys the number of ships navigating it is as great during the
dark tides as in the day time. Gas buoys are made of sheet
steel and are spherical in shape. A tripod supports the burner
at the height of 12 feet above the water. Gas from petroleum
is used as coal gas is said to lose much of its illuminating power
by compression. From the gas holder the gas is drawn by a
pump and forced into cylindrical receivers having a capacity of
370 cub. ft. containing 3700 cub. ft. of gas at a pressure of 150
lbs. per sq. inch. These receivers are conveyed to the buoys in
a boat and the gas is transferred to the receiver in the buoy by
a pipe connection, having a stop valve. The gas in the buoy is
at a pressure of 90 lbs., and the quantity of gas so passed into
the buoy at this pressure is sufficient to keep the light burning
day and night for two months. Two cylindrical receivers of
the above dimensions are sufficient to charge three buoys. The
consumption of gas in the buoys is at the rate of 0.8 cub. ft. per
hour, and each light consumes about 9000 cub. ft. a year. The
emission of the gas is intended by an automatic regulator, which
allows it to flow at a pressure of 0.5 inches of water. The flame
is protected by a specially designed lantern having a dioptric
lens and provision is made to meet the sudden extinguishment
of the light by means of a blow from a vessel or from a mass of
wreckage. My means of the lens the illuminating power is
increased to 30 candles, London standard, and the light can be
seen from 3 to 5 miles.
AN experienced Civil Engineer recently remarked that the
great advance of his art iu the near future, would largely depend
on the extended use of two materials, hydraulic cement and
aluminum. We shall not now discuss the correctness of this
statement. We freely admit, however, that the applications of
hydraulic cement have multiplied wonderfully, anil that the
number and cpacity of its manufactories have greatly increased
and their output enhanced manifold.
For many years the cause of its property of hydraulicity or
settiug under water was a mystery. Chemistry has solved the
general problem, but exceptional cases occur in practice, the
causes of which provoke active discussions, indicating in turn
a wide diversity of opinion.
Hydraulic limestones were at one time the only sources of
hydraulic cement. Although varying iu competition, they always
contain clay with the limestone, wliich is frequently
slightly magnesiau. But the demand for the cement, long ago
far outstripped the supply of hydraulic limestone, and in England
where the cement is known as " Porland," and on the
Continent it is prepared on an immense scale, by mingling chalk
aud clay and celuning the mixture in kilns at a high temperature.
The preparations contained iu the freshly burned cement,
as shown by analysis are Silica, 23.32 ; Alumiuae and oxide of
iron, 12.13; lime, 61.56; magnesia, 1.07; sulphuric acid, 1.28;
carbonic acid, o.'30. None of these substances should be in a
free state after burning. The sulphuric acid and carbonic acid
are combined with lime, the silica and alumina forming silicates
and alumiuates of calcium. The temperature must be
sufficient to semifuse or clinker the mass, which should have
the specific gravity of 3.1. To insure perfect homogeneity the
chalk and limestone are finely pulverized, thoroughly mixed
with water and carefully dried before introduction into the
kiln. After burning the cliukered pieces are finely ground,
(millstones being frequently used for that purpose) and pressed
through a sieve having about 25.00 meshes to the inch.
The setting of hydraulic cement under water appears to be
due to hydration, that is, to the combination of both the silicate
of calcium and the alumiuate of calcium with water. In
order that the setting be complete, the full quantity of water
necessary to convert both the silicate and alumiuate of calcium
into hydrates must be added at once, and if need be prevented
from evaporating until all that is required is taken up. If this
be not done the external coating or skin of the block of plaster
hardens first, while the interior continues to take up water during
a longer period, and the "heaving" of the mass and the
consequent destruction of the work of whicli it constitutes a
part follow :
For hydraulic cement concrete to be used for hard aud fresh
water foundations, 3 parts of clean sharp sand to one of cement
is the favorite proportion. To this, gravel or rubble to the extent
of 4 to 7 parts is often added. For foundations and other
structures iu sea water, 2 parts of the sand to 1 of cement, is
held to be the proportion best able to withstand the action of
the saline substances contained in sea water. Of these, magnesium
sulphate, and magnesium chloride are said to be the
most injurious, the theory being, that iu time the magnesium
takes the place of the calcium, and the block of concrete undergoes
disintegration. This is the view taken by eminent
engineers, of the cause of the destruction by sea water, of the
graving dock and breakwater at Aberdeen, Scotland, in 1SS7, a
few years after their completion. Other works of similar character
and like material, have withstood the action of the sea
for many years without needing repairs, a fact that has led to
the suspicion that some defect iu the mixing or in the casting
of the concrete blocks existed at Aberdeen harbor.
Iu determining the adaptedness of a clay to use with chalk

2oo ENGINEERING MECHANICS. [August, 1892.
or other limestone in the preparation of a hydraulic cement,
chemical anilysis is not to be exclusively relied on. Not the
preparation of the silica, but rather its form and condition is
the more important. A mechanical test on a small scale should
therefore be carefully made; the clay and limestone hardened,
mixed, calcined, ground, water added and cast in moulds, into
prisms about i A inches square and a foot long. The prisms
and moulds then placed under water, one removed at the end
of a week, the prism reduced to an inch square, and tested for
traction and cross strains. The former is conducted as for
metals; the latter by placing the prism ou supports 0 inches
apart. It should have a weight of 75 lbs. The other prisms
removed from the water at intervals of a week, similarly treated
should bear increasing weights.
Steps towards the establishment of a uniform standard of
quality for hydraulic cement, and the appointment of Government
inspectors of manufactories, have been taken in several
countries. The necessity for such supervision is apparent, but
the results do not appear to be as satisfactory as was anticipated-
The manufacture of hydraulic cement for blast furnace slags
is attracting much attention. The slags differ widely iu their
composition, but all of them are adapted to the purpose. Those
containing sulphur aud a large percentage of magnesia are
utterly unfit. After the slag has been tested as described for
clay (omitting the calcination) and the fluctuations in the
quality of the daily product of the blast furnaces been fouud
to be but slight it may be selected. The slag as it flows from
the furnaces is passed through a stream of water. It is then
reduced to a sponge and readily crushed, known as "slag
sand," sometimes used for roofing. This sand is dried, finely
ground and then mixed in the requesite proportion, usually
about 23 percent, of the mixture with slacked fat lime which has
fallen iuto dry powder. The mixture is introduced iuto a metal
drum about s,A f ee t diameter, partly filled with iron balls 1 to
2 inch diameter. The cylinder is made to revolve slowly until
the complete intermixture is secured, and the mass feels like
flour. When mixed with water it sets more slowly than ordinary,
but hydraulic cement is reported to become equally
hard.
EDITOR MECHANICS :—I am interested in the following prob­
lem, and being ou unfamiliar ground, I request you to tell me
where to go for the information :
Am I very far off in counting on using a metal diaphragm
about as shown, to be exposed to a pressure of 50, or better, 100
lbs. per sq // , which is to be taken up by the rod R1
Diameter in the clear about 4", "stroke" required about 11,
inch. I should not venture to trust to my most scientific calcu­
lations, and at present I only care to know whether I am en­
tirely off or whether there is a chance of a solution by experi­
menting.
Perhaps you can judge at a glance, if so I shall be greatly
obliged for your opinion ; if not, kindly tell me who can.
Yours truly,
O. SONNE.
ANSWER :—The thickness of such a diaphragm need not be
greater than one which is not corrugated, and the object ofthe
corrugation is merely to provide for the deflection without pro­
ducing additional stress upon the metal. Applying the for­
mula in \ 19 ofthe Constructor :
yf~* -/-
we have, when r = 2, p == 100 lbs., and -S = 10,000 lbs., which
latter is a fair stress permissible for copper or wrought iron :
il = :
V W 10,000 °
This gives a thickness sufficient to resist the pressure, buj
the stresses induced by the flexure depend much upon the frequency
ofthe strokes as well as the character of the material.
Rapid aud frequent vibrations will undoubtedly crystallize the
material, even if it be very tough and elastic, and if the diaphragm
is to be subjected to such vibrations it would be best to
make a trial one, aud connect it to a continuously running
shaft and record the number of vibrations before breaking oc­
curred. It will be found that the endurance increases greatly
as the number of vibrations is reduced, and such tests should
be made with various materials if the matter is of sufficient importance.
A GREAT AQUEDUCT.
The longest aqueduct in the world was set to work a few days
ago to carry off water from an artificially made lake 68 miles
from Liverpool to that city. It consists mainly of tunnels to
carry a supply of 40,000,000 gallons a day aud has three lines of
pipes each having an internal diameter varying, according to
the fall of the different sections, from 39 in. to 42 in. For
the greater part of their length these pipes are buried beneath
the ground, and are elsewhere carried on arches, or passed
through tunnel subways. Ofthe three lines of pipes, only one
is at present constructed, and the supply of water available is
one-third of the ultimate supply when the three lines are laid,
and the Cowny and Marchnant tunnels constructed. Upon the
aqueduct there are four balancing reservoirs, situated on hills
rising to the hydraulic gradient of the pipes, aud one reservoir
upon a tower reaching to the same gradient line. The aqueduct
commences iu the Cynon Valley, with the Hirnant Tunnel two
miles three furlongs in length. The entrance of the river
Cynon into the lake is seen on the map near the commencement
ofthe aqueduct at the southeast corner ofthe lake.
This Hirnant tunnel is governed by valves at the inlet. From
the outlet, iirthe valley of the Hirnant, a tributary of the river
Tanat, the water enters pipes, the first seven miles of which are
underground, passing beneath the rivers and streams by in­
verted syphons, except at the Afou Rhaiadr, which they cross
near the village of Llaurhaidryu Mochuant, and three miles
southeast of the beautiful waterfall known as Pitsyll Rhaidr.
This section of the aqueduct discharges into the Pare Uchaf
balancing reservoir situated on a hill rising to the hydraulic
gradient of the pipes, approximately midway between the Hirnant
Tunnel and the next break, which occurs at the Cynynion
Tunnel, six miles one furlong nearer Liverpool.
The Cynynion Tunnel, nearly seven furlongs, aud the Llan-

August, 1892.] ENGINEERING MECHANICS. 201
forda Tunnel, nearly a mile in length, are only separated by the
narrow valley of the Morda. As in the case of the Hirnant, the
water flows through these tunnels without filling them, and
crosses the valley by inverted syphon pipes carried over the
Morda by a bridge.
The outlet of the Llanforda Tunnel discharges into the Oswestry
reservoir. At this point the contour of the ground is
favorable to the construction of a larger reservoir than at any
other point risiug to the hydraulic gradient ofthe aqueduct, and
advantage is taken of the fact to give the reservoir a capacity of
46,112,000 gallons, which will insure continuance of the supply
to the remaining portion ofthe Liverpool aqueduct, during any
stoppage from accident or other cause in the somewhat inacces­
sible mountain districts between Lake Vyrnwy and Oswestry-
The sand filtration beds are placed about three-quarters of a
mile on the Liverpool side of the Oswestry reservoir, and below
them again are provided, for each third of the ultimate
supply, that is to say, for the supply which each line of pipes
is designed to convey, a clear water reservoir having a capacity
of 2,812,500 gallons.
The filter beds are so arranged that the water can be passed
through auy combination of them that may be desired. The
Oswestry reservoir and the three clear water reservoirs give an
aggregate storage capacity of 54,549,500 gallons. At Oswestry
are the principal gauges for the measurement of water passing
along the aqueduct.
From the clear water reservoirs at Oswestry to Malpas, a distance
of seventeen miles five furlongs, the aqueduct is wholly
below the ground level, except at the valley of the Wych Brook,
which is crossed by nine arches. On this length of aqueduct
the Great Western Railway—Oswestry branch—and the Great
Western Railway—Shrewsbury and Chester Branch—is crossed
in subways. The Shropshire Union Canal is crossed near
Hindford.
From the Malpas reservoir, the aqueduct passes wholly below
the ground level for a distance of eleven miles five furlongs to
a hill, near the vilage of Cotebrook, rising to the hydraulic
gradient. Upon this section of the aqueduct the London and
North-Westeru Railway—Whit-church aud Tattenhall branch,
near Malpas—and the London and North-Western Railway—
Chester and Crewe branch, near Beeston Castle—are crossed
by subways, and the pipes pass beneath the Shropshire Union
Canal, near Beeston. This length of aqueduct discharges into
the Cotebrook balancing reservoir.
The next length of subterranean aqueduct is eleven miles to
Norton, in Cheshire, and crosses over the Sheffield and Midland
Committee's Lines—West Cheshire Railway, near Delamere
Station, and under the river Weaver, and the London and North-
Western Railway—Aston, Ruucorn, and Ditton Branch, near
Sutton Weaver Station.
In the Act of 1S80 was inserted a clause which made it necessary,
in case of difference between the engineer of the Corporation
of Liverpool and the River Weaver Navigation Trust
concerning the mode of crossing the Weaver, that the question
should be referred to the decision of an arbitrator. Work of
the kind has hitherto, both in this country and abroad, been
carried out either within a coffer dam formed across the river.
or by sinking ball-and-socket jointed pipes in a trench excavated
under water. In this case, however, and for crossing the Mersey,
Mr. G. F. Deacon, M. Inst. C. E-, the engineer of the works,
proposed a different method, one which the use of modern
mild steel made possible. The Weaver, where crossed is over a
hundred feet in width, and the Mersey over eight hundred feet
wide. According to this method, which would avoid all inter
ference with navigation during the progress of the work the pipes
to be sunk into the bed of the river were to be built up of steel
plates rivetted together. These, having been floated out into
position over a trench sunk to a sufficient depth across the whole
width of the bed, were to be sunk into their place by filling them
with water.
The Vyrnwy Aqueduct, where below ground but not in tunnel,
will ultimately consist of three lines of pipes, but throughout
the greater part of the whole length only one of these has
at present been laid. Iu the case of the Weaver crossing, the
Act of Parliament required that the three lines should be laid at
one time. On page 7, a section of the Weaver is shown to a
large scale, the section being given in two parts. From the engravings
it will be seen that the large cast iron 42 in. main is
gradually reduced in diameter iu the curved parts near the
junction with the smaller built up 32 in. steel pipes. On the curved
short length cast iron pipes forming the upper bends trunnions
are cast, and over these are placed connecting links designed to
prevent any separation of the pipes under the action of the
water pressure, or as a result of any settlement. The engravings
show the depth to which the pipes have been sunk and
covered by concrete. Besides the plates and angles connecting
the tubes together, a cast iron frame was fastened to the pipes
near the ends, forming a rectangular plate, by means of wliich
sheet piling at the two shores could be placed so as to make a
water tight joiut when the pipes were sunk into their place.
The three pipes were made at Warrington, by the Pearson and
Knowles Coal and Iron Company, aud the temporary cast iron
covers being placed on the ends, they were floated down the
Mersey and up the Weaver Navigation. The trench was excavated
chiefly by grabs worked by steam cranes on barges. Two
rows of sheet piling were previously driven along the river
banks, at such a distance apart as to allow the tubes—108 ft. in
length to be let down betweeu them, tlie piles on either side
forming a little dock open to the river, aud ready to receive the
pipe ends. The Weaver at this part is from 14 ft. to 15 ft. in
depth, and the bottoms of the tubes had to be laid at a depth
of 21 ft. On the 7th May, 1890, the trench and the various preparations
being ready, the pipes were rapidly floated iuto position,
aud their four ends attached by chains to four winches,
ready to control their descent. The ceutral pipe was then
charged with sufficient water, and the three pipes lowered
quickly aud steadily into their position, the sinking only occupying
fifteen minutes. The pipes being thus in position, the
next process was to drive sheet piling parallel with the previously
mentioned piling, and against the rectangular frames
already mentioned, the space above the pipes and this frame
being also filled iu. The ends of the pipes were thus cut off
from the river, and were within a little dock on either shore.
Within these docks or dams the excavations for the ends ofthe
cast irou pipes were made, and th° water being pumped out,
the temporary cast iron covers were removed from the ends of
the steel tubes and connections made. This being completed,
the piling was drawn, the cast iron frames removed, the space
between the steel tubes and some depth above them filled with
Portland cement concrete, and the bed aud shores of the river
made good. The success of Mr. Deacon's novel method of crossing
a river was complete, aud would have done perfectly for the
Mersey.
Norton Hill, the terminus of this section of the aqueduct, is
three miles south-east of Runcorn, but as the top of the hill is
more thau 100 ft. lower than the hydraulic gradient, the balanc­
ing reservoir is placed on the Nortou masonry tower.
This water tower is of Roman Doric design, and, like all
the other architectural work, seems perfect in its fitness
for the place and the purpose. Of the masonry, it is only
necessary to say that it is ashlar set in Portland cement mortar.
The blocks are of great size, and are cut from the soundest
beds of certain Cheshire quarries in the new red sandstone formation.
It is upon this tower that the inscription is engraved.
It is not possible to render this adequately in English, but it
may be very freely translated as follows :—" This water, derived
from the sources of the Severn, is brought to the city of
Liverpool, a distance of eighty miles, through the mountains
and over the plains of Wales and the intervening country, at the
cost ofthe municipality, in the year of our Lord 1S92."

2o: THK CONSTRUCTOR.
Translated by Henry Harrison Suplee.
Fig. S71 a, shows Butter's belt fastening. This is a form of
belt hook which has been found very serviceable, reducing the
strength of the belt but little, and permitting easy renewal.
Another form is Moxon's belt fastening,'" shown at b, is a pin
Tmsm>
f^-mwm
FIG. S71.
point, the ends of the pin being riveted over, aud from its construction
should be very strong. At c is a butt joint with a
reinforcement piece especially suited for cotton belts. When a
belt is made for special service it can be in several layers as at
d ; the joints overlapping, but thus giving no opportunity for
change of length.
The stretching and joining of heavy belts is a matter requiring
much care in order to secure the desired tension, = A
(T -f- I) A Belts which are subjected only to light tensions may
be cemented by scarfing the ends and using a cementcomposed
of common glue mixed with fish glue, or of rubber dissolved in
bisulphide of carbon,
I 2S3.
THE PROPORTIONS OK PULLEYS.
Pulleys are usually made of cast iron and of single width, i. e.,
oue set of arms. The arms, which formerly were made curved,
in order to resist the stresses due to contraction, are now made
straight, and for wide face pulleys two or even three parallel
sets of arms are used.
£*
FIG. S72.
fy+ ^4.»l-*4"l
Fig. S72 shows both single and double arms. The dimensions
of arms and rim have been determined by experience, based
upon practical considerations. For the number A of arms for
a single set, we get serviceable values from :
w hich gives, for :
A = 5 + ':)
-7f-=I 23456789 IO II 12 13
A 3 4 5 6 7 8 9.
(266)
The width li of the arm, if prolonged to the middle of the
hub, may be obtained from :
/l=02Sty± + AX
4 10 A
(267)
The width /'| of the arm at the rim is equal to 0.8 h, and the
corresponding thicknesses are e = A b, and r.-, = *2 It..
Pulleys with two or three sets of arms may be considered as
• * See Chronique industrielle, 1882, Vol 5, p. 07 ; also Mechanical World
1882, Vol. 12, p. 56t
Leloutre has used a dynamometric belt stretcher tor tensions of '
(T + t) = SSoo pounds.
[August, 1892.
Translation Copyright, 1890.
two or three separate pulleys combined in one, except that the
proportions ofthe arms should be 0.8 or 0.7 times that of single
arm pulleys, or in the proportion of A /- and As
The thickness of the rim may be made : k = \ to % h, this
being frequently turned much thinner. The width of face
should be from § to | the width ofthe belt.
The thickness of metal iu the hub may be made W •= h, to
% h. The length of hub may =- b, for single arm pulleys and
2 b for double arm pulleys. Light pulleys are usually secured
to the shaft by means of set screws, as in Fig. 875 aud 877 ;
heavier ones are keyed as in Fig. 191, either with or without
set screws.*
For many purposes pulleys are made in two parts, such being
commonly called "split pulleys. The forms of split pulleys
are shown iu Figs. 873 to S75.
The arrangement of the two
halves is clearly shown, that
of Fig. 874 with hollow clamping
section, being especially
good.f
The form in Fig. S75 is the
design of the Walker Mfg. Co.
of Cleveland, Ohio, the clamps
FIG. 873.
being made of malleable iron
or steel. In all three cases
there is no especial method of
fastening to the shaft. Iu
Fngland and America pulleys
are frequently made with
wrought iron rims and cast
iron hubs. This construction
greatly simplifies the casting
of the arms, and at the same
time gives pulleys 25 to 60 per cent, lighter than those of cast
iron, which in large transmissions greatly reduces the friction
p
•
1
•
|||j
1" 1 . . 1 • Mini
lliLc
'ill 1UCL_
9—|
h
Ml Illlil! U |_
h-ej^^SB
I Si L T = — 1
FIG. 874.
at the bearings of the shafting. Fig. 876 shows the Medart
pulley. The rim is curved in bending rolls, and also given a
rounding face, and is
countersunk for the
rivets at the attachment
ofthe arms. The
pads on the arms are
truly finished, as is
also the rim after it is
riveted on, thus giving
an accurate and
useful pulley.J
A metal pulley by
the Hartford Engineering
Company 60"
diameter and 16" face
weighed 320 pounds.
A cast iron pulley of
the same dimensions
IAJ-TBJ
made by the Berlin-An
halt Works, weighed
FIG. S75.
700 pounds, and one
by Bri gleb, Hansen & Co., a little narrower face weighed 528
pounds
In order to determine the necessary friction to secure a pulley to the
Shalt, the force p on the belt will serve. In ordinary cases, assuming a coelticient
ot Inctioti on the key of one-half that on the belt, there should be
a pressure/. 011 the key of about 4000 times that on the belt, which, according
to -, zo will not give more than 5000 to 7000 lbs. for/'.
H his is the construction ofthe Berlin-Anhalt Machine Works.
1 Made 111 England by George Richards & Co., Manchester.

August, 1892.] ENGINEERING MECHANICS. 203
Fig. 877 shows Goodwin's
split pulley, with
wrought rim, the face of
the rim being rounded by
turning.
These constructions
naturally led to the use of
wrought iron arms also,
although these are somewhat
difficult to make;
but for very large diameters
(say 16 to 25 feet)
they possess advantages.*
Pulleys made entirely of
steel are used by J. B.
Sturtevant of Boston, in
connection with fail blow-
FiG- 8 76- ers, Fig. 878. The hub
with web, is screwed on the steel shaft of the fan wheel, and
the rim, which has a groove turned iu it, is expanded by warming,
and shrinks into place,
the whole being finally
turned in position, and carefully
balanced. Sturtevant
uses these pulleys up to 10
iu. iu diameter, and 7 in.
face, the thickness of rim
beiug from 0.08 to 0.16, and
the velocity at the rim reaching
5000 feet per minute.
By covering the rim with
leather the co-efficient of friction,
fi, and can be increased
between the belt and pulley,
and the modulus of stress
T reduced, and the specific
capacity ofthe belt increased.
This is sometimes useful because
a reduced modulus of p G g77
stress T permits a smaller
cross section of belt and lighter pulley. In large transmissions
reduction of stress is important since it is accompanied with
reduced journal friction
and higher efficiency.
The observation of the
author leads him to believe
the specific capacity
of a belt is not
greater with leather
covered pulleys than
with uncovered ones,
and the cost of covering
is an important item.
The greater the angular
velocity of a pulley
the more important it is
that its geometric axis
should be a so-called
"free axis." This requires
that the center of
gravity of the pulley
should be on the axis of rotation and also that the various portions
of the mass should be so distributed that the axis of
inertia should coincide with the axis of rotation and tbe centrifugal
moment equal zero.t This cau be done empirically by socalled
balancing, the unequal distribution of material being
equalized by attaching pieces of lead or other metal, or more
accurately by balancing when revolving, for which purpose a
beautiful apparatus has been made by the Defiance Machine
Works, Defiance, Ohio. Careful balancing of pulleys is of great
importance at high speeds, the rapidly increasing vibrations
will soon limit the speed. This is to be considered in connection
with the advantages to be gained by the use of high speed
shaft as discussed in i 146.
NOTE.—The recent investigations upon paper rim pulleys f
are instructive. This construction gives a very high modulus
of friction, the modulus of stress r being only 1.2. This gives
T = 1.2 P as against 2.5 P, for iron pulleys. Hence follows a
great increase in the specific capacity of the belt, and increased
efficiency with smaller and lighter pulleys. This leads the way
to further investigations which prove of material value in the
science of belt transmission.
* Pulleys with wrought iron arms are made in Germany by Starck & Co.,
Mainz ; in England by Hudswell, Clark & Co., Leeds, these latter with
arms of round bar iron. .
f See an article by the writer, " Ueber das Zeutnfugal-Moment, in Berliner
Verhandlung, 1876, p. 50.
J See Am. Machinist, May 23, 1885, p. 7.
EFFICIENCY OF BELTING.
i 2S4.
Three causes of loss exist in belt transmissions, viz.: journal
friction, belt stiffness, and belt creeping. For horizontal belting
we have, according to formula (99) for the journal friction,
expressed at the circumference of the pulley a loss Ez when 7
^=2.5 P, t = 1.5 P:
-p = E> = ~P yf d f 2R\J
-f (A + £)
\R^ Rj
(26S)
in which i/andi/, are the journal diameters, and /"the coefficient
of journal friction. This loss is doubtless the greatest of the
three. For lack of better researches the loss of belt stiffness
may be deduced from Eytelwein's formula for ropes. For the
coefficient of stiffness s, for force S', which includes both pulleys
;
-^^ E,
4-s
1 +
P
\R + RJ
in which 5 = 0.009 — = 0.012.
AR + RJ
(269)
The loss from creep is due to the fact that the greater stress
ou the driving pulley over that 011 the driveu requires for a
given volume of belt, a longer arc of contact ; for the expenditure
of force G' for creep on both pulleys, we have for a stress
•Sj on the leading side of the belt :
9L-E-
1 +
T_
E
Sx
0.4 SL
E + S,
(270)
In this E is the modulus of elasticity ofthe belt, which for
leather is 20,000 to 30,000 pounds. The losses from stiffness
and creep are small.
Example.—Let d and d^ = 4"; R = R = 20", 5 = 0.2, / = 0.08, .9 =J 0.012
8 X o 08
E = 28,440, S\ = 425, we have 7- 1 — P — X 0.4 = 0.08 P;
also S- = P (o 048 X 2) — = 0.0048 P,
20
o 4 '< 425
and C P -• 0.0059 P.
28,440 + 425
The total loss is therefore : 0.08 + 0.0048 -f- 0.0059 =9-* P er cent.
CHAPTER XXI.
ROPE TRANSMISSION.
I 2S5.
VARIOUS KINDS OF ROPE TRANSMISSION.
If iu the tension driving gear, shown in Fig. 810, the rope be
used only for the transmission of power we have what is called
a Rope Transmission. Since the details of construction must
vary, according as fibrous or wire rope is used, we may distinguish
between three kinds of rope transmission, viz. : those for
Hemp, Cotton or Wire Rope, and these will be considered in
this order. The oldest of all these is hemp rope transmission,
but this was gradually being superseded by belting until
Combes, of Belfast, revived it, about i860, since which time it
has been extensively used for heavy transmissions. The character
of the material permits a wide variety of applications.
The same is true of cotton rope, which is extensively used for
driviug spinning frames, travelling cranes and many other machines,
the softness and flexibility of the material giving it advantages,
but within limits. Wire rope transmissions, since its
introduction by the brothers Hirn, at Logelbach, in 1850, have
developed a high degree of efficiency and utility for long distance
transmission. As will be seen hereafter, the applications
of rope transmission appear to be capable of still further extension.

204 ENGINEERING MECHANICS. [August, 1892.
I 2S6.
A. HEMP ROPE TRANSMISSION.
SPECIFIC CAPACITY-. CROSS SECTION OF ROPE.
It is important first to determine the specific capacity for
hemp rope (\ 280). This is obtained from the general statement
according to (262) :
N0 =
4 -S,
in which S, is the stress on the tight side of the rope, and r the
modulus of stress. The value for the co-efficient of friction fi
depends upon the form of the groove or channel in the sheave
over which the rope runs.
_ il
i l —
FIG. 879.
If the groove is semicircular, as at b, Fig. S70, the friction is
but little greater than it is upon an ordinary cylindrical pulley,
as at a ; if, however, the groove is made wedge-shaped, as at c
(see wedge friction wheels *) 196), the driving power is increased
although the surface of contact is reduced. In determining the
value of T, from formula (239) the influence of the shape ofthe
groove can be included by using a corresponding co-efficient of
friction fi 1 . According to the recent investigations of Leloutre
aud others, the value off for cylindrical pulleys and new hemp
rope is 0.075, f° r semicircular grooves, 0.0S8, and for wedge
grooves with an angle of 60°, fi = 0.15, which accords well with
the action ofthe wedge, doubling the pressure, see (185). For
fi 1 = 0.088 and a contact of a half circumference, we have fi 1 a
— 0.3, and hence r = 3.86 ; with fi 1 = 0.15, fi'- a = 0.47, aud r
= 2.67. The latter value, which is even reduced in actual
practice, may be adopted, since wedge grooves in general use.
The stress is usually taken while low, and may be put at 5 =
l__ J5°_ .
350 lbs., which, taking r = 2.67, gives N„
33000 ' 2.67
0.0039; see (262). In practice N D is fouud even one-half this
value, and we may take as a practical rule in hemp rope transmission
for the specific capacity, i. e, the horse power transmitted
per square inch of cross section, for each foot of linear
velocity per minute ;
No = 0.004 to 0.002 (271)
the cross \ 265, section as that being due taken to the as full in \
outside diameter ofthe rope.
When great power is to be transmitted a number of ropes are
used side by side, the pulleys being made with a corresponding
number of grooves. For machine shop transmission such
ropes are conveniently made about two iuches in diameter
although they are used as small as lA, and as thick as 23f
inches.
The cross section of the rim of a pulley for five ropes is
shown in Fig. 880. For large steam engines the grooves are
sometimes made on the
r. i ra i .i ! n i a fly wheel, such con­
structions sometimes
being very large and
heavy.f
The application of
rope transmission in
manufacturing establishments
simplifies the
mechanism very ma-
FiG 880. terially, since it enables
the jack shaft and gearing
to be dispensed with.
Such an arrangement is shown in Fig. 881, in which five
to the rope, taking r = 2 —, gives a loss due to one shaft —
Example i. A steam engine of 60 H. P. has its power transmitted through
five ropes of 2 inches, the pulley being 11.28 feet diameter, making 45 revolutions
per minute. This gives 7' - 1592 feet per minute. The cross section
of the rope 3.14 sq. inches. Hence N0 — — 00024 This
5 1592 X 3-14
is taken from an existing installation.*
FIG. 881.
different Hues of shafting are driven from one horizontal steam
engine, sixteen hemp ropes beiug used in all.
Examples. In the jute mills at Gera the fly wheel of the engine is grooved
for 30 ropes, ot 2.36" diameter, each rope transmitting 25 //. P. ; the velocity
being 3000 feet per minute.
25
— o.ooig.
This gives a specific capacity of .V0 =
3000 X 4-375
Example3. The Berlin-Anhalt Machine Works has design rope transmis­
Ez = ——
(272)
sions in which ropes of 1.18", 1.57", 1 97" diameter transmit forces respectively,
of 92.4, 165 and 264 pounds. The respective cross sections ofthe ropes
jV P
2R
Example 1. In the first of the preceding examples we have also d = 6.3
are 1.09, 1.93 and 3.04 square inches. Since —
11
which gives in each ofthe three cases .
3300041
= - we have JV =
iZtsao °
- 0.0026.
inches, and 2/1
cent.
•35*4 inches, hence — — = 0.046 or a little over 4 per
*See Zeitschrift d. Verein deutscher Ingenieure, Vol, XXVIII, 1
p. 640.
§ 287.
SOURCES OF LOSS IN HEMP ROPE TRANSMISSION.
The use of hemp rope transmission reduces many losses
which exist in other methods and which materially reduce the
efficiency ; the principal ones which need to be considered are
the resistances due to journal friction, stiffness of ropes, and
creep of ropes.
a. Journal Friction.—In rope transmissions from steam engines
the journal friction is usually great, because the large fly
wheel requires journals of large diameter. The usual calculations
can only be given by indeterminate results, because the
tension of the ropes sometimes acts with the weight of the
other parts, and sometimes against it.
If we consider the rope tensions T and t by themselves, as
acting horizontally, we have from formula (100) the friction F
= —fi (T f- t), which reduced to its corresponding resistance
2
~f \ 2 J + x J) {yyj • If we take / '=- °
double the result for both shafts, calling this combined loss Ez"
we have : Ez = — x 0.09 x 4-33 which reduces to: (AA
t See Engineer, Jan., 1884, p. 38, for such a fly wheel 15 ft. face, 30 ft. dia.
weighing 140 tons, to transmit 4000 H. P. by 60 ropes.
I See I 300.

August, 1892.] ENGINEERING MECHANICS. 205
b. Stiffness ofi Ropes.—If we apply Eytelwein's formula (252)
we have Q = J£ ( T-\-1) taking both pulleys into consideration,
and taking r = 2":3' and introducing 7"+ t, gives Q = 4 \ P.
It -must be considered that the ropes are usually quite slack,
and that the co-efficient stiffness S, may be taken somewhat
less than Eytelwein's value. If we take 2 3 as a fair approximation,
the ratio of loss is
S 2 , d- 1
A
s
In case c, the radial pressure Q, of the rope is divided into
two forces Q' acting normal to the wedge surfaces and equal
1 Q
to —r-—:-£• in which 8 is the angle ofthe groove, and taking the
sin ._, u
contact surface on each side as J the circumference ofthe rope,
we have
P _ _j d_
S sin 0 ' ~R
which, for 1 ; 30 0 , gives approximately :
P_ d
S = 4 R
(276)
Even uuder these unfavorable conditions the superficial pressure
is not important, on account of the small value of S ;
whicli, as already seen, is about 350 pounds.
Example.—If .S* = 350 pounds, anil
we have for a cylindri-
_ = TXo. 463^X4_
and calling this loss Es , we get:
cal pulley / = 350 X 2 X = 28 lbs. for semicircular grooves, p = lbs
2
5.
cf
i-33
R
( 2 These low pressures cause but little wear upou the rope,
and for wedge grooves, when ft = 30°, p ^-- 56 lbs. per square inch.
hence the great durability of hemp transmission ropes, some­
I 2S9in
which d is the diameter ofthe rope.
73)
times extending to two or three years of use.
B. COTTON ROPE TRANSMISSION.
Example 2. In the case ofthe preceding example, d = 1", R = 67.75''. Cotton rope is not so extensively used for purposes of trans­
This gives Ea = 1.33 . - — 0.078 or 7.8 per cent.
mission as hemp rope, although it possesses the advantages of
great strength and flexibility; the impediment to its use being
/• ' / B 1 > ML 1 «. L • its higher price. The application of cotton rope for driving
c. Creep of Ropes—-The loss through creep is more important innf m£ l e spindies referred to \.ixx \ 265, is shown in Fig
in rope transmission than with belting .see \ 284) and should
not be neglected, although it cannot be so readily determined,
gg fa | h j c h K ^
*•
1 ^ £ ^.^ s
r owing to the division of the power among a number of ropes.
It is practically impossible to insure a uniform tension upon a
number of adjacent ropes, or to have them of exactly the same
diameter, besides which the "working " diameters of the various
grooves differ slightly, so that additional slippage must occur.*
The resulting frictional loss is estimated by some at
as much as 10 per cent., when the number of ropes is 20 to 30,
and it is at all times important enough to be given consideration.
The losses from stiffness and creep should be investi­
-
r J
gated whenever practicable, as the resulting information would
be of much technical value.
FIG.
Assuming the loss from creep in the case previously considered
to be 5 per cent., we have a total resistanoe of 4 + 7.8 -f- 5
= 16.8 per cent.; which, since small values were taken in all
cases, is not to be considered higher than the actual loss.
This explains the numerous objections which have been raised
(as in England) against the use of hemp rope transmission for
very large powers (see \ 301).
i 2S8.
PRESSURE AND WEAR ON HEMP ROPE.
As already seen, the surface of contact ofthe rope and pulley
may be one of three kinds: upon a cylindrical pulley, in a
semicircular groove, or in a wedge-shaped groove (Fig. 879),
and to these formula (241) can be applied. In case a, we can
approximate b' as equal to { the circumference of the rope.
This gives for the superficial pressure
- whence :
-dR
R
For case b, we have b 1 ou the carriage. This latter pulley is on the axis of a drum T,
from which light cords drive the spindles 7",. At L, L, are
guide pulleys. The usual diameter of rope for 7, T, is 0.86",
and for large machines with many spindles two such ropes are
used, the pulleys being made with double grooves, these always
being of semicircular section.
On the ring spinning frame cotton rope of 0.4" diameter is
used on cone pulleys of 12 steps, giving changes of speed from
3:1 to 2:3. The proportions of such pulley may be determined
as shown in \ 279, the grooves being semicircular
As already shown in \ 265 cotton ropes have been used by
Ramsbottom for driving traveling cranes. For this purpose
ropes of \ to j inch diameter are used, running at speeds of
2500 to 3000 feet per minute, a weighted idler pulley keeping
the rope taut.
In view of the slow movement of the load, viz : 2 3 to 40 feet
per minute, it is questiouable whether cotton rope transmission
involving such a great transformation of speed, is advantageous, f
C. WIRE ROPE TRANSMISSION.
(274) I 29°-
SPECIFIC CAPACITY. CROSS SECTION OF ROPE.
= — d, whence
In considering the transmission of power by means of wire
rope the points to be determined are the cross section of the
2
rope, and the deflection of the two portions of rope due to its
x_ d
2 R
(275)
weight. The cross section will first be considered by determining
the specific capacity (See \ 2S0). This we get from (262)
1 S,
0 _ T
33°°° '
*The variation in adjacent ropes may be shown by putting a little
coloring matter on the ropes and watching its distribution.
in which S, is the stress in driving half of the rope, considered
either in connection with the driving or the driven pulley.
The modulus of friction p is taken somewhat higher than for
belting, since the angle of contact a is greater, aud also because
the co-efficient of friction /, for pulleys fitted with diagonal
leather strips (see below) is very high ; early and recent tests
giving/— 0.22 to 0.25 and higher. The first value gives ef" —
2
2 (See Fig. 816), and also the stress modulus r = ——y ="" 2
(See 239). This gives, in (262) if we neglect centrifugal force :
_i *L = _A_ Nn
33000 " 2 66000
(277)
tin some instances leather transmission ropes are used, formed ol
twisted thongs, these being used for light driving, as foot lathes, or
light spindles.

206 ENGINEERING MECHANICS. [August, 1892.
This gives high numerical values, which is also borne out in
practice, since large powers are successfully transmitted with
wire ropes of small diameter. It is good practice to take 5[
for iron wire as high as 8500 pounds, and for steel wire up to
20,000 pounds aud even higher. This gives for the specific
capacity, when :
5t = 2000, 4000, 6000, 8000, io,ooo, 12,000, 14,000, 16,000, 18,000,
20,000.
N0 — 0.03, 0.06, 0.09, 0.121, 0.151, 0.182, 0.212, o 242, 0.273, °-3°3
or approximately :
For wrought Irou Wire N0 = 0.03 to 0.121.
For Steel Wire . . . • N0~ 0.03 to 0.303.
The cross section q is readily obtained, since N = q v N0
hence:
N
(278)
q — 66,000 — —
v .*->,
We then have, if i is the number of wires in the rope, a diam
eter of work : S — i —

August, 1892.] ENGINEERING MECHANICS.
EMINENT AMERICAN ENGINEERS.
Faank W. Grogan was born May 21st, 1S57, iu Portsmouth,
N. H.; he was educated in the public schools of that historic
town and thereafter by private teachers. At the age of sixteen
he commenced to learn shipbuilding ; served five years as a regular
goverumeut apprentice iu the Kittery Navy Yard, during
which time he passed through the various stages, such as the
handling and use of tools iu ship coustruction, launching and
docking of vessels, the making of ships' models, laying down
of vessels ou the mould loft floor, designing aud calcula­
tions.
When twenty-one, he was appointed Naval draughtsman at
the Kittery Navy Yard.
In 18S1 he was ordered to report to the committee of Naval
construction, having charge of the new vessels of the Navy in
connection with the Advisory
Board, wheu he was
given charge of the design
aud calculations for a type
of gunboat for the Chinese
waters.
In March, 1883, he was
ordered by the Secretary
of the Navy to report to
Chief Constructor Theodore
D. Wilson, for tempo­
rary duty in the Bureau of
Construction aud Repair,
Navy Department, Washington,
D. C, upon the desigus
of the well-known
" White Squadron." After
the awarding of contracts
for these vessels, he was
ordered to return to the
Kittery Navy Yard, to prepare
for permanent orders
to the N. Y. Navy Yard ;
he was stationed at this
yard about two years, and
then recalled to the Navy
Department in 1885.
During his connectiou
with the Bureau of Construction
and Repair in
this department, he was
intrusted with some of
the most intricate work of
the Bureau, comprising the
designing and calculation
of the vessels for our new
Navy, and had complete
charge of the designing
and preparation of the
drawings of the battleships,
'' Massachusetts,''
" Indiana " and "Oregon."
With the approval and concurrence of Commodore Theodore
D. Wilson, and Assistant Chief Constructor Philip Hichborn,
Mr. Grogan was appointed April, 1891, on the recommendation
of Commodore Richard W. Meade, U. S. N., an assistant to the
Board of Management, U. S. Government Exhibit, World's Columbian
Exposition, aud ordered to report for duty as "Naval
Architect and Chief Technical Assistant" to the Representative
of the Navy Department, on that Board. He designed, and is
now supervising the construction of the model battleship " Illi­
nois" at Jackson Park.
Mr. Grogan is a member of the General Committee of the
World's Congress Auxiliary, on Engineering Congresses of the
World's Columbian Exposition of 1893.
FRANK-W. GROGAN.
LUXURY OP MODERN RAILWAY TRAVEL.
A recent trip over the Royal Blue, New York to Washington
aud return, impressed the writer most strongly as to the won­
derful possibilities regardiug speed and luxury in railway travel
in America. Having been in nearly every State in the Union
aud over a large part of Europe we are prepared to feel ourselves
acquainted with railway transportation thoroughly, and
while in no way failing to recognize the splendid service furnished
the public by the great railway lines of America, the
writer believes that he is stating nothing too strongly in saying
that in his judgment there is not a service in the world, which
taken as a whole, will compare with the famous Royal Blue
Line, composed of the Central Railroad of New Jersey, the
Philadelphia and Reading and Baltimore aud Ohio Railroads.
Not only is the time made between these points, via this line,
the quickest ever made
between New York and
Washington, but with a
road bed that is simply
perfect, and an equipment
so luxurious as to leave
nothing to be desired, it
furnishes no doubt the
fiuest service of auy line in
the world.
Every train via the Royal
Blue Line is vestibuled from
end to end, aud consists
not only of the most luxurious
parlor aud sleeping
cars ever made by the Pullman
Palace Car Company,
but also of palatial day
coaches far superior to the
parlor cars run on many
lines, with smoking compartments
fitted up with
chairs aud sofas, the same
as in drawing room cars.
Although the service is so
superior and the time so
quick, on uo train are there
an)- extra charges. To
those who desire accommodations
in the drawing
room or sleeping cars
only the regular additional
charges are asked, and on
all of the trains vestibuled
day coaches are run open
to the public without auy
extra charges whatever.
The dining car service attached
to the principal
trains is in keeping with
the splendid character of
the line's services aud the
cuisine equal to the best hotels of the country. It is 110 wonder
that the Royal Blue Line has attained phenomenal popularity,
and it has not attained its positiou by any other reason than
that it deserved it. It is so incomparably superior to any service
ever inaugurated between New York and Washington that it
would be surprising if the public did not patronize it so liberally
; certainly no one who wants the best should take any other,
and when it is considered that for the finest service in the world
no additional charges of any description are required, it should
receive, as it does, the endorsement and patronage of the public.

2oS ENGINEERING MECHANICS. [August, 1892.
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
§71 bis*
BY MAURICE LEVY.
ON THE PLAN OF THE CURVES OF PRESSURE.—Let us con­
ceive of continuous forces the locus of whose points of application
forms a line, and let us admit, to be brief, that these forces are
vertical. If they were not, everything that has been said of the
vertical lines or sections would apply to lines or sections made
according to the lines of action of the given forces.
Fig. ci.
Let (Fig. n) A,-, Bo A B be a body or system of bodies subject
to vertical forces succeeding each other in a continuous man
ner according to any law.
Let Co r0 be the reaction on the support A0 B0 and let Co C
be the curve of pressure drawn in broken lines.
Let us form a definite number of vertical sections which cut
on throughout. Let A\ R2, ... be these resultants,
According to the very definition of the polygon of the pres­
sures, the polygon Co s, s2 . . . s6 Q is a polygon of the pres­
sures, relative to the sections ;/•,, m.,, •«,, mt, mb. Hence, inversely,
if, in the system of bodies considered, we make a definite
number of vertical sections if we can, by some means, find
the partial resultants of the forces acting between these sections
and if we construct the polygon of the pressures relative to
these partial resultants, it will circumscribe the curve of pres­
sures .of the continuous forces, at the points where it is cut by
the sections ; the draught of the inscribed curve can thus be
made with great exactness, since the points of contact Co m,
m2, . . . are known.
If the forces are such that their points of application cover
sections with the polygon drawn.
Let us always suppose the case ofthe vertical force whose points
of application cover an area. Let us imagine a system of in­
clined sections succeeding one another in a continuous manner
—for example, sections normal to the arc Ao A, Fig. b.
Let us conceive of two sections infinitely near together ab,
a' b', and let us construct the partial resultant of all the forces
acting between these two sections. These forces may be com­
posed of the weight of the portion of the body aba'b' and of a
* This paragraph is not indispensable to understand the following.
weight as that shown in hatchings. By composing them, we
obtain a partial resultant (not represented on the figure).
Let c/be the point where the vertical line of action of [this
resultant cuts the section ab. The locus of the points cv will
furnish a curve.
Besides, let Co C be the curve of the pressures of these partial
resultauts. It will give pressures not ou any'sections whatever,
as in the cases 1" and 2" ofthe theorem of \ 68, but only on the
sections considered, i. e., on every section normal to Ao A.
In order to have the line of action of the pressure on ab, it is
sufficient through the point o-to draw the vertical cow, and
the tangent at tn to the curve of the pressures will be the line
of action of the required pressure. The corresponding'polar
radius will be the magnitude of it.
This granted, among the sections considered, let us take a
definite number of them; those which cut the locus of the
points o< at oc,, ot 2, ot s,. ..; let us determine these points cx ,,
Ot 2, OC 3, . . . by the consideration of each section cx and
of a section infinitely close, and the construction of the
this curve at the point ms, m.,, mit m„ m:,, and through three partial resultant of the forces acting between them, as we have
points let us circumscribe to the curve a polygon. Let 5,, s2, done for the point o- . This construction is easy and will be
s3, s.„ 53, be its apices. According to a property of funicular especially so if we are aided by the theory of the centre of
curves (§ 45 bis), the apex s, is a poiut of the resultant of the gravity of which it will be spoken farther on.
vertical forces comprised between the extreme section Co and Let us draw the verticals c/ ,-*•,, cz 2;«2, a 3w3, ... a 6***6,
the section ••/,; likewise the point s, is a point of the resultant cx A'ht to their meeting with the curve of the pressures at /«„
ofthe forces comprised between the section >«, and m.,, aud so m.L, m3, mit . . .; through these points, let us circumscribe a
polygon to this curve the apices st, s.,, s3, ... of this polygon
give the positions of the partial resultauts of the forces acting
between the sections considered, and the polygon itself is
strictly a polygon of the pressures relative to the particular
sections czj.cz.,, ot 3, . . .
Then, reciprocally, having chosen a finite number of sections
among those relative to which we can draw a curve of the pres­
sures, determine the points ot i, ot j, . . . on these sections and
the partial resultants Rlt R2 . . . of the forces comprised be­
tweeu them (a thing which cau be done only approximately) ;
draw the polygon of pressures relative to the forces in definite
number 7?,, 7?2, 7?3, . . . and draw the verticals of the points
cz,, cx 2, ... to their meeting at ml ,m2, . . . with this poly­
gon. Inscribe a curve in said polygon, the points of contact
an area, we know that the same rule holds, i. e., that the poly­ beiug in,, m.,, . . . you will have the required curve of presgon
ofi pressures relative to the partial resultants 7?! R.,, ... of sures with close approximation.
the forces comprised between a definite number of vertical sec­ REMARK.—In the arches in masonry, where this construction
tions circumscribes the curveof pressuresxcA&tivtito vertical sec­ cau be utilized, we shall see that the curve ofthe pressures should
tions succeeding one another iu a continuous manner, and the not be far removed from the centres of the sections ; it is the same
points of contact are the points of intersection of the vertical with the points cx ; hence, we sometimes neglect to determine
the points cz and we inscribe the curve in the polygon without
the points of contact having been determined. But we must
guard against believing that these points of contact are the
points where the sections themselves cut the polygon of pres­
sures. It is only in the case of vertical sections that it would
be so.
? 72.
CONDITIONS OF THE PRESSURES TO BE ABLE TO BE DE­
TERMINED BY STATICS.—In order that bodies like those defined
in \ 66 be in equilibrium, it is necessary and sufficient that we
find at least one funicular polygon of the given forces which

August, 1892.J ENGINEERING MECHANICS.
may serve as the polygou of pressures (*). Now three condi­
tions are necessary and sufficient to define a funicular polygou.
Hence :
ist. If the jointings are such that, by reason of their very defini­
tion, they subject the polygon of pressures to three conditions,
the latter will be able to be traced, aud will furnish the pres­
sures which arise in the system ;
2d. If the jointings are such that the polygon of pressures be
subject to more than three couditious, it will not, in general,
be able to exist , and hence, the equilibrium of the system will
be impossible, unless among the given forces there exist certain
relations which Statics will always allow to be found ({* 50). If,
for example, the polygon of pressures is subject to pass through
n points, n being superior to 3, we shall trace the funicular
polygon of the given forces passing through three of the n
points. If it is found that it passes of itself through the 11—3
others, equilibrium will be assured and the pressures deter­
mined. In the contrary case, equilibrium is impossible, since
it is necessary, for equilibrium, that there exist a funicular poly­
gon which is the polygon of the pressures;
3d. If the jointings subject the polygon of pressures to less
than three conditions, then there will exist an infinity of funi­
cular polygons being able to serve as polygon of pressures-
Equilibrium will be, in a Statics point of view, equally well as­
sured by each of them, and, to find what the true one is, it is
necessary to make allowance for the nature and form of the
bodies, which requires that we have recourse to the theory of
elasticity or, if temperature comes in, to that of heat.
Some applications will make these general considerations
plain.
I 73-
REMARKS ON THE HINGES.—We shall regard a hinge as a
cylinder of dimensions infinitely small, or even as a circular
cylinder of finite dimensions crossing two or more bodies. The
point where the axis of the cylinder pierces the plane of symmetry
containing the forces is called the centre ox point of articulation.
It is possible to apply forces at the same time to the bodies
and the axis of the hinge, or to apply them ouly to the hinge
or only to the bodies.
Let (Fig. 11) (A) be one ofthe bodies in any number crossed
by the hinge whose centre or point of articulation is C. The
hinge may be suppressed and the body (A) regarded as free,
provided that to the forces which incite it, we adjoin a force 7?
equal to the reaction which it experiences on the part of the
hinge. This reaction is normal to the cylindrical surface ofthe
hinge at the point where the latter presses the body ; but this
last point is not known a priori ; it depends ou the forces
which act on the body and on the hinge. Hence, if two forces
F and Fu equal and opposed and of any direction, passed
through the point C, the hinge would cause to arise on the
body (A) a reaction 7? equal and opposed to F and on B a re-
(*) We shall always speak of the polygon of pressures, it being understood
that, if the forces are continuous, the polygon is replaced by a
curve. In speaking of polygons, all cases are included, since, what is
true for a polygon of any number of sides is true for a curve, while the
inverse takes place. Likewise, in considering isolated forces which can
be as near as we wish, we include the case of continuous forces, while
this latter case does not include the first.
action Ry equal and opposed to/* 7 ,. If the forces /-'and Ft
changed in flow or direction, the same thing would occur with
the forces R and /?,, and the points of contact of the hinge and
the bodies, i.e., the points where the pressures are produced
would both be on the new diameter determined bv the common
line of action of the two forces.
This point is not always so easy to determine as in this ex­
ample ; but, whatever it is, if we lay aside the friction, the re­
action between the two surfaces in contact is directed according
to their common normal, and, as one of these surfaces is cylin­
drical, all its normals pass through its centre C. Hence, in
order to render free one of any number of bodies crossed by a
hinge C, it is sufficient to apply to it a force Rpassing through
the poiut C or centre of articulation. The magnitude and di­
rection ofi this force are moreover a priori undetermined and
depend on the conditions of equilibrium between the forces
acting both on the hinge and the bodies which it binds together
Every direction given to these forces is compatible with the
mode of jointing of the system, i. e., the hinge can resist forces
passing through the centre, whatever be the directions of these
forces, aud, consequently, also exercise on the bodies which it
binds together reactions of any directions whatever. The joint­
ing betweeu each body and the hinge is made precisely for the
body to be able, 011 its part, to resist such reactions.
z 74-
CONDITIONS OF EQUILIBRIUM OF THE ARTICULATED POLY­
GONS WHEN FORCES ARE ACTING AT THE SAME TIME ON THE
SIDES AND THE APICES OF THE POLYGON.—Let us consider a
system of bodies all having one and the same plaue of symmetry
in which the forces act which incited it, articulated in
such a manner as to form au articulated polygon, i. e., in such
a manner that each body bears onl)- two hinges (the line of
juncture of their centres forms one side of the articulated poly­
gon) and that each hinge crosses only two bodies.
THEOREM.— Whatever be the forces applied, whether to the
different bodies, or to the hinges, whether the extreme bodies be
supported by fixed articulations or fitted in (i. e., fixed at all
points ofi a plane section terminating them), in order that the sys­
tem be in equilibrium, it is necessary and sufficient to be able
to find a funicular polygon of all the forces acting (without dis­
tinction between those applied to the bodies and those applied
to the hinges) which passes through all the points ofi articula­
tion. This polygon, which will be the polygon ofi pressures,
will furnish then, not only the reactions of the supports and the
actions between the bodies and the hinges, but the resultant of
the elastic fiorces acting in any section made in one of the bodies.
(To be continued.)
THE Watertown Steam Engine Company of Watertown,
N. Y., combines excellent and energetic business management
with good work. Its workmanship is now fouud scattered over
many States, and is commanding the esteem of all who try it.
WITH reference to the proposed tunnel to connect Prince
Edward Island with the maiu land, Senator Howland, promo
ter of the scheme, says : "We are going to bore on the line ot
the tunnel every 500 yards, a distance of 60 ft. into the bottom
all the way over and to make borings from 100 ft. to 200 ft.
down to'the bed rock on either side. These borings will be
taken out by steam drills in cores of 10 ft. in length. When the
borings are completed the cores will be boxed up and sent to
the Public Works Department at Ottawa for the information of
the government and also for affording complete information
to contractors should the government decide to call for tenders.
These will be accompanied by a complete trigonometrical sur­
vey, so at all times to accurately lay out the alignment. Mr.
A. W. Palmer, Civil Engiueer, has arrived with the proper ap­
pliances to commence work.

2IO ENGINEERING MECHANICS. [August, 1892.
ELECTROTECHNICS.
A Compilation of Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
The base of the condenser is a smooth cast-iron plate, with a
gutter around the edge to contain the superfluous paraffin, wliich
is melted out over a gas flame, slight pressure being applied at
the same time. The paper leaves should project about 25 mm.
(1") on each side. Two adjacent corners of the sheets of paper
should be cut off, and also each alternate corner right and left
corresponding to the paper corners. The series 18 and 19 are
then easily clamped or soldered together.
A layer of paper is first placed on the gently-heated iron base
and brushed with melted paraffin. Upon this is laid the first of
the " 19" series of tin foil sheets, which is varnished with shel­
lac. Upon this is placed a second leaf of paper similarly coated,
and then the first leaf of foil iii the 18 series, and so on. Wheu
completed it is submitted to a pressure of about 400 kilograms
(8S1 lbs.) in order to express the superfluous paraffin. During
construction, a battery of 10-20 cells is connected to the series,
including a galvanometer. This action is taken to detect any
fault liable to occur in the insulation. When the arrangement has
cooled to a normal temperature its capacity is determined by
any of the methods previously described. If it is too great, a
leaf or part of a leaf is removed ; if too small, greater pressure
is employed, and if this is not sufficient another leaf is added.
When the condenser is finally calibrated it is compressed between
two blocks of wood which are held together by screws.
The combination is placed in a wooden box and the series connected
to suitable terminals. Practically the same method is
employed when mica is substituted for the paraffined paper.
Volume for volume the mica condenser has the greater
capacity, due to the greater value of its specific inductive
capacity.
Siemens and Halske employ a system of well-insulated metal
discs, hermetically sealed in a box, for a standard condenser.
When used dry air at 20 0 Cis blown through the box.
Air condensers consisting of two metal plates separated by a
layer of air may have their capacities directly calculated as
follows:
A
M = 4.452-io 6 /
Where M is the capacity iu microforads,
A the surface in sq. in. of either plate, aud
t the distance in inches betweeu them.
These condensers are not employed, however, iu practical
measurements.
6. POWER.
Power is the rate of doing work, and the power per second
necessary to force a current through a resistance r, is
c . e watts AA. H.P.
746
where C and e are current and E. M. F. respectively. If r is a
passive resistance (•'. e. without polarization), theu
P — t?t watts — 746 IIP.
1 watt = 44-25 foot lbs. per miu. = 0.7375 ft- lbs. per sec. =
1
H.P.
74 6
The movable coil of the electro-dynamometer is formed from
a thick wire, the stationary coil having many turns of fine wire.
FIG. 73-
The movable coil is connected in the circuit as shown, and the
stationary coil shunted between the ends of the resistance r.
The instrument is calibrated by comparison with standard
curreut and E- M. F. galvanometers. If the spiral spring is sub­
jected to torsion by turning the milled head, so that the pointer
attached to the movable coil is brought to zero on the scale, the
power is then directly proportional to the angle of torsion
through which the spring is turned. Fig. 74 shows the Siemen's
electro-dynamometer, in perspective.
FIG. 74-
It consists of a fixed coil, and a movable coil whose ends dip
iuto mercury cups. The movable coil is suspeuded by a thread
aud a delicate spiral spring, which latter can be twisted by turning
a milled head through an angle which is measured on the
divided scale by the pointer attached to the head. The instrument
after being levelled is so adjusted that the plane of the
movable coil is at right angles to that of the fixed coil, which is
indicated by the pointer attached to the movable coil when at
zero. When no current is passing, the pointer on the head
should also register 0°. Wheu current flows through the coils
the movable coil tends to place its plane parallel to that of the
fixed coil, which tendency is resisted by the torsion of the
spring, and the couple exerted between the coils is balanced by
that exerted by the twisted spring, the moment of the latter
being proportional to the angle through which the pointer
attached has been turned.
If the coils are connected in series, the turning moment, and
also the angle of torsion, are proportional to the square of the
current passing.
Since the coils always maintain their positions relative to
From this it is seen that the power may be determined by
each other, the instrumeut is a "zero" instrument, and its law
being known one comparison with a standard is sufficient cali­
measuring the current and E. AI. P., or the current and resis. bration.
tance. The first is the more accurate. The measurements may The coils being fixed in positiou, alternating currents may be
be combined into one by employing an electro-dynamometer. measured with fair accuracy. The reversals of current being
a.) Siemeu's Method. Fig. 73.
simultaneous in both coils, the force between them remains of

August, 1892.] ENGINEERING MECHANICS. 211
the same value. The instrument, however, is not dead beat,
the mercury cups employed are a source of bother, and the in­
strument must also be placed so that the movable coil is at
right angles to the magnetic meridian of the earth. The movable
coil is liable to be blown by currents of air, the connections
are troublesome to make and the direction of current is not indicated.
The instrument is most valuable as a standard for
laboratory use, where the above disadvantages from a stand­
point of portability are easily obviated.
b.) fouberl's Me/hod. Fig. 75.
FIG. 75.
Another method is that of a combination of both methods ol
current aud E. AI. F. measurement by meaus of an electrometer.
This is the only method which directly measures the energy
of periodic and alternating currents. A non-inductive resistance
r is connected in the circuit. The terminals a and b are connected
with the quadrant pair as shown, from which the needle
is insulated. The needle is then alternately connected by a
switch to the terminals of the portion of conductor AB, the
energy expended in which it is desired to measure. If cz and
cz ' are the electrometer readings the energy,
c
E = — ( cz — cz ').
2>"
For the determination of C, see Joubeit's method in /. — Current.
c.) Blathy's Method.
Blathy's wattmeter, fig. 76, is arranged similarly to an electro-
vVWVWWVWWVWVVVWWWVVVW
FIG. 76.
dynamometer. The main current flows through a stationary
spool of wire, which is made up of two coils. A is made of a
few turns of thick wire, while B is of many turns of fine wire.
1. To connect coil sl alone in the main circuit,
2. To send the main current through both A and B, or
3. To cut out both coils from the circuit.
The movable coil C, which is connected in shunt, is wound at
right angles to the stationary coil, and consists of as few turns
of fine wire as possible,—this to minimize its self-induction.
Additional resistance is supplied by the box, which is provided
with binding posts P, R, F and G. The first two are
connected to P and 7? of the watt-meter, the other two to the
terminals of the apparatus undergoing measurement. The resistances
•-„ i\ r.L (bifilar or return winding) are connected between
Fatxd R, and adjusted according to circumstances. The
resistance of the first coil is taken as the unit, and is generally
250 or 500 ohms. The other coils are multiples of this unit.
The manipulation of the apparatus is as follows : A'and L are
two poiuts of a conductor between which the energy consumed
in watts is to be measured. The connections are as shown in
figure.
If cz is the angle through which the torsion head must be
turned to bring the movable coil 0°, the c, constant ofthe watt-
CC
meter is then cc, = where C and C are respectively the
currents in the stationary and movable coils.
c = also c1
CE CE_
cx
c, is called the watt-meter constant, i. e., the energy measured
by a deflection of one degree when the resistance of the shunt
circuit, in which the movable coil, is included is r.
Electric Meters.
Electric energy is commercially measured by meters,—instruments
which record the amount passing through them.
This amount depends upou the quantity of electricity and the
pressure at which it is furnished. CE = rate of supply iu
watts, and the total supply = C.E.T = volts x amperes X
time, or volts x coulombs.
An instrument capable of recording this is called an ergmeter,
orwatt-hourmeter. Where the pressure or potential may
be considered constant, instruments capable only of recording
the quantity passing are employed. They are termed coulombmeters
and their readings multiplied by
the constant pressure gives the measure
of the total energy.
The Edison meter is a coulomb-meter
based on the electrolytic actiou between
two plates of metal immersed in a solu­
tion of a salt of that metal when a current
passes. This meter cousists of bottles
(2 or more) in which two plates of
amalgamated zinc are suspended iu a 10
per cent, solution of zinc sulphate. The
meter is placed as a shunt to the main
circuit and is designed to take 5lF of
the current passing. This fraction of
the current removes metal from one
plate and deposits ou the other the
weight of zinc determining the amount.
The loss of the positive plate is taken
as a basis of calculation.
One ampere hour is the amount of energy
required to deposit 1224 milligrams
of zinc. A meter works best when so
proportioned; one ampere deposits
about 150 milligrams per month. Lowrie, Hall & Co., an
English firm, have brought out a method of utilizing an
electrolytic cell to meter alternating currents. This cell is
The ends of both eoils are connected to the terminals n, m,a.xxA placed in the secondary circuit of the transformer in series
a, so that by means of plugs it is possible:
with a storage battery cell.
(To be continued.)

212 ENGINEERING MECHANICS. [August, 1892.
PUMPS AND PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
(Continued from page 192.)
If the piston speed is 100 ft. per minute, S .V. = 1200, theu
Diam.in inches = 15. 65

August, 1892.] ENGINEERING MECHANICS. 213
ways au advantage, and on long or high suctions or
on fast running pumps, is absolutely necessary, as it
equalizes the flow of water through the pipe, and
prevents "pounding" or "water hammer," which
(without one) is always incident to long suctions.
Water at high temperature cannot be raised any
considerable distance by suction, as the vapor rising
from it follows the receding piston, destroying
the vacuum and resisting the entrance of the water ;
therefore, to pump hot water, always have the
supply above the pump, so that the water will flow
to it by gravity.
The delivery pipes should not be smaller than
given in the table, and when very long a size larger
should be used to avoid friction. Every pipe
FIG. 57. SETTING OF A STEAM PUMP.
should be run in as direct a line as practicable, and
where convenient use full round bends rather than
elbows, and gate or straight way valves should
always be used for water. The steam and exhaust
pipes should also be as large as given in the tables,
and as straight and free as possible.
Oil the pump well before starting, and turn it
over once or twice by hand to see that everything
is all right and that the packing is not too tight.
Opeu the drain cocks and let out all the condensed
water from the steam pipe. See that the stuffing
boxes are kept well packed (but not too tight) ;
A vacuum-chamber is shown in dotted lines, together with wipe a off the oil where it is not needed, and keep the pump
tee in the suction-pipe. This is not always necessary, but when clean, in fact take as good care of it as of a steani engine.
it is it should be placed uear the pump. If the suction-pipe Pumps should always be drained wheu left standing in cold
goes into a deep well, and the distance from the well to the weather, as freezing of water in pipes or cylinders is sure to
pump is short, the delivery-elbow may be changed to a tee, and burst them.
the vacuum-chamber placed directly over the high lift.
In Ordering or Inquiring about Steam Pumps, it is for the
The steam pipe should be so arranged that the water of con­ interest of correspondents to give as full information as possidensation,
when the pump is not running, will drain back into ble on the following poiuts :
the boiler. The exhaust may be led to auy convenient poiut I. For what purpose is the pump to be used?
for escape into the atmosphere, or it may be used in steam-coils 2. What is the liquid to be pumped? And is it bot or cold,
for heating, or if desired, it may be condensed.
clear or gritty, fresh, salt or acidulous ?
Condensing Exhaust Sleam from Steam Pump.—When an 3. What height is the liquid to be lifted by suction ? Also
ordinary condenser is not employed the exhaust steam from a diameter and length of suction pipe, and number of elbows or
steam pump or from an eugine driving a centrifugal pump is turns.
sometimes condensed by forming au annular chamber round 4. To what height or against what pressure is the liquid to be
the delivery or suction-pipes, a pump or trap being fitted to re­ forced ? And what is the diameter aud length of discharge pipe?
move the water when condensed. By enlarging the chamber a 5. What is the maximum quantity to be pumped per hour?
combination of water jet and surface condenser may be made- And what is the average pressure of steani used ?
Sometimes the exhaust steam is discharged directly iuto the All pumps, unless otherwise specified, are arranged for fresh
suction-pipe; in these cases, however, it is important that it is cold water. If wanted for other duty, full particulars should
not allowed to overheat the water or cause back pressure. be given as above.
Directions for Setting and Running Sleam Pumps.—Directions
similar to the following, are given in many of the pump THE GASKILL COMPOUND PUMPING ENGINE.
makers' catalogues :
The Gaskill pumping engine belongs to the general class of
Pumps should always be placed as near as possible to the fly-wheel pumps, examples of which have been given earlier in
source of supply, especially when the liquid is to be drawn into this series of articles. It is built by the Holly Manufacturing
the pump by suction, so that the pump barrel can fill readily. Co., of Lockport, N. Y. This engine was first introduced at
Never have the pump barrel more than twenty-eight feet above the Saratoga Springs (N. Y.) water works in 1SS2, aud such has
the water, and always have it as much less as practicable. been its success, that from 1882 to 1890, one hundred and
The suction pipe should always be as large as the size given eighteen engines were sold by the company, ranging in capacity
in the table, and if long, it is better a size larger, to conpensate from one million to twenty million gallons with an aggregate
for the extra friction due to the length. See that all joints are capacity of five hundred and fifty-five million gallous daily.
made perfectly air-tight, and that pipes are run in as direct a A sectional view of the Gaskill horizontal engine is given in
line as possible using as few bends and valves as practicable. Fig. 58, and a section of the steam cylinders, showing the valve
Valves, elbows, etc., increase friction more rapidly than length motion, is shown in Fig. 59.
of pipe, and no pump can work satisfactorily that does not The following is a description of the engine :
have a full supply of water. A foot valve, having an opening, On a heavy iron bed plate are mounted two pumps, and iu
at least equal in area to the pipe, should be used on long or high direct line therewith two low-pressure steam cylinders with the
suctions, and where there is danger of foreign substances being piston rods of the low-pressure steam cylinders connected to
drawn into the pump, a strainer is necessary, it should have an ag­ the piston rods of the pumps. Betweeu the pumps and steam
gregate area of openings of from three to five times the area of the cylinders are placed two beam supports, which are firmly bolted
pipe, to allow the water to pass through readily and fill the pump. to the bed plate and also rigidly stayed by wrought-iron struts
An air chamber on the suction pipe close to the pump is al­ to the pumps and steam cylinders. These beam supports carry

2i4 ENGINEERING MECHANICS. [August, 1S92.
FIG. 58. THE GASKILL HORIZONTAL PUMPING ENGINE.
the beam shafts and beams, the lower end of the latter being The pumps are of the single-acting plunger variety with out­
connected to the cross heads of the low-pressure cylinders by side stuffing boxes placed 3' 5" from centre to centre of plunmeans
of links. On the top of the pumps are placed the main
shaft bearings, which support the shaft, fly-wheel and cranks,
the latter being keyed to the shaft at right-angles to each
other. On the top of the low-pressure steam cylinders are
mounted the two high-pressure steam cylinders, with their
centres in the same horizontal plane as the centre of the main
crank shafts. Two cross heads for the high-pressure steam
cylinders are connected by means of links to the upper ends of
the beams, and the beams are in turn connected by means of
connecting rods to the crank pins. From the high-pressure
steam cylinders heavy cast-iron girders extend to the pillowblocks.
On the inner end of the beam centres an arm is keyed
from which the air pumps are driven. The valves ofthe steam
cylinders are operated by means of eccentrics keyed on a shaft,
which is at right-angles with and driven by the main shaft
through small bevel gears. The admission valves to the highpressure
steam cylinders are ofthe double beat puppet pattern,
so arranged as to open at the proper time and to close at any
desired point of the stroke as shown in Fig. 59. The exhaust
valves from the high-pressure cylinders serve also as admission
valves to the low-pressure steam cylinders, and are ofthe ordinary
slide-valve type, and are set so as to remain open somewhat less
time than is required to make a complete stroke. The exhaust
valves from the low-pressure cylinders are also plain slide valves,
operating in the same manner as the high-pressure exhaust valves.
The plungers are arranged to work through glands in the centres
of the pumps, and are accessible from the covers at the ends
of the pump cylinders. The pump valves are placed on horizontal
plates below and above the line of the plunger travel. The
glands above mentioned divide the valves of one end ofthe pump
from those of the other end, at the centre of the valve plates.
The Gaskill engine is sometimes made with vertical steam
and water cylinders, one of this style, erected at Kalamazoo,
Mich., being shown in Fig. 60.
FIG 59. VALVE MOTION OF THE GASKILL PUMPING ENGINE.
gers, one plunger being driven by the H. P. steam piston and
the other by the L. P. steam piston.
(To be continued.)

August, 1892.J ENGINEERING MECHANICS. 2I 5
ELBOWS.
HYDRAULIC EXPERIMENTS. *
BY E. M. H0LBRO0K, M.C.E.
The resistance to the flow of water through common elbows
for wrought-iron pipe was investigated for a single size of pipe.
Owing to a lack of time it was impossible to continue the experiments
with larger sizes.
The following cases were considered :
1.—Loss due to one right elbow (90°).
2.—Loss due to one quarter elbow (45 0 ).
3.—Loss due to two quarter elbows.
4.—Loss due to three right elbows.
APPARATUS.—The water was supplied from a tank at the top
of the building, aud was brought in a two-inch pipe to the
laboratory iu the basement. The water from the supply pipe
was conducted into a cylindrical iron "pressure chamber" one
foot in diameter resting horizontally on a platform at a convenient
height above the floor. Into oue end of the chamber
could be fitted mouth-pieces into which pipes of different sizes
could be inserted. The pressure in the chamber at the level of
the mouth-piece was indicated by a mercury manometer.
In the present experiment a pipe 12 feet in length and 0.575
iuches in diameter was used. It was supported horizontally,
and the water from the discharging end was turned into a tank
resting ou scales. The volume of discharge was calculated
from the weight, and the mean velocity in the pipe from the
formula Q = Ev; where Q = discharges in cubic feet per
second, F = area of mean cross section of pipe in square feet
and v = velocity in feet per second. Velocities were thus found
for varying heads, and a curve platted with heads in feet of
water for ordinates and velocities for abscissae. The pipe was
then cut and the two pieces connected with a right elbow. The
velocities were then found for different heads and a curve
platted as before. Now the difference in the heads required to
produce the same velocity in the two cases, is the loss of head
due to the elbow, the same pipe being used ; the loss due to
friction and other causes are the same in each case. The loss
of head for any velocity was fouud by scaling the distance between
the platted curves on the ordinate corresponding to that
velocity. Having found the actual loss of head, the coefficient
b 2
of resistance was found from the formula h = m —, where h'
29
= loss of head, nt = co-efficient (abstract number), and v =
velocity in pipe. This form of expression is based on the wellknown
fact that the loss of head is nearly proportional to the
square of the velocity, other things being the same. The results
for one right elbow are given in the following table :
Vel. in ft. per sec.
Loss of head in feet.
6
1.0
8
1-4
IO
2.2
12
2.3S
with those produced by the right elbow. Two quarter elbows
were theu used, the water discharging in the same direction as
in the case of the right elbow. The results are shown iu the
*The following pages describe some experiments performed by the
writer two years ago in the Hydraulic Laboratory of the College of Civil
Engineering at Cornell University. As some of the subjects treated have
not been much investigated by experimenters, it is thought that the results
giveu may be of interest. The formuke and other necessary information
were taken from Prof. Church's Hydraulics.—Mechanics of Engineering.
'4
4-4
16
5-6
table, m is the co-efficient for the loss of head of thecombina
tion.
TWO QUARTER ELBOWS.
Veloc'y ft. per sec.
Loss of head in ft.
Co-efficient m. . ,
4
0.6
2.4
6
1-57
2.8
8
2.40
2.6
10
3- 6 5
2-3
Mean value of m = 2.5.
'3
5 r »o
2-5
14
7-57
2.4
16
9.70
With three right elbows eight inches apart the results were
as follows :
THREE RIGHT-ELBOWS.
Veloc'y ft. per sec
Loss of head in ft.
Co efficient »i. . .
4
o.9
3-6
6
2.1
3-6
8
3-5
3-5
10
5-
3-
Mean value of m = 3.47.
The experiment was then repeated with the elbows several
feet apart, and the result shows a slight decrease in the co-efficient.
THREE RIGHT-ELBOWS.
Velocity ft. per sec. . . . 6
1.6
3-°
8
2.7
2.8
10
4.0
2.6
Mean value of ••• = 2.75.
22
5-9
2.7
>4
8.0
2.6
2.4
16
11.1
Some experiments were performed to determine the effect on
the co-efficient of not inserting the pipe iuto the elbows the
full distance. There was found to be a slight increase in tn.
From the above results we may arrive at these conclusions :
1.—The values of the co-efficient are nearly independent of
the velocity.
2.—The values of the co-efficient are nearly iu proportion to
the number of elbows.
3.— A right elbow produces less resistance than two quarterelbows.
4.—Placing a number of elbows close together increases the
value ofthe co-efficient for the combination.
VENTURI-TUBES.
With the same pressure-chamber as was described in the
paragraph on elbows, several series of experiments were performed
to determine the co-efficient of discharge from Venturi-
Co-efficient in.
1.8 1.4 1-4 1-4 i-5 1.4 tubes.
The tubes were of three classes : 1.—The sharp-edged cylin­
Mean value of in = 1.41.
drical. 2.—Cylindrical with rounded entrance, succeeded by
an abrupt, though curved, enlargement. 3.—Conically diver­
The experiments were then repeated with one quarter-elbow,
gent with rounded entrance. These tubes were the same as those
and the curve platted showed the losses of head to be identical
used in the experiments described in the Journal of the Franklin
Institute for April, 18S9. In those experiments the greatest
head was only 4 feet. The tubes were of brass aud had smooth
interior surfaces. The diameter of each was one inch at both the
entrance and the discharge end. The length of each was three
inches.
The co-efficient of efflux was computed from the formula,
Q — c F\t 2gh where Q is the actual discharge in cubic feet
2.8

216 ENGINEERING MECHANICS. [August, 1892.
per secoud, F= sectional area (in sq. ft.) of discharging orifice,
the same for all, and h is the head in feet; c is the co-efficient have the head due to pressure in chamber h =
r iS,
whence m = 294
- - + m
2g 29
The results have been tabulated for each case, together with
the value of the co-efficient as determined by " Borda's Formula,"
GH) :
(abstract number). For the sharp-edged cylindrical tube (Fig l) ^ _ Q ^ iuches d> _
CASE 1.
0.325 inches F, = .0037 sq. ft. Fl =
a series of experiments with low heads gave a mean value for
c of 0.S10.
OQI2 ^ ft
CYLINDRICAL TUBE-ROUNDED ENTRANCE, ETC (See above,
and Fig. 2).—For low heads a mean value for c of o 890 was
found. For higher heads the following table gives the results
43-7 33-7 23-3 17.6 10.4 3-o
obtained :
'4-3 12.9 10.9 9-3 7-i 36
IS.6
•913
16.7
.900
Mean value of c = .902.
12.7
.901
9-9
.902
7-°3
.S92
CONICALLV DIVERGENT TUBE-ROUNDED ENTRANCE (Fig. 3).
—For low heads the average value of C was .905. The table
gives the values for higher heads :
Head in ft 6.9 14.4
Mean value off = .925.
.909 .930 .929
18.3
•931
The results of these experiments show that the effect of a
rounded entrance is to materially increase the value of the coefficient.
Since the enlargement in the conically divergent
tube is more gradual than in the cylindrical with rounded entrance,
the former gives the greater discharge.
It is to be noticed that the results reached with heads higher
than four feet are of about the same relative magnitude for the
three tubes respectively as those obtained in experiments with
low heads, as mentioned also in the Journal of the Franklin
Institute for April, 1889.
SUDDEN ENLARGEMENT.
The loss of head due to sudden enlargement of the crosssection
of a pipe was determined for three cases.
Fiat. tSudtien £~Tiiet-r«Tn*.ni;
Iu Fig. 4 F, and Fx represent the sectional areas of the two
pipes and v„ v2 the simultaneous velocities of the water in the
two pipes respectively. The velocity v., was determined experi­
mentally for different heads. The pipes were but a few iuches
in length, the smaller being screwed into a smoothly rounded
brass mouth-piece inserted in the end of the pressure chamber,
so that the loss of head is mainly due to the sudden enlarge­
ment, and is treated as a whole. Denoting it by m
H
12.7
4.0
12.04
4.0
CASE 2.
11.9
4.0
12.1
4.0
12.3
4.0
dl •=• 0.475 inches, 7-*, = 0.0012 sq. ft.
d2 = 0.625 inches, F2 = 0.0020 sq. ft.
I
43-5
m Experimental 2.8
•
... Borda O.45
z< in feet per sec
36.S
25.6
2.6
0.45
CASE 3.
31-7
24-3
2-4
o.45
23-7
22.5
2.0
0.45
'39
4.0
16.4 10.3 3-o
190
1.9
15.0 77
19
1.1
0.45 o.45 °-45
dt = 0.827 inches, 7-", = 0.0037 sq. ft.
d, = 1.05 inches, F.L = 0.0060 sq. ft.
18.0
23.0
2.2
°-37
VALVES. -
12.2
I9.O
2.2
o-37
5-4
12.6
2.2
°-37
2-5
8.05
'•5
o-37
Some interesting results were obtained from the experiments
with valves. Three of the most common types for connecting
wrought iron pipe were used, and two sizes of each—one inch,
aud three-quarter inch :
Globe Valve.
Gate Valve.
Plug Valve.
The co-efficient of resistance m was found from the formula
v 2
IA = m — where IA is the loss of head determined in the
29.
same manner as that described under Elbows, and v is the velocity
of water in the pipe just down-stream from the valve.
1. GLOBE VALVE.—A longitudinal section of pipe and valve
is shown iu Fig. 5.
Iu the following tables we will speak of the Direct and the

August, 1892.J ENGINEERING MECHANICS. 217
Reversed position of the valve, the Direct being shown in the
figure, where the flow is taking place in the direction of tbe
arrows.
FIG. 5.
a) One-Inch Globe Valve.—This valve is intended to connect
with nominal one-inch piping. The diameter of the opening
in the seat is one inch. The diameter of the pipe in this case
was 1.08 inches.
We will give the results for two turns of the stem and for
three aud one-half; in the latter case the valve is fully open.
Vel in ft. per sec.
4
6
8
10
12
14
m—(two turns.)
Direct.
IO.O
II.2
IO.9
IO.9
10.6
11.0
Reversed.
7-9
9.0
8.9
8.5
9.0
tn- (Fully open.)
Direct.
96
9-5
9.2
9.1
9-7
Reversed.
7- 1
7-7
7-7
7.6
7-9
The lift of the valve above its seat was one-third of an inch
for two turns, and seven-twelfths of an inch when fully open.
b) Three-quarter Inch Glabe Valve.—The valve connected
three-quarter inch piping. The diameter of the opening in seat
was three-quarters of an inch. The results will be given for one
turn ofthe stem and when fully open. In the former case the
valve is raised from its seat one-seventh of an inch, and iu the
latter five-fourteenths of an inch.
Vel in ft. per sec.
4
6
8
10
12
14
16
m— (one turn.)
Direct.
27.O
27.O
27.O
Reversed.
•3-2
I2.I
II.2
II.I
II.2
II.I
Fully Open
Direct. Reversed.
13-6
9-i
7.8
7-3
7-3
7-5
7-4
7-i
6.5
6.5
6.5
6-5
6.4
An inspection of the tables will show that there is a marked
decrease in the co-efficient when the valve is placed in the " Reversed"
position, or when the flow takes place in the direction
opposite to that shown in the figure.
2. GATE VALVE.—This valve is the most common one in use,
and consists " a double disk or gate which projects into the
pipe and contracts the area of cross-section, giving to it the
shape of a crescent. The longitudinal section is shown in Fig.
6. We may say here that the same piping was used in all
valves ofthe same size, in order to secure the same conditions
throughout.
FIG. 6.
Co EFFICIENT m—ONE-INCH GATE VALVE.
Vel. in feet per. sec.
6~
8
10
12
>4
16
18
P'= 0 28 sq. in. F. O. 57 sq. in. F. = O67 sq. iu.
24.6
23-7
24.7
4.0
3-3
3-°
2-7
2.5
2.5
O.90
O.9O
O.76
O.62
O.62
O.68
F = area of crescent shaped opening in sq. inches.
The gate projects slightly into the passage-way when the
valve is fully open.
Sectional area of pipe is 0.916 sq. ins.
CO-EFFICIENT ;••— THREE-QUARTER INCH GATE VALVE.
Vel. in feet per sec.
4
. 5
8
10
12
14
16
F = O 16 sq. in. F = 0 32 sq. in. /*'= O 41 sq. in.
16.4
I8.I
16.5
'5-5
16.7
.Sectional area of pipe is 0.442 sq. ins.
I.O
1.6
'•3
i-7
1.6
O.68
063
O.45
0.45
0.50
°-43
3. PLUG VALVES.—A longitudinal section is shown iu Fig. 7.
In this valve a hollow conical plug having slits cut along its
diametrically opposite elements, revolves about its vertical
FIG. 7.
axis. The valve is fully open when both openings are in line
with the axis of the pipe, aud is closed by turning the plug
ninety degrees.

2i8 ENGINEERING MECHANICS. [August, 1892.
Vel. in feet per sec.
4
6
8
10
\i
14
if.
CO-EFFICIENT m—PLUG VALVES.
F= 0.252
30.0
3 1 - 2
One -Inch.
F = 0.504
4.6
4-7
4-5
4-5
4-3
4-3
Three-quarter Inch.
F= 0.158
2S.0
26.4
27.7
26.7
F = 0.316.
3- 01
3.00
3.10
3.02
3.00
F= area of opening in square inches.
Sectional areas of pipes are 0.916 and 0.442 sq. ins.
It being impossible to secure openings of the same area in
the three classes of valves, au exact comparison cannot be
made. Tables giving a comparison of co-efficients when the
valves are fully open, will give the best idea of their relative
values.
CO-EFFICIENT m—VALVES FULLY OPEN.
Vel. ft. per sec.
6
8
10
12
'4
lb
Mean ....
Gate.
.80
.90
.76
.62
.68
•75
In One In Pipe.
Plug.
4.60
4.70
4-50
4.50
4-30
4-3°
4-5°
Globe
(Reversed.)
7-1
7-7
7-7
7.6
7-9
7.60
Gate.
In Three In. Pipe.
Plug
.68
•63 3°'
•45 3-°0
•45 3-1°
.50 3.02
•43 3-o°
•52 3-° 2
Globe.
(Reversed.)
7-i
6-5
6.5
6-5
6-5
6-4
6.60
The above table shows, as far as resistance to flow is concerned,
the decided superiority of the Gate valve over the
others. It offers but about one-sixth as much resistance as the
Plug, and the latter but about one-half as much as the Globe.
The results given were compared with those of Mr. G. H.
Thayer, M.E., who experimented with the same valves and to
whom the writer is indebted for the cuts, aud were found to
agree quite closely.
WEIRS.
Crest of each weir formed a brass plate one-eighth of an inch
thick beveled to a sharp edge, from the down-stream side.
Tank so wide and deep that velocity of approach was neglected.
The head /• was measured by a hook-gauge reading to the 0.0001
of a foot. The measurement in each case was taken at the
surface of the still water.
We/n NOTCHES.
4
b = width for head h.
tion.
There is perfect and complete contrac-
°-3 , S3 0.2670 0.2125 0.2893 0.2495 0.1989
•594
•594
Meau value of c = .593.
.588
•595
•594
0.3018 0.2645 0.1934 0.1238 0.1389 0-2343
6.03
.601
.609
0.2773 0.3260 0.3153 0.2704
.607
.583
.609
Mean e = .606.
.684
.605
.607
t
0.2092 0.1126
.600 .608
Semicircular Weir. Radius four inches, = r ; d = diameter
= 8 inches.
Actual discharge Q} — 4ch' \j S r 0.409-0.107? -j J-0.01S
(0 + -]
Head in feet. . .
HYDRAULIC RAM.
1
O.134 0.1S06
.60S 1 .589
O.I999 O.2013 0.1704 0.1466 0.2178
•583 -595
Mean c = .59'.
.600
.5S0
•583
EFFICIENCY TEST.—The ram used was manufactured by the
Gould Co., of Seneca Falls, N. Y., and was designated as No. 2
in their catalogue. The water was supplied through a A inch
drive-pipe about 16 ft. long under a head of 4.5 feet. The water
discharged through a § iuch pipe against au effective head of
47.3 feet.
In the first test the total volume of water supplied was 43.3
cubic feet aud the volume pumped was 0.81 cubic feet. There-
r .u a: • O.S2X47-3
fore the efficiency was = 20 per cent.
43-3 X 4-5
In the second test the total volume supplied was 4S.4S cubic
feet, and the volume pumped was o.SS cubic feet.
Efficiency
o.SS X 47-3
48.48 x 4-5
= 19.1 per cent.
This low efficiency is doubtless due to the short length of
drive-pipe employed. With the length prescribed by the
makers of the ram, i. c., from 50 to 75 feet, a much higher figure
would probably have been attained, but the employment Qf so
great a length was impracticable at the time.
FIG. 10. FIG. II.
1.—Triangular, in which the angle of the notch is a right
angle.
The coefficient was determiued from the formula Q 1 = c —-
b h S 2 tA !l . where Q l THE Philadelphia Blue Print Company have added 41 N. 7th
St. to their plant, and have fitted the upper floors for the quick
execution of special work. Their line of drawing materials is
complete in standard articles, and iucludes Drawing, Detail
aud Tracing Papers, Tracing Cloth, Profile Papers, Hardmuth's
Pencils, Liquid and Stick India Inks, French Water Colors, etc.
Their "French Satin" blue process papers are in general re­
= actual discharge, c = co-efficient and quest.

August, 1892.] ENGINEERING MECHANICS. 219
COMPRESSED AIR AS A MECHANICAL MOTOR.
We suppose that compressed air, like other mechanical
motors, must submit to a long period of probation before its
employment becomes general. Its application to the driving
of machinery would seem to be so simple and easy that we
confess to a sense of disappointment when we find its uses so
restricted. For sending "carriers" through pneumatic tubes,
aud for driving rock-drills its use is almost universal. The
method of working the latter by installing the engine and com­
pressors ou the surface, near the month of the mine or quarry
and distributing the air through pipes to the drills, it may be,
in the utmost recesses ofthe excavation, is very suggestive.
Now, suppose this installation to be sufficiently large and
powerful to constitute the Central Station of a city and the
power therefore to be transmitted to a multitude of small engines
in a contiguous district where the kiud of labor needs
such engines ; we then get a conception of the system success
fully operated in Paris and Birmingham. Plans for its introduction
into Dresden, Berlin, Vienna, Leeds and other cities
have been prepared. Why similar plans have not been got
ready for as many American cities is partly we apprehend, due
to the comparative iguorance of our municipal authorities on
the subject of the adaptedness of compressed ait to the safe,
clear, and economical distribution of power.
Like other motors, compressed air has suffered from the imperfection
ofthe machinery employed in its application. This
was the case even at La Fargeau, Paris. By the engines and
compressors the air was delivered into the mines at a pressure
of six atmospheres. Transmitted five kilometers, the mains
having a diameter of 11A iuches, the pressure was reduced to
four aud a half atmospheres wheu used cold, iu an air motor
of 10 H. P. An iudicated H. P. expended in the steam cylinders
and compressors gave only 0.26 effective or brake H. P. at
the air motor. In other words the combined efficiency of compressor
main and motor was 26 per cent.
Much of this loss of pressure was ascribed to the mains
which were of cast iron and laid in the sewers. This involved
the use of many bends and stock valves, as well as drainage
tanks and traps of siphons for condensed moisture, which
also increased the resistance. For the new Central Station
wrought iron pipes 20 inches in diameter are used. The line
going and returning extends xoj^ miles ; initial pressure of the
air delivered to the mains, 106.6 lb. per square iuch ; loss of
power by resistance of mains, 29.4 lb. per square inch ; the loss
of power in steam cylinders aud air compressors is of course
increased, because of the high temperature imported to the air
by its condensation. Obversely it should be cooled before delivery
to the mains, and the cooling is effected by devices similar
to the surface and jet condensers of steam engines.
Compound compressors were, we believe, first constructed in
this country. By them the air is partially condensed in one
cylinder, then cooled by a device called an " mter-cooler," and
then the compression completed in a second cylinder, followed
by cooling. Economy has been further secured by using the
air in the motors expansively, and still farther by heating it
to 300 0 F. just before it enters the motors. The reheating appliances
are extremely simple and cheap. In actual practice
31,000 cubic feet of air per hour were raised from atmospheric
temperature to 300 0 F. by using 15 lb. coke. The air from the
exhaust of course undergoes rapid refrigeration as it expends
iuto the atmosphere, but if it has been previously reheated this
does not bring its temperature inconveniently low.
With these improvements introduced aud a 30-iuch main a
long distance (20 miles) compressed air installation can be run,
including all unavoidable losses, with a terminal pressure of 40
to 50 per cent, ofthe initial, if the air be fed to the motor cold,
aud 59 to 73 per cent, if the air be reheated. The sole loss
neglected in the statement of results is possible leakage iu the
mains. The transmission af power from a central station to
small factories along the line of the mains promises to be re­
munerative. But the application need not be thus restricted ;
it may be extended so as to include the propulsion of city passenger
cars. A working model of such a system was to be
seen running in Machinery Hall, Centennial Exhibition, Philadelphia,
1876. The main was sunk below ground just outside
the track, and openings, called "air plugs," connected it with
the surface at proper distances. The car contained an air ves­
sel which was charged at starting from the station, and whicli
was beneath in the air motors that drove the wheels. When
the pressure in the air vessel fell below what was required to
propel the car at the prescribed speed, it was stopped at an air-
plug and the vessel replenished. The pressure in the mains
was kept at four atmospheres and the car moved smoothly and
promptly.
THE CAMERON DIRECT-ACTING STEAM PUMP—THE STAN­
DARD OF EXCELLENCE.
This pump is manufactured in the United States and Europe
under patents granted to Mr. A. S. Cameron, by whom it was
first introduced to the public, since which time the number of
steam pumps produced under these patents exceeds that of any
other establishment in the business, which should be considered
a substantial evidence of their excellence.
Patented improvements recently applied have removed every
objection that experience has urged against some direct-acting
pumps. In the Cameron, the motion of the pistons at the end
of the stroke corresponds with that derived from a crank, turning
the centers softly, allowing the valves to seat easily, avoid­
ing concussion, and rendering it impossible for the piston to
strike the cylinder covers, even when traveling as fast as steam
will drive it.
The great success of this pump is due to its simplicity aud
reliability.
It has a fewer number of working parts than any other pump
made.
The steani mechanism consists of four stout pieces only, in­
cluding the main slide valve.
It is the most compact and the least liable to breakage, as
none of the working parts arc exposed to damage.
It will always start at any point of the stroke.
It will ruu at any speed desired.
The valve movement of the steam cyliuder working in a di
rect line with the main piston without the intervention of arms
or levers, enables the pump to be run faster than any other
without danger of breaking.
While under a full pressure of steam the suction pipe cau be
lifted out of the water without danger of the piston striking
the ends. This is a condition hitherto never approached in this
class of machines. The advantage is apparent, for a pump
may be running along on a regular duty under a full pressure of
steam, and the supply of water be suddenly cut off.
Every pump can be taken apart without disconnecting the
pipes.
The parts of the water cylinder are so arranged that they
cannot possibly become deranged ; there are no valve bolts nor
screws to become loose ; the whole iuterior of the valve chest
is exposed by simply removing one bonnet, and the water
valves can be taken out and replaced almost instantly.
They are stronger and heavier for capacity than any pump
made.
Every pump is thoroughly tested before it leaves the works,
and guaranteed to give perfect satisfaction or the price will be
refunded.
ALL pumps, unless otherwise ordered, are arranged for fresh
cold water. Parties ordering pumps to be used on other duty
than this, will please give full particulars of the work to be
done.

THE BARNES WATER EMERY GRINDER.
The accompanying engraving represents an improved method
of mounting au emery wheel, which possesses advantages
wliich are apparent at a glance. To the front of the treadle,
wliich is pivoted to the rear standard and bent to encircle the
water columu, is attached a lever, whose free end carries a
float. By pressing with the foot upon the treadle, the float
may be made to enter the water chamber, thereby displacing
the water and forcing it to rise and supply the wheel. When
the machine is uot in use the float rises and the water settles
back out of the way of the wheel. This arrangement does
away with all pumps and valves, which are liable to get out of
order, simplifies the machine, and makes it more practical
under all conditions.
The chamber in which the float is suspended—resting upon
the water—is divided from the chamber in which the wheel
revolves by a partition, in the lower part of wliich is a small
hole through whicli the water slowly enters the wheel chamber.
The action of the wheel carries the water to the front upper
quarter of the wheel, where it is arrested and thrown into a
pocket, from wheuce it falls to the wheel aud tool. The pocket
is shown in the engraving by the outer shell broken away.
Without the partition referred to, the water would be flooded
into the wheel in a body or rush, which would not be desirable.
The small hole being in the bottom edge ofthe partition,
allows all the water to flow back into the reservoir when the
float rises. The curved treadle can be conveniently reached, no
matter whut position the operator may assume when grinding.
This construction not only greatly simplifies the machine
and renders it far more efficient, but it also allows it to be used
in shops where there is no piping. The grinder, which is most
substantially made, is built by the W. F. cc John Barnes Co., of
Rockford, 111.
PROFESSOR CLOWES, in a lecture delivered at the University
College, Nottingham, England, February 6'h, 1802, on testing
for gas iu coal mines, made the following observation :
ENGINEERING MECHANICS. [August, 1892.
If there should exist amongst managers any unwillingness to
use the most perfect means of gas testing, simply because they
do not wish to know the worst concerning the state ofthe ven­
tilation of their mines, either as regards its amount or its proper
distribution, this feeling must surely give way in the present
age of scientific progress, and in view of the preventable
danger which is incurred by such recklessness^
John Fulton, geueral mining engineer of the Cambria Iron
Co., Isaac Taylor and Andrew L- Nelson ofthe mining depart
ment of same company to unite in the statment that during the
past three years the Cambria Iron Company has had the use of
an instrument devised by Mr. Thomas Shaw, M. E., of Philadelphia,
Pa., at its Morrell Mine, in the Counellsville Coke Region,
for testing the air in mines, and detecting if present any mix­
ture of dangerous gases.
The instrument affords quick and accurate determinations,
and is so simple iu operation that any intelligent superintendent
of mines can readily learn to use it.
Its accuracy is self evident. It detects the presence of T^s
part of explosive gas in the air brought out of the mine. It is
very valuable iu thus affording p'recise and accurate information
to the managers of fiery mines.
The Company has now purchased this instrument, and ex­
tended its tests to the adjoining Wheeler Mine.
It has also purchased another instrument for testing the air
iu its large Rolling Mill Mine, at Johnstown, Pa.
THE weight of a cubic inch of Tobiu Bronze and Copper
is respectively .3021 and .3176 of a pound, a difference of .0155
of a pound in favor of Tobin Brouze. This very important
feature of lightness, in addition to its great tensile strength,
and resistance to the corrosive action of sea water, renders it a
most suitable metal for Condenser Plates, Steam Launch Shafting,
Ship Sheathing aud Fastenings, Nails, Hull Plates for
Steam Yachts, Torpedo aud Life Boats. Its durability, great
density and imperviousness to water at the highest pressure,
has proven it to be a superior metal for liuings of Hydraulic
Cylinders and Water Cylinders of Steam Pumps.
THP; manufacture of gelatin dynamite has reached a high degree
of perfection and its employment is increasing on that of
the ordinary dynamite made from nitro-glycerin. The manufacture
of smokeless powders is also rapidly increasing, nitrocellulose
entering into the composition of many of them. Some
samples of gelatin dynamite formed part of the cargo of a vessel
which had sunk at Liverpool. When recovered they were very
wet and after drying the parchment paper was incrusted with
sea salt, yet the explosives had not suffered in any way. A
sample of gun cotton was in the bed of a river for 16 years and
another buried in the earth for 19

August, 1892.] ENGINEERING MECHANICS. 221
FIG
CAHAUST OUTLET
THE IMPROVED NATIONAL FEED WATER HEATER.
The cut (Fig. 1) represents the Improved National Feed
Water Heater which is manufactured by the National Pipe
Bending Company of New Haven, Conn., and of which style of
Heater they have sold over 500,000 H. P. in the last ten years.
The Heater consists of a shell containing coils of seamless drawn
brass tube so made that the coils are able to take up the contraction
and expansion occasioned by the cold water and hot
steam without rupturing the coils or producing any leaks.
These Heaters are in use in hundreds of Electric Light Stations
throughout the country and all give satisfactory results.
They also manufacture these Heaters to be placed horizontally
and to be used with condensors as shown by accompanying
cut (Fig. 2). The Heater is one that cau be placed in any positiou
desired and the exhaust can be on the end or on the sides as
may be suited to the location. These Heaters .are guaranteed
to heat the water up to 200 degrees and over and are sure of
being reliable.
Among the recent sales by the Company are three of 1500 H.
P., one of 1600 H. P., three of 800 H. P., five of 500 H. P., two
of 650 H. P., six of 400 H. P., one of iooo H. P., seventeen of
200 H. P., nine of 300 H. P., eleven of 150 H. P., and large num
ber of smaller sizes 100 H. P. and less.
EDWARD FLAD, C. E., 118 Laclede Building, St. Louis, Mo.,
has been retained in two or three very large engineering opera­
tions in the West
THE Wm. Cramp & Sons Ship and Engine Company are
ab'e to report a steady growth in the demand for their American
Manganese Bronze.
THE Ball & Wood Company, 15 Cortlandt St., New York, are
putting in some of the largest sizes of their Ball Automatic
Cut-off Engines yet turned out.
FIG. 2.
J. K. GRIFFITHS Stopper and Nozzle for Open Hearth anil
Bessemer Steel Ladles have earned a permanent place in the
foundry. They are in use in all the larger steel and iron works
aud are found to be a decided improvement over the old style
of steel ladle stoppers.
THE Builders' Iron Foundry of Providence, R. I., is now
finishing and assembling for the U. S Government, for coast
defence, forty-three twelve-inch Breech-Loading Rifled Mortars,
making, with those finished under a previous contract, seventythree
guns of this type from the works of this company.
THE contract for the two Compound Pumping Engines,
Boilers, Heaters, Piping, etc., for the Madisouville, Ohio, Water
Works has been awarded to the Laidlaw & Dunn Co. of Cincinnati
and Chicago. This concern is full of orders. They
have several water works jobs iu hand, and are now adding
some large tools.
RIEHLE BROS.' Testing Machines are commanding increasing
attention. They are able to furnish recent aud especially
valuable testimonials for special machinery in all varieties for
testing chain, wire aud hemp rope, bridge bolts, iron and steel
rods and wire, iron and steel boiler plate, leather belting, etc.,
etc., by tensile strain ; car springs, iron, steel, wood, etc., by
transverse and compression strains.
THE firm of Johnson & Flad, civil aud mechauical engineers,
was dissolved by mutual consent on the 1st day of July, 1892.
Prof. Johnson retires from the firm on account of his increasing
duties at Washington University and the Testing Laboratory.
Mr. Edward Flad will continue in business as civil aud mechanical
engiueer in the office ofthe firm, 118 Laclede Buildiug, and
will execute all outstanding contracts made iu the name of the
firm.
FOR SALE,
One 21 in. x 13 ft. LODGE & DAVIS ENGINE LATHE, complete.
One 24 in. x 20 ft. FIFIELD ENHINE LATHE, complete.
()ne No. 3 GARVIN UNIVERSAL MILLING MACHINE, complete.
The above-mentioned machines are new, never liaving been used,
but will be sold at a sacrifice to settle up an estate.
DANIEL KELLY,
51 North Seventh Street, - Philadelphia, Pa.

Ill ENGINEERING MECHANICS. [.August, 1892.
THE GARVIN MACHINE CO. THE NATIONAL AUTOMATIC BOLT CUTTER
1*0, 1 Univ. Milling Mach.
UNIVERSAL AND PLAIN
| Milling Machines,
" SCREW MACHINES, MONITORS, CANS DRILLS,
PROFILERS TAPPING MACHINES,
[=1 GEAR CUTTERS and CUTTER GRINDERS'.
CATALOGUE ON APPLICATION.
ID-A-INTIEXJ KELLY,
AGENT,
r>l North Sevontli Street, - Philadelphia, Pn
For Cutting Bolts. Also Bolt
Headers and Pointers.
THE BEST MACHINE IVIADE.
The advantages of this machine are
~y convenience in handling and good work-
/ manship.
/ Sole Specialist in Bolt and Nut Machinery
DANIEL KELLY,
51 NORTH SFVENTH STREET, - - PHILADELPHIA, PA.
THE NATIONAL FEED WATER HEATER,
A BRASS COIL HEATER delivering Water to the
Boilers at 212° Fahrenheit.
400,000 HORSE POWER NOW IN USE
PRICES LOW. SATISFACTION UNIVERSAL.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE.
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
SEPARATORS
FOR REMOVING WATER, OIL, GREASE AND IMPURITIES FROM
STEAM.
THE COCHRANE SEPARATORS, HORIZONTALOR VERTICAL
MANUFACTURED BY SOLD ON 30 DAYS TRIAL.
ARE BEING INTRODUCED ON THEIR MERITS, VIZ : EFFICIENCY AND PRICE.
HARRISON SAFETY BOILER WORKS,
GERMANTOWN JUNCTION, PHILADELPHIA, PA.
THE IMPROVED BALL ENGINE,
SIMPLE, COMPOUND AND TRIPLE, HORIZONTAL AND VERTICAL,
AS BUILT BY
THE BALL & WOOD CO.,
Office, 15 Cortlandt St., New York,
Is superior in DESIGN, FINISH and WORKMANSHIP. In REGULA­
TION and ECONOMY it has no equal. Built with new tools, from
new patterns, and after long experience, it should and
DOES mark the latest step in steam engineering.
REPRESENTATIVES:
THOS. G. SMITH, Jr., No. 11 Hammond Building,. .CINCINNATI, OHIO.
W. B. PEARSON & CO., Home Ins. Building CHICAGO, ILLS.
A. M. MORSE, & CO., Commercial Building ST. LOUIS, MO.
W. A. DAY, No. 128 Oliver Streel, BOSTON, MASS.
HYDE BROS. & CO., Lewis Block, PITTSBURGH, PA.

September, 1892.] ENGINEERING MECHANICS. 221
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering,
Published by JOHN IU. DAVIS, at 430 Walnut St., Philadelphia.
London Office, 270 Strand, D. NUTT, Agent.
Water vessel, graduated ; inverted glass bell to hold gaseous
Entered at the Post-office in Philadelphui as Second-Class Mail Matter. products : Tubular connection with oxygen bottle and platinum
crucible. A compressed oxygen container supplies the oxygen.
SUBSCRIPTION RATES.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
PHILADELPHIA, SEPTEMBER, 1892.
BERLIN, Germany, is soou to be provided with an electrical
underground railway, the total length of which when completed
will be thirty miles, aud cost per mile -f+oo.ooo. As one-half
the population travels a considerable distance from place of
residence to business, it is believed the lines will be abundantly
patronized. The trains will run at three minute intervals, 1000
yards apart, 4S in all, hauling 144 carriages. The tunnel will
run through sand and gravel. Wrought iron plates 27 '< in.
broad, 4 thick, flanged inside for bolting, make the wall. Joints
made with pine wood strips, tow and cement, and outside coated
with cement. Air pressure will work a large shield with rotal
ing cutting tool, which will advance 16A feet per day. Rails
40/-2 lb. section are supported at 27 *, distances by flanges. The
three insulators will be laid between the rails. The gauge will
t> e 39-37- The sharpest curve will be 164 feet radius, and next
264 feet, both for only short distances. Two power stations
will be erected, pressure 500 volts ; motors, slow speed with
varying resistance gearing, running in oil to diminish friction
and noise.
A NEWLY discovered enemy of cement, an exceedingly
minute object, as described, consists of lime, alumina, sulphuric
acid and water of crystallization, and which is visible only
when magnified 200 times. These minute crystals belong to
the tetragonal system. The damage is done to cement in the
formation of these crystals in the hardened cement through
their increase of volume, thus destroying cohesion. To 162
parts by weight of calcic alumiuate, there attaches themselves
447 parts by weight of sulphate of lime and water. This requires
additional room and something weaker thau crystalline
action has to get out of the way, which happeus to be the
cement—hence the destruction so often noticed and not explained.
FIRE-PROOF floors are beiug laid in England made of concrete
re-enforced by iron rods on side exposed to tension. The ^-rods
are curved and made into a network and bound with wire. After
the concrete is poured iu the network is raised oue half inch
from bottom of mould and the lower face of the concrete slab.
Tests show great strength. One slab 6 feet square and 2 inches
thick supported at edges and loaded to a pressure of 213 pounds
per sq. ft. suffered a deflection of 1J-2 inch, aud at 231 pounds
the slab cracked in two. A like slab received a pulley weight
of 224 pounds at 7 feet, making a hole but not breaking the
slab.
IF politicians and those who manage to be entrusted with the
care of government aud legislation were as earnest, honest,
capable and exact in their methods and conclusions and applications
of principles to conditions as the engineers are iu their
profession of creating and guiding forces where they did not
exist before, there would be better laws, greater and more even
prosperity, more activity in the industries and practical professions,
and greater energy displayed. Scaliwaggery too much
dominates in politics. Opportunities for the more rapid growth
and development of the country are not taken advantage of.
THE suggestion has been made to sell coal according to degree
of thermic efficiency, or on the basis of calorimetric unit value,
as ore, manganese and other raw material. This suggestiou is
an outgrowth of the adoption in so mail}- laboratories and works
of the Bertholet-Mahler calorimeter. Its parts are as follows :
By use of this instrument the thermic values of various fuels
can be readily determined.
RAILROAD companies will enter upon the policy of more
liberal expenditures in the improvement of road-bed, more rolling
stock, more engines, and additional equipments and devices
intended to effect more economical and safer operation of roads.
The enforced economies of the past few years have beeu submitted
to by the managements as a matter of necessity. More
liberal earnings aud a broader spirit amoug controlling stockholders
are already leading to the adoption of a more sensible
policy.
A CLOSED conduit for electric lines is proposed as follows : It
is proposed to build the conduit with a wide slot and cover it
with a rail flush to the surface of the street. By a neat device
this rail is raised from its seat as the car moves by means of
rollers beueath it which are carried ou U's attached to the car,
and which fall back in place as the car passes, this being done
to allow the collector to come iu contact with the cable.
CHIEF ENGINEER ISHERWOOD, U.S. N., in the last number
of the Journal of the American Society of Naval Eugineers,
disputes the statestneuts and figures of Mr W. H. White, Chief
Director of Naval Construction in Great Britain, wherein the
decreasing speed of vessels due to shoal water is given. Chief
Engineer Isherwood says: " The water, judging from au extensive
personal experience in such trials, and having regard to
the manner in which the speed was ascertained iu the particular
cases given, is of opinion there was a probable run of about
5 per cent., which would be about five sixths of a knot at the
average experimental speed, a quantity more than sufficient to
cover the supposed difference due to the shoaling of the water.
The depth of the water in the clear beneath the bottom of a
vessel must be considerably more than its draught of water
probably twice as much, in order that the shoalness may not
affect the speed of the vessel. For very high speeds of vessels
the depth of water from the surface should probably be about
from three to four times the vessel's draught of water. The
enormous influence exerted upou the vessel's speed by shoal
water is due wholly to the 'after body ' of the ship." The following
is a careful summary of results:
" That the displacement of water by the fore body of au advancing
vessel is wholly vertical and not at all horizontal or
sideways, the displaced water being delivered into the elastic
atmosphere aud above the level of the surrounding water; that
the continuous advance of the vessel maintains a constant
elevation of the displaced water at the front of the fore body
above the surrounding water level, producing a permanently
greater pressure there than is to be found in any other portion of
the indefinite mass of water in which the vessel moves ; that the
height to which the displaced water is lifted against the front
of the fore body is proportional, other things equal, to the
length of the inclined side of the fore body ; that the displaced
water so lifted flows outward by gravity over the surface of the
surrounding water and in directions at right angles to the inclined
side of the fore body; that this flowing outwards is
purely a surface phenomenon, and does not iu the least affect
the water lying below the general surrounding level; that the
work of this displacement consists iu lifting the displaced
water above the general water level, and is measured in quan-

222 ENGINEERING MECHANICS. [September, 1892.
tity hy the mass of water lifted in a given time and the height
above the general water level to which it is lifted ; that the
work done by the fore body in displacing water is entirely in­
dependent of any effect produced by the aft body ; that if the
back of the fore body be not supported by water in such manner
as to maintain a static equilibrium on the opposite sides of
the greatest immersed transverse section of the vessel, there
must be added to the above work of displacement the work
due to overcoming the difference of pressure on these opposite
sides ; that as no such equilibrium of static pressure can ever
exist, the work done by the fore body is always greater than
the work of displacement; that this additional work done by
the fore body is greater, other things equal, as the length ofthe
inclined side of the fore body is less ; that to the above two
kinds of work done by the fore body must be added a third,
namely, overcoming the resistance of its wetted surface, which
work is proportional to the surface and to the cube of the velocity
of the water molecules passing along the inclined side of
the body ; this work is so large a fraction of the total work
done by the fore body as to modify enormously the dynamic
value of length of body abstractly considered, or considered
solely in relation to its economic displacement of water;
lengthening the fore body, other things equal, diminishes the
work of displacement but increases the work of the surface resistance,
so that a length is soon reached, depending on absolute
speed, beyond which any additional length is economically
injurious, and the greater the speed of the vessel the longer
will be the body before the length of maximum economy is
passed ; the length for maximum economy at one speed is not
the proper length of another speed, but there is, with all vessels,
a considerable interval of speed during which the losses
and gains are so nearly balanced that the difference is insignificant
; that the advance of the vessel leaves in the water a
cavity extending aft from the greatest immersed transverse
section a certain distance depending on circumstances ; that
this cavity is filled and wholly filled by water flowing into it
vertically from the bottom thereof; that the quantity of water
which flows into the cavity in a given time is exactly equal to
the quantity displaced in the same time by the fore body, but
the length of the cavity is proportional to the speed of the
vessel ; that the cross section of the cavity at the greatest immersed
transverse section of the vessel has the form and
dimensions of that section ; that the water filling this cavity
comes in a horizontal stream from the stem of the vessel to its
greatest immersed transverse section, the upper surface of the
stream being the horizontal plane of the rabbet of the keel,
but no portion of the stream is in contact with the fore body.
" BREATH figures " can be made mechanically or by electrical
action. They can be produced by laying a coin on a freshly
split surface of mica. A coin laid on glass for some time leaves
its traces. Perfect reproductions of printed matter have been
obtained by placing a paper, printed on one side only, between
two sheets of glass for ten hours. Some substances, such a?
silk, in contact with glass, gives white figures, whilst wool,
cotton, etc., give black ones. It can be done electrically this
way. A coin is placed on a glass plate for insulation. Another
glass plate, which is to receive the impression, is well polished
and laid on the coin, whilst a second coin is placed above the
first. The coins are put in connection with poles of au electrical
machine, giving i-in. sparks for two minutes. When the
coins are removed aud the glass breathed on, clear frosted pictures
of the coins are seen on the glass. The microscope shows
that moisture is deposited on the whole surface, the size
of the minute water grauulatious increasiug as the part of the
picture is darker in shade. The thickness of the glass seemed
to make no difference to the result, and several plates and
coins might be piled up alternately. If carefully protected,
time appears to have little effect on the figures, but they cau be
removed by rubbing whilst the glass is moist.
THE; formula for ascertaining the theoretical strength of recb
IA
tangular beams is M— -5—5 where
6 '
.]/= bending moment,
b = width of beam,
h = height of beam,
S = stress in extreme fibre.
The existing theory of the strength of beams being based on
the wholly unwarranted assumption that the tensile strength of
the material (or its compressive strength as the case may be) is
the same whether the bar is in tension (or compression) or bent,
leads to anomalous results which render the old formula practi­
cally useless and misleading.
The present formula, under certain conditions, could weaken
a beam to zero by deepening the vertical rib.
The new formula proposed for this purpose is
Ayfi,
M=SS-~
where
M —- bending moment as before.
5 = permissible stress in extreme fibre as in the old formula,
derived from experiments on the strength of
the material in simple tension or compression.
A = area of the cross-section of the beam.
g = distance of the centre of gravity of either the stretched
or compressed portion ofthe section from the neu­
tral axis.
/ = moment of inertia of the whole section about the
neutral axis.
e — distance of the extreme fibre from the neutral axis as
in the old formula. In unsymmetrical sections the
two lengths g aud e are to be measured on the same
side of the neutral axis.
In the case of circular sections the new formula is
M •- tPS\/A
V 192
.1279 d 3 S,
d 3 S
or approximately , It gives values over 30 per cent, in excess
of the old formula.
The new formula, as proposed above, is based upou the work
performed by the fibres during deformation. To test this formula
take a beam of rectangular section 12 in. deep, 6 in. wide, and
then make it cruciform by adding a rib at top and bottom,. 3 in.
deep and 1 in. wide. Here is the result
Section.
Without ribs ....
With ribs
By usual
Formula.
I44
•34
Modulus of Section.
By new
Formula.
176
187
The modulus of singular sections can be ascertained readily,
but it is first necessary
(1) To find the centre of gravity of the whole section, say by
the aid of a funicular curve, or mechanically by means of a zinc
template balance flatwise ou the point of a needle, as proposed
by Sir Benjamin Baker some years ago.
(2) By drawing a tangent to the funicular curve at the point
where it is cut by the line passing through the centre of gravity
of the whole section, the centres of gravity of the compressed
and stretched portions ofthe sections are found separately. Of
course, with a zinc template already to hand, it will be quicker
to repeat the balancing process with each half of the template.
(3) Find the area of each half separately, and the distance of
the extreme fibre from the neutral axis.
(4) Find the " effective flange area," i. c., the area of the figure
of uniform stress, and its centre of gravity in each half. The
distance between the two centres will be the " effective depth."

September, 1S92.] ENGINEERING MECHANICS.
SOMF: valuable lessons were learned iu the prosecution of the
difficult and dangerous work involved iu the boring of the tunnel
under the River Mersey, England. A writer says of it:
A romantic and instructive account might well be written of
the battles with the elements, of the repeated failures and successes,
aud of the hairbreadth escapes, with ultimate pronounced
success, which attended this subterranean aud subaqueous work.
From first to last the operations, including stoppages, occupied
forty-seven months. The first contractors had completed the
work of driving aud lining the tunnel from the Cheshire Shaft
to a distance of 57 ft. out of a total of 805 ft. required, when,
having sunk the greater part of the Lancashire Shaft, they
ceased work at the end of twenty months. The second contractors,
rather than reopen the disturbed ground of the old
workiugs, began, with permission, at a higher level on the Lan­
cashire side. At the end of a further period of twenty-one
months, they had driven aud lined 1S2 ft. from the Lancashire
shaft. They then relinquished the work, and it was taken up
by the Corporatioi of Liverpool, most of the men being retained,
and one of the contractors contiuuiug to superintend
them. .After this the remaining length, about 620 ft., was
driven and lined in 4)2 mouths, the maximum progress being
57 ft. per week of no hours.
The shafts are lined with cast-iron cylinders, the tunnel with
cast-iron segments bolted together and planed on the abutting
edges. The peculiar difficulties of this work arose from the
fact that, while the whole of the material—except certain small
lenticular masses of clay—through and beneath which the tunnel
was driven, was perfectly loose and full of water under direct pres­
sure from above, it constantly varied in the size of its component
parts from the finest mud to the coarsest shingle containing comparatively
little sand. In homogeneous mud the operations would
have been comparatively easy, but the face of the excavation
was quite commonly composed of three totally different materials,
such as open shingle, sand, and mud, all three under the
full and varying pressure of the tidal water above, and all three
behaving in a totally different manner ; while in some cases a
band of hard clay was met. with, impervious in itself, but surrounded
by water under pressure, never covering the whole face,
but sometimes in the bottom, sometimes in the middle, and
sometimes in the top. The following considerations will make
the great difficulty thus presented more obvious. In sinking a
shaft under air pressure, we free the ground by excavation
within and beneath the circular cutting edge attached to the
lowest cylinder. That edge being horizontal, we are generally
able to maintain the air within the vertical cylinders at such a
pressure that the water is kept back at every point of the cutting
edge. The cylinders then, owing to their own or a superimposed
weight, sink further. They are from time to time
lengthened by adding cylinders at the top ; and by freeing the
ground below the cutting edge this lining is sunk to the re­
quired depth.
In order to understand rightly the nature of the problem, regard
must be had to the following considerations :—Imagine a
face with loose material at the end of the finished portion of the
tunnel subject to the pressure, let us say of 30 ft. of water to
the top, and of 40 ft. of water to the bottom of the tuunel, the
tunnel being charged with air to balance, let us suppose the
40 ft. One of two things immediately takes place. Either the
air pressure, overbalancing the water pressure where at the
higher part of the face it has only a head of 30 ft., rushes out in
such quantity as to form an upward funnel through the strata,
in which case water rushes in below where the pressure in front
of the shield is 40 ft, or the air simply displaces the water iu
the interstices of the porous ground. This action is very rapid.
The wet surface of the face seems instantly to dry up, in fact,
so complete and rapid is the drying that in a few seconds it is
difficult to imagine that the face has been wet within the last
twenty-four hours. But with this change the whole condition
of equilibrium is altered. The head of water at the face is
partly displaced by a head of air—a great bubble—in the interstices
ofthe ground having the form of a balloon, continuously
supplied with air from the end of the tunnel, which it dissipates
from its upper surface into countless smaller bubbles, so that
the total pressure at the face is suddenly much diminished.
POOR'S MANUAL OF THE UNITED STATES is just out. Briefly
outlined, the contents of the work are :
Introductory statements showing iu tabular form the mileage,
equipment, capital stock, funded and floating debts, cost of
road and equipment, investments, train mileage, passenger and
freight statistics, earnings, expenses, interest and dividend payments,
etc., etc., of the entire railroad system of the country,
arrauged by States and groups of States. The completeness of
these tabulations has secured for the Manual the prestige of
official recognition in all statistical circles.
Statements showing for a series of years the total mileage,
construction, stock, debt, and cost of the railroads of the country,
the total mileage of all the railroads of the world, and
numerous other selected statistics.
Detailed statements for every railroad company in the country.
These are the most imporaut feature of the book, comprising
1,000 of its 1,500 pages. Following are the important
points of the statement : Terminal points and mileage of main
lines,branches, leased lines, etc. ; second track, sidings and other
tracks ; gauge, weight of rails and mileage of steel rails ; details
of equipment ; complete sketch of corporate history; terms
of leases or other contracts ; operations, earnings, etc., for last
fiscal year, and (for all larger corporations) comparative tabular
statements for eight years ; detailed balance sheet; statement
of funded debt, with description of security, rate of interest,
place of payment of interest, names of trustees, date of maturity,
etc, statements of all dividends paid since organization ;
time of holding annual meeting; names and addresses of directors
and general officers ; location of general and transfer of­
fices, etc., etc.
The current number of the Manual contains 50 new maps of
the leading Railroad Systems of the country. These are in addition
to the Manual's sectional maps (20 in number), which
are presented as heretofore.
ELECTRICIANS engaged in the experimental field have long
sought for reliable measurements of the internal resistance of
cells. The experiments of E. Wythe Smith make this possible
without sensibly altering the current through it. The same
method will determine the resistance of dynamo armatures
when working a quantity which has hitherto not been determined
by direct measurement. The plan presented by Mr.
Smith has received endorsement of eminent electricians. One
pole of the battery to be tested is connected to the similar poles
of two other batteries. Each battery has a separate circuit
through which currents are allowed to pass. Selecting a point
A at the opposite pole of the battery to be tested, points B and
C in the circuits of the auxiliary batteries found whose poten­
tials are equal to that of A. The resistances between each pair
of points A B, A C, B C are then measured by a Wheatstoue's
bridge. Calling fthese resistances R,, R2, and R3 respectively it
is shown that the internal resistance required is given by the
v 2 -r' , R, + R. — R3
formula b = x -\ 1 r +, &c, where x =
r r- 2
and r is the external resistance of the circuit containing the
battery tested. For an accumulator discharging, b = .r to within
about 2 per cent.
GREAT BRITAIN is now building io armored ships of war,
France 14, Russia S, United States 9, Spain 5, aud Germany 5.
The 10 British vessels represent an aggregate burden of 124,200
tons, the 14 French vessels 94,000 tons, the 8 Russian vessels
77,520 tons, the 9 American vessels 54,06c tons, the 5 Spanish
vessels 39,470 tons, and the 5 German vessels 24,400 tons.

224 THE CONSTRUCTOR.
Translated by Henry Harrison Suplee.
We then have N = q v 1V0= 0.172 X 6500 X 0.117 = '3° H. P.
e , , „ I4,200,OCOX OO78 „ , ,.
from (275 R = -sl—' '— = 64.9" say 65".
For R we have
i7.--(*+£
(284).
, .. . 14,200,000 X 0,078 „ , ,,
stead of 34,128, and thus obtain R = —- „
28,440
= 38.9 sav only 40'
When the resistance P is directly given, which is rarely the
case, we have from the relation q SY = T P, taking r = 2.
(280)
S,
The maximum statical moment which may have to be overcome
upon the driven shaft is sometimes given, as in the case
of pumping machinery, etc. Dividing the preceding equation
by (279) we have
qs-. 2 -A^-..PR
ind since q
14,200,000 6 S\
TT
— ii' 2 , this reduces to :
= 0.00564 V — V PR. (281)
1
S
and if we substitute for the moment P R the quotient of effect
N
from formula (135) PR — 63,020 — we get

September, 1892.] ENGINEERING MECHANICS. 225
a
•1
Dividing (288) by (293) we have, after some reductions :
I, S-^A'—Sm'
S„.
1293).
1294)
2I1 2
— = —.
a
In the figure, 2 . 5' = 2 . 4
From this we obtain the following geometrical construction
of Fig. 885. With a diameter = Aa, describe the semi-circle
1.2.3, and join the point 3 of the quadrant 2 . 3 with 2, or 1 ;
a
/ -= h', also 4' . 6' = —;
a
2
c 2
and 6' . 7' perpendicular to 6' . 3' gives at 4' . 7' the parameter
, and //,, and is equal to :
ho 0.67/.., + 0.28/.,
• (295)
It may readily be constructed graphically from the first expression.
It is not essential that the driving part of the rope should be
the upper portion, as the lower part may drive, as in Fig. 886. The
ropes will not touch, when stationary, if h2 — /-, < 2R. Owing
to the fluctuations due to the actiou of" wind, or of sudden
changes of load, the minimum distance should not be too small,
and is best kept greater thau 20 to 24 inches.
NoTE.- -Weh ave "rom (287)
dS = ij. \_dh
mum of S:
[-
+ ,'
a
A
1 ,
s
1,
1
di
till which gives for the mini-
o-f
*(
But — is the parameter, or Cm,
oil
Cm
hence 0 = 1- or t -in = ^ hm = —— and hence from (2S7):
lim
*/8
-,( hm +
8/-„ r
+ •/'- V/2
"'Lw + T/s ]
In Fig. 8S4 is shown graphically how for each value of/;, the
parameter c can be found, by constructing the proportion
a
4" . 7" = e".
To determine the vertex 4" ofthe lower parabola we have :
h ' + At - h ' + -jjL whence */-*'-.£ (^ - i)
_ a 2 h'-
' T ~h>
= hm'.
This gives h' h' which as shown above
FIG. 885.
Lay off this distance perpendicular to 1 . 2 at 2 . 4, and on any
scale (not too small) lay off from 2 to 5, the stress Sm. determined
from (292). From 5 lay off, on the same scale, 5 . 6, equal
to the given stress .S*, and from 6 draw the arc 5 . 7. This gives
2 . 7 =6 .5 — 6.2=6.5 — \/(6 . 5) 2 If, as before, we make 2 . 8 = hm, and 2.5' = h' and
draw through S a normal to 8 5' the normal will intersect
2 4" at 4" which is the desired apex. The lines 5 . 6, 5' . 6',
$" . (>" intersect each other at the middle of the half-chord of
the parabola at 9. This may be used in the construction by
drawing from 9, the line 9 . 6, 9 . 6', 9 . 6", and the corresponding
normals give the parameter points 7, 7', 7". The directrix
of the parabola lies at a poiut distant )z e from the vertex. For
the mean parabola the directrix is Lm, midway between 4 and 7,
aud the focus Fm is at the middle of hm, and is also the centre
of the circle 5.6.7. I.
In the figure is also shown another curve wliich indicates the
values of S. The proportional value of h from formula (287)
taken from the line 2 . II, shows that h is in inverse proportion
to the hyperbolic line IO
— (5 . 2)-', which is = .S* —
vo*'— Snf. If we now draw 4 . 8 parallel to 5 . 7 we have
2 . S
— -1—, and hence 2 .8 = //.
2-4 S
/ . 10. io // . The ordinates of the hyperbola,
taken from the axis of abscissas 2 . 7 gives the values of S
for the corresponding values of /'. The ordinates 4' . io' and
4" . \o" give the equal stresses .S y aud S"', and 4 . 10 the minimum
stress Sm. The dotted hyperbola on the upper right, gives
the corresponding thrusts in a parabolic arch, and the curve in
an arch corresponding to the catenary is the Hue of thrust. In
this also wc find the mean height the most economical, the
lower ones being stable, and the higher in an unstable equilibrium,
dependent upon the thickness of arch ring and distribution
of load for their stability.

226 ENGINEERING MECHANICS. [September, 1892.
TIGHTENED DRIVING ROPES.
i 293.
The deflection of transmission cables often becomes inconveniently
great. In many cases, however, it is possible to
reduce its amount by increasing the tension to a greater extent
than is necessary to prevent slippage. This requires the cable
to be made correspondingly stronger in order to resist the increased
tension. The modification in the preceding discussion
of forces and dimensions is here given, the various terms being
given the subscript 5 to distinguish them, (Ts, Is, Ss, b"s, instead
of T, t, S, rf). The tension T, as shown in \ 290, should not be
less than 2P, and if this is increased by a given factor m, we
have ts = Ts — P, and also :
PL 4= m T'= 2111 P,
ts = (2111 —I) P,
ts 2tn — 1
Ts 2m
(296).
In order that the stress S, in the driving part shall not be
changed we have for the stress in the driving part, instead of
S
—, the following :
2m
(297)-
The diameter rf of the wire, if calculated from (280) is modified
to
Ss — bVm (298).
or if taken from (281) or (282), we take
& — &&m (299).
from which the following table has been calculated. Tightened
cables are frequently applicable where moderate powers are to
be transmitted.
TABLE FOR TIGHTENED CABLES.
Ts
m = —
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3-0
3-2
3-4
3-6
3-8
4.0
4-2
44
4.6
4.8
5°
Ts
P
3-2
3 6
4.0
4-4
4.8
5-2
5-6
6,0
0-4
6.8
7.2
7.6
8.0
8.4
8.8
9.2
9.6
10.0
ts ts -SoJ •S„S ts
A~~p~ s.
2.2
2.6
3-0
3-4
3-8
4.2
4,6
5-°
5-4
5-8
6.2
6.6
7.0
7-4
7-8
8.2
8.6
9.0
5," ~~ Ts
0.69
072
o-75
0.77
0.79
0.81
0.82
0.83
0.84
0.85
0.86
0.87
0.88
0.88
0.89
0.89
0.90
0.90
rf,
a~ — v-w-
1.26
'•34
1.41
1.48
i-55
1 61
1.67
1 73
1.79
1.84
1.90
••95
2.00
2.05
2.10
2.14
2.19
2.24
rf* ,3/—
-=- = ~ nt
0
1.17
1.22
1.26
1.30
•-34
1.38
1.41
1.44
1.47
1-5°
1-53
1.56
«-59
1.61
1.64
1.66
1.69
1.71
Example.—Given, N = 5 . 5, n = 100, a = 590.4 ft. = 7086 in. It is required
to cover this distance with a single stretch of cable. If we take 5i = 14,22,
H •'.376 5-5
lbs., and s = 11,376 lbs., we have —dr- X
X — = 0.044. If
•*>l
14,220 100
14,200,000 X 0.026
12 feet. According to (279) R -•
11,376
32.45, say 32^ inches,
which gives h2 — A, *> 2 /? and the driving part of the cable must be above.
The above result shows that the centre of the pulleys must be more than
R -r hn or 24'* + 2ft ^VA 1 above the ground in order to clear. To reduce this
height we must tighten the cable. Suppose we made the diameter of the
wires = 0.04" instead of 0.024". This gives — 1.67, and from the table, col-
0
umns 4 and 6, line n, Si' = o.l 1, S = 12,650, and hence we have hit
„ (7086)2
0.0408 - A =162", and hit —
12,650
h, 162 — 144 = 18".
„ 14,200,000
We also have R = ,— X 0.04
",376
50" These values give his — h-,
FIG. 887.

September, 1892.] ENGINEERING MECHANICS. 227
For the parameter c, we have from (286) A'=p(h-\-c) or
Sa = '/' q (h -\- c) and if we consider the lower pulley as bearing
FIG. 888.
the lighter load we have : S' = '/' (c -\- .r,) whence c= — xv
Substituting the value of x„ from (300) we obtain after reduction,
r^ + 2 ^
v
A (•+*-?) (302)
The plus sign before the radical indicates that we have chosen
the "stabil" parabola (see Fig. 884), and hence obtain the
greater of the two values for the parameter. The parameter
thus being determined, we have xx and y\ from (300) and (301).
For the upper branch of the curve the stress St' is to be de­
termined at the upper pulley. We then have S" = ip (c -\- x2).
Subtracting from this S' = ip (c -\-xx) we have
S" = S' + iP(x2-x,) = S'+i>H (303)
and if 6H (304)
Example i 8500 —Let a = 328 felt = 3936", S' = 8500 lbs. If // = 0, we have from
+ 0
-V
8500 N -
0.3266
(302) c =
°-3266 ) _39|6 2 = 25g5I inches.
2 y 8
This value in (300) gives xx = x2 -- "1 :
3936=
Sc 8 X 25,951
For the slack half of the rope we have S f 2 = 4250, and
425o_
0.3266 t/ ( 0.3266 J 39362
whence /14
= 1505 •
Suppose now that H — o 05 a -
(a) For the Driving Side :
We then have :
= 74 62".
c Sr+«" J(&++*\\ 3936=;
2+0.05 T V 2 + o.052 J 8(l+O.OOI2S)
which is slightly greater than when // = O.
39362 26,018 1
We have also, from (300) h\ = 0-/r. - + X 0.0025
o X 20,010 2
and hx" •= k^ + 197" = 205.45".
The distance ji then becomes :
^?36«
: 8X 12,86
_ 393 —Q yr 26oi8 = 667.1.
•** 2
(b) For the Driven Side :
s +98 % •v r 39362
- : = 12,962.
*ra^v__-i -O.OOI25)
c
~ 2+0.052
+
T V I + o.052 / 8(.+
The deflection is :
/,.,'= 39,6S +
8 X 12,962 T
whence
12,962
; 0.0025 — 98.5 -67.1", and h2" = h2' + 197=264.1
y, — 1968--0.05 X 12,962 = 1319.9.
The stress on the rope, instead of being exactly 8500 and 4250pounds, will
be, according to (304):
8500 -f- 0.3266 X 197 — 8564 lbs., and
4250 -|- 0.3266 X 197 -= 4314 lbs. respectively.
(00 m—
The arrangement is shown in Fig. 889, the vertical dimensions being three
times the scale of the horizontal, and all dimensions being in metres.
Example 2.—Suppose the distance a = 3936 inches, and S\ = 8500, and S2
4250, as before, but the vertical distance ff= 1968", or —. We then have
2
(a) For the • Driving VIII 'lis Side aiuc . :
8500
o 3266
2 + 05
. , 393*5- , „, v 23361
h \ = xi = j— +0.25 X
8 X 23361 2
and jfi = 1968 — 23361 X 0.5 = — 9712 inches,
393*5 2
" 2+o.T"
V-*>- 8^7. +0 ' 25X
and^-j = 1968 — 12271 X 0.5
and the apex again lies outside.
-984 = 2019 inches,
the minus sign indicating that the apex of the parabola lies without the
space between the pulleys.
(A) For the Driven Side :
4250
_ 0.3266
2 4-o.5 2 •/" 42 lr + 5 !
4- -T— -= 12271, whence
o 3266
8(1+0 125)
FIG. 890.
- 984 = 708 inches,
12271
4167 inches,
The general arrangement is shown in Fig. 890, all dimensions being given
in the metric system, and the vertical and horizontal scales being the same.
The increase in the stresses is more marked than in the previous example,
on account of the increase in the value of H. We have Si' = 8500 + 0.3266 X
1968 = 9142 lbs., and SS = 4250 + 0.3266 X 19 68 = 4892 lbs.
FIG. 891.
The upper limit for this form of rope transmission is that in

22S ENGINEERING MECHANICS. [September, 1892.
which the parts of the rope are vertical, in which case the parameter
= 00. In this arrangement the necessary tension must
be obtained by the use of weights, spring, or the like. By using
guide pulleys, a combination of horizontal and vertical transmissions
may be made, as in Fig. 891, and the tensiou obtained
by the deflection in the horizontal part.
fj 296.
CONSTRUCTION OF THE ROPE CURVE.
We have considered the curve as an ordinary parabola.
.', .x.wr,^^'^W*'xT- J HiH'^^!^ | y-''^

September, 1S92.] ENGINEERING MECHANICS. .29
pulley, but this gives an excessively heavy middle rib for the
double pulley, and hence the inner angles are made 15 0 as
shown. The smallest diameter of rope for practical use is
d = 0.04". The superficial pressure p, mav- be calculated from
(274). If, for example, i = 36, we have from (244) — = 8, and
A*
if —r- = iooo aud S = S500, we have :
_ S = 2.S : = 1 ,6 lbs. per sq. 111,
Fig. 899 a, in order to avoid injurious stresses from shrinkage
in casting. The spaces are afterwards filled in with fitted pieces
of iron and a ring shrunk on each side to hold all together.
The proportions of hubs are the same as in \ 283.
a pressure readily borne by the leather filling.
The bottom grooves are made with a dovetail bevel in order
to keep the filling from being thrown out by centrifugal force
The filling of leather may be made of pieces of old belting
placed on edge and forced by driving into the dovetail groove ;
if new leather is used it should be softened by soaking in train
oil. Rope sheaves for hoisting machinery, which are only used
for guiding and supporting the rope, were formerly used without
any filling, the rope resting on the bare metal. It is becoming
more and more the practice to use a filling in the bottom
of the grooves of such pulleys, vulcanized rubber giving
good results. FIG. 899.
FIG. 898.
The construction of the rim of Fowler's " Clamp Pulley," referred
to in Fig. 794 c, is shown in Fig. 898 a, the clamps being
pivoted to blocks by means of bolts with anchor-shaped heads.
The pressure upon the rope is the same as in the case of a wedge
groove of equal angle, and the pulley as made by Fowler,
has one clamp ring mounted upon a screw thread cut upon the
pulley, thus enabling adjustment to be made for wear upon the
clamps aud for the reduction in the diameter ofthe rope. Fig.
898 b shows an American form of clamp pulley, somewhat simpler
in construction than Fowler's. The clamps are pivoted on
half-journals (see \ 95) and the angle is not so small as in the
preceding form.
The arms of rope pulleys are usually made of cast iron as well
as the rim, although the intermediate supporting pulleys are
sometimes made with wrought iron arms, as in Fig. 901. Large
pulleys, when of cast iron, are usually made in halves, for convenience
of transportation.
The number of arms A, may be obtained from :
A =4 + A 3
(3°5)
40 d
Cast iron arms may be either oval or cruciform in cross section,
and the width of arm h, in the plane of the pulley, if prolonged
to the centre is :
h = 41/
R_
A
(3°6)
For arms of cruciform section, the thickness of the arms e
may be made \ h, and the rib thickness e' = 73 e. Arms of oval
section may be made of the same proportions as for belt pulleys,
tbe thickness being made one-half/- at all points and the width
at the rim being % h.
Arms of cruciform section are usually made straight as at a,
Fig 899, but arms of oval section are frequently made curved
as at b.
To draw the curved arm make the circle O A of a radius =
A R and divide it into spaces for the desired number of arms.
Make A £ = 2 i A B, and draw O Cnormal to A O and (Twill
be the centre for half the arm, and the other centre will be at
D, the radius D E being equal to C E.
When straight arms are used the hub should be divided as in
The distance between journals for the intermediate and supporting
pulleys varies from \ R to A R. The load upon the
bearings consists ofthe sum ofthe weight ofthe pulley and the
vertical component of the various forces upon the rope, and
this cau best be determiued graphically as shown in Fig. 900.
FIG. 900.
The weight (7, of the pulley is so dependent upon slight
variations in the thickness and section of rim aud arms that a
general formula of practical value cannot be giveu. The following
examples from practice are given :
Examples.—In an executed transmission by Rieter & Co., at Oberursel,
near Frankfurt a. M., the pulleys are made with twelve straight arms of
oval section and are 12 ft. 3.6 in. diameter. The main driving pulleys at the
end ot the transmission, with single groove, each weigh 2525 lbs. and the
intermediate supporting pullej-s, with double groove, each weigh 2780 lbs.
The rope is made of 36 wires, each being 0.07" diameter.
Example 2.—The Berlin-Anhalt Machine Works Company makes a line of
rope pulleys with wrought iron arms as in Fig. 901, the w-eights being as
follows:
R .
G- I76 211
23"
248-308 281-343 3i°-3 3 7 3'6-5o6 528
60"
74S
70'
968
In these instances the weight upon the bearings is not great.
The journals for these pulleys should be made long, in order to
reduce the superficial pressure, and swivel bearings with cast
iron boxes (\ 116) can be used, which with self-oiling devices
will give good service. In many cases the journals are made of
hardened steel in order to combine the greatest security with
the minimum size-
Example 3.—The intermediate pulleys in Example 1, give a total pressure,
according to Fig. 900 b, upon the bearings, of 3036 pounds, or 1513 pounds on
each journal. II we make I = 1.5 it according to the table in | 91 we get for
./ only iV, in In the actual case, however, the journals are As in. diam­
eter giving a greatly reduced superficial pressure and thus insuring the
most complete 1
most complete lubrication. In this case we have the actual length / = 4.7,
1518
whence p
lbs. per sq. in. If, iu order to use formula ^89)
3-75
we take = //and make 5 = 8500 as before we have:
.41/=8". This gives:
1518
/ 16 X 4 /
. 95 lbs. per sq. in.

230 ENGINEERING MECHANICS. [September, 1892.
which is such a low value that even half boxes, similar to those in Figs. 324-
325 could be used. By using hard steel bearings even this small frictional
resistance could be reduced to J 4 the amount due to the above dimensions.
The pulleys for rope transmission should be most carefully
balanced, as any vibration causes serious oscillation of the rope
?. 299.
CONSTRUCTION OF THE PULLEY STATIONS.
The extraordinarily high specific capacity of wire rope transmission
has, as already said, caused it to be used especially for
FIG. 901.
the long-distance transmission of power. It has been found
particularly adapted for the transmission of the power of natural
falls of water to places where it can be utilized and has thus
FIG. 902.
materially advanced the use of natural sources of power. In
such transmissions one of the most important and difficult portions
of the work consists in the construction of the stations
upon which the pulleys are carried. * The following are examples
of well designed and constructed stations.
Fig. 901 shows a design for an intermediate station of masonry.
The foundation is of rough stone-work and the superstructure
of brick-work.
Stations similar to this are used in the transmission at Oberursel,
referred to in the preceding section, and erected in 1858.
This installation is used to transmit 104 horse power over a dis-
FIG. 903.
tance of 3168 feet (966 meters) divided into eight stretches, giving
two terminal and seven intermediate stations. Each
stretch = zy. = 396 feet long ; R = 74 inches, n = 114.5, V =
. e7tV'i*4A4-.'.;' yfluwusi*.
FIG. 904.
4400 ft, rf = 0.07", i = 36. The difference in level between the
two terminal stations in this case is 145 feet.
The transmission ofthe water power from Schaffhausen, con-
f These have been fully discussed in a work by D. H. Ziegler treating of
the installations made by Joh. Jalr. Rieter, Winterthur, 1876, and printed
privately. • 1 • r

September, 1892.] ENGINEERING MECHANICS. 231
structed by J. J. Rieter & Co. and in operatiou since 1866, is
used to transmit a total of 760 horse power developed by the
Falls of the Rhine. Of this 200 horse power is transmitted
direct to the left bank by means of shafting ; 560 horse power
is carried across the Rhine in one stretch, the distauce a being
385 feet, using two similar ropes carrying 530 horse power.
(n = 180, R s= 88'4" V —4636 ft.) and a third single rope carrying
30 horse power (11 = 180, R = 35.4'''). Of this power there is
about 4S0 horse power transmitted over three principal stretches
of 37S, 332, and 455 feet. The number of wires in the heavier cables
is • = 80, the thickness of wire rf = 0.074''', the rope beiug made iu
S strands of 10 wires each. One of the intermediate pulley stations
is shown in F'ig. 902, and this is an excellent example of
good style in construction. In this case there are two pulleys,
side by side. There is a guard shown over the pulleys, to pre­
vent possible jumping of the cables out of the grooves in the
pulleys, but this has been omitted in later instances as unnecessary.
Messrs. Rieter & Co. have also installed a system of turbines
and rope transmission at Freiburg, for the Societe generate
Suisse des eaux fiorels, of which 300 horse power is in a longdistance
transmission. The power is carried in five stretches of
502 feet each, to a saw mill, the difference in level being 268 feet.
Oue of the stations with two supporting pulleys is shown in
Fig. 903, this one being quite high ; a similar station, No. II, is
placed in a tunnel, through which the rope passes. The num­
ber of wires i = 90, the diameter of wire rf = 0.072", the cable
being made in 10 strands of 9 wires each, R = 88.6", n — 81,
*' = 3743 ft- From this point the power is divided by an angle
station and one part is delivered to the saw mill and balance
transmitted to a number of minor establishments.
An angle station is shown is Fig. 904, and this form is also
used when a portion of the power is to be taken off.
A fourth large installation of turbines and rope transmission has
been executed by the firm of Rieter & Co., for the Compagnie
generale de Bellegarde, at the latter place, for the utilization of
the well-known Perte dn Rhone. The combined power of the
Rhone anil the Valserine is exerted upon five turbines of 630 horse
power each, giving a total of 3150 horse power which is transmitted
by cable to the Plateau of Bellegarde.*
At Zurich, the city has utilized the power of the Limniat by
means of turbines and rope transmission built by the firm of
Escher, Wyss & Co. In this case the stations, wliich for various
reasons are quite high, are made of wrought iron, as shown in
Fig. 905. The entire installation develops n 50 horse power,
of which 750 horse power is used for the city water works.
At St. Petersburg a rope
transmission iu ten stretches .
is used to drive the Imperial
Powder Works, the power
beiug delivered into the
buildings by shafting from
each of the ten stations.
A modification of Herlaud's
device for putting on belts,
has been made by Ziegler for
the purpose of putting the
wire cables upon the pulleys.
As shown in "Fig. 906, it
consists of a curved piece of
angle iron, clamped temporarily
to the arm of the
pulley iu such a manner as
to lead the rope iuto the
groove of the pulley. The FIG. 906.
short radius to which the
rope is thus once bent does not
appear to have an injurious effect.
When a transmission rope is carried
over a public or private road
a guard should be used as a protection
in case of breakage of the
rope. A simple form used by Rieter
& Co. is shown in Fig. 907, and
consists of a sheet iron trough about
18 inches deep and ten feet wide,
carried by two stationary suspen-
FIG Q07 sion cables is H H.
\ 3°°-
EFFICIENCY OF ROPE TRANSMISSION.
The injurious resistances in wire rope transmission are mainly
those due to journal friction and stiffness of the rope ; the slip
and the atmospheric resistance of the pulley arms being insignificant,
t
4
a) Journal Friction.—We have from formula (100), F= —f O,
in which Q is the load upon the journal. For a circumferential
speed c, at the journal, we have a resistance in foot pounds :
Fc
4 . _ TT nd
—f Q
1T 12
find Q
F. =
3
(307)
Example i —In the case of the transmission at Oberursel a number of experimental
determinations were made. For a pair of journals Q — 2948 lbs ,
d = 3.75" and n = 114.6. For a coefficient of friction/^ 0.09 (experimentally
determined) we have :
0.09 X 114.6 X 3-75 < 2948
= 37,658 foot lbs.
3
37°58
33000
1.14 horse power.
This gives for 8 stations a total loss of 8 X 1.14 = 9-'2 horse power. The
maximum power transmitted is 104 H. P. and the minimum 40.3 H. P., so
that this gives a loss of about 9 per cent, of the maximum and 22 per cent.
ofthe minimum. This shows the objection to the use of too large journals.
*See Engineering, Vol. 37, 1874.
t See Leloutre.

232 ENGINEERING MECHANICS. [ September, 1892.
b) Stiffness of Rope— Using Weisbach's formula (253) given
in \ 26S:
S = 1.07S -f- 0.093 Q
R
we have, calling T' the tension ou the rope :
JL
S-.. = 0093 v [ 11.6 + (3°8)
R
for the resistance iu foot pounds.
Example 3.—\n the preceding case, v = 4400 ft.,
(T -\- t) = 0.5 X 202S =1014 lbs., whence :
Su = 0.093 X 4400 ( 11.6 + - J = 10368 ft. lbs.
73.8", and T'
This resistance comes twice at each station, and fur eight stations we have a
total of 2 X 8 X 10,368 = 163,888 foot lbs., or nearly 5 horse power. Adding
to this the journal resistance we have a total of 9 12 + 5 •= 14.12 H. P. The
direct measurements of Ziegler gave 13.341 H. P , which is a reasonably close
verification ofthe calculations. The total loss of efficiency is therefore:
14.12
13.6 per cent, of the maximum,
104
and
35 per cent, of the minimum,
the lesser of these being a very excellent result.
1301.
The intermediate stations may all be supporting stations
meiely. unless power is to be taken off at an intermediate point.
If tbe transmission is a normal one, not using the method of increased
tension (see \ 293 1 the same deflection will be obtained
wr%
REULEUX'S SYSTEM OF ROPE TRANSMISSION.
in both portions of the rope by making the stretches for the
In the preceding sections the utility and importance driven of wire part half as long as those of the driving part, so that
rope transmission has been shown. The various applications of every other station may be provided with a double-grooved
the methods already discussed exhibit much ingenuity and abil­ pulley, Fig. 909.
ity on the part of the designers. At the same time there appears
to be a possibility of improvement, especially in the case
of the transmission of large powers over long distances involving
a number of stretches.
The Ziegler system of intermediate pulleys has given excellent
results, but the following points may be enumerated as ob­
FIG. 909.
jections :
a. The great height of the supports usually necessary because If no change in direction is necessary the cable is thus carried
of the large size of the pulleys.
to the driven pulley, the two parts being separated by a distance
b. The large base required for the supports, not only for clear
equal to the diameter ofthe driving pulley 'fi, and entering the
ance for the lower part ofthe rope, but also to resist the tension
building where the power is to be received the cable passes over
of the rope.
guide pulleys Lf„ L-, and around the driven pulley T2.
c. The necessity of making the supports of great strength
When the load is reduced by throwing off machinery in the
when gearing is to be carried.
manufactory, the tightener carriage is drawn toward the turbine
These three points are all well shown in the Zurich station,
(Fig. 90S) by the driving part of the rope, since both parts give
Fig. 905.
a pull of '2 (T-\- I). A spring buffer is provided to check the
a. The resistance due to stiffness of the rope. This has
motion of the carriage in that direction. A spring dynamometer
usually been considered unimportant, until the recent investi­
may be connected with the bearing of the other pulley Lx and
gations have shown otherwise. (See the preceding section.)
the tension thus measured experimentally. When the trans­
e. The loss of power when the rope becomes slack.
mission is set in motion
f. The necessity of giving sufficient tension to the rope to in­
from a state of rest the
sure satisfactory action in warm weather aud consequent exces­
tightener pulley L moves
sive tension in winter.
slowly back until the
g. The unsightly soiling of the exterior of buildings caused
tension in the driven
by the grease from the cable defacing the wall upon which the
part of the rope becomes
receiving pulle}- is placed.
equal to t. Should the
h. The necessity of making the intermediate pulleys strong
rope have much stretch,
enough to carry the heavy stress of the cable, thus increasing
the carriage must have
the weight and consequently the journal friction.
sufficient travel pro­
It therefore appears advisable to devise a system which should
vided, and when neces­
permit the supports to be made low and light, to use a light
sary the rope must be
cable under moderate tension, also to reduce the number of
shortened. The stretch
splices, and to place the terminal pulleys inside of the building,
of the cable is less in this
the pulleys being made as light as practicable.
arrangement than with
All these points have been attained to a great extent in the
intermediate driving
following system.
pulleys, because it is
In the first place, the cable, whenever possible, is made iu
bent less frequently
one endless leugth from the drivitrgto the driven pulley, thus
around the pulleys, and
making the intermediate pulleys merely supports and permit­
the wear of the rope is
ting them to bafonstructed very light. It is also desirable to
much reduced for the
arrange the caole so that both parts shall be at the same height
same reason.
from the ground and that this height should be as moderate as
If angle stations are
possible.
FIG.
In Fig. 90S is shown the arrangement ofthe power house, the
910.
needed the arrangement
of Fig. 910 is used ; this
first driving pulley fi being directly upon the motor shaft and
requiring only two pulleys to each part of rope, instead of three,
lying in a horizontal plane. The driving part of the rope then
as formerly, and the use of gear wheels is avoided.
passes around a staionarv pulley L, and is carried off in the
If the first driving pulley is in a vertical instead of a horizontal
desired direction. The driven part of the rope passes around a
plane, the arrangement shown in Fig. 911 a is used, this requiring
pulley L' mounted on a carriage running on a track parallel to
one more guide pulley than before. In this case the track for
the direction of the line of transmission aud by means of
the tightener carriage is inclined so that its weight is used to
weights a pull somewhat greater than 2/ is brought upon the
produce the required tension. If it is desired to place the
carriage. This tightener pulley L' is placed so as to bring the
tightenerpulley horizontal the arrangement shown in Fig. 911 b is
driven part of the rope to the same height as the driving part.
used. In the cable of the Brooklyn bridge the tightener car­
The whole arrangement may be protected under roof as shown
riage is provided with a brake in order to check the suddenness
and the rest of the building used for other purposes, but if
of motion due to variations of load. A friction device similar
necessary the track and carriage may extend out of doors.

September, 1892.] ENGINEERING MECHANICS. 233
to a Fig. 7C9 will serve for this purpose if the angle rf is made
somewhat greater than is given by formula (233).
If it is desired to place the driven pullev T, in the same plane
as one of the parts of the main line cable, the other part 111 ust
be led over another angle pulley. If power is to be taken off at
intermediate stations these may be constructed as the angle stations
of Fig. 910.
Various other forms of intermediate power stations may be
used without involving the use of gearing, as shown in Fig. 912,
These rims are bent by means of special rolls, and a tongue is
formed in the sides of the groove to hold the leather filling in
place. The arms are made of light flat iron and the hub of cast
iron ; the arms either being bolted fast or cast into the hub, the
latter being made in halves. Pulleys made in this manner are
very light *-
The construction ofthe supports is also peculiar, as showu in
Fig. 913. The two posts are made of channel iron secured to a
block of stone in the ground by means of lead run in around
the holes in the stone. The whole is steadied by guy rods, and
brackets are provided so that the bearings can be reached by a
ladder. In many cases these supports of iron are cheaper than
those built of stone.
FIG. 912.
For the intermediate driving pulleys of cast iron, the form
shown in Fig. 915 is used. The hub is outside of both bearings,
but the plane of the pulley is midway between the journals.
The connection between the arms and the hub is made by
means of a hemispherical shaped device, somewhat resembling
the frame of an umbrella, and hence these have been called
in which a is for a shaft at right angles to the cable, and b " and umbrella " pulleys. -This construction enables the pulley to
e for inclined shafts for either direction of revolution.
be firmly secured and readily removed without disturbing either
The very moderate force which this system brings upon the bearing.
supporting pulleys permits them to be made very light. This In Fig. 915 b, a modification of this form of pulley, the
has been difficult of accomplishment with a cast iron rim. A umbrella shaped hub being made separately, and a straight arm
light wheel can be made of wrought iron, using angle iron pulley fitted upon it. This permits a single pattern to be used
riveted to a special shaped centre piece, as shown in Fig. 914. for the centres of a number of sizes of pulleys, or wrought iron
pulleys may be used ou cast iron hubs of this form. Instead of
FIG. 913. FIG. 914. two journals a single longer oue may be used, two forms of
hangers being shown in dotted lines.
The use of the umbrella
pulley enables a very simple
form of support to be
used, either for single or
double stations.
Fig. 916 a, is a single
b.
station composed of a
wooden post upon which
a projecting bearing is
bolted, and in which the
journal of the pulley runs.
At b, is a double station,
the post being made of
iron The dotted lines at
D indicate a small roof
to protect the bearings
from the weather. A
comparison of these forms
with the older style, as
for example, Fig. 903, will
show that merely the use
of the continuous rope
and the umbrella pulley
will effect a great economy
iu construction. The
A__AA
umbrella pulley is also
well adapted to be used
for rope sheaves for hoisting
machinery and
chain sheaves.*
for
FIG. 916.
(To be continued.)
•Various applications of the umbrella pulley will be shown hereafter.
The principle is also applicable to bell pulleys. At a, is a simple counter-

23 + ENGINEERING MECHANICS [September, 1892.
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION,
BY MAURICE LEVY.
This condition is besides sufficient by reason of the theorem
of \ 71 ; for a funicular polygon passing through the centres of
articulation being considered as a polygon of the pressures furnishes
between the hinges and the bodies only mutual actions
passing through these centres aud consequently A. 7A compatible
with the jointings of the system.
Remark.—Let us suppose (Fig. 12) that no force acts on the
hinge and that the two forces bordering on the hinge are T\ and
F.,; then the pressure that supports the section ab A cd should
coincide with the side 1.2 ofthe polygon ofthe pressures join­
ing the forces of Ft and F2 (? 68).
If we make the section a'b' A' c'd', the pressure at the point
of contact A' of the second body crossed by the hinge should
coincide with the same side, since the points of application of
the forces F, and F2 are also bordering on this second section.
Hence.'in this case, the polygon ofi the pressures does not present
the apex at the point of articulation.
The forces exercised at A and A' by the hinge on the two
bodies have the same direction ; the points of contact A and A'
diametrically opposed, as they should be, since, the whole system
being required to be in equilibrium, the hinge in particular
should be in equilibrium and, as it supports no other forces than
the reactions at A and A', these two reactions should both be
directed according to A A'. Our general theorem indicates besides
that they are equal and opposed, being both represented
by th polar radius parallel to 1.2 traversed in the two flows.
have for common magnitude the polar radius corresponding to
the side of the polygon of the pressures which passes to the
point C.
2° If a force is acting at the point C, it passes at this point
two sides of the polygon of the pressures; the action of each
body on the hinge is equal to the polar radius correspondiug to
the oue of the two sides which is placed on the side of this body,
2 75.
THRUST OF AN ARCH ON SIMPLE SUPPORTS, WITH A HINGE.
THEOREM.— Whatever be the weights which an arch resting
on two fixed axles A and B (level or not) and carrying C at
one of its points, the funicular polygon of the forces which incite
it, passing through the three points A, B, C, is its polygon
ofi pressures. Consequently, Ihe extreme sides of this polygon
furnish the directions ofi the reactions ofi the supports; the
magnitudes of these reactions are given by Ihe corresponding
polar radii. This polygou is-besides easy to draw I \ 45).
Let (Fig. 13) O be the pole of this polygon and a-** (Fig. 13) the
resultant of the forces acting on the entire arch and on the hinge
(if this latter itself carries a weight) ; the reactions of the supports
are represented by O a and b O. Then, if we draw- a
parallel O u to A B, the thrust of the arch is given by the
length Ou, the vertical reactions by c, a and b w. That being
the case, if we find only the reactions of the supports, it is suffi
cient to determine the position of the pole. If, on the contrary,
we wish to have the elastic forces and actions of the
bodies on the hinges, it is necessary to draw the funicular
polygon.
Remark.—If there was no hinge C, the condition for the
polygon of the pressures to pass through this point would not
exist. All the funicular polygons having their poles on the indefinite
line ts O drawn through the point a parallel to A B,
passing through the points A aud B (i, 4:3), would be able to
serve (\ 71) as polygon ofthe pressures and would assure equilibrium
in a Statics point of view, so that one condition would
be, in this ease, to borrow front the theory of elasticity for the
determination of the polygon of the pressures.
'i 7.
ARCH FITTED IN AT ONE END, SIMPLY SUPPORTED AT THE
OTHER WITH TWO HINGES ; REMARK ON THIS ARCH WITHOUT
If (Fig. 12 bis) a force .Facts at the point C, then the pressure HINGE.—If an arch is fitted in (Fig. 14) according to a section
exercised ou the section ab A cd coincides with the side 1 C of A B aud simply supported on au axle fixed at its other extremity
the polygon of the pressures which unites the two forces I\ and A0 and if it carries two hinges C and C, its polygon of the
/"bordering on this section, while the pressure exercised on the pressures is defined by the condition of passing through
section a'b' A' c'd' coincides with the side C2 which unites three hinges A0, C, C; we know therefore how to draw it
the forces F and F. bordering on this second section. Hence, (j 45).
in this case, Ihe polygon ofi the pressures presents an apex at the Let .l0 1.2.3.4.5.6.7 D be this polygon (Fig. 14) and O
point of articulation.
its pole (Fig. 14). The reaction of the fixed support A0 is
We can recapitulate this observation thus:
directed according to Aa 1 and represented by the correspond
i° If no force acts on a hinge C, these mutual actions of the ing polar radius O a.
two bodies and those which they both exercise on the hinge The resultant of the reactions of the fixed support A B is,

September, 1892.J ENGINEERING
likewise, directed according to D 7 and equal to the corresponding
polar radius b 0.
of this section.
B
Fig. iS.
I
I
Remark.—If we suppress the hinges, we possess no longer
a priori any condition to which the polygon of the pressures
may be subject.
MECHANICS. 235
All the funicular polygons ofthe given forces, without exception
can be adopted as the polygon of the pressures without the
conditions of equilibrium failing to be satisfied. Consequently,
the three conditions necessary to define the one of these funicular
polygons which constitutes in reality, the polygon of the
pressures, are theu to be borrowed from the theory of the elasticity
or of resistance of the materials (see Vol. II.).
§78.
POLYGON OF VARIGNON.—The theorem of the polygon of
Varignon which this celebrated geometer has given in 1725 and
which constitutes the poiut of departure of all Graphical Statics
is a particular case of the one laid down in \ 74. It is the case
where forces act only on hinges and uot on the bodies themselves.
Lleuce, since the polygon of the pressures passes
through all the points of articulation, it coincides necessarily
When the arch is completely fitted in, i. e. when there is ad­ with the polygon having these points as apexes. Hence :
hesion between it and its support along A B, the centre of THEOREM.—In order that a system of bodies as those defined
pressure D can be found outside the body. If, on the contrary, in the theorem ofi $ 74 bearing no force, the system being sub­
it is simply laid on the support A B without being unchangeject only to forces acting on the hinges, be in equilibrium, il is
ably bound to it, then, this support being able to resist only necessary and sufficient that the polygon -whose apexes are the
pressures, the centre of pressure is necessarily between the points of articulation be one ofi the funicular polygons of /he­
points A and B (\ 04, Rem.).
ading fiorces.
.It the hinge C where there is no force directly applied, the This polygon is then the polygon of the pressures of the
action of each body on the hinge is directed according to the system.
side 2.3 of the funicular polygon and represented by the cor­ By reason of its historic role and importance, we are going, in
responding polar radius. These two actions are equal and a few words, to establish this theorem directly.
opposed.
Let (Fig. 16) 1.2.3.4.5 be the points of articulation upon
On the hinge C where a force is acting and where, conse­ which the given forces act.
quently, the polygon ofthe pressures has an apex, the action of Each body is crossed by two hinges and the extreme bodies
the part C C of the arch is directed according to the side 4 C 1 C0 and 5 C are supported on fixed hinges or are fitted in.
or 4.5 aud equal to the corresponding polar radius 4.5, and the Let us suppose, for example, that the first is carried on a fixed
action of the part A B C on the same hinge is directed accord­ hinge C0 aud that the second is fitted into the wall according
ing to the side 6.5 or 6 C and represented by the correspond­ to a fixed plane C
ing polar radius 6.5.
Let us observe that this body is thus entirely fixed ; it cannot
Remark.—If the arch did not carry the two hinges C and C, as the others, turn around a hinge. The hinge 5 which crosses
the polygon of the pressures would no louger be subject to any­ it is then itself fixed, and everything is as if we were considering
thing but the sole condition of passing through the point A0. only the polygon C0 1.2.3.4.5 supported on fixed hinges at
The lic'O other conditions necessary to its determination would its two extremities.
be then to borrow from the theory of elasticity (see Vol. II.). In order that the system formed :
§77.
1° Through the bodies :
2
ARCH FITTED IN AT BOTH ENDS HAVING THREE HINGES.—
If the arch Aa B0 A, Bx (Fig. 15), fitted in according to its two
extreme sections, carries three hinges C, C, C", it will still be
necessary that the polygou of the pressures pass through these
three points, a thing which admits of drawing it (§ 45), and if
C0 1.2.3.4.5.6.7 C, is this polygon whose three apexes 2, 4
and 6 are found to coincide with the hinges, because we have
conceived forces directly applied to each of them, the extreme
sides and their corresponding polar radii (these latter not represented)
gives the resultants of the reactions of the supports, and
likewise, for any section A B, the side 3.4 and the corresponding
polar radius" give (J 68) the resultant of the elastic forces
0 Through the hinges not fixed 1, 2, 3, 4 be in equilibrium,
it is necessary and sufficient that each body aud each hinge be
separately in equilibrium under the action of the forces which
are applied to them.
Now, if we consider the body crossed by the two hinges 3
and 4, we can (I 73) suppress these two hinges and regard
the body as free, provided that we apply to it a suitable force
passing through the centre of each hinge. But here, the body
sustaining no other force than these two reactions, in order that
it be in equilibrium, it is necessary and sufficient that they be
equal and opposed, which requires that they both be directed
according to the side 3.4 of the polygon formed through the
centres of articulation. Let fiH be the one applied at 3 and /,.,
the one equal and opposed to the preceding applied at 4. We
shall thus assure the equilibrium of all the bodies by applying,
according tothe lines of junction, pairs of forces equal and opposed
and of indetermined magnitudes. These forces are :
(1'o be continued.)

23b ENGINEERING MECHANICS. [September, 1892.
PUMPS J\XI> PUMPING MACHINERY. Diameter of crank pins (steel) 7-5 inches.
BY WILLIAM KENT, M.E. Length of crank pins (steel) 9 iuches.
, _ , , . , Length of beam betweeu centres 63 iuches.
(Continued from page 214.) "* . ,
Length of upper beam pin 14 inches.
The working beam centres turn in bearings in the engine Diameter of upper beam pin 6 inches.
housings, which are located centrally between the centre lines Length of lower beam pin 6 inches.
of steam cylinders, and about midway between the steam cylin- Diameter of lower beam pin 6 inches.ders
and pumps. Diameter of fly-wheel 16 feet.
The crank-shaft is bent at the centre to form a pm or bearing Depth of rim of fly-wheel 16 inches.
for the outer end of connecting-rod. The crank-shaft over- width of face of fly-wheel 14 inches.
hangs the bearings 111 the housings and carries a fly-wheel at Weight of fly.wheel] about 28,000 pounds.
each end.
The crank-shaft, wheels and bearings in the engine housing The steani cylinders are jacketed, both on the sides and ends.
are set off laterally from the steani cylinders and pumps, and The jackets are supplied with live steam from the boilers,
the pin in the working beam from the inner end of the connect- which, with the jacket condensation, passes on to the feed
ing rod set down to compensate for the angular position of the water heater, and there serves to heat the greater part of the
rod. feed water, which is taken from the main. The condensation
In 1S90 the Holly Manufacturing Co. issued a book contain- in the jackets and heater is trapped off into the feed tank,
ing the full reports of twenty-seven tests of (iaskill engines. whence the feed pumps—four iu number, and single acting—
The following table gives the figures of duty obtained in these draw their supply.
tests with the names ofthe experts employed. The clearance space in all of the cylinders is small, and is
DUTY TESTS OF THE GASKILL PUMPING ENGINE.
Place.
Year, Capacity
f of Engine
Test. Tested.
Name of Expert.
Saratoga Springs, N. Y.
1882 5,000,000 112,899,983
Saratoga Springs, N. Y.
Columbus, Ohio . . .
1883 5,000,000
1SS4 10,000,000
127,170,000
106,838,000
115,400,000
Burlington, N, J . .
1SS4 1,500,000 77,770,400
Buffalo, N. Y
1SS5 15,000,000 125,907,297
Jackson, Mich
4,000,000 111,781,072
1886
Leavenworth, Kans
4,000,000 110,478,000
1S86 3,000,000 102,728,884
Kalamazoo, Mich
1SS6 5,000,000 95,420,216
Norfolk, Va
(8S6 12,000,000 110,632,166
Chicago, Hyde Park
1SS6 2,000,000 (Capacity. Test.)
Beverly, Mass
1SS7 3,000,000
110,482,946
Lima, Ohio
18S7 5,000,000 122,309,829
Erie, Pa
12,000,000 102,583,585
1887
20,000,000 125,022,730
Chicago, No Side Station .... 1SS7 2,500,000 '01,772,977
Philadelphia, Penn
1S8S 2,500,000 101,183,587
Washington, D. C. (East Engine) I8SS S, 000,000 109,421,100
Washington, D. C. (West Engine) ISSS 5,000,000 102,638,723
Boston, Mass
1SS8 12,000,000
ioS,6oo,ooo
Port Huron, Mich
20,000,000
iSSS
5,000,000 "22,255,512
Chicago, Town of Lake
lS8q
1
8,000,000 '3,395,447
Buffalo, N. Y
1889 10,000,000 II7,93
Springfield, Ohio
ISS9 2,000,000
Saratoga Springs, N. Y
1889 6,000,000
Dayton, Ohio
ISS9 2,000,000
Binghamton, X. Y.. . ...
10,000,000
ISS9
Brantford, Out
IS90
Nashville, Tenn
1890
6 , 6 9 S
Prof. D. M. Greene and John W. Hill, M. E.
'- Charles T. Porter.
Prof T. C. Mendenhall.
H. P. M. Berkinbine, C. E.
John W. Hill, M. E-
Charles Christopher, Ch. Eng.
Thomas J. Whitman, C. E.
John W. Hill, M. E-
William Wright, Ch. Eng.
Charles Hermany, C. E.
Walter H. Sears, C. E.
J. D. Cook, C. E-
Frederick A. Scheffler, M. E.
Prof. Robt H.Thurston, J. S. Coon, C. E., Jas. N. Warrington, C. E.
John E. Codman, C. E.
]- G. W. Baird, Passed Asst. Eng. U. S. Navy.
William Jackson, City Eng.
Henry Burton, Asa R. Cole.
Beuzette Williams, C. E.
Louis H. Knapp, Supt. and E
Charles A. Bauer, C. E.
124,782,157
Prof. D. M. Greene.
62,968,000 - Board Water Commissioners.
Arthur 1 Giesler, M. E.
96,735,49'
Thomas 1 Worswick, M. E
116,503,690
George Reyer, Supt. W. W.
The following abstract of the report of the test of the Sara­ taken at 2.7 per cent, and 3 per cent, in the high and low-prestoga
engine made in 1S89 by Prof. D. M. Greene furuishes data sure cylinders, respectively.
which may be useful in comparing records of other pumping
engine tests :
The steani valves of the high-pressure cylinders are qf the
double-beat type, and the cut-off, which is practically instan­
The principal dimensions of the engine and pumps are as
follows :
Diameter of high-pressure cylinders 27 inches.
Diameter of low-pressure cylinders 54 inches.
Dameter of pump plungers 25 inches.
Stroke of steani pistons and pump plungers . . . 40 inches.
Diameter of high-pressure piston rods (steel) . . 3.5 inches.
Diameter of low-piston rods (2) (steel) 4.5 inches.
Diameter of pump rods 5 inches.
Diameter of crank shaft (fagoted iron) 12.5 iuches.
Diameter of hub of crank 22.5 inches.
Depth of crank 11 inches.
taneous, is varied by the load on the pumps by means of the
Holly automatic register.
The steam is admitted to, and exhausted from, the low-pressure
cylinders through gridiron slide-valves.
The pumps, which are double-acting, are each fitted with 700
"Troy " valves, each of about iM inch diameter and Vg inch
lift.
At each end of each pump, therefore, there are 175 induction
and 175 eduction valves, giving an aggregate valve opening for
the reception and discharge of the water equal to more than
0.6 ofthe effective area ofthe plunger.
This large valve arc insures the passage of the water to and
from the pumps with the minimum of frictional resistance. The

September, 1892.] ENGINEERING MECHANICS. 237
loss of head, due to the passage of the water through the pumps
ought not to be, and probably is not, greater thau 0.25 of a
foot.
THE TEST.—The provisions of the contract with the Holly
Manufacturing Company, as to capacity and duty, were :
I. That the capacity of the engine should be S,ooo,ooo U. S.
gallons of water, pumped against a pressure of 100 pounds per
square inch in 24 hours at a piston speed of, or uot exceeding,
115 feet per minute—equivalent to 17.25 revolutions per
minute.
2. That, while iu operation at the specified speed, and
against the specified pressure, the engine should develop a duty
of 105,000,000 foot pouuds per hundred pounds of coal consumed
—the coal cousumption to be based upon a hypothetical rate of
evaporation of 10 pounds of water per pound of coal.
3. That the engine and pumps shall be capable of operating
against a pressure of 140 pounds per square iuch, with safety to
all its parts-
From the tables of results we extract the following values :
Mean steam pressure in boilers per gauge. . . 81.05 pounds.
Mean steam pressure at engine, per gauge . . . 7S.01 pounds.
Mean steam pressure in jackets per gauge . . 70.075 pounds.
Total mean pressure on pumps 103. 735 pouuds.
Mean vacuum, per gauge on condenser .... 28.9 inches.
Mean vacuum per gauge on engine 27.87 inches.
Mean temperature of feed water, Fahr 203.55 0
Mean temperature of fire room, Fahr 62.57 0
Mean volume of water, at 51 0 , passing the
meter perhour 88.014 cu. feet.
Mean revolutions of engine per minute. . . • i7-°4
Mean period of cousumption of 900 lbs. coal . 1 h. 30 m.
Mean rate of coal consumption per hour . . . 600.00 pounds.
FIG. 60. THE GASKILL VERTICAL PUMPING^ENGINE.
H. F. GASKILL'S
VERTICAL COMPOUND PUMPING ENGINE.
SECTIONAL ELEVATION.
Mean rate of coal consumption per minute . . 10.00 pounds
Mean rate of consumption per hour per square
foot of grate 9901 pounds.
Mean rate of evaporation per minute .... 96.135 pounds.
ESTIMATE OF DUTY.—For this purpose it will be couvenient
to construct a little duty formula, as follows:
Area of pump plunger, 25 inches diameter . 490.875 sq. inches.
Deduct one-half section of rod 9.8175 sq. inches.
Mean effective area of plunger 4S1.0575 sq. iuches.
Under a pressure of one pouud per square
iuch, aud at one revolution per minute, the net
2 x 40
-work of two pumps will be 481.0575 x 2 X = 6414.1 ft-lbs.
Then, if in any case,
;- number of revolutions per minute,
and/>= mean pressure, in pouuds per square inch on the
pump plungers, the foot-pounds, or work per minute, will be
64'4-i p.r. (a)
Now, the duly is the number of foot-pounds due to the combustion
of 100 pounds of coal,which, iu the present case, is assumed
to evaporate 10 pounds of water per pouud, or 1,000
pounds of water per 100 pounds. The expression (a) must,
therefore be divided by the ratio of the actual rate of evaporation
per minute to 1,000 pounds. Theu D being the duty and
W the number of pounds of water evaporated per minute, we
have :
6414. \ p. r.
D = _ y__ s 6,414,100 x A r -
iooo zv
(A)
(To be continued.)

23S ENGINEERING MECHANICS. [September, 1892.
ELECTROTECHNICS. The time constant ofthe coil
Compilation ofi Rules, Tables and
HY CHARLES M. SAMES, ELECTRICAL ENGINEER.
Data.
TheiT. AI. F. of cell being constant in direction combines with
the alternating E. M. /'"., the result being that more current
flows oue way than the other, which is recorded in the cell.
The Shallenberger alternating current meter consists of an
oblong coil of wire through which the current to be measured
passes. Within this coil are fixed a number of copper punchings,
which form a secondary circuit. The planes of the two
are inclined at about 45° to each other. Within the copper
punchings is a thin ring of soft iron attached to a steel shaft pivoted
vertically. The alternations of the current induce a rotary
motion in the ring, whose speed is proportional to the
square of the current, or approximately so. The motion is
controlled or damped by au air fan.
The Thomson recording watt meter consists of a peculiarly
constructed motor whose motion, depending on the energy of
the current is retarded by a damping system of three magnets
between whose poles a closed circuit is moved. This motor consists
of an armature wound with very fine wire on a hollow
frame, containing no iron. It is connected through its commutator
to a high non-inductive resistance. Surrounding this are
oblong field coils having 110 iron cores. These fields are in
series with the current to be metered.
A variation of the current is the armature due to a variation
of potential, and of variation of the field current, due to variation
of load put on or thrown off together act to vary the speed
of the register. The meter multiplies these two together aud
registers energy.
The Forbes-coulomb meter depends for its action on the
heating effect of the current. A flat spiral of wire through
which the current flows becomes heated and causes currents of
air to rise, which impinge ou vanes attached to a vertical axis
capable of revolution, and thereby drive the registering apparatus.
Elihu Thomson has devised a number of meters based
on the heating principle, most of whicli depend on the oscillation
of a lever about a fulcrum. One of them consists of a tube
terminated at each end with bulbs, the tube being pivoted iu
the centre. The tube and bulbs are nearly filled with a liquid,
and normally rest in a horizontal position. Iu the bulbs are
sealed spirals of wire of high resistance, whose terminals project
and dip alternately into mercury cups. The actiou is as
follows : The current, wheu passing tlirough one spiral, heats it
quickly. This heat is transmitted to the liquid and a part
evaporated. The pressure iu the bulb is thereby increased, and
the liquid is forced toward the other bulb. This produces au overbalance,
and the arrangement tilts over, breaks contact with
the first mercury cups and making contact with the others
under the second bulb. This oscillation is recorded by suitable
mechanism, and it is obvious that the rapidity of these oscillations
is a measure ofthe quantity of electricity passing. Meters
based on the heatiug effect are adapted equally to direct or
alternating currents.
7. SELF-INDUCTION.
a) Appropriate calculation of (Perry).
For hollow cylindrical coils.
••'-' a 1 -4- IO 7
y
~R
r
72S a + 1.5 b + 1.33,where
R — resistance aud Kthe volume of copper in cubic cm.
b) Measurement ofi, with Carden Voltmeter. (Brew.)
The apparent resistance r, is measured by two deflections of
the voltmeter /), and D., the first when circuit includes coil
whose induction is to be measured, the second without. R is
the ohmic resistance of voltmeter.
- A (')
also
V-
I (in secohms) —-— -— 7—-
1.844 a + 3.5 b + 3.1 c
where 11 = number of windings.
a = mean radius windings in centimeters.
b = axial length.
C = radial length, b and c must be less than —
+ 4_^2 L 2
yV2
(2)
where r = resistance in ohms of inductive coil.
L = co-eff. of self-induction.
'F—- time in seconds of a complete alternation.
11 = number of alternations per second.
from (2)
L
T
2TT V (3)
T = L = A' (4)
„/).,
If —" does not suit the range of the instrument, a non-induc-
1 '1
tive resistance is placed in series with the voltmeter, having a
resistance equal to that of the inductive coil. With the arrangement
r, (in 1) A 4 TT'1 IA it 1
and R = res. of voltmeter
4- non inductive resistance, whence L (5)
This formula neglects difference in phase of potentials or coil
and voltmeter. If this is to be considered then
A _ JjR+rp + 4vr-1} fT
R
i=AAJAA r*±L\
21T ,y n* —{^ R J
where R is resistance of voltmeter and r that of the induction
coil.
c) Measiiriiiciit ofi, by Means of Seeohm-mctcr (Fig.//.
This instrument, due to Ayrton & Perry consists of two rotary
commutators, each having four stationary brushes. The commutators
are on the same spindle, one at the front the other at
the back, not shown in the cut. For convenience, however,
they are represented iu Figs. 78, 79 and 80 as if they were in the
same horizontal plane ; as a matter of fact, the brushes *„ b2, b3,
(•>„ are at the top of the instrument. One commutator G Cis
used for periodically reversing the galvanometer connections,
and the other, B C for reversing the battery connections. An
adjustment is provided for enabling the relative positions ofthe
two commutators to be varied, so that both reversals can be
made to occur simultaneously, or one a little before or after the
other, or one reversal midway between two successive reversals
of the other. The commutators can be driven at one or other
of two speeds relatively to that of the driving handle. With
one arrangement there are rather more than eight reversals of

September, 1892.] ENGINEERING MECHANICS. 239
both the galvanometer and of the battery for one revolution of
the handle. The secohmmeter can be conveniently driven by
hand, so as to obtain a steady speed of 300 to 6000 reversals per
minute of both the galvanometer and the battery.
The following are substantially the directions whicli accom
FIG. 77.
pany the instrument. The secohm equals io\centimeters ou
the earth's quadrant. The legal secohm = .99S X io 9 cms. due
to the difference between the true and the legal ohm.
To shift from one speed ratio to the other, press down the end
ofthe locking lever at the left ofthe secohmmeter, and slightly
push in or pull out the handle, turning it slightly to assist the
toothed wheels engaging properly ; when engaged, let go the
end of the locking lever.
1. To Compile Two Co-efficients ofi Self-induction (Fig. 78).
Connect as in Fig. 7S. Then if the non-inductive resistances
2. To Compare Two Capacities (Fig. 79).
Connect as in Fig. 79, as a balance will be obtained on rotating
secohmmeter, when
m 4-
Iy y
F2 r2
l-\ and F. being the capacities of the con­
densers, "and r, and r, the non-inductive
resistances of bridge. This method is in­
dependent ofthe speed.
3. In similar manner two co-efficients
of mutual induction may be compared
with one another, or a co-efficient of
mutual with a co-efficient of self-induction,
or either of these with the capacity of a
condenser, started by a non-inductive re­
sistance.
To Measure a Co-efficient ofi Self-induc­
tion Absolutely in Sccohms.
I). Comparative Deflection Method Fig.
So).—Attach a speed indicator to the commutator
spindle, which is prolonged for
this purpose, and.'connect apparatus as in Fig. 80, L being the
co-efficient of self-induction to be measured, and /-„ r,, r:„ values
of the three non-inductive resistances that balance with a steady
curreut. Rotate the secohmmeter handle at some convenient
FIG. 78.
r, r2 be balanced with a steady current, they will also balance
I
di n p_
secohms approx.
d,' r, tin
when spindle is rotated, when
In this test the relative positions of the commutators are unimportant.
They may be as iu Figs. 78 and 79, in which case
IA = A
L2 r2
L and L are the co-efficients of the inductive branches of
bridge The higher the speed the greater the sensitiveness, but
its vtlue is immaterial. It should not be so high that the currents
do not have time to reach their steady values between two
reversals.
FIG. 79.
speed, causing the commutator spindle to make 11 revolution
per second, and observe the steady deflection, rf,, of the galvan­
ometer. Next stop the secohmmeter, and increase oue of the
resistances rx for example, by a small amount /> ohms, obtaining
a steady deflection d. of the galvanometer with the battery
previously used ; then
the reversal of the galvanometer occurs midway between two
consecutive reversals of the battery. The greater the value of
n the greater will be the deflection d„ aud the more accurately
can it be read ; but the speed must not be too great to prevent
the currents reaching their steady values.
(To be continued.)

240 ENGINEERING MECHANICS. [September, 1892.
EMINENT AMERICAN ENGINEERS.
Charles Louis Strobel was boru October 6, 1852, in Cincinnati,
O., aud received his early education in the public schools of that
city. At the age of seventeen he went to Germany to complete
his education. He entered the polytechnic school at Stuttgart,
aud graduated from that institution four years later in the department
of civil engineering.
Returning to Cincinnati, he began his professional practice
on the Cincinnati Southern Railway in the spring of 1S74. The
work of construction ou this road had theu just begun. It included
many iron bridges and viaducts, some of which were of
unusual magnitude or remarkable for novel characteristics.
Among them may be
mentioned the Ohio
River Bridge at Cincinnati,
with its great channel
span of 519 feet, and
High Bridge over the
Kentucky River, the first
example of a large cautilever
bridge, and one of
the highest viaducts ever
built.
Mr. Strobel remained
on the road four years,
which covered the main
period of construction,
and during most of that
time he was in immediate
charge of bridge construction,
more particularly
superstructures, as
assistant engineer. His
thorough theoretical
training was of great service
to him in this position,
aud his application
of exact scientific methods
in American bridge
practice, for which there
presented themselves
such extended opportunities,
resulted in many
important improvements
in the structures which
were built.
In May, 187S, Mr. Strobel
removed to Pittsburgh,
having accepted
an offer of the Keystone
Bridge Co. to fill the position
of Assistant to
President and Engineer
to the company. He remained
in this position
until October, 18S6, when
he removed to Chicago
and opened an engineering office there, retaining a connection
with the Keystone Bridge Company as consulting engineer.
In 1889 he again resumed a more active connection with the
Keystone Bridge Co. as its chief engineer, and, besides filling
the positiou of consulting engineer to Carnegie, Phipps &. Co.,
Ltd., and Carnegie Bros. & Co., Ltd., became an associate in
these partnerships.
As engineer of the Keystone Bridge Co. Mr. Strobel designed
most ofthe important structures built by that company, among
which may be mentioned the Susquehanna River bridge of the
Baltimore & Ohio R. R. at Port Deposit, and the Ohio River
bridge of the Ohio Connecting Ry. below Pittsburgh.
He is widely known as the editor of the handbook of useful
CHARLES LOUIS STROBEL.
information for engineers and architects published by Carnegie,
Phipps & Co., Ltd., the first edition of which appeared in 18S1.
This firm early appreciated the advent of the change from iron
to steel for constructional work and prepared for it. In this
connection Mr. Strobel designed, and the firm adopted, entirely
new sections for steel beams, to take the place of the irregular
and clumsy patterns which the mills had been using in irou,
and these new sections have now been generally adopted as the
standard in this country. The change, while it reduced the
weight of beam required to carry a given load considerably (as
much as 667. for one size) proved advantageous to the firm by
greatly stimulating the demand for beams. In 1887 Mr. Strobel
introduced the rolling
of Z bars in this country,
and invented the Z bar
column, now so extensively
used in fire-proof
buildings. Both improvements
were important
elements in bringing
about the present era of
high-building, steel-ribbed,
fire-proof construction.
A notable feat with
which Mr. Strobel was
connected as engineer
and superintendent was
the placing in position
on masonry piers by floating
of one 523 ft. and one
416 ft. span of the railroad
bridge over the Ohio
River below Pittsburgh.
The spans were moved
while resting on their
falseworks, and making
a total height of structure
above water of 140 feet,
from a position alongshore
to their final resting
place on the piers.
The work was done in
August, 1890. Less than
a day's time was required
for the transferring, and
the appliances were very
simple, ordinary Ohio
River coal barges serving
for pontoons to carry
the load, which was 915
tons for the larger span,
not couuting the falsework.
Mr. Strobel has contributed
to engineering
publications. He is also
a member of the American Society of Civil Engineers and
other American engineering associations, aud ofthe Institution
of Civil Engineers of Great Britain ; he is also a member ofthe
executive committee representing the engineering societies at
the Columbian Exposition.
A BELGIAN ELECTRIC RAILWAY.—M. Vanden Kerckhore, of
Gand, has been negotiating with the Belgian Government with
a view to the establishment of an electric railway between Antwerp
and Brussels. The line will be exclusively devoted to
passenger traffic, and it is expected that the run between the
two cities would be made in about 25 minutes. The proposed
line will have no curves, and only slight inclines.

September, 189 2. J ENGINEERING MECHANICS. 241
_, Philadelphia, slue, is, /SQJ.
ENGINEERING MECHANICS :
^•".—I enclose herewith a rough sketch, showing a vertical
shaft, attached at its lower end to a turbine wheel, and carrying
t.^^ll
For strength d = 3.33
For stiffness d = 4.7
at its upper end a mortice-gear,
by which the power is trans­
mitted through a pinion to a
horizontal shaft.
The distance between the
centers of hubs of gear and tur­
bine is 26 feet, and the shaft is
held in solid bearings close to
these hubs.
The power of the turbine at
40 revolutions per minute is 65
H. P., and a shaft of soft steel
of a tensile strength of 60,000
lbs per sq. inch is to be used.
What will be the diameter of
this shaft? Is it to be calculated
for torsion only? and how is
the length of the shaft to be
introduced into the calculation
?
By giving the above informa­
tion you will greatly oblige
Yours, very truly,
W. OTTO GRONF.N, M.E.,
Principal Assistant Mechani­
cal Engineer.
Answer.—Iu all such cases
the diameter should be calcu­
lated both for strength and for
stiffness, and larger value used.
The most convenient formu­
lae are those giveu the "Constructor,"
Chapter IX, \ 144 :
•US
n
in which 4V = Horse Power, n = revolutions.
C3:)
(^33)
Formula (133) takes the length into account, although it does
not appear, and gives a permissible torsional deflection of not
over 0.0075 0 per foot of length.
In the above case N = 65, n = 40, which give :
*/65
For strength d = 3.33 V — = 3-9' say 4.
1-7 For stiffness V A d =
4°
40
5-3
hence the latter should be used. This value, however, is for
wrought iron, and for steel we multiply by 0.84, or d = 5.3 x
0.84 = 4.72 say4*4.
A YEAR ago in July the Ball & Wood Company of 15 Cortlandt
Street, New York, turned over the shafting for the first time at
their shops at EHzabethport, N. J., which they erected for the
purpose of building their Improved Ball Engines. Their first
engine was shipped iu October last year, and since then their
works have been running night and day to fill their orders. ,"\t
present over 6000 H. P. in Simple Engines, Cross Compound
Eugilies, and engines of their Tandem type are on the erecting
floor in process of construction. Among their last important
contracts was one for iooo H. P. plant in Lancaster, Penna.; two
Tandem Engines for Bethlehem ; a Cross Compound Engine of
300 H. P. for Hartford, Ct, and another for Paterson.
THIS office is prepared to furnish a complete Binder for ENGI­
NEERING MECHANICS as shown in illustration. It has a solid
wooden back ; the Journal is securely bound by thin steel slats
which run the length of the magazine, and can be removed at
pleasure. For binding periodicals, as fast as they arrive, it has
no equal, since the Binder appears nearly as neat as when completely
filled.
These Binders will be furnished, on application, at 75 cents.
Subscribers renewing their annual subscription will be furnished
with a Binder for $2.50.
8. & CS NEW THROUGH LINE.
Prepcring for tbe immense traffic incident to tbe World's Fair.
The management of the Baltimore and Ohio Railroad is preparing
for an immense business in 1S93 while the World's Fair
is open in Chicago. The terminals at Chicago are capable of
accommodating a much heavier traffic than is now being done,
and important changes are being arranged for the handling of
very heavy freight and passenger business to the West from New
York, Philadelphia and Baltimore. New equipment for largely
iucreased passenger business and an extensive stock of freight
cars have been ordered. The various roads of the system will
be improved by straightened lines, reduced grades, extra side
tracks, and interlocking switches. The new line between Chicago
Junction and Akron has shortened the distance between Chicago
and tide-water twenty-five miles, aud between Pittsburgh and
Chicago fifty-eight miles.
The distance between Chicago and Pittsburgh and Chicago
and Cleveland by the construction of the Akron line and the
acquisition of the Pittsburgh and Western line and the Valley
Railroad of Ohio, is about the same as via the Lake Shore from
Cleveland to Chicago, and by the Pennsylvania from Pittsburgh
to Chicago. The alignment is to be changed and grades reduced
to a maximum of twenty-six feet. It is expected that within
twelve months the old Baltimore & Ohio through line between
Chicago aud the Atlantic Ocean will have passed away, and the
new line via Pittsburgh be established, with no greater grades or
curvature thau on any of the trunk lines.
Work has already begun east of Pittsburgh to meet improve­
ments making west of Pittsburgh. These improvements will
consist of additional second and third tracks, a general correction
of the alignment, and completion of the double track on
the Metropolitan branch. It is expected that the new through
line will be ready simultaneously with the completion of the
Belt Line through the City of Baltimore, which is intended to
unite the Washington Branch with the Philadelphia Division
and do away with the present line via Locust Point. Forty new
and powerful locomotive engines were added to the equipment
during the last two months, and others are in process of con­
struction. The permanent improvements now under wav and
in contemplation involve the expenditure of some five millions
of dollars.—Baltimore American.

242 ENGINEERING MECHANICS. [September, 1892.
THE BRUSH INCANDESCENT MACHINES
BRUSH INCANDESCENCE DIRECT CURRENT MACHINE.
The Brush Electric Company now has upon the market a complete
line of direct incandescent machines, which embody the
latest and most improved practice iu dynamo construction. These
machines are ofthe close coil type, entirely new in design ; the
improved ring armature having many bobbins and few turns of
wire. The new commutator is of the bar type, made of pure
copper aud mica aud is entirely sparkless and indestructible.
Frame.—The frame of the new machine is cast in one piece,
requiring no bolts or screws to hold it together. This frame is
fitted on to V's, which are formed on a bed-plate, also iu one
piece. The machine frame is moved back and forth on this bedplate
by means of a screw wheel or lever, so that the belt can be
readily tightened or loosened.
Bearings.—The dynamo frame is bored out at each end to receive
the adjustable ball bearings, which carry the shaft of the
armature. These bearings are not split as in other machines,
but slip over the shaft, and are provided with ring oilers, which
dip into large pockets in the support of frame. . The use of
these pockets, which are filled with oil, make the old style oil
cups unnecessary, aud this part of the machine requires no
attention whatever.
Field Magnets.—Because of its high maguetic permeability, the
field magnets are made of soft cast steel. They are then wound
with a very thin layer of wire, which is used with a small current.
There is no heating of parts aud no burning of insulation.
The magnets are compouud wound to rise from ioo to 105 volts ;
from no load to full load. Only about three per cent, ofthe output
of the machine is required to excite these magnets.
Armature.—The armature is of the smooth, ring type, of newdesign
and construction, with irou spacing lugs only. It is made
of very thin iron ribbon, wound like a tape. The section of the
armature ring is about as large as the rest of the magnetic circuit.
There are 36 bobbins in the armature, each entirely separated
from the other. The ends of these bobbins are connected with
36 bars in the commutator, by means of wires passing directly
from the armature to the commutator outside of the shaft.
Commutator and Brushes. - The commutator is made up of 36
bars of pure copper, held betweeu two heads, each bar thoroughly
insulated from the other with mica. The brushes are
made of alternate layers of fine copper wire and thin sheet
copper, and are about one-half inch thick. They are fitted to
suitable adjustable brush-holders, which give them au easy and
smooth pressure on the commutator, the euds of the brushes
being pressed against the commutator at an angle. The commutator
becomes polished, and if properly cared for, will remain
bright, operating with 110 sparking, no heating, and with very
slight wear. Change of load causes almost no rocking of the
brushes from one position to another ; slight changes not affecting
the machine in any way. The machine, as a whole, requires
less attention than any other dynamo on the market, the close
attention given to designing the commutator, and the nice adjustment
of the brushes and automatic lubricators, rendering
attention to these three parts practically unnecessary.
Capacities and Dimensions of Closed Coil Incandescence Machines.
LATEST PATTERN.
No. '3-j|
3-s
J-9 35
j-11 75
1-12 IOO
J-14 '5°
J-16 250
f -i6 400
J-20 600
Diam. £
of t
Arm. E
, <
9 in * 21
11 "' t 45
12 " | 60
14 " T 90
16 " f 153
iS " f 240
20 " f 360
S*s "0-5[BS
w*a«s kjLgs asr
•Tfi ; E . Lcfe
' _Ǥ: _
FLOOR SPACE.
Length.
2 ft. 10% in. 1 ft. 5 in. 1 ft. sH '"•
23IO l6DO 4 700
3 ft. 5!,": in. 1 ft. 8 in. 1 ft. 9r
4950U450; 8 '1300
3 ft 8},', in. 1 ft. 9% in.
6600 1375! 10 • 1500 4 ft 4% in. 2 ft. 1 J/g in.
9900 1300 15 2300 5 ft. A/% in. 2 ft. 314 in.
165OO I200' 25 360O 5 ft. n-H in. 2 ft. 6 in.
26400 noo' 40 5100 6 ft. 4'/a in. 2 ft. 9 in.
3960O. IO50', 60 630O
5 8in.
1 ft. 10-H1 in.
2 ft. 2\4, in.
2 ft. 6U in.
2 ft. io [ 4 in.
3 ft- i%in.
* Voltage 100 to no. f Voltage 1 to.
OTHER USES FOR GRAPHITE.
Width.
Height.
A correspondent says :
I have read an article on graphite taken from the American
Machinist. Let me say that I have used graphite for many purposes,
some that the correspondent did not name, which I will
give as it may benefit some of my brother engineers, who perhaps
have uot experimented to any great extent with the article.
I have used handhole and manhole gaskets eight to tell times
by carefully smearing the surface next boiler shell, taken out at
periods of three to four weeks, using steani pressure as high as
100 lbs. Iu packing water glasses, by putting a little graphite
and oil on the gasket they would vulcanize as soft as lamp wick
aud retain their elasticity until the glass was changed, when the
old rubber could be removed without trouble, while bv the old
way I have spent much time in digging out the rubber, baked
hard as vulcanite. Another thing I used it for was after putting
back mr handhole plate or plugs in back connection, I carefully
brush away all the soot and ashes, then with a small brush paint
a good coat of graphite over flange, stud and nuts. After ruuniug
boiler from three to six months, and using coke for fuel,
with forced draft, the nuts cau be removed without trouble as
the heat has not been great enough to burn the lead.

September, 1892.] ENGINEERING MECHANICS. 243
ELECTRIC LOCOMOTIVES.
Siemen Bros. & Co., of London, recently constructed two
electric locomotives, of which the following particulars are
given : The side frames, floor-plate and cab are all of steel ; the
wheels are of cast iron with steel tyres and axles ; the hornplates
are of steel riveted to the side frames. Chief dimen­
sions : Length, 14 ft. ; width, 6 ft. 3 in. ; height from rails, 8
ft- 5)2 in.; gauge, 4 ft. S', in. The locomotive runs on two
pairs of wheels, having a wheel-base of 6 ft. ; the wheels are 2
ft. 3 in. in diameter. The locomotives are fitted, in addition
to hand brakes, with Westinghouse brakes, the air reservoir,
which serves for the carriage brakes as well, has a capacity of
17 cubic feet, this being sufficient for oue up and down journey ;
the pressure is no lb. per square inch. The locomotives
are fitted with central buffers and are lighted by glow
lamps.
The current is collected from the conductor, wliich is in the
form of a central rail, by a sliding contact shoe fitted at each
end of the locomotive.
The locomotive is constructed to develop 100 brake horsepower
at a speed of 25 miles per hour. There are two Siemens
H. B. type motors with drum armatures on each locomotive.
The armatures are built directly on the wheel axles and are
coupled in series. The electro-magnets are suspended at the
yoke end from a girder built into the locomotive frame, the
polar ends being carried by gun-metal brackets and bearings,
which rest upon the axle. Inside the cab is fitted the controlling
gear, comprising one main switch for stopping, starting
and regulating the current, a reversing switch, a plug commutator
for the counections to the magnet bobbins, a main cutout
and a main switch ; au ammeter is also fitted and a tachometer
to show the speed in miles per hour.
Each locomotive carries two motors, and the use of all gearing
is obviated by winding the armatures of the motors on the
axles of the wheels of the locomotive. This method of construction
was illustrated by a model shown at work at a meeting
of the Society of Arts on May 18, 1SS1, and had been first
suggested by Sir William Siemens, who, at the time of his
lamented death, was actively preparing a proposition to work
the Metropolitan Railway by electric locomotives.
The motors for the two locomotives were tested before they
were fitted into their places by means of a Prony brake.
Since the two locomotives have been set to work on the railway
they have had to keep the same time as the others, so that
their full power caunot be utilized, but it has been found that
their efficiency is satisfactory in every respect.
Observations ofthe current and the electromotive force have
recently been made simultaneously, by taking sets of readings
on the ammeters and voltmeters, both at the generating station
and on the locomotive. When the locomotives had run about
800 statute miles the brushes were wearing at the rate of about
an eighth of an inch per thousand miles run ; this small wear
being a consequence of the motors running sparkless and
practically without heating. The curves mapped after long
tests show that there is no similarity whatever between those
representing the volts at the generating station and on the locomotives
respectively ; this is, however, easily explained by
the consideration that the volts at the generating station are
influenced by all the trains in motion at the same time, while
the volts on each locomotive are principally influenced by the
demand ofthe locomotive itself.
When the train is started the current is regulated by the
driver, so as not to exceed a certain amount, by means of
switches inserting resistances into the main circuit, but these
resistances are cut out within half a minute of starting, so that
the waste of energy of the resistances is kept as low as possible.
Each locomotive fully equipped weighs 13A tons, and the
weight of the train of carriages it has to draw is about 21 tons.
To this the weight of the passengers has to be added. The
average powei developed by each locomotive requires a current
of not more than above 50 amperes, although in starting as
much as 140 amperes are required.
This fact illustrates at the same time the peculiar difficulties
which have to be grappled with in the construction of such
locomotives, which have to work under conditions almost diametrically
opposite to those of generating dynamos in electric
supply central station.
TEST OF A HYDRAULIC RAM.
SIBLEY COLLEGE, CORNELL UNIVERSITY.
In No. 248 of ENGINEERING MECHANICS was given a test of
a hydraulic ram which, as the author states, was working under
adverse conditions, not having the proper length of supply pipe.
The following are the results of four tests of a ram constructed
by Rumsey & Co., Seneca Falls. The ram was fitted for pipe
connection for 1'4-inch supply and )4-inch discharge. The
supply pipe used was x l /2 inch in diameter, about 50 feet long,
with 3 elbows, so that it was equivalent to about 65 feet of straight
pipe, so far as resistance is concerned. The supply was taken
from an open tank and the head was nearly constant, as shown
in the data and results.
The supply and discharge heads were both measured at the
ram by mercury manometers, the water wasted fell into a large
tank, from thence passed over a weir and was measured; the
water usefully delivered was caught in a tank on a pair of scales
and weighed. The weir notch was triangular in form, with an
angle of 6o° ; its coefficient of discharge had been carefully
determined as equal to 0.59. Each run was made with a different
stroke for the waste or clack valve, the supply and delivery head
being constant, the object of the experiment was to find that
stroke of clack valve which would give the highest efficiency.
Length of stroke, per cent . . 100
No. of strokes per min . . . . j 52
Duration of run, minutes . . . 30
Depthof waste water over weir, ft. o. 1443
Supply head, inches of mercury, 4.95 ,
" feet of water . . I 5.67
Delvy. head, inches of mercury; 17.44
" " feet of water ... 19-75
Total water wasted, pounds . . j 1318
Total water pumped, pounds . 297
Total water supplied, pounds . 1 1615
Efficiency, per cent 64.9
80
56
30
0.1423
5.02
5-77
17-44
19-75
1271
296
1567
66
60
61
3°
0.1385
4.78
5-5§
'7-44
'9 75
1217
301
151S
74-9
46
66
30
0.1370
4-94
5-65
17.44
'9-75
H57
2 97-5
'455-5
70
The efficiency 74.9, the highest realized, was obtained when
the clack valve traveled a distance equal to 60 per cent, of its
full stroke. The full travel being |§ of one inch.
Truly Yours,
R. C. CARPENTER.
THE largest aluminium works in the world are in Switzerland,
where a water power of 1500 horse power is used on
the manufacture. These works produce about 1200 lbs. of the
metal daily.
FOR SALE.
One 21 in. x 13 ft. LODGE & DAVIS ENGINE LATHE, complete.
One 24 in. x 20 ft. FIFIELD ENGINE LATHE, complete.
One No. 3 GARVIN UNIVERSAL MILLING MACHINE, complete.
The above-mentioned machines are new, never having been used,
but will be sold at a sacrifice to settle up an estate.
DANIEL KELLY,
51 North Seventh Street, Philadelphia, Pa.

i ENGINEERING MECHANICS. [September, 1S92.
THE GARVIN MACHINE co. THE NATIONAL AUTOMATIC BOLT CUTTER
UNIVERSAL AND PLAIN
Milling Machines,
SCREW MACHINES, MONITORS, GANG DRILLS,
PROFILERS TAPPING MACHINES,
i. -f@a GEAE CUTTERS and CUTTER GRINDERS'
^''^•&$CG>cy
. 1 Uu.v. Milling Mach
CATALOGUE ON APPLICATION
D A N I E L K E L L Y ,
The advantages of this machine are
For Cutting Bolts. Also Bolt
Headers and Pointers.
THE BEST MACHINE WADE.
convenience in handling and good workmanship
Sole Specialist In Bolt and Nut Machinery
DANIEL KELLY,
51 North Seventh Street, - Philadelphia, Pa. 51 NORTH SEVENTH STREET, - - PHILADELPHIA, PA.
THE NATIONAL FEED WATER HEATER.
A BRASS COIL HEATER delivering Water to the
Boilers at 212° Fahrenheit.
400,000 HORSE POWER NOW IN USE
PRICES LOW. SATISFACTION UNIVERSAL.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE.
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
HARRISON SAFETY BOILERS
COMBINE IN THE HIGHEST DEGREE:
ABSOLUTE SAFETY FROM DESTRUCTIVE EXPLOSION.
ECONOMICAL AND RAPID GENERATION OF DRY STEAM.
DURABILITY, LOW COST OF MAINTENANCE, GENERAL EFFICIENCY
MERITS PEOVEN BY T-WEISTTY-riVE YEj5l.ES SEE."VICE.
First Cost Moderate, owing to Simplicity of Construction and Inexpensive Setting.
New pamphlet, describing latest improvements of setting, together with drawings and specifications of boilers
of any size, from 4 H. P. to 240 H. P., promptly mailed upon application.
HARRISON SAFETY BOILER WORKS.
Germantown Junction, Philadelphia, Penna.
New York, N. Y., *1 Dey Street. Atlanta, Ga., 9 North Pryor Street.
Chicago, III., ISr Ln Salle Street.
THE IMPROVED BALL ENGINE,
SIMPLE, COMPOUND AND TRIPLE, HORIZONTAL AND VERTICAL,
AS BPII/T BY
THE BALL & WOOD CO.,
Office, 15 Cortlandt St., New York,
Is superior in DESIGN. FINISH and WORKMANSHIP. In REGULA­
TION and ECONOMY it has no equal. Built with new tools, from
new patterns, and after long experience, it should and
DOES mark tbe latest step in steam engineering.
REPRESENTATIVES:
THOS. C. SMITH, Jr., No. 11 Hammond Building,
W. B. PEARSON & CO., Home Ins. Building, .
A. NI. MORSE, & CO., Commercial Building, .
W. A. DAY, No. 128 Oliver Street,. .
HYDE BROS. & CO., Lewis Blo;k
CINCINNATI, OHIO.
. CHICAGO, ILLS.
ST. LOUIS, MO.
. 305TON, MASS.
PITTSBURGH, PA.

October, 1892.] ENGINEERING MECHANICS. 243
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering.
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
London Office, 270 Strand, D. NUTT, Agent.
tion and concentration of effort is needed and will bring grand
Entered at the Post-office in Philadelphia as Second- Class Mail Matter. results • to every branch of engineering in a wider and deeper
and more exact knowledge of primary forces and their diversi­
SUBSCRIPTION RATES.
fied methods of action.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
PHILADELPHIA, OCTOBER, 1892.
THE smoke stacks of the " Puritan " and " Terror " will be
protected for five feet above the hull armor by 6 inch plates
forming a circle 12 feet iu diameter.
THE sixty-third meeting of the American Institute of Mining
Engineers will be held at the new Neversink Mountain Hotel,
Schuylkill Valley, commencing Oct. 11. Excursions will be
made to surrounding manufacturing plants aud to one or two
large coal mines.
A NEW rock cutting dredge with cutters weighing eight tons
each, has been set to work in an English harbor, which cuts
rapidly under water aud removes the rock without blasting.
The engineers regard this machine with a good deal of interest
as it overcomes all the difficulties attendant on blastiug methods.
THE Chief Locomotive Superintendent of the Cape of Good
Hope Railways says what he will find very difficult to prove or
induce people to believe, that the Baldwin engines burn 25 per
cent, more coal than his new English engine when doing the
same work, because of inferiority of boiler and construction.
Where are his tests ?
CHEAP labor is not always a blessing or an incentive to enter­
prise. An English journal mentions a case where labor on a
Chinese railroad is only ten cents per day, but where its actual
cost is almost prohibitory. Lord Brassey tested that fully in
his world-wide experience.
AT a small cost a movable coke oven, consisting of a cylindrical
shell of steel, is now made which can be run out with its
hot coke and unloaded, and run back, thus preserving the heat
of the oven for the next charge, reducing time of discharge to
ten minutes, and saving time and cost iu other ways. This increases
the output and saves loss of heat.
AMONG the papers read before the Iron and Steel Institute at
its meeting in Liverpool, September 20-23, were " On the condensation
of Ammonia from Blast Furnaces," "On alloys of
Chrome and Iron," " On the Siemens Martin Process at Witkomitz,
Austria," "On Failures in the neck of chilled rolls,"
" On a new process for the Illumination of Sulphur.
RAILROAD building in Great Britain is hampered more or
less by the severe Board of Trade regulations which make cost
of road extremely high and the cost of stations also. Fewer
stations are therefore built than traffic requirements call for,
and the agricultural interests for which increased freight traffic
would be expected are left without the needed railway facilities.
ENGLISH engineers are very much pleased with the succes in
making projectile proof armor plates, but they admit that the
products of the Bethlehem works astonish the world. The
Harveyized plates have stimulated inventive talent in a new
field, and there are engineers who believe that plates of greater
resisting power will yet be made out of some new alloy or com­
position or coating.
THE correspondence columns of engineering journals reveal
the need of a more scientific knowledge of elerueutals and of
forces, chemical, electrical, physical. There is a wide untrod­
den field, black because unknown, awaiting the few who have
the patience aud love and ardor to plunge into it. A co-ordina­
E. L- COTTRELL, chairman of the Executive Committee of
Associated Engineering Societies has asked for 1200 feet of space
in the Transportation Building of the World's Fair. A feature
of the display will be large photographs of bridges and metal
sections of bridges and viaducts. The engineers of Portugal
have asked for 96 square feet, for books, photographs, drawings
and engravings. The State of New York will use 5000 square
feet to exhibit the State canal system, elevators, boats, feeders
and towing systems.
IT is a question whether it pays to apply rigid rules to Chinese
immigration. It is also a question whether wise financial economy
on our part, with reference to silver would not result in
sufficient room being made for all the Chinese that would likely
come Our exclusiveness is puttiug the prosecution of all
great engineering and industrial enterprises in China, in t*he
hands of Non-Americans, China is fast becoming Europeanized,
but American engineers and inventors aud promotors are
occupying back seats.
THE crude condition in which naval engineering still stands
was recently shown in naval manceuvers off the coast of Ireland.
The purpose of the manceuvers was to ascertain what a
Power weak in battle ships and strong in torpedo boats, could
do with a Power strong in battle ships aud cruisers but weak in
torpedo boats. The result appears to have established the
superiority of battle ships and cruisers against torpedo boats
though the possibility of battle ships being blown up by sub­
marine devices was not considered.
ANOTHER step has been taken in discovering foreign elements
in alloys which will save much time, trouble and
expense. It is done through micro-chemical reactions. The
microscopical examinations of polished services is fouud to
reveal characters which serve to identify various qualities of
metal as has heretofore been done by observing the microscopic
structure of steel. In this way lead is easily detected, to the
extent of approximate quantitative results in anti-friction alloys
containing tin, antimony aud copper.
NAVAL and marine engineers are deeply interested in the
coming monarch of the Atlantic, the " Campania," the largest,
most costly and designed to be the swiftest vessel afloat. The
increased speed is expected to be a knot and a half per hour;
displacement 18.000 tons, length 620 feet, six decks. She has
two sets of five-cylinder triple expansion engines. The propellors
are of manganese brouze, three bladed and weigh eight
tons ; the rudder is under water, weighs ten tons iu single piece.
She will be in service next spring.
NUMEROUS applications are being made of compressed timber
for useful aud ornamental purposes. The compressing of
timber either dry or steamed is somewhat new, but experiments
so far as they have gone show that there is a wide field for its
use. Dried ash is readily compressed 25 per ceut. in thickness,
and other woods more or less, accordiug to degree of porosity.
It will no doubt be found profitable to use compressed wood in
many cases instead of iron or steel. The compression is found
to uot injure the fibre.

244 ENGINEERING MECHANICS. [October, 1892.
LONDON has a water monopoly which furnishes a daily supply
of 184,000,000 gallons. The supply cannot be increased
effectively because of its opposition, and a counter proposition
is now under discussion of creating a competing source of supply
under municipal management. In this way the London gas
companies were reduced to terms. The monopoly is willing to
sell but names an exorbitant price.
PROF. FITZGERALD thinks teaching " cripples to run," a poor
business for technical and engineering schools and colleges.
Doubtless a great many "cripples"' rush into these institutions
under the impression that a few years of alleged study will fit
them for responsible positions in engineering and electrical
work. The cripple contingent is always in danger of growing
to large proportions, and it would no doubt be an act of kindness
for educational managers to divert the ambition of this unfortunate
class into fields more easily trodden.
SEDAN started a new era in military and naval affairs throughout
Europe. Anns and armor, tacties and evolutions have all
been changed. Gunnery has been revolutionized aud the
French very properly are leading the way. Krupp and Armstrong
have found better guns replacing theirs in France, Japan,
Greece and other countries. Krupp's quick firing guns are
excelled by French makers who copy the best ideas of foreigners
and add their own improvements. The struggle is now on
and the brightest minds in engineering circles are directed
to the production of a gun that will kill the greatest number
of men in a minute.
THE Hungarian " Zone" system of fixing passenger fares on
railways has given such abundant evidences of its soundness
that it has been gradually extended iuto other European coun­
tries, and it is now suggested that it be tried in Ireland, where
at least it can do no great harm, if it does not stimulate travel
at all. The question of its possible introduction into the United
States has not yet been mooted. Conditions are vastly different,
but it ought to be said that the graduated system of charges
has some features, that, if they could be transplanted to our
side would work to the advantage of the traveling public,
without doing harm to the earning capacity of our railroads.
ENGLISH engineering papers admit that our Bethlehem Steel
Works have astonished the world with the wonderful success
achieved in armor manufacture. The Ellis-Tresidder io'4 inch
plate is England's best, and in a recent trial resisted 6 in. projectiles
with 1950 feet velocity, while our Harvey plate 10 in.
resisted an 8 in. Holtzer projectile with a striking volocity of
1700 feet, which is admitted to be a more severe test. The perforation
in the American plate was II.7 in. aud the weight per
ton, 542.5 foot tons, while the English plate perforation was
9.95 in. aud 310.1 foot tons per ton. The engineers are not at
all satisfied that the limit of efficiency has been reached.
TRADES-UNIONISM iu England has made such sfrides aud is
such a powerful social and political factor, and wages have
advanced to such a point under these agencies, that manufacturing
iuteiests feel obliged to turn to the engineering fraternity
for labor saving devices in nearly all branches of manufacturing.
The tendency toward minimizing labor with mechanical
devices has set in, and though uot of great importance now will
soon make itself felt. The outcome will be advantageous to both
sides as increased meehanical efficiency increases production
and lessens cost. No harm need ever be anticipated from the
increased production of wealth. The British engineers can
meanwhile pick up a good deal of useful information from
aud among American engineers in the devising and use of labor
saving appliances
IT is only after 50 or 75 years of industrial activity that a
systematic study of nature's secrets is to be undertaken. A
national laboratory for physical research is proposed by a number
of the leading scientific men of England, based in part on the
plan of the National Physical Laboratory at Berlin. Professor
Oliver Lodge, Lord Kelvin aud others favor the establishment
of such a laboratory. Herein much useful work can be done
in fundamentals. At present there is a vast amount of wasted
effort, and the same ground is trodden over and over again by
investigators. The great mass of engineers and workers are
interested only in practical results, and hence overlook a great
deal that ought to be known. There is a lack of personal
interest in many questions and problems that ought to be
solved for the good of all.
MR. SPRAGUE is to be thanked for clearing the subject of
electrical propulsion of some of its fog. His conclusions are
probably disappointing to many who have been trying to do
what he says cannot be done. But in pointing out improbabilities
and impossibilities, and iu defining the limits of the field
in which successful work can be done in the future, he has performed
a most excellent and necessary work to the elctrical
interests on both sides of the water. Possibly all of his conclusions
are not exact, but for the present it may be safe to accept
them as substantially correct. He is obliged to condemn the storage
system of having a separate motor under each vehicle. The
distributed motor system has numerous practical difficulties to
overcome and for the present some other system must be
adopted. An overhead conductor, thus far, seems to be the most
practical method in conjunction with a separate locomotive for
railway work.
THE policy of accepting the very lowest bid, especially for
importaut engineering work is both right and wrong. Public
engineering work should be done in the very best way with the
very best material, by the very highest skill and at the lowest
price consistent with good work. Municipal and other officials
take it for granted that when they accept the lowest bid for any
work, no matter how important, they have done all that is expected
of them. The successful bidder then sets to work in the
cheapest possible way. The history of municipal management
is fat with work of this kind. A better method of doing public
work is sadly needed. But it is easier to point out what ought
to be than to suggest the remedy. The bidding for all kinds of
work is attended with disadvantages besides the narrow margins
often realized. But the evil is gradually correcting itself.
The force of competition compels competitors on one hand to
do pretty good work and to bid so as to be able to do it.
EIGHTEEN governments were represented at the Inland Waterway
Congress held last summer in Paris. This Congress was
called to devise how the cost of transporting merchandise could
be reduced. The rivers and canals of France and Germanv
are now freed from tolls. What is wanted is more extended
canal facilities, and in the consideration of this subject railway
managers rendered friendly advice and co-operation because of
the advantages which increased canalization bring to railroads.
Germany has spent large sums in connecting her canal and railway
systems by which traffic can be quickly and cheaply exchanged.
The canalization of the Main increased the traffic at
Frankfort 64 per cent, by water in five years and 36 per cent, by
railway. At Mannheim the water and rail traffic increased fivefold
in 22 years. The railway authorities recognize the great
advantage of improved canal facilities in additional rail traffic.
The policy of no tolls will be adhered to and the governments of
Europe will probably pay the cost of canal building themselves.
Projects are under consideration for the digging of several hundred
miles of canal in different countries of Europe to increase
intercourse and develop more markets at small cost. The movement
is a very important one and will be attended with political
and social advantages that have been too long lost sight of.

October, 1892.J ENGINEERING MECHANICS. 245
PROF. HORACE B. GALE in a paper ou the efficiency of
hydraulic elevators, concluded that the efficiency of the hydro-
steam elevator as at present in use for passenger service is
about equal to that which can be obtained with tank elevators
operated by a good compound pump. Compared with the per­
formance of the non-compound pumps often used for elevator
work, the hydro-steam system would therefore have a considerable
advantage ; and a further advantage maybe gained, doubtless,
by the use of the throttling governor iu the steam pipe.
Two English engineers have patented au improved saw sharpening
machine, for sharpening both frame and circular saws,
by means of a revolving emery wheel. It is fixed ou a
counter-balanced arm, which is brought down by hand on the
saw to be sharpened, and it is so arranged that it will top, gullet,
and bevel either frame, crosscut or circlar saws, with any form
of tooth. The bracket carrying the saw is adjustable, and can
be fixed in any position, so as to give any amount of lead to
the tooth, and the gullets are sharpened at the same time.
AN instrument for drawing a series of parallel lines at unusual
angles, called a clinograph is now introduced in England,
and consists of a set square with a swivelling blade, which can
be instantly set to any required position, the friction of the
joint being sufficient to hold the blade firmly while in use. The
joint is finished flush with the surface, so that the square can be
used with either face resting on the drawing-paper, and parallel,
perpendicular, or symmetrically inclined lines in any direction
can be drawn with one edge of the instrument always resting
against the edge of the T-square. The instrument should prove
very handy for the special work for which it is designed.
J. B. PITCHFIELD, C. E., member of the Technical Society of
the Pacific Coast favors a greater speed of the Corliss eugine
and thinks that the advantages of greater speed are not fully
understood by users of that engine. In a paper read before
that Society he shows what large fly wheels are necessary to
give the required speed to transmit the power, and the advantage
of increasing the speed of Corliss engines in order to
reduce the size of their fly wheels as well as other parts of the
engines. For electric purposes dynamos cau be constructed
with revolving field magnets to take the place of the fly wheels,
and these can run at 150 or more revolutions per minute, and it
will certainly make an economical machine if driven by a Corliss
engine direct. For these and many other reasons he advocates
increasing the speed of Corliss engines, and thinks that a
non-liberating valve gear is better suited to high speed, than
anything that can be made with a liberating device.
A CORRESPONDENT in an engineering paper asks a series of
questions like these which have often been asked before. Why
is it that under apparently identical conditions of pressure,
number of revolutions, and ratios of expansion, different
engines give widely different results ? Does not this go to prove
that there is some influence at work, the nature of which is not
at all understood, the existence of which has not yet been recognized
as it ought to be ? Is it not time that the energies of
thinkers should be directed to this point? It appears to me
that there is reason to suppose that the shape of an engine, and
the nature of the metal surfaces over which the steam passes,
have some special influence on the economy of the machine.
As an example of what I mean, let me call attention to a triple-
expansion engine of iooo horse power. This eugine without
jackets has given a result which has scarcely ever been reached
by any jacketed engine, namely 12.83 lb, of feed water per indicated
horse-power per hour. Why, I would ask, was the cylinder
condensation in this case in the high pressure cylinder only
8 per cent, instead of being double or treble as much as is
usual ?
A NUMBER of conditions have changed since the construction
of the Great Eastern to permit of the gradual increase in size
of ocean vessels to its magnificent proportions. Traffic is more
abundant, facilities for loading and unloading are better, more
ports are open to very large vessels. The latest contract given
out was for a steam ship to be 700 feet long, 65 feet lAz inches
beam, and 4500 horse power; speed, 22 to 27 knots; three
screws, and to be appropriately named " Gigantic." .Ship builders
have lost their fear of large vessels. Marine engines and
equipments of all kinds have been vastly improved. Increased
power cau be put in smaller space, greater rigidity of parts is
possible, oscillation and all vibratory action is reduced to a
minimum ; the greatest efficiency of engine and boiler power is
secured, and electrical devices at every point below aud on deck
further facilitate the management aud operation of the great
ocean monsters. The tendency is in the direction of still
larger ships, aud marine engineers do not specify auy definite
line beyond which it may not be safe to go.
THE disposal of refuse is now receiving more attention from
engineers than formerly. There are many methods in use,
none of them complete. With the growth of cities the problem
will become more important. New York dumps its refuse into
the lower bay. Philadelphia uses vacant lots and the "neck."
Other American cities follow the same primitive and unscientific
method. Liverpool last year sent 145,032 tons to sea and several
other English sea coast cities do the same, but iu some
cases the rubbish is not carried a proper distauce out to sea.
The utilization of refuse for manure is quite common and much
experimenting is being doue in English cities, resulting in
some instances in paying cost out of product. At Rochdale a
drying system reduces to lAx per cent, of original bulk. The
average of five English cities gives the total refuse collected
including house products at 400 tons per annum per thousand
of population. This is exclusive of street sweepings, which averages
in the towns mentioned 100 tons per annum per thousand
of population, making a total of 5 00 tons. These figures do
not apply to American cities but they serve to indicate that the
question of the disposal of refuse and sewage is an important
one. No scientific or even rational treatment has yet been suggested
which is practical. Theoretically perfect systems have
been formulated and are even in practical operation iu this
country on a small scale, but the methods are not adapted to
the urgent necessities of the large municipal communities.
THE enormous exodus of European population to this country
continues. Ofthe 619,32c persons who came during the past
fiscal year, 117,068 came from Great Britain, 130,622 from Germany,
57,153 from Sweden and Norway, 117,419 from Russia
and Poland, 45,797 from Bohemia and Hungary, and 60,914
from Italy. All Europe, then, is more or less on the move to
the United States, it has been said, and the figures seem to
justify the statement. Favorable agricultural conditions stimu­
late the movement. During the past few years apprehensions
as to the effect of this outflow have been expressed in the
greater or less intelligent comprehension of the problem. If
the tide of humanity seeks agricultural employment and thus
supports itself, so to speak, it becomes a stimulus to manufacturing.
The danger lies in the growth of an idle foreign popula­
tion in cities. While the facts are not altogether what might
be desired, the general drift of the new comers is into useful
channels. The great body of conservative Americans are
willing to see the movement progress having confidence iii the
absorptive power of the country. Manufacturing is expanding
apace, aud regions are being prepared for cultivation : the mining
of coal aud the precious metals is expanding, and a multitude
of activities are being opened up wherever the added human
energy can find opportunities for employment and subsistence.

246 THK CONSTRUCTOR.
Translated by Henry Harrison Suplee.
In this case the rope passes the entire round of stations 7*„
7*2, T3, T4 to Tu, returning to the main power house. The
rope returns to the power house at any angle with a tension /,
giving T = 2 P-\- /• All stresses are regulated automatically
for each stretch of the rope, as the forces vary at each station.
If the work at an)' station is reduced or even becomes zero, the
tightener carriage responds and alters the deflection so that
T— / = 2 . /' in which t remains constant. A transmission of
this kind, in which the cable makes a complete circuit of a number
of stations, maybe called a "ring" system. In Fig. 917, the
supporting stations are indicated by small rectangles or triangles,
according as the line is straight or makes an angle, and
shaft, at 1.. a simple headstock for a small lathe, and at c. is a head for a
boring machine, the loose pulley running 011 a stationary sleeve, as already
shown in Fig. 862.
[October, 1892.
Translation Copyright, 1890.
A comparative example with that in \ 300 will be a practical
illustration.
Example.—The transmission at Oberursel is made in eight equal stretches
and seven stations with two pulleys each, one driving pulley and one driven.
This gives 16 semi-circular wraps of the rope about the pulleys, causing a
loss of 5.13 H. P. from stiffness. By the adoption of the new system there
would be three semicircular wraps at the power house (see Fig. 90S), one on
the driven pulley and two quarter wraps on the guide pulleys L&, L1 (see
Fig. 909) There are also n short arcs of con tact, about ^ of a circle each, on the
supporting pulleys, which latter would be very lighi and on supports constructed
as already described. The combined arcs of contact make practically
about 5 semi-circular wraps or A of the resistance of the old arrangement, that
isT r the power stations as shown are circles. At Te the rope passes
off iuto an auxiliary circuit, which may be called a "ring"
transmission ofthe second order (see \ 260). The stations may
all be constructed very simply. The supporting stations are
made with one pulley when the line is straight, and with two
at the angle stations ; the power stations can generally be made
with only two pulleys, providing the necessary arc of contact a,
is obtained, or three pulleys used if necessary, see Fig. 918.
g. 5.13 or about 1.6 H. P. This is not too favorable an estimate, as we have not
included the effect of the excessive tension which often occurs by the contraction
of the cable in cold weather, and which is entirely avoided by the
use of the tightener pulley and carriage.
The reduction of journal friction is also important, as the weight ofthe
pulleys and the effect ofthe rope tension are both much less. The total
weight of the pulleys will be only about % that of the old system, although
more pulleys would be used, and the journal diameter may be reduced to A
of the previous value. This gives a loss of 3, • 3 = I of the previous value of
9.36 H. P., which is 2.08 H. P. To this we must add a resistance of 0.40 H. P. for
FIG. 91S.
the guide pulleys which have been added in the new system,giving a total loss In many cases it is desirable to use the system for under­
of-M* = 1.60 -f- 2.08 -(- 0.40= 4.08 H. P. The loss in the "first instance is with the ground transmission, as iu Fig. 919*
new system 4 per cent, and in the second 10 percent., as against 13 9 and.35.9
per cent, for the old system.
In this example there are no intermediate power stations, the
entire amount of power less only the hurtful resistance. In
considering the question ofthe stress iu the driving part of the
cable it is important to know whether the entire power is to be
transmitted to the end ofthe line or if a portion is to be taken
off at intermediate stations. If the initial force-* at successive
FIG. 919.
intermediate power stations be indicated by P., P.,, P3, Pt, etc.,
In order to determine when an arc of contact c* , of the
the successive tensions in the cable will be reduced, and hence
the deflection /• should be determined for the stretches preced­ proper magnitude has been obtained, we have, from (239). if P
ing and following each station, aud the tension in the cable will is the greatest force to be transmitted by the pulley with a ten­
vary according to the power taken off at intermediate points. sion T':
The sum of all the forces P, will in every case be determined by
taking the tension /, in the driven part at the first driven pulley,
gf'a.
t> — 1 T'
from the initial tension T, so that we have T—t—
this equation we cau deduce important results.
2, P. From
ef"
77 J_
As an illustration we can assume the entire power transmitted
P
to be divided up among a number of intermediate stations, all We will call the ratio -=.f, which is the reciprocal of the modu­
being operated by one continuous cable, as shown in diagram
in Fig. 917.
lus of stress, the modulus of transmission, and let it be repre­
=0T,
sented by 8, whence :
ef" — 1
e/' a
(309)
Neglecting the influence of centrifugal force, we have, from
\ 290, for fi the values f = 0.22 and 0.25 to consider. Taking
these we get the following values for various angles :
cx =
y= 0.22
y= 0.25
15°
0.06
0.07
30°
O.II
O.I2
MODULUS OF TRANSMISSION ft.
45°
0.16
0.1S
60°
0.21
0.24
90 0
I20° I50° 180°
0.29 O.3S
°-33 O.4I
0.44
O.48
O 50
O.54
27O 0
O.65
O.69
360° 45o° 54o°
°-75
0.79
0.86
0.81
0.88
0.87
These values are shown graphically in the following diagram,
Fig. 920:
O.J
•
0 /
^
-A
r •'
—t
Mg
p
J*-
-5^
rAf 1 -
jTTO
|
1
360
J52H -y'
FIG. 920.
'fiA
From this it will be seen that an arc of contact of 30° will permit
the transmission of ft; the power due to the teusion T', and
an arc of 90° gives about A-
A convenient application of this principle is found in the
arrangement of a "ring" transmission when a large arc of contact
is obtained upon the first or main driving pulley by redu-
* This has been done in San Francisco by Boone, using a conduit for the
rope similar to a cable railway.
4.'>0
640

October, 1892.] ENGINEERING MECHANICS. 247
plication of the rope over a counter pulley, as in Fig. 795, and
also shown 111 the case of the double-acting belt transmission in
Fig. 860. By using a single-grooved counter pulley and doublegrooved
driver we get cx i 360 0 , so that 8 is at least equal to 0.75.
In this way the specific capacity of the rope cau be materially
increased, practically about i}i times. If we give r = LL the
6
value J in the first equation of \ 290, we have for the specific
capacity of a cable transmission with a counter pulley :
N„ = .
33O00
or say PIa =
25000
JL
3
24750 ^
(310)
The adaptation of the mechanism to receive the counter pulley
is usually not difficult.
The adaptability ofthe "ring" system of transmission to use
in distributing power in manufacturing establishments is apparent,
and for this purpose hemp rope is very suitable. This will
be shown by the following example :
The conditions of this example are hardly such as to demand
Example i.—The transmission shown in Fig. 8Si, \ 286, contained 16 hemp the introduction of the counter pulley, but when large powers
ropes 2 inches in diameter, each having a specific capacity N0 — 0.0021 and
are to be transmitted its use is most advantageous. In some
v = 2360 feet per minute. The cross section of each rope is 3.14 sq. ins.
instances the cou.iter pulley may be arranged, as in Fig. 911,
Hence tf = JVQ q v = 0.0021 X 3-M X 2360 = 15.57 H. P. for each rope, or
249 H- P. for the 16 ropes.
so as tosustaiu a part of the weight of the fly wheel ofthe engine,
aud hence materially reduce the journal friction.
In many instances the power in factories may be arranged so
as to use the "ring" system of transmission, and dispense with
the use of the spur or bevel gearing, and some examples are
here given.
In Fig. 923 a is shown the usual arrangement of the transmission
of power in a weaving establishment.
FIG. 921.
Substituting the arrangement shown in Fig. 921, we take a single wire
cable composed of 60 steel wires, and use a stress of 17,000 pounds in the
driving side ofthe cable and iucrease the speed to 3150 feet per minute. We
then have from (278):
q = 66,000 249
-= 0.307 sq. in.
17,000 X 3*50
and hence the area of each wire is
0.307
— = 0.0051 sq. in., and the diameter 5 = 0.08"
In the original hemp rope transmission the main driving pulley had a
radius of 71 inches, and as we have increased the speed % times, the driving
pulley must be proportionally increased, and hence the radius will be 95".
This gives a stress due to bending,
Q
;95
12,000 lbs. nearly; see formula (279),
FIG. 922.
If it is desired to use a counter pulley with the above transmission, the arrangement
in Fig. 922 may be adopted. In this case the counter pulley G,
and tightened pulley /-', are both inclined so that the rope shall be properly
guided for the double grooves in the main driving pirlley. The arc contact
a is in this case greater than 360 0 , and the specific capacity will be 1 14 times
greater. This will enable the cross section of the rope to be reduced to \ the
previous value, or q = 3. 307 - 0.204 sq in. If we use 36 wires instead of 60,
we have for the cross section of each wire
= 0.0056 sq. in., and S • *= 0.084 i n >
a*
The diameter ofthe rope will be from 8 to 9 6 or |'' to 2", the latter when
the rope is new.
! 1 ; .....j... 1 !, J
FIG. 923 a.
S =
In this instance the two shafts which extend each way from
A", drive the line shafting by seven pairs of bevel gears, while
in some factories as many as 12 to 18 pairs are used.
FIG. 923 b.
Fig. 923 b shows how a ring transmission can be used to drive
the same shafting, there being seven guide pulleys and one
tightener I', the guide pulleys being of the "umbrella " pattern,
as in Fig. 915. The tension weight for the tightener is
equal to 2 T'.
this being not too great to give satisfactory results. We have, instead of a
wide face pulley made with 16 grooves, a single groove pulley made with
leather filling, as in Fig. 879 a, of 15 ft. 10" diameter. An important point
to be considered is the stress due to the bending of the rope o-^er the pulleys
T>, T3, etc. These pulleys were 36" radius for the hemp rope, and
hence §. 36 = 48" radius for the wire rope, or 8 feet diameter. We then have
from. (279)
14,200,000
0.08
FIG. 923 c.
46
23,666, which added to the working stress of
Another arrangement is shown in Fig. 923 c, this being used
when the alternate shafts are to revolve in opposite directions.
This permits the rope to be used double acting, as described in
17,000 lbs. gives a total of 40,666 pounds, which is not too high for steel wire, \ 277 and shown in Fig. 860. Those portions of the rope
according to \ 266. The idler pulley Lt is made the same size as the driven marked 1 in Fig. 923 c, are in one plane, and those marked 2
pulleys T-i, T^. etc., and the tightened pulley V can be made a little larger.
in a second plane, giving clearance to the parts of the rope,
The loss of efficiency will be somewhat less than in the case of hemp rope,
since for wire rope there is a smaller modulus of stress T, (/. e. 2 instead of
aud the rope is guided from one plaue to the other by the
2\, see \ 287), and the initial force P, is smaller, because of the increase in guide pulley L, and tightener U. Five of the seven driven
velocity aud the loss from stiffness will be less. The loss from stoppage pulleys are double acting, and hence are made double grooved.
and creep should also be considered as not unimportant (see g 287).

248 ENGINEERING MECHANICS. [October, 1892.
Shafts which lie at right angles but in parallel planes, one
above the other, are also readily driven by use of a ring transmission
system.
FIG. 924. FIG. 925.
In the preceding^-ases it is desired to obtain a double wrap
ofthe rope about the driving pulley A', the arrangement in
Fig. 9 2 4 may be adopted. In this case two idler pulleys G1 and
G., are used to guide the rope from one plane to the other. The
rest of tbe rope, when either of the planes shown in Fig. 923 b
ox c is used, is guided in a third plane by suitable pulleys In
Fig. 925 is shown an arrangement by means of which a series
of parallel vertical shafts, revolving alternately in opposite directions,
can be driven from a single horizontal shaft K.
FIG. 926.
The ring system is well adapted for driving a number of mill
stones, as arranged in Fig. 926, for example, in which all the
mill spindles revolve in the same direction. The direction of
the stones may be readily reversed by a corresponding change
in tbe cutting of the furrows, and hence the double-acting
arrangement as in Fig. 925 can be used if so desired.
The arrangement of the double-grooved pulley on the spindle
in this case is showu in Fig. 927. This is a modified form
of the umbrella pulley of Fig. 915, the hub being made in the
form of a hollow sleeve carrying a cone or other suitable clutch
A", K', by which any pair of stones can be stopped without interfering
with the
others. An adjustable
step for the
spindle is provided
at H.
In machine shop
transmissions it is
frequently required
to drive a series of
parallel counter
shafts, which revolve
in one direction,
sometimes in
the opposite, and
any of which may
need to be stopped.
Such an arrangement
is shown in
Fig. 92S. The rope
is carried over the
various pulleys of
one series around
the tightener pulley
IA, and back over
the other series At
A', and A"2 are friction
clutches which
are thrown into engagement
on one
FlG. 927.
side or the other,
according to the direction
of revolution
required, or which may be left disengaged. If two adjacent
shafts are desired to revolve in the same direction, au inter-
greatly simplified by using the above system. In all these arrangements
the modulus of transmission is determined as already
discussed in formula (309) and the proper arc of coutact
determined. For example, if in an arrangement similar to
Fig. 925, each part of the rope is in contact 30 0 ou the pulley,
and the coefficient of friction fi is 0.22, we have from the preceding
table for the modulus of transmission 6 = o. 11. If the
tension on the respective sides of cable be T' and t', acting
upon the pulleys, we have for the maximum force transmitted
by the rope P' = O.II ( T' -\- I'). In this case we have always
T' + / = P -f t, and hence 7* = 2 2 P,t—iP (see \ 264).
Hence we have I" = 0.11 x 3 2 P, or about \ 2 P. If there
were but three driven pulleys, each offering the same resistance,
the system would operate well, and still better with a
greater number of driven pulleys. For mills of 20, 30 or more
pairs of stones, this arrangement is especially applicable, since
it furnishes a far simpler transmission system than heretofore.
This system, however, should not be carried beyond its proper
limits, and for small, light running mills, such as are used for
grinding paints, graphite, etc., belts are generally more advantageous,
beiug easier thrown in and out; the rope system
being better adapted for the transmission of greater powers.
In all the various classes of heavier mills, such as are used
for grinding plaster, cement, and the like, also for paper mill
machinery, the rope transmission is best adapted, replacing all
the heavy shafting, gearing and belting otherwise necessary.
An example will illustrate the method of applying the foregoing
principles.
Example 2.—Let there be two sets of wood pulp mills each requiring 60
H P. to be driven from a pair of turbines bv a " ring transmission " svstem,
the first moving shaft making 125 revolutions per minute. The main shaft
is driven by the two turbines by means of spur gearing, and carries the
driving pulley of the rope system, making also 125 revolutions. We have
for the specific capacity of the rope, from (277) Na = y~, and if we use steel
66000
wire and take i, = 21,300 we get N0 = 0.323. Also we make the velocity v of
the rope = 3150 leet per minute, and we get for the cross section of the rone
from (278)
vNa N 3150 120 X 0.323
1 — Ar = — = 0.118 sq. in.
If we make the cable of 36 wires we have for the cross section of one wire
0.118"
— z— = 0.0033 and the diameter 5 = 0.073".
From the number of revolutions and the chosen speed of rope we have for
= the 48'', pulley and radius, using R this in (279) we get for the
2 rr X 125
bending stress, .r 14,200,000 =
= 21,500 lbs., which is satisfactory. The
entire 120 H. P. is carried by the rope to the first set, where 60 H. P. is used
and the balance is transmitted to the second set, the necessary supporting
pulleys being introduced between the two points, and the required tension
t being given by the tightener carriage. Following the course of the rope
we have at the driving pulley the tensions Tand t, respectively equal to
V jPand 2 P, whence 2 P- 23000 X 120
3150
"57 .
251.
1257 lbs. = t and T =
lbs. The tension at the first set is reduced by P' = 628.5 lbs., whence
r . - o~,i 5I4 —6 , 28 ; 5 = *885.slbs. At the second point again is taken off I' =
628.5 lbs and the tension becomes .885.5 - 628.5 = 1257 lbs., which is equal
to the above value of I. and which is obtained by loading the tightener carnage
with 2514 lbs. or a little more, b o
This system requires the use of clutches for starting and stopping the
machines, and for this purpose Adyman's coupling, ('i 307), is suitable.
In some instances it is found practicable to drive two pulp
mills with one pulley, the pulley being between the machines
on an intermediate shaft with a fraction coupling at each end.
Another case may be given where a number of machines with
horizontal shafts each requiring the same amount of power, are
arranged in a row and drawn by a ring transmission system
Fig. 929.
FIG. 929.
In this case friction clutches are placed at A\ K, for stoppine
FIG. 928.
and starting the machines, while the intermediate pulleys A A
mediate guide pulley is introduced, as shown at /.,. The sub­
which may be of the umbrella pattern, are carried on hangers
sequent belt transmission from these counter shafts can be
from the ceiling. The rope and the driving pulleys are covered
by guards 5 5 to protect the workmen. This arrangement is

October, 1892.] ENGINEERING MECHANICS. 249
especially convenient if there is a second series of machines ou
the floor above, when the pulleys /. A become the driving
pulleys of the upper set, and no guide pulleys are required at
all. It is sometimes desirable to make the driving pulleys of
umbrella form, supported on independent bearings, so that any
machine cau be repaired or entirely removed without interfering
with the rest of the transmission.
It should not be forgotten that the ring system of rope transmission
generally involves au entire rearrangement of the
establishment, and that it can rarely be substituted for a shafting
transmission to much advantage.
A comparison of the last example with the older s}-stem in
which a separate rope is used for each portion of the transmission
will be of interest. In the previous method the pulleys
could not be brought close together because the tension would
require to be too great, and slight variations in temperature
would produce excessive variations in tension. These difficulties
are overcome iu the ring system by the use of the tightener
carriage, which may also be used to much advantage in those
systems of belt transmission which lie in one plane, such as
have been shown iu Fig. S44. The construction is similar to
that for rope transmission, and the umbrella hub may be used
to advantage. In many cases the specific capacity may be much
increased in this way.
The new system is also highly advantageous for long distance
transmission, especially where power is to be taken off at
several points, or it may be used iu combination with the old
system, retaining the latter and using the new system for purpose
of distribution.
The difficulties of construction are much less for long distauce
transmission than with the old system, aud the cost of
installation and supervision much smaller.
The application of the" new system appears likely to increase
very greatly, since it involves less first cost than electrical
transmission plant, and also a higher efficiency when the losses
from transformation of electrical currents are considered.
This subject will be further considered iu Chapter XXIV.
CHAPTER XXII.
CHAIN TRANSMISSION. S'IRAP BRAKES.
FIG. 930.
The method of friction driving can be used with ordinary
link chain as at a, Fig. 930, and may also be used with the flat
link chain of Fig. S30 d, if so desired. The .circumferential
friction F= T— t may be determiued from the following rela­
tion (see 'i 264)
T -A
(1 -|- 2/ sin ft
)
(3")
in which Aand t are the tensions in the driving and dnveu
sides of the chain respectively, and f is the coefficient of friction
The angle ft is that subtended by the pitch length of a
link of the chain at the centre of the chain sheave, and may be
obtained from r sin % ft = 'A I * the exponent m is the number
mation may be obtained by taking ft — —, which gives for the
modulus of friction [1 :
P I +/- (3'2)
f=(
In chain transmission the modulus of friction is not independent
of r, as with rope transmission, but varies somewhat with
y
the ratio —. This latter ratio in practice seldom goes below 5.
Taking this limit, and also putting f = 0.1, we have for practical
values of 0 the following, in which it equals the number of
half wraps of the chain arouud the sheave :
-f-O+i*
whence 1
T = i-37" (313)
The following table has beeu calculated for 1 to 8 half-wraps,
T
and gives the modulus of friction p = —, the modulus of stress
T
T = — and the modulus of transmission ft (see (309)).
$ 3°2-
These values for p aud r are similar to those obtained for ten­
SPECIFIC CAPACITY OF DRIVING CHAINS.
sion organs generally, as indicated in the diagram already giveu
in Fig. 816. It will be noted that the transmitting capacity of
The use of chain for purposes of power transmission is neces­
chain even with a single half-wrap about a smooth sheave is
sarily more restricted thau the use of rope, but for single trans­
good.
missions in special cases it is well adapted, and its applications
Since the specific capacity of a driving tension organ (see
are increasing. Chain is especially capable of resisting varia­
(262)) is equal to
tions of temperature and exposure to the weather and to dust,
and hence is well adapted for driving revolving drums in
mining machinery, washing machinery, the machines iu bakeries,
etc. In mining machinery chains are very extensively
N0 =- — . — or — — Sft
33000 T 33OOO
used, both above and below ground, not only for continuous we have for ordinary open link chains the following values for
tramway driving, as in Fig. S02, but also for the transmission of
rotary motion over extended distances.
various stresses 5:
Chain sheaves are made either with smooth wedge shaped
grooves, or with pockets for the chain links as already indicated
in i 275. Iu the first case the driving is due to friction in the same
manner as with belting and ropes, while iu the second case the
5 a = 1 2 3 4 5 6 7 8
actiou is similar to that of toothed gearing.
b
1 t
5000
7000
8500
N0 = 0042 0.071 0.092 0.109 0.120 0.129 0.135 0.140
0.057 0.099 0.129 0.153 0.168 0.180 0.189 0.197
0.070 0.121 Q-157 0.185 0.203 0.219 0.230 0.237
It =
p =
r =
ft =
I
'•37
3- 6 9
0.27
2
1.88
2-13
0.47
3
2.57
1.64
0.61
4
3-53
'•39
0.72
5
4-83
1.26
0.79
6
6.61
1 iS
0.S5
7
9.06
1.12
0.S9
8
12.41
1.09
0.92
The specific capacity is in all cases high, and for the generally
accepted stresses in the chain cross section it varies from
0.042 to 0.237. Various applications permit variations in
the value of S, the value beiug taken lower when it is desired
that the wear through friction shall be reduced. The cross section
of chain is determined from the equation N = 2 q v NJ
(see *) 280) in which TV is the horse power to be transmitted at
a velocity v, and q is the sectional area of the irou of which the
chain links are made. We have :
1
2 v J? (314)
The value of V is always low, aud hence the influence of centrifugal
force upou p may be neglected.
Example i.—It is required to transmit ro H. P., by means of a chain
making a half wrap about a smooth sheave, the velocity v being 1180 feet per
minute and S = 8500 lbs. We then have for the cross section q of metal:
1 10
of liuk contacts, hence m = -j. A sufficiently close approxi­
2 X 1180 ' 0.070
which corresponds to a diameter of 0.3 in.
: O.0609 S Q* Ul -

25° ENGINEERING MECHANICS. [October, 1892.
Example 2.—By using the counter sheave (Fig. 795) and thus obtaining
three half-wraps the value of S may be reduced to 5000 lbs., whence
I IO .
q = - . = o 046 sq. in.
2 X 1180 0.092
or a diameter of 0.27 in.
This gives a lighter chain and at the same time a more durable one, as the
friction is materially reduced when entering and leaving the sheave (see
I 303)-
By using grooved and pocketed sheaves the specific capacity
may be greatly increased, the chain being held so securely that
111
am. 3560 80 78
ff-- •**• «l*--**l
FIG. 931.
as many as eight half-wraps may be used. Two very practical
arrangements for such sheaves are shown in illustrations, which
FIG- 933-
are from executed examples in the chain tramway of the Decido
iron mines in Spain, built by Brill], of Paris. The dimensions
are given in millimetres, and the chain is operated under a
stress of about 5000 pounds per sq. in.
..SMM..
FIG. 932.
The sheave shown in Fig. 93' is for a 25 mm. (linearly)
chain, and is made with inserted teeth of steel, and the form of
Fig. 932 is similar, and is for an 18 mm. (0.7 in.) chain. In both
cases the teeth are radial, and formed to rec-ive the chain links,
being secured by jam nuts in the second case, and by nuts
fitted with the Belleville elastic washers, which latter have
worked well in practice.

October, 1892.] ENGINEERING MECHANICS. 25 1
. , n -f.'S- 933 is given an arrangement of chain sheave gearing,
including a solid massive form of bearing, as used in many
Jiuglish collieries* Here the sheave is made with eight semicircular
ridges or ribs, similar to the old form of capstan shown
already in Fig. 794,? ; and both parts of the chain are carried
on supporting pulleys. In many instances this arrangement is
used, b,y widening the face of the sheave, to receive several
wraps of chain, as showu in the upper right corner of Fig. 933.
If we may safely assume that the ridges increase the coefficieut
of friction at least three times, in the preceding formulas (311)
aud (312), we have for the corresponding modulus of friction p':
which gives for
ll
p' =
T =
6' =
A
1.5s
2.72
0.37
I
2.50
1.67
0.60
2.5" (315)
2
6.25
1.19
O.84
3
15.63
1.07
094
4
39.06
1.03
0.97
from which the security against "lippage aud also the specific
transmitting capacity may be determined for any given case.
Within moderate limits chain transmission may be used as a
" ring " system, as for instance in driving the rollers of carding
machines, also in wood pulp grinding mills a ring chain transmission
is used for driving the feed rolls.
Iu this case the pitch length / of the links is taken = 3.5 d,
and making 1=5/, we get A, = ( T -f- /) 0.036^, and if we put
for the loss at both sheaves:
we get: A-*-
Ek = o 072 /, P+i
(316)
Example 1.—Taking the coefficient of friction /., — 0.15 on account of the
small bearing surface we have for a chain transmission ou smooth sheaves
with half-wrap; p being = 1.37, as in the preceding section :
2.37
Etc — 0.072 X 0.15 = 0.0692
°-37
or say 7 per cent.
Example 2.—If the sheave is made with ridges, as in Fig. 933, we have p'
= 2.5, and hence
Ei. = 0.072 X 0.15 I -1=0 025
or only 2 1 1. per cent.
Example 3.—By using carefully made pocketed teeth and making u — 8,
we have p = 12 41, whence
Ek -- 0.072 X 0.25 / - | = 0.0126
\n.4i/
or only i"4 per cent., this reduction beingdue to the reduction in the tension
on the chain, showing the importance ol considering the question of chain
tension ill this connection.
?303-
EFFICIENCY OF CHAIN TRANSMISSION.
In the preceding examples the friction ofthe links upon each
other has been considered, but not that of the links upon the
sheave. This latter is a very variable quantity, being unimportant
with a smooth sheave, as Fig. 930 a, and sometimes
becoming excessive, as shown already iu Fig. 83S b, I 275.
The loss of efficiency in a chain transmission is due to jour­ In every case all possible care should be taken to produce as
nal friction, dependent upou the chain tensions T saxA t; and little rubbing contact as possible.
upon the friction of the links in entering and leaving the
sheaves. The journal friction is determined as already shown
in \ 300, and for high values of ft, it is uot great. The loss from
chain friction is due to the rotation of each link about its
I 3°4.
INTERMEDIATE STATIONS FOR CHAIN TRANSMISSION.
adjoiuing link as an axis through an angle ft. This gives, with The most important applications of chain transmission are in
a coefficient of friction fi, a circumferential resisting force Flt
due to chain friction (see formula 100)
mining work, both above aud below ground ; and especially in
coal mines. In this branch of work England takes the lead,
followed by America, where, however, wire rope is more extensively
applied, while in Germany the most applications are
found iu the Saarbruck district.
:
The illustration is from Newchurch colliery at Burnley.
A very interesting application of endless long distance chain
transmission is shown iu Fig. 934, which gives two views of the
fe'//" /. w w w est
FIG. 934-
(Dimensions iu Metres.)

252 ENGINEERING MECHANICS. [October, 1892.
Gannow mine at Burnley in Lancashire. The driving pulley
is at T, and guide pulleys at A, while at L' is a tightener pulley
hung between two idlers, a construction which is frequently used.
The rotation is modified iu various ways iu the English mines,
stations similar to those of rope transmission systems being used.
FIG. 935.
In Fig. 935 is shown an intermediate station at Tx T2, and
also on angle station at A. In many instances combinations of
bevel glaring and shafting are found in connection with chain
transmission, but the examples here giveu are coufined to the
use of chain alone.
FIG. 936.
In Fig. 936 an intermediate station is shown at A, T4, and a
change station at A, A2. At 7j, Fig. 936, the chain makes an
entire wrap around the sheave, the latter being made with a
wide groove, and interference ofthe two parts ofthe chain prevented
by guide sheaves. The simple supporting stations are
made with small horizontal guide sheaves, with wide grooves.
The velocity of the chain varies from 200 to 500 feet per minute.
\ 3°5-
STRAP BRAKES.
If a driven pulley is embraced by a tension organ, either belt,
rope, strap or chain, the ends of which are subjected to tensions
Aand /, and also held from moving, the pulley is hindered from
moving toward t, so long as the force acting to rotate it does
not exceed P= A — t. The tension organ then forms, with the
pulley and stationary frame work, a friction ratchet system in
which the tension organ forms the pawl. If the tension Abe
reduced until A — t

October, 1892.] ENGINEERING MECHANICS. 253
The question of the pressure between the braking surfaces is of interest.
Accordiug to formula (241) -^ = —2— we have for the tight end, where
c»*= 14,220.
°- oS
/ = 14,220 = 72 lbs.
aud at the slack end, since . 72 = 48 lbs., both of which are
such small values that the wear must be very slight.
This example show-show, in a properly arranged construction,
a great ratio of force to resistance can be obtained. In large
winding engines the brake pulley can readily be cast in one with
the rim of the drum gear.
The method of securing the ends « t
ofthe metal strap is shown iu Fig.
940. The form at a, is secured by
countersunk rivets, and that at b,
by an anchor head and a single '
small rivet to prevent lateral slip- ~PXG. 940.
page.
(b) Sliding Brakes.—In using clamp brakes operated by hand
for lowering heavy loads in hoisting machinery, great care must
be taken, since the throwing out of the checking pawls puts the
entire resistance on the brake. With this arrangement there is
always more or less insecurity, the safety depending upon the
handling of the lever, and serious accidents have frequently
occurred. This danger can be avoided by the use of automatic
sliding brakes, the following form being designed by the author,
and shown in two forms in Fig. 941. The brake pulley a, is
loose on the shaft, but engages with it by means of a ratchet
system a' b' e'. The brake is subjected to a tension equal to
a. b. c.
==>-
FIG. 941.
Strap brakes may be used in internal pulleys, in a manner
similar to the internal ratchet gear of Fig. 711, for example.
the greatest braking force desired ; i. e. so that the weight K The outside ofthe strap then acts upou the inner surface ofthe
must be raised in order to permit the load to run down. If the pulley, the strap being subjected to compression instead of ten­
lever is let go, for any reason, the descent is checked. In form sion,* thus becoming a pressure organ, a subject treated more
a, the pawls are attached to the pulley, and the ratchet wheel fully in the following chapter.
a' keyed to the shaft; in b, the pawl is on a disk c'. When the
load is raised the combination forms au ordinary ratchet train.
A silent ratchet, Figs. 673, 674 may be used for this device. At
c, is shown a pendulum counterweight, which can be adjusted
so as to vary the braking power to suit various loads.
Another form of sliding brake, also designed by the author,
is shown in Fig. 942. In this design the strap b, is giveu such
(at least 0.20) increased by 3- which when used to multism
2
ply the value oi fi ot , requires a very small force to overcome
the teusion t.
I 306.
CHAIN BRAKES.
Chain may be
used as the tension
organ in
brake construction,in
which case
it is generally
—
lined with blocks
ofwood, as in Fig.
943. The tensions
A and I, to be
given to the two
parts of the chain,
are readily obtained
from formula
(312). The
ratio of chain
pitch length /, to
the pulley radius
r, is increased because
ofthe use ofthe wooden block. Wheu / = A rand the
arc of contact is less thau 180° we have :
-f-(•*•* ./
For wood on iron we may take fi = 0.3
This gives:
and
A
p = —- = 1 . I 9 = 2.35 ; also
T_
P
I
d
' p — l
JL.35_
1-35
i-74
I = 0.74, or t = 0.74 P.
(3i6)
(see section 193).
These proportions should not be strictly followed for heavy
brakes such as iu Fig. 939, as such should be determined for
each case.
I 307.
INTERNAL STRAP BRAKES.
FIG. 942.
tension /, by means ofthe screw e 7, and lever c, as to hold the
load from descending ; a rubber spring being introduced at 7.
If the load is to be lowered, the clamp c, is loosened, but is
again tightened on ceasing. When hoisting, the tension / at 2"
is readily overcome. This is in reality a form of running ratchet
gear, and as shown it is made with a strap of wedge section, the
angle 8 being 45 0 The pressure of the internal strap brake is of the same magnitude
as with the external brake, but in the opposite direction,
so that the previously determined value of p from the forces A
and t, may be used. Fig. 944 shows three forms of such brakes,
these being used for friction couplings, and not in hoisting
machinery (see Fig. 449). Fig. 944 a, is Schurman's friction
coupling, f The brake lever c, acts by means of a wedge 4,
upon one end of the strap. The other end of the strap is held
by a pin 3, to the member d, which is to be coupled to a by
means of the strap b. The lever c, is also pivoted to the member
d. For the forces A and /, we may use formula (239), and
since a is nearly = 2 VT, or say = 6, we have for fi = o. 1 the
valueA 0< = 0.6, which from the table of (i 264 gives p — 1.82,
and T = 2.22, whence I = 1.22 P. The strap must be released
by the action of a spring.
Fig. 944 b, is Adymau's coupling,]: which is made with a
. The wedge portion is made of wood on iron heavy cast iron ring. The ring b, is made in halves, b' and b",
fitted with projections 4' and 4" which eugage with an intermediate
sheave keyed on the shaft.
(To be continued.)
* See Theoretical Kinematics, p. 167 ; p. 548.
f Zeitschrift des Vereins Deutscher Ingenuiere, Vol. V, p. 301.
j Made by Bagshaw & Sons, Batley, Yorkshire.

254 ENGINEERING MECHANICS. [October, 1892.
IMPROVED METHOD OF PUTTING IN AND LEVELING FOUNDA­
TIONS UNDER WATER.
THE following is a description of an improved method of
putting in and leveling foundations under water, by which
some of the more serious difficulties of harbor work are avoided.
The process is as follows: Let a b represent the level at which
it is required to found the lowermost course of blocks at any convenient
depth below water. Careful longitudinal sections are
taken along the lines of the inner and outer faces of the foundations,
as at c, c, or, if it be a wide one, upon intermediate lines
also, and these are plotted, full size, upon a floor. Planks are
then cut aud made up, by nailing or boarding, where required to
correspond with the irregularities ofthe bottom, as represented
in Fig. 2. These are weighted with iron to the extent necessary
to make them sink, and they are fixed by means of bolts, from
2 ft. to 3 ft. in length, let into the rock, as shown, and secured
by iron wedges. Wedges are used in preference to making the
bolts in the form of lewises, in order that they may the more
easily be withdrawn for use
in the succeeding lengths of
foundation.
The planks are fixed by
divers, and in moderate
depths their level is determined
by means of an ordinary
field level and staff, the
latter being provided with a
10-ft. or 15-ft. lengthening
piece if necessary. A diver
holds the foot of the staff
upon the top of the plank,
which is raised or lowered
according to signal. It is
thus fixed at its correct level
with perfect ease and accuracy.
If found to be more convenient, the divers may themselves
adjust the plank by means of an ordinary spirit level. This
having been done, coach screws are inserted through the eyed
ends of the bolts for the purpose of holding the planks in place.
Before lowering the planks for fixing, the surfaces which will
be in contact with the concrete are covered with jute sacking, a
flap of the same material, from 15 in. to iS in. wide, being left
so as to extend under the concrete and prevent its escape. A
length of about 20 ft. of foundation is usually dealt with at one
time ; but this, of course, is merely a matter of convenience
which may be regulated as circumstances require.
Where the mass of concrete required to level up a foundation
is large, it may be composed of, say, 4 or 4^2 parts of good
clean sand and gravel to I part of Portland cement, ihe top
being finished off with a layer, about 6 in. in thickness, of rich
concrete composed of xfz or 2 parts of fine gravel and sand to
1 of Portland cement. Where the thickness of the concrete is
small, only the richer compound should be used. The concrete
is lowered to the divers in bags specially designed for the purpose.
These are illustrated by Fig. 3 above.
The mouth of the bag is closed by one turn of a line which is
provided with loops through which a hard-wood tapered pin
passes. This is attached to the tripping line, as shown in the
engraving. The folds of the bag hold the pin in position, but
a slight pull is sufficient to withdraw it and release the contents
of the bag. The bags are made slightly tapered, say 3 in. on a
side, so as to facilitate the discharge of the concrete. They
should be lowered, mouth downwards, until they almost touch
the bottom. The divers then place them over the site where
the concrete is required, and on giving the signal "all right,"
the tripping pin is withdrawn and the contents of the bag deposited.
The loss of cement by this system is so small that the water
is scarcely discolored. The bags used at Peterhead contain 2*+'
cubic feet each, but bags of any convenient size may be adopted.
A straight-edge (a light section Vignole's rail makes a good
one) rests upon the upper edges of the side planks, and spans
the distance between them.
The divers commence the foundation at one end and work
backwards, so as not to disturb the newly deposited concrete.
The concrete is merely pressed down by the flat hand to the required
level, and gently struck off by the straight-edge. In this
way a perfect surface is formed, which, at a depth of 5 ft. or 6
ft. below low water, is undisturbed by small waves.
In the course of a few hours the concrete has set sufficiently
hard to resist a moderate sea, and after three days it was hadr
enough to bed blocks upon. These are lowered and bedded
"dry" in the usual way, and are afterwards caulked round the
beds and joints and grouted through a tube with cement grout,
composed of two parts of Portland cement to one of Medina,
which sets exceedingly hard. It is essential to success that the
concrete used iu forming foundations, as described, should be
thoroughly well mixed ; enough water being used to form a not
Fin.1. Cross Section Rail Straight edae.
Fig . Z. Elevation of PlanU
showing boarding ice
too stiff slimy paste,
which should be put
into place as soon after
mixing as possible.
The system is applicable
tothe leveling of bagwork
or rubble foundations
as well as rock ; but
in the case of rubble
foundations it is necessary
to cover the entire
area with jute sacking
in order to prevent the
concrete finding its way
down amongst the
stones. Where rock is
very irregular or "side-
laying," it may be benched out by means of small charges of
gelatine dynamite. Those used at Peterhead for this purpose are
limited to half au ounce each, in order that the rock may not be
broken up to a greater extent thau is required.
It seems likely this system will supersede that of levelling-up
foundations by means of quarry chippings and small sealing
bags, which, in some cases, has proved very unsatisfactory, and
giving rise to serious failures.
AN electric riveting machine is being introduced by a Paris
firm. Essentially the principle of the machine is that of the
hydraulic jack ; a small ram being moved by the motor, brings
a heavy pressure ou the larger area of the ram, which does the
riveting. The machine is intended for outdoor work where
hydraulic pipes may be difficult to run, but leads from a dynamo
to the riveter motor can be easily laid down.

October, 1892.] ENGINEERING MECHANICS. 255
STEAM BLAST IN FUEL COMBUSTION.
BY J. M. WHITHAM.
Steam is used to propel air into a closed ash pit under the
furnaces of many boilers. Its usefulness as a means of produc­
ing an artificial draught has been clearly established, particularly
in burning culm aud other inferior grades of coal.
We propose to here give the theory of the action of steam as
a promoter of combustion. Steam is a chemical combination
of atoms of hydrogen aud oxygen iu the proportion by weight
of 1 to S respectively. It represents a completed combustion,
which has taken place probably ages ago. The bond or chemical
affinity of the hydrogen for the oxygen is great, (however
intense may be the repulsion between the individual particles
ofthe water vapor), and it can be overcome only by imparting
to it as man}' heat units as were liberated when the combustion
or combination was effected. This is some 62,000 heat units per
pound of the hydrogen present in the steam.
Grove and Deville have proven that steani or water vapor can
be dissociated by heat, without the presence of any other element
for which either hydrogen or oxygen has a chemical affinity,
and without even the presence of an indifferent or neutral
atmosphere. The}' prove that this dissociation begins at 1800 0
F., is continued more rapidly at 2200 0 F., and is not completed
till a temperature exceeding 4500 0 F. is attained, if, indeed,
at any temperature. Steam may, however, be entirely
decomposed in the presence of an element with which hydrogen
or oxygen has a greater affinity than has the one for the other ;
that is, by chemical affinity, and at temperatures much below
those cited above.
This decomposition by affinity is the method used in the
manufacture of water gas, in which a furnace, deeply covered
with burning coal, is brought to incandescence by a strong air
blast, which is then shut off and steam turned on. The steam in
rising through the bed of incandescent coal is first heated, after
which the oxygen is liberated and combines with the carbon,
so that free hydrogen and carbonic-acid gases are discharged
from the bed of fuel. These gases are enriched by hydro-carbon
oils, fixed, purified aud stored for the consumer. But during
this process of decomposing the steam, heat has been
abstracted from the bed of coal on the grate, so that, to prevent
the extinguishment of the fire, the steam is shut off, and the
air blast turned on. The process of manufacturing water gas
is therefore intermittent.
We have given a description of water gas making in order to
show that steam may be decomposed. To render it further
apparent we will investigate the action of a gas producer.
Producer gas is obtained continuously by giving steam and
air to a deep mass of burning coal on a suitable grate. The
oxygen from the air and from the steam unite with the coal,
forming carbonic; acid and carbonic-acid gases, which with the
liberated hydrogen and free nitrogen rise from the producer
and pass to a gas furnace, where the combustible gases, (hydro­
gen and carbonic-acid gases), are, while yet hot, burned iu the
presence of air.
Now a steam blast under a boiler acts on the principle of a
gas producer, differing from it only in that more air is admitted
with the steam—in fact more than is sufficient to convert the
carbon in the coal to carbonic-acid gas. In other words, a
steam blast is a combination of a gas producer aud a furnace
for burning the gas after having been made. There can be no
possible gain or loss of heat by the actiou of the steam in the
fire, provided, of course, that the combustion is equally effi­
cient with and without its use. If only the same amount of
coal is burned on the grate by the use of a natural draught or
by a steam blast, then it is readily seen that the furnace temperatures
are lowered by the steam blast, aud the economy reduced,
as a high furnace temperature is necessary for good combustion.
But the application of a steam blast is usually made either
for increasing the capacity or power of the boiler by burning
more coal of the same grade than is possible with the natural
draught, or by replacing a good grade of coal by an inferior
grade, which latter case allows more coal to be burned to
accomplish the same result. Hence under these conditions the
high furnace temperatures and the economy ill the use of the
coal may be maintained.
A steam blast will convert culm or any of the inferior grades
of anthracite coal into a gas making coal. By natural draught
it is usual to see a light, lambent blue flame rising over a bed of
incandescent anthracite coal for only about 8 inches. A steam
blast will, however, envelop the boiler in flames, showing a
flame from 20 to 30 feet from the grate. The flame means combustion
taking place. We may, then, say that the furnace of a
steam blast boiler is the gas producer, and that the combustion
chamber is the burner for the gases thus generated. This flame
is the burning of carbonic-oxide gas into carbonic-acid gas, and
hydrogen iuto water vapor. When at a low temperature, say
from 1100 0 to 1500° F., the flame is of a lambent blue color, but
the color is what is known as a "Nile green " at higher tem­
peratures.
A steam blast is therefore a useful means for helping a poor
draught, or for burning inferior grades of coal, but it can not
perse increase the economy of the furnace, nor can it be as
economical as natural draught unless ample space is provided
for the combustion of the large quantity of gases geuerated. It
is therefore doubtful if it can be economically applied to the
ordinary marine or locomotive boilers, since their combustion
chambers are small. Its use for marine purposes is also to be
condemned as the steam used is lost up the chimuey. In practice
from 0.4 to 0.6 of a pound of steam is used for supplying
tbe air requisite for burning one pound of coal. Deducting
this from the steam generated, we see that the available steam
is only about 95 per cent, of that formed in the boiler. Hence
about 5 per cent, of the coal burned is required for running the
steam-air blast.
THE Federal Institute of mining engineers of Great Britain,
held a general meeting, September 6th, at Shelton, England.
Membership has increased in one year from 11S7 to 1380. Two
papers of interest were read dealing with the increasing difficulties
of mining coal. They first dealt with the application of
the long wall system to seams of moderate inclination, 14 deg.
to 20 deg. Extra attention was recommended to timbering and
packing, and to set timbers at angles corresponding to the dip
of the mine to avoid slipping of prop. The regular weightbreaks
being nearly at right angles to the dip, the line of greatest
pressure, owing to the additional pull due to gravitation
downhill, comes upon the edge of the coal, and iu order to
throw this forward in advance of the face-line it becomes necessary
to sprag the roof, just as it is necessary to sprag the coal
while holing. This, however, can only be done to a limited
extent, for if it is attempted to support more than a small area
of roof the timber will be broken. For this reason the timbering
is kept within the smallest possible limits, so that, without
using an excessive quantity, the roof is kept well supported
after the removal of the coal, and the wastes are allowed to
break down within an easy distance of the face, so as to get a
good supply of packing materials close at hand, at the same
time preventing excessive preassure being thrown ou the timber
by the sinking of the roof in the wastes. It is also important
that the posts should be set in exact line at right angles to the
face, three lines being used at regular squared iutervals to give
vertical support, which is not done if the intervals are triangulated,
as is the custom in some districts. The breadth of roof
so supported varies from 4 ft. 6 in. to 9 ft., the timber being only
left in the 9 ft. breadth for a very short time after the coal is got
down, as the lower row is withdrawn as the work progresses.
The three rows of posts give effectual support while the packs
are being carried forward, and the posts being only 2 ft. 3 in.
apart, there is much less danger in taking them out thau there
would be if they were set at greater distances.

256 ENGINEERING MECHANICS. [October, 1892.
G RAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
lated polygon be one of the fiunicular polygons of the fiorces
BY MAURICE LEVY.
/io. fm according to the side C0 1 ;
A12. f\ according to the side 1.2 ;
and so on up to the forces /,- and filt directed according to the
side 4.5. As for the last body as it is fitted in, it is in equilibrium
whatever be the forces wdiich incite it; it furnishes therefore no
condition of equilibrium.
If we consider, now, any one of the hinges, for example, the
hinge 3, it sustains: i° the force directly applied F3; 2° the
pressure ofthe body ad a'd', which is equal and opposed to the
reaction fi4 which the hinge itself exercises on this body ; let
fi'3i be this force ; 3° the pressures of the body articulated at
2 and 3, which is, likewise, a force/',., equal and opposed to/,,-
Therefore, the three forces fi'3i, fi'u, F3 should be in equilib"
rium, which requires that the forces/B and fiM admit A3 for a re.
sultant or are the components of F3 according to the two adjacent
sides of the polygon formed by the points of articulation.
Hence, ifi we decompose each ofi the fiorces F„ and F2, . . .
into two others according lo the adjacent sides of the articulated
polygon, the two components such that fi0, fim ; fi12, fi.n ; . • .
directed according to each side of the polygon, should be equal
and opposed, those are the conditions necessary and sufficient
for the whole system to be in equilibrium.
Now, as we see on Fig. 16, where the decomposition is made
or by going back to i, 33, it amounts to saying that the articulated
polygou should be a funicular polygon of the given forces_
Each polar radius expresses the pressure of the corresponding
side.
The extreme radius gives in magnitude, direction and flow the
pressure fi exercised on the plane C; for the point 5 rendered
free ought, as the others, to be in equilibrium under the action
of the force A5 and of two forces equal and opposed to the
forces fiM and fi'.
COROLLARY I.—Let (Fig. 16) f" be the reaction of the fixed
plane C, and/",,, that of the fixed point C0. We can render the
polygon C0 1.2.3.4.5 A, free provided that to the forces Flt
F2, . . . , Fb acting on its apexes we adjoin forces applied
according to its extreme sides and equal to fim and / // acting. I 79.
PROBLEMS ON THE POLYGONS OF VARIGNON OR ARTICU­
LATED POLYGONS.—PROBLEM l.—A polygon C0 1.2.3.4.5 C1
(Fig. 16), the length ofi whose sides are given, as well as the
fiorces acting on the different apexes, is supported at one ofi its
extremities on a fixed pivot C0 and filled in at the other on a
fixed plane Cv The body fitted in has its hinge in a given point
5 *, besides, one side 2.3 of the polygon is subject to pass through
a given point H; lo find: i° the form ofi equilibrium ofi the
polygon ; 2
.
Hence :
In order that an articulated polygon formed of bodies like
those specified above and free be in equilibrium under the action
of forces acting: i° on its apexes, 2° on its extremities, it is
necessary and sufficient that it be one ofi the funicular polygons
of the forces acting on the apexes and that the two forces acting
al the two extremities be directed according to the extreme sides
of this funicular polygon and equal to the corresponding polar
radii.
COROLLARY II.—Hence, we deduce for the case where the
polygon is closed :
In order that an articulated polygon, closed and free, at Ihe
apexes ofi which fiorces act, be in equilibrium, it is necessary and
sufficient that the polygon of these forces be closed (a condition
evident by reason of js 35 and 46) and that the given articu­
0 the resultants of the pressures or tensions ofi the
articulated bodies of ivhich it is formed ; 3° the pressures on the
supports.
It is sufficient to draw the funicular polygon of the given
forces subject to pass through the three points A, 5, H(\ 45).
Let O be the perfectly determined pole of this polygon. One
of the bodies, the one crossed by the hinges b and b', for example,
undergoes two pressures equal and opposed fi3i,fii3 represented
by the polar radius 3.4 (Fig. 16). If we make any section
A B, which divides this body into two parts (a) and (b),
the part (b) is in equilibrium under the action of the force fil3
and the resultant/, of the forces exercised on (b) according to
the section A B. It is therefore necessary that this resultant
be equal and opposed to fii3, i. c., equal to the radius 4.3 and
directed according to the line of action 4.3, whatever be ihe
orientation of the section A B.
Remark.—In a general way, if a body, whatever be its form,
is in equilibrium under the action of two forces, the resultant
of the elastic actions of any section (uot parallel to the common
line of action of these two forces) is constant, equal to each
of these two forces and directed according to their line of action
That is what is meant by saying that such a body is subject
to a constant pressure or a constaut tension.
Here, for each body, this tension or pressure is furnished by
the polar radius parallel to the line which joins the two points
of articulation of the body. The polar radius O a gives the
tension of the side C0 1 and at the same time the reaction of
the fixed point Ca. The extreme side 5 A, of the polygon is
the line of actiou of the resultant of the reactions of the fixed
plane A, and the polar radius b O gives the magnitude of this
reactiou.
All this arises, moreover, immediately from the fact that the
articulated polygon is a polygon of the pressures ($ 68, 69) of
the system.
PROBLEM II.—Inversely, having given an articulated polygon
fixed at its two extremities, as well as the directions ofi the
forces acting at its apexes, to find the magnitudes to give lo
these fiorces in order that ihe polygon be in equilibrium.
Through a point 0 (Fig. 16 and 16) let us draw radii parallel
to the given sides of the polygon ; then (Fig. 16) from a point a
arbitrarily chosen on the first radius, let us draw lines I, 2, 3,
. . ., parallel to the given directions of the forces Fv A"2, F3,
. . .; these parallels limited to the different radii represent the
magnitudes of the forces sought.
The point a having been chosen arbitrarily, we see that the
magnitude of one of the forces can be given arbitrarily, and
then the magnitudes of the others follow.
2 So.
POLYGONS AND CURVES SUSPENDED, SUPPORTED.—When, as
in Fig. 16, all the articulated bodies are compressed, which is
expressed by saying that all the sides ofi the polygon are compressed
or pressed, we say that the polygon is suppoiied by its
two points of support; in the contrary case, which would be
presented if we changed the flow of all the forces A„ A",, . . .,
we say that it is suspended, because the first case is presented
generally in bridges or arches supported, and the second in
bridges suspended.
In these latter, we could, without disturbing the equilibrium,

October, 1892.] ENGINEERING MECHANICS. 257
replace the solid bodies which form the sides of the polygon
by flexible bodies, such as threads, cords or cables of iron. It APPLICATION TO A PORTION OF A REGULAR POLYGON BEARis
just from this that the generic name of funicular polygon ING A UNIFORM NORMAL PRESSURE.—Let us suppose that the
comes (in German, Seil-Polygon, polygon of cord or thread). polygou bears a uniform normal pressure of pkg per unit of
If the points of articulation approach one another indefinitely, length ; it is required to find the tension or pressure of its sides.
the polygons of equilibrium, supported or suspended, are re­ It is an application of the theorem of \ 78, more general thau
placed by curves or arcs of equilibrium, supported or sus­ that of Varignon.*
pended. For the suspended curves, we may use a body per­ The resultant of the pressures acting on each side of the
fectly flexible and compressible, as a thread, a cord, etc.
polygon (Fig. 17) is a force//applied tothe middle of this side.
For arcs or curves supported, we can also represent clearly. For equilibrium, it is necessary and sufficient (\ 74) that the
articulations succeeding one another iu a continuous manner, funicular polygon of these forces pl passes through the points
by using a body perfectly flexible, provided that it resists com­ of articulation. Now, if we construct: 1° the circumference
pression, for example, a steel band.
circumscribed to the given polygon ; 2° the polygon circum­
However, an arc perfectly flexible compressed is never in scribed to this circumference according to the apexes of the
stable equilibrium ; the least disturbance changes its form com­ given polygon, we obtain a regular polygon which will be the
pletely and removes it from its primitive form ; while a cable or funicular polygon sought and which plays, in connection with
a cord suspended, when it is in equilibrium, is in stable equi­ the forces pl, the same role that, in the problem of the preceding
librium, i. e., if it is moved a little from its positiou it returns paragraph, the given polygon relative to the forces A plays.
to it after several oscillations.
Therefore, in order to have the polar radius of this new
881.
APPLICATION TO A REGULAR POLYGON BEARING FORCES AT
ITS APEXES.—AS an application of Problem II of \ 7t>, let
(Fig. 17) A 1.2.3.4 B be a portion of a regular polygon resting
at its extremities on fixed pivots A and B, subject to forces
Flt A,, A3, A4 directed according to the bissectrices of the angles
of the polygon.
Fig. 17. Fig. 17.
Let us construct (Fig. 17) the polar radii and the forces.
From the fact that the lines of action are the bissectrices of
the angles of the polygon, it follows that the triangles O ac,
O cd, ... are equiangular and, consequently, isosceles and
equal. Therefore the force polygon is also a portion of a regular
polygon; all the forces A,, A2, . . . are therefore equal; let
Abe their common value. We have
F = Oc ss cd = de = eb.
a normal pressure. The equilibrium is unstable if the arc is
supported, stable in the contrary case. The apothem of the
The pressures of the sides Al, 1.2, . . . ofthe given polygon
polygou mentioned in the preceding paragraph here becomes
are also all equal, being represented by the radii O a, O c, . • . .
the radius of the arc. Hence : if (Fig. 18) an arc A IB with a
Let us designate by I the value of this pressure and let C be the
centre of the given polygon, i?= C1 = C2, . . . its radius
r= C K its apothem.
The similar isosceles triangles a O c and C AX give
a c O a
AAT^AAA
or, by designating by / the length of the side of the given
polygon
whence
F_ _ t_
T~ R'
Hence, a portion of a regular articulated polygon, fixed at its
extremities, is in equilibrium under the action of forces equal
to one another of some common magnitude A, directed accor­
ding to its bissectrices ; all the sides of the polygon are equally
pressed (or stretched, if the polygon is suspended) aud the
value of the pressure is to that of the force A as the radius of
the polygon is to the length of its side.
2 82.
polygon, it is sufficient to apply the last formula ; the first mem­
ber will be the polar radius sought which we shall call /'. It
is necessary, in this formula, to replace F by pl.
Moreover, the radius of the new polygon is C A, its side is
//; hence
V_ _CI _ %. CI _fC2_ _Ji_r_
Jl ~ A J ~~ ~F2~ T2 K ~~ 2 JA
2
by designating by r the apothem of the given polygon. Hence
t=pr,
a result easy also to establish directly.
But the polar radius I', parallel to a side If, represents the
common value of the mutual actions which two contiguous
sides exercise on each other or, if we wish, the action of each
side on the hinge Hence : a regular polygon subject to a uni­
form pressure p is in equilibrium and the common value of the
mutual actions which its different sides exercise on one another
is the product ofi p by the apothem of the polygon.
\ 83.
THRUST OF A CIRCULAR ARCH SUPPOSED FLEXIBLE SUBJECT
TO A UNIFORM NORMAL PRESSURE.—What precedes being true
for a regular polygon of any number of sides is true for an arc of
a circle and shows that an arc of a circle itself flexible, supported
at its extremities, remains in equilibrium under the influence of
Fig. 18.
radius r is fixed at its two extremities and if it supports a uni­
form normal pressure (from the exterior toward the interior), it
is compressed and its pressure at each point is i — pr.
(To be continued.)
* We could relegate the problem to the preceding by decomposing the resultant
of the pressures acting on each side into two others of the same
direction as it and applied to the apexes. We prefer to treat the question as
a simple application of the theorem of 'i 74.

258 ENGINEERING MECHANICS. [October, 1892.
PUMPS AND PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
(Continued from page 237.)
Substituting the values already found in (A) we get, finally,
for the duty :
103.735 X 17-04
D = 6,414,100 x
117,936,69s foot-lbs.
9"V35
This result exceeds the guaranteed duty 105,000,000 by 12.32
per cent., or by nearly one-eighth.
The duty, based upon the actual coal consumption, may be
found as follows;
C being the coal consumption per minute, in hundreds of
pounds, the duty formula will be :
PAL
A> = 6414.1 (B)
c
In the present case the rate of coal consumption per minute
was 10 pounds.
10
Whence c = = o. 1
100
This in (B), gives us for the duty :
D = 64141 p. r.
= 64141 x 103.735 X 17-04-
= II 3.37S,479 foot-pounds.
This result is 7 9S per cent, greater than the duty guaranteed
by the Holly Manufacturing Company in their contract.
The Capacity.—The capacity of the pumps of the new
Saratoga engine is :
4 X 481.0575 x 40
333-
231
2 U. S. gallons per revolution.
The rate at which water was pumped during the period of
eighteen hours was therefore,
17.04 x 333.2 x 1440 = 8,175,928 gallons
in twenty-four hours, at a piston speed of 113.6 feet per minute.
This rate is something more than two per cent, greater
than is required by the contract, w-hile the pumps were operated
against a pressure 3.73 per cent, greater than was required.
The quantity of water actually pumped during twenty-four
hours against a pressure of 103,575 pounds, and at a piston
speed of 115 feet per minute, was 8,277,354 U. S. gallons ; exceeding
the contract capacity by 3.47 per cent, against a pressure
3.57 per cent greater than was acquired by the terms of
the contract.
Volumes of Sleam.—The following facts have been deduced
from the steam cards :
Mean distance which the steam followed in right
high-pressure cylinder 0.294
Mean distance which the steam followed in left
high-pressure cylinder 0.306
Mean distance which the steam followed in both
high-pressure cylinders 0.300
Clearance of high-pressure cylinders equivalent
to fraction of stroke 0.027
Mean volume of steam at cut-off in both highpressure
cylinders, fraction of piston displacement
°-3 2 7
Volume of cylinders, plus clearance 1.027
Steam expanded in both high-pressure cylinders,
times, mean 3-M 2 5
Mean pressure of steam above zero, at cut-off in
both high-pressure cylinders 95696 pounds.
Clearance, low pressure cylinders, fraction of
stroke 0.030
Mean absolute pressure at cut-off high-pressure
cylinders 95696
Mean absolute pressure, end stroke \ = 2.933
high-pressure cylinders. / " ' 32.629
Mean absolute pressure at end of stroke, highpressure
cylinder 32.629
Mean abs'te pres. at end of st'kelow pres. cyl. • 7-7565= 4-2°7
Total expansions, 4.207 X 2-933, by pressures = 12.339 times.
Volume of high pressure cylinder, and clearance
(less half the rod) 13.4971 cu. ft.
Mean volume of steam at cut-off, including clear­
ance, 0.3 X 13.1423 X 0.3548 4- 2 975 cu. ft.
Mean expansion in high-pressure cylinders by
volume 3.141 times.
Volume o f low-pressure cylinder, less one rod . 5 2 - 6 4 6 3 cu. ft.
Volume of clearance, 3 per cent '-5794 cu. ft.
. Volume of clearance, high pressure cylinder . . -3548 cu. ft.
Final volume of steam 54.5S05 cu. ft.
Mean expansion, low pressure cylinder .... 4-°44 times.
Total expansion by volumes, 4.044 X 3.141 = 12.702 times.
Water Accounted for in the Cylinders.—1. At the point of
cut-off, in the high pressure cylinders per minute :
4 X 4-2975 X 0.2212 X 17.04 = 64.793 pounds.
2. At end of stroke in the high pressure cylinders per minute :
4 x 13.4971 X 0.0803 x i7-°4 = 68.474 pounds.
3. At end of stroke in low-pressure cylinders, per minute :
4 X 54.5805 X 0.0207 X 17.04 = 77.808 pounds.
Pounds of steam entered cylinders per minute .... 87.348
Of this there is accounted for at cut-off:
64-793 pounds or 64-793 X 100 = 73.95 per cent.
87-348
At the end of stroke in the high-pressure cylinders :
68.847
6S.847 pounds, or 87.348 X 100 = 78.S2 per cent.
And at the end of the stroke in the low-pressure cylinders ;
77.808 pounds, or 77.808 X 100 = 89.08 per cent.
87-348
Thus it appears that at the cut-off there was, in the highpressure
cylinders each minute, 22.555 pounds of water, constituting
26.05 per cent, of the steam and water which entered the
cylinders. At the end of the stroke in the high-pressure cylinders,
there appears to have been, each minute, 18.874 pounds of
water, constituting 21. iS per cent, of the water and steam ori­
ginally entering the cylinders.
At the end of the stroke in the low-pressure cylinders, there
was, each minute, 9.54 pounds of water, constituting 10.92 per
cent, of the steam and water which originally entered the cyl­
inders.
ELEMENTARY FORMS OF PUMPS —In the beginning of this
series of articles wete shown the elementary forms of bucket,
piston and plunger pumps (Figs. 1 to 6). The single-acting
bucket pump, invented over 2000 years ago, remains as the simplest
form of pump in use to-day, and the one generally adopted
for raising small quantities of water, as in hand pumps, in
which cheapness of first cost is of chief importance.
The height to which the water can be lifted above the bucket
is limited by the power applied aud by the strength of the
parts, but the height to which the water under the bucket can
be raised above the level of the water in the well is limited by
the amount of vacuum that can be obtained. A perfect vacuum
would raise the water about 33 feet, but as this cannot be obtained
in such a pump, on account ofthe clearance space between
the two valves, and the vapor of the water itself, and of leaks
in the bucket and valve, it is not generaUy practicable to raise
water by the suction of a pump more than 25 feet.
The principal cause of failure of the solid piston pump was
its liability to be jammed in the barrel by sand or gravel.
The Plunger-pole Pump, designed and first practically introduced
by Trevethick, in 1797, although it was iuvented by
Samuel Moreland in 1675, replaced these earlier forms, and it
is still largely used.
Iu this pump the plunger-pole is a cast iron pipe turned on
the outside aud working in a cast iron case, the sides of which
were not touched by the pole. The pole case was provided with
a stuffing-box and the necessary valves.

October, 1892.J ENGINEERING MECHANICS. 259
Fig. 61 shows a longitudinal section and a
sectional plan. A is the plunger-rod of wood,
fastened into the hollow cast-iron pole ; b the
pole or plunger ; c the pole cas« allowing space
for the passage of water round the pole ; D the
stuffing-box ; e the bottom valve or suction
valve, allowing the water to ascend into the
pole case, on the ascent of the pole ; / the
top or delivery valve, through which the water
is forced upward on the descent of the pole.
Trevethick's plunger-pole pump was espe­
cially adapted to the Cornish engine, the down
stroke of this single-acting engine rapidly
raising the pump rods, which theu slowly fell
by their own weight against the resistance offered
by the water to the downward motion of the
plunger in the pump case.
The Bucket and Plunger Pump, Fig. 62, is
simply an ordinary bucket lift pump with its
pump-rod one-half the area of the bucket. Its
invention is attributed to Smeaton (born 1724,
died 1792). Its action is such that when the
bucket B is raised it sucks a column of water
equal to its area, its length being the same as
the length of the stroke ; at the return stroke,
wheu the bucket is traveling downwards, the
water passes through the valve in the bucket
FIG. 61.
POLE-PLUNGER
PUMP.
to the upper part. The ram or plunger H, being one-half
the area of the bucket B, leaves an annular space round
the ram equal to half the area of the entire space of the
suction side, therefore it will be found that half the quantity
of the water is raised into the rising main /, through
FIG. 62.
BUCKET AND PLUNGER PUMP.
the delivery valve G, the other half
portion remaining in the working
barrel above the bucket; when the
bucket again moves upwards, the
remaining half of the water is then
lifted into the delivery pipe /.
From this it will be seen that half
the quantity is delivered at the up,
and half at the down stroke ; conse­
quently the pump is double acting,
but delivers only the same quantity
as a single acting pump of the same
area as the bucket, or as a double
acting pump of the same area as
the ram.
The Piston and Plunger Pump
resembles this, but instead of the
delivery valve being fitted into the
bucket it is placed in the delivery
valve box. Its invention is attributed
to Henry Thompson, foreman
to Sir William Armstrong, in 1851.
Pumps for Deep Mines.—The
earlier pumps used in deep mines
were made of wood, hooped with
iron, having buckets with leather
cups, packing and valve, which
only raised water with the upward
motion of the rods. The rods had to
be strong enough to bear their own weight and also that of the
column of water. Pistons, without valves, working in brass or iron
barrels, were next used, forcing the water upward with the down­
ward motion of the pump rods. Their descending weight about
balances the ascending water, so that they did not require to be
made as strong and heavy as the rods of the lifting pump.
The Oscillating Pump.—A simple form of oscillating pump
is shown in Fig. 63. The oscillating diaphragm, or piston, C,
carrying the delivery valves D and E, receives motion through
its spindle, shown in
section. The chamber
beneath the piston is
divided into two parts
by the casting G, which
carries the suction
valves H and /. By
the oscillation of the
piston the delivery
valves D and E, and
the suction valves V
and AT are alternately
opened and closed. It
is chiefly used as a hand
pump. Another oscillating
pump is shown
in Fig. 64. The opera­
tion is clearly seen by
the position of the | I
valves in the cut. Vxc 63. OSCILLATING PUMP.
Tube Well Pumps (Proc. Inst. M. E-, Feb. 1888).—Fig. 65.
shows a pair of tube well pumps used for irrigation in California,
FIG. 64. OSCILLATING PUMP.
The tubes or barrels A,
which constitute both well
aud uptake, are made of
galvanized iron, from No.
18 to No. 14 B W. G, or
0.050 to 0.085 inch thick,
with the longitudinal
seams riveted and sol­
dered throughout. They
are made from 6 to 14
inches in diameter ; and
are sunk to depths vary­
ing from 100 to 200 feet,
sometimes more when
pure water is wanted. The
distance the tubes are
placed apart is usually
from 10 to 20 feet. These
crude looking pumps are
much more effective and
economical in their work­
ing than would be sup­
posed. The pump rods are of wood, their section being
equal to half the area of the working barrel; consequently
FIG. 65. TUBE-WELL PUMP.
in both the up and down stroke the delivery is equal to ha
the capacity of the barrel. In effect, therefore, the pumps are
double acting, with only one set of valves, and the load is in
a measure equalized betweeu the up and down strokes; they
correspond with the ordinary bucket-and-plunger arrangement.
The working barrel is either a brass casting, bored out, or made
of drawn brass tube. The foot-valve at bottom is inserted from
the top, and cau be drawn out and replaced without trouble, after
the pump rod and bucket valve have been removed.
(lo be continued.)

260 ENGINEERING MECHANICS. [October, 1892.
ELECTROTECHNICS.
A Compilation ofi Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
II) Zero Method of Greater Sensitiveness.
I'n r 2, r i< are termined, and the other part contains an equal non-inductive
resistance r'.
The deflection produced is instantaneous and without velocity
at its close, and is started by the inverse extra current in one
coil being stopped by the direct current in the other.
adjusted to balance with steady current. i\, say, Two deflections are obtained, x and x'. x' is taken with the
is altered a ohms so that balance still is made when commuta­ above arrangement, x is taken when the inductor is in circuit
tor spindle revolves n revolutions per second, then
with one ofthe coils of the galvanometer, and includes a resist­
r k
A = —

October, 1892.] ENGINEERING MECHANICS. 261
The ratio B
H
p. which is called the permeability or specific
conducting capacity for lines of force.
The permeability of all non-magnetic substances is the same
as that of air, viz., i. The permeability in iron decreases as the
magnetization is pushed to a high point, the practical limits
being about 125,000 lines per sq. in. for wrought iron and 70,-
000 for cast iron, which has a much lower permeability. The
following tables (I and II) are derived from the results of Hopkinson
on commercial samples of metal and are valuable
averages to base calculations upou.
TABLE I (SQUARE INCH UNITS.)
B,v
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
110,000
120,000
130,000
140,000
B
5,000
9,000
10,000
11,000
12,000
13,000
14,000
15,000
16,000
17,000
18,000
19,000
20,000
Annealed Wrought Iron.
f
4,650
3,877
3.o3«
2,159
1,921
1,409
9°7
408
166
76
35
27
H,,
6-5
'0.3
16.5
27.8
364
56.8
99.2
245
664
1,581
3,7f4
5,'8s
Annealed Wrought Iron.
f
3,000
2,250
2,000
1,692
1,412
1,083
25,000
30,000
40,000
50,000
60,000
70,000
TABLE II (SQ. CM. UNITS.)
823
526
320
161
90
54
30
H
1.66
4
5
6-5
8-5
12
17
28.5
5°
105
200
35°
666
B
4,000
5,000
6,000
7,000
8,000
9,000
10,000
n,ooo
Gray Cast Iron.
763
756
2 58
114
74
40
Gray Cast Iron.
1"
800
500
279
133
IOO
71
53
37
32-7
39-7
'55
439
807
1480
H
5
10
215
42
80
127
188
292
The limiting values of B have been variously set by different
experiments. For wrought iron, 18,250 (Hopkinson) ; 16,250
(Kapp).
Kapp also gives 20,500 for charcoal iron sheets, and 23,250
for charcoal iron wire. Ewing, by means of abnormally high
magnetizing power, has forced B up to 45,350.
Between 6,000 and 16,000 (values of B) or 38,700 and 103,200
(values of B")
17,000—B^\ =
109,650 — B//
~3^5 S 22 -57
Hysteresis or intermoleculai magnetic friction causing iron to
heat accompanies the action of magnets designed to be operated
with alternating currents. Table III gives loss in Watts on account
of hysteresis in a well laminated soft charcoal iron core
for two different frequencies of alternation. Viscous hysteresis
is the name given to the gradual building up ofthe magnetization
when a magnetic force is applied to a piece of iron. It
may continue for half an hour and amount to several per cent.
ofthe magnetization.
TABLE III.—POWER WASTE BY HYSTERESIS.
B
4,000
5,000
6,000
7,000
8,000
10,000
12,000
14,000
16,coo
17,000
18,000
B„
25,800
32,250
38,700
45.'5°
51,600
64,500
77,400
90,300
103,200
109,650
116,100
Watts wasted per
Watts wasted per cu. ft. at 100 cy­
cu. ft. at 10 cycles cles or complete
per second. alterations per
second.
40
57-5
75
9 J -5
111
15°
206
262
324
394
487
c) General Principles ofi Design.
400
575
75°
9 2 5
1,110
1,560
2,060
2,620
3.240
3,940
4,870
Magnetism is considered as flowing through the different
media forming its circuit. In the case of a horseshoe magnet,
the flow is from S to N pole in the iron magnet core, from N
across air space to armature held a short distance from the
pole, through armature, crossing air space between armature
and S, and finally into S, completing the flow. The flow is
caused by a magneto-motive force. This law of the magnetic
circuit is analogous to the law of Ohm concerning electric currents.
_, . _ „ . Magneto-motive fiorce.
The magnetic flux (or flow) =
reluctance.
Reluctance is the term applied to the resistance which the
magnetic circuit offers to the flow of lines of force.
The magneto-motive force varies with the number of convolutions
of conductor wound on the magnet and the strength of
the current circulating around them.
Let S = number of turns or spirals of wire,
i = current in amperes,
/ = length of magnet core,
A = area of cross-section,
p = permeability,
N = total magnetic flux or number of lines. Then
Magneto-motive force =
4 T Si
10
Magnetic Reluctance =2 — /_
pA
Magnetic flux N
4 IT. J* 1
2 /
A p
2 signifies the summation
of the reluctances of the
sepa rate parts of the circuit,
J core, armatuie, air space,
j etc., where / and A are
,' taken respectively for each
[ part.
The number of ampere turns, or the magneto-motive force
necessary to produce the flux N is then from last formula
If inches are employed,
Si= N .2 A p where measurements are expressed
in centimeters.
• 257
Si
<
=0.3132 N . 2 — f —
A u
Law ofi Traction.
B A
P =
11,183,000
(To be continued.)

262 ENGINEERING MECHANICS. [October, 1892.
EMINENT AMERICAN ENGINEERS.
ROBERT WOOLSTON HUNT, metallurgical engineer, was born
at Fallsingtoii, Bucks Co., Pa., December 9, 183S. His father,
Robert A. Hunt, a graduate of Princeton College and the Uni­
versity of Pennsylvania, was a successful practicing physician,
belonging to the Trenton (N.J.) branch ofthe Hunt family
His mother, Martha Lancaster Woolston, was of a well-known
Quaker family. Owing to failing health, Dr. Robert A. Hunt
gave up his practice and moved to Covington, Ky., where he
died in 1855, leaving a widow and an only child, Robert W.
The latter had to assume a man's duties, but after continuing
his father's drug business for two years, impaired health com­
pelled him to relinquish it. He removed to Pottsville, Pa.,
where, after a short rest,
he entered the iron rolling-mill
of John Burnish
& Co., aud devoted several
years to acquiring, by actual
work, a practical
knowledge of puddling,
heating, rolliug aud the
other details of the iron
business. He entered the
laboratory of Booth, Gar­
ret & Reese in 1S59, to
take a course of analytical
chemistry, was employed
by the Cambria Iron Co.,
of Johnstown, Pa., as a
chemist in i860, estab­
lished a laboi atory at their
works (this being the first
instance of an iron or
steel company's having a
laboratory in America),
and assisted in starting
the Elmira Rail Mill, at
Elmira, N. Y., in the
spring of 1861. He entered
the United States
military service the following
fall, was in command
of Camp Curtin,
Harrisburg, Pa., in the
fall of 1862, served as
mustering officer for the
State of Pennsylvania in
1863, assisted in recruiting
Lambert's Independent
Mounted Company Pennsylvania
Volunteers, in
1864, and was mustered
out of the United States
service as a sergeant, having "tossed up " with a friend as to
which should take a lieutenant's commission. Returning to
the employ of the Cambria Irou Company, he was sent, May 1,
1865, to the experimental Bessemer works at Wyandotte, Micb.,
of which they were part owners. He was placed in charge of
these works in July, and so continued until May, 1866, when he
was called back to Johnstown to take charge of their steel business
there. He assisted George Fritz, the company's chief engineer,
in designing and building their Bessemer works, of which
he afterward had charge, from July 10, 1871, until August, 1873,
when he resigned his position. He became superintendent of
the Bessemer works of John A. Griswold & Co., Troy, N. Y.,
Sept. 1, 1S73, and in March, 1875, general superintendent ofthe
Albany aud Rensselear Iron and Steel Co., formed by the con­
solidation of John A. Griswold & Co and Erasmus Corning & Co.
This, later ou, became the Troy Steel and Iron Co., of which
Mr. Hunt remained iu charge until April, 1888. During those
ROBERT WOOLSTOIN HUNT.
years he almost completely rebuilt the various works of the
company, besides erecting a large blast furnace plant of the
most complete character. He has taken out several letters
patent on steel aud iron metallurgical processes and machinery,
both individually and in conjunction with John E. Fry, William
R. Jones, Dr. August Wendel, and Max M. Suppes, the Hunt-
Jones-Suppes rail mill feed tables being used uuder license by
the majority of the rail mills in the United States. In April,
1888, he established the bureau of inspection, tests and con­
sultation of Robert W. Hunt & Co., with central office in
Chicago, 111., to which city he removed the same spring. He
was president ofthe American Institute of Mining Engineers in
18S3, and has at different times served on the board of managers
of that institute, as well
as of the American So­
ciety of Mechanical En­
gineers, of which he was
elected President in November,
1890. He is a
member of the American
Society of Civil Engineers,
and a trustee of the
Rensselear Polytechnic
Institute, Troy, N. Y. He
has frequently contrib­
uted papers to the vari­
ous scientific societies of
which he is a member,
and has lectured before
the Franklin Institute
of Philadelphia and the
graduating classes of the
Rensselear Institute, and
Sibley College, Cornell
University. He served
for three years as commander
of John A. Gris­
wold Post, No. 338, of
Troy, but resigned on
leaving that city.
NAPHTHA yachts are
beiug made, ranging from
2 to 6 horse power, weigh­
ing from one ton to one
and a half tons, and con­
structed of wood, steel or
aluminium. Ayachtmade
of aluminium, and 43 fett
long,has justbeen launch­
ed from the yard of a
Zurich firm. The weight
of the yacht is only iA
tons ; naturally she is constructed on very light scantlings. The
keel, stem aud stern-posts are of forged aluminium 7 in. by I in.;
the frames are 1 iu. by 1 in. by T l s in. except in the engine-room,
where they are x\e\ in. by iA in- by % in.; the frames are spaced
throughout the vessel 16 iu. The shell plating ranges from j\
in. to f, in. in thickness, and 15,000 aluminium rivets hold the
ship together. She is fully equipped, having a balanced rudder
aud quadrant of aluminium, bollards and fair-leads of the same
material, aluminium awning stanchions which support a pinkcolored
sunshade extending the whole length of the yacht,
aluminium flag poles surmounted with silken flags. In starting
the engine air is first pumped into the naphtha reservoir by a hand
pump provided for this purpose ; when a suitable pressure is obtained
here, a valve leading to the small burner is opened, and
the vapor, when it issues there, is lighted. Naphtha is then
pumped by a second hand pump into the copper spiral, where
it is heated by th ; small burner and vaporized ; when the pressure
has riseu to a proper amount the valve leading to the injector
is opened, admitting thus mixed vapor and air to the large
burner.

October, 1892.] ENGINEERING MECHANICS. 263
CORROSION.
Corrosion is responsible for a large class of the defects that
we meet with in the inspection of boilers. It causes rapid deterioration,
and is especially dangerous because it is often unsuspected;
even in bad cases. When the action is internal it
may be due to impurities in the water, but it is more frequently
caused by allowing the boiler to stand idle for considerable
lengths of time, with water in it, ready to start up ; and it is
particularly uoticeable in boilers used for heating purposes, for
these are frequently left all summer with water standing in
them.
If the boiler is kept lukewarm, as, for instance, when it is
fired up only once or twice a week, the action is usually more
rapid than when it is constantly cold ; but iu any case, pitting
and corrosion are more destructive in boilers that are comparatively
idle than in those that are in constant use. This fact has
not escaped the attention of the chief engineers of the fire departments,
who now almost universally put iu auxiliary boilers
iu connection with those on the engines, in order to keep up a
proper circulation and maintain a steam pressure. Many persons
suppose that the arrangement is designed to ensure having
steam up in case of fire ; but while this is certainly one great
advantage of the plan, the increased durability of the boiler is
au equally important one.
The effects of the pitting and corrosive action of water is frequently
met with in the inspection of the fire-boxes of internallyfired
boilers. The space between the fire-box and the grate bars, in
these boilers, becomes filled with ashes, which are often allowed
to get damp and attach themselves to the plate, or to pack
themselves tightly in between the plate and the bars. Then if
there is the slightest leakage or dampness these ashes begin at
once to corrode everything in contact with them, and in a short
time the boiler becomes unsafe.
The rapidity of the action iu cases of this kind is caused partly
by the character of the ash, and partly by the closeness with which
it clings to the plates. The engiueer is easily deceived as to
the real state of things if he allows these incrustations to collect,
for there is no evidence of corrosive action until the plate
is destroyed, unless the coating is removed. No furnace should
ever be allowed to get into such a condition. The accumulations
should be removed every day by passing the cleaning
hook between the grate and the plates of the water leg. It is
good practice, also, to remove the grate and thoroughly clean
the adjacent plates once in six months, painting them, after
cleaning, with red lead and oil. This will check the corrosion
in all cases, and unless leakage occurs it will stop it entirely.—
The Locomotive.
THE LOSS OF HEAT FROM UNCOVERED STEAM PIPES.
It is well recognized that there is a material and important
loss of heat, by radiation and otherwise, from long lines of unprotected
steam pipe ; yet many engineers, if asked how great
this loss would be in any proposed case, would be unable to
give more than a rough guess at it. If the pipe is covered with
some approved kind of non-conducting material the loss may
undoubtedly be greatly diminished ; but pipe covering costs
money, and the owners of factories and mills naturally want to
know, before investing in it, how much it will lessen their running
expenses, and which ofthe many kinds of non-conductors
will give the best satisfaction in the end. This problem is by
no meaus easy to solve, yet it is coming up all the time, and we
propose to present a few general facts tbat may make a serviceable
foundation to base estimates upon.
In the first place, we shall have to look into the phenomena
of cooling somewhat. We shall find that however simple it may
look at first sight, the problem presented by the steam pipe
resembles a great many other heat-problems in its deceptive
complexity. A hot steam-pipe, for example, is radiating heat
constantly off into space, but at the same time it is cooling also
by convection. By convection we mean that the air in contact
with the pipe becomes heated, grows lighter, and flows upward|
giving way to a fresh supply of colder air, which then acts
in the same way. A good illustration of simple radiation is
afforded by the open grate fire, used for heating dwellings.
Nearly all ofthe air that is warmed by direct contact with the
fuel passes up the chimney, and the only part of the heat that
is available for heating the room is that which is radiated directly.
Most ofthe heat felt by the crowds who delight to gaze
on burning buildings is also purely radiant, for the air that is
heated by direct contact with the building is free to rise high
over their heads, its course being indicated by the sparks and
smoke. On the other hand, the heat poured into a room
warmed by the " indirect" system is eutirely convective.
Iu addition to the problems presented by radiation and convection,
the conducting power of the pipe conies up for consideration
; for it is the temperature of the outside of the pipe
that determines how much heat will be lost by radiation and
convection, and unless the pipe is an absolutely perfect conductor,
the outside will be cooler than the inside by an amount
that depeuds on a good many things, and is not easy to calculate.
In all practical work, however, it may be assumed that
the conducting power of ordinary steam-pipe is great enough
to keep the temperature ofthe outside pretty nearly up to that
of the inside, so that for most purposes we can consider these
two temperatures equal.
When we come to look for experimental data on which to
base calculations of the heat radiated and otherwise lost by
steani pipes, we find that they are neither numerous nor satisfactory.
In his famous article on Heat, in the Encylopedia
Britannica, Lord Kelvin gives Mr. Macfarlane's measures of the
total loss of heat of a copper sphere (including radiation and
convection), and no others, apparently thinking that such other
other measures as have been made are unsatisfactory. Mr.
Macfarlane's experiments were made with a copper sphere
about 1.6 inches in diameter. The ball was enclosed in a
blackened sphere of tin, the temperature of which was kept at
14 0 Cent, the initial temperature of the copper ball ranging
from 19 0 to 74 0 Cent. Prof. Tait has also published measures
made by Mr. J. P. Nichols ; but as there is a marked discordance
between the two, we do not ueed to reproduce the results.
Iu Box's Practical Treatise on Heat, a number of results are
given for the amount of heat radiated by different substances
when the temperature of the air is i° Fah. lower than the temperature
ofthe radiating body. A portion of this table is given
below. It is said to be based on Peclet's experiments.
TABLE I—HEAT UNITS RADIATED PER HOUR, PER SQUARE
FOOT OF SURFACE, FOR I° FAHRENHEIT EXCESS
IN TEMPERATURE.
Copper, polished 0327
Tin, polished 0440
Zinc and brass, polished 0491
Tinned iron, polished 0S58
Sheet iron, polished .0920
Sheet lead 1329
Sheet-iron, ordinary 5662
Glass 5948
Cast-iron, new 6480
Common steam pipe, inferred 6400
Cast aud sheet-iron, rusted 6868
Wood, building stone, and brick 7358
When the temperature ofthe air is about 50°or 6o° Fah., and
the radiating body is not more than about 30 0 hotter than the air
we may calculate the radiation of a given surface by assuming
the amount of heat given off by it to be proportional to the difference
in temperature between the radiating body and the air.
This is " Newton's law of cooling." But when the difference in
temperature is great, Newton's law does not hold good ; the
radiation is no longer proportioual to the difference in tem-

264 ENGINEERING MECHANICS. [October, 1892.
perature, but must be calculated by a complex formula established
experimentally by Duloug and Petit. Box has computed
a table from this formula, which greatly facilitates its application,
aud we cannot do better than follow his lead.
TABLE 2.—FACTORS FOR REDUCTION TO DULONG'S LAW OF
RADIATION.
Differences in
Temperature between
Radiating Body
and the Air.
18° Fah
36° "
54° "
72° "
90° "
io3° "
126° "
•44° "
162° "
180° "
198° "
216° "
= 34° "
252° "
270° "
288° "
306° "
3=4° "
342° "
360° "
378° "
396° " ......
4.4° "
43=° "
TEMPERATURE OF THE AIR ON FAHR. SCALE
32° 1 50°
1
59° 68° 86°
1
104 0
1
122° 140°
158° 176°'194° 212°
1 »
1-70 I.85 I.99 2.15
The use of this table will be made plain by the following
illustration. EXAMPLE: HOW many heat units will be radiated
in one hour by au iron pipe io feet long and 2\\ inches in external
diameter, carrying steam at a temperature of 355° Fah.,
the air and surrounding objects being at 32° Fah. ? Ans.: The
circumference of this pipe is 2*4 x 3.1416 = 7.363 inches -=
0614 feet. Hence the area of its surface is 10 X 0.614 = 6.14
sq. ft. We see by Table No. 1 that one square foot of such a
pipe will radiate about 0.64 of a heat unit per hour, for one degree
difference in temperature. Hence the proposed piece of
pipe will radiate 6 14 X 0.64 = 3.93 heat units per hour, for one
degree difference in temperature. The real difference in temperature
beiug 355° — 32°= 325 0 . Newton's law gives us 3.93
X 323 •= 1.267 heat units as the amount of heat radiated by the
pipe in one hour. But Newton's law is not accurate for auy
such range of temperature, aud we have to look iu Table No. 2
for the proper correction factor to reduce the result into conformity
with Dulong's law of radiation. The temperature of
the air being 32°, we look in the column headed 32°, and opposite
324° we find the factor 2.07. Then multiplying our previous
result by this we have 1,269 x 2.07 =2,627, which is the
number of heat units the pipe may be_expected to lose in one
hour, by radiation alone.
The loss of heat by convection appears to be independent of
the nature ofthe surface ; that is, it is the same for iron, stone,
wood, and other materials. It is different for bodies of different
shape, however, and it varies with the position of the body.
Thus a vertical steam pipe will not lose so much heat by convection
as a horizontal one will ; for the air heated at the lower
part ofthe vertical pipe will rise along the surface of the pipe,
protecting it to some extent from the chilling action ofthe surrounding
cooler air. It is for a similar reason that the shape
of a body has an important influence on the result; those bodies
losing most heat whose forms are such as to allow the cool air
free access to every part of their surface. The following table
from Box gives the number of heat units that horizontal cylinders
or pipes lose by convection per square foot of surface per
hour, for one degree difference in temperature between the pipe
and the air :
TABLE 3.—HEAT UNITS LOST BY CONVECTION FROM HORI­
ZONTAL PIPES PER SQUARE FOOT OF SURFACE PER
HOUR, FOR A TEMPERATURE DIFFERENCE
OF 1° FAHR.
External
Diameter
of Pipe in
Inches.
Heat Units
Lost.
O.728
O.626
o-574
O.544
0523
External
Diameter of
Pipe in
Inches.
7
8
9
10
12
Heat Units
Lost.
O.609
O.498
O.489
O.4S2
0.472
External
Diameter of
Pipe in
Inches
iS
24
36
48
Heat Units
Lost.
0.455
0.447
0.438
0.434
1.36 1.47 *--58
1.12 1.16 I.25 1.30 1 40 1.52 168 1.76 1.91 2.06 2.23
I.O7 I.l6 1.20 1.25 1 35 «-45 1.58 1.70 1.83 1.99 2.14 2.31
I 12 1.20 I 25 I.30 1.46 1.52 1.64 1.76 1.90 2.07 2 23 2.40
1.16, 1.25 1.31 I.36 1.40 1.S8 1.71 1 84 1.98 2.15 2.33 2.51
i2i 1.31 1 36: 1.42 I.S2 i.bs 1.78 1.92 2.O7 2,28 2.42 2.02
1,26 1.36 1.42 1.48 1.59 1.72 1.86 2.00 2.l6 2-34 3.52 2.72
1.32I 1.42 1.48 1.54 1.65 1.79 1.94 2.08 2.241 2 44 2.64 2.83
1,37 1 48 1.54 r.60 1 73 1.86 2.02 2.17 2 34 2 54
1.44 1.55I 1.61 1.68 1.81 I9S
1 so 1.62 1.69 1.75 i.«9 2.04
i,S8 1.69 I.76 I.83 1.97 2 13
1.64 1.77 I.84 I.90 2.06 2 28
1.71 1.8s 1,92 2.00 21^ 2.33
1.79 "•93 2.01 2.09 2.22 244
1 89. 2.03 2,12 2.20 2.37! 2.56
1.98 2.13 2.22 2.3I 2.49 2.69
2.07, 2 23 2.33 2 42 2.62' 2.81
2.17 2.34 2.44 2.54 2.7312.95
2.27 2.45 2.56 2.66 2.86 3.O9
2.39 2.57 2.68 2 79 3.00 3-24
2.50 2.70 2.81 2.93 3 IS 3.4O
2.63 2.84 2.95 £.07 3.31 -)-5i
2.76 2.98 3.10 3.23 3.47 3.7O
1 2.74 2.96
2.11 2.27 2.46 2.66 2.87 3.10
2.21: 2.38 2.s6 2.78 3 oo
2.32 2.48
1 3 24
2.68 2.91, 3- T 3 3-3-5
2.43 2.52 2.80' 3.03 3.28 3.46
2 52 2.71, 2.92 3.18 3.43 3.7O
2.64 2.84 3.06 3.32 1 3.58 3.87
= •78 2.99 3 22 3.50 3.77 407
2 90 3.I2 3.37, 3.66 3.95 4 26
3.04 3.28 3.53 3.84 4 14 4.46
3'9 3 44 3-7° 4-° 2 The loss of heat by convection is nearly proportional to the
difference in temperature between the hot body and the air;
but the experiments of Dulong and Peclet show that this is not
exactly true, and we may here also conveniently resort to a
table of factors for correcting the results obtained by simple
proportion.
TABLE 4.- -FACTORS FOR REDUCTION TO DULONG'S LAW OF
CONVECTION.
4-34 4-68
3-35 3°° 3-88 4 22 4.55 491
Diff in Temp.
between Hut
Body and Air.
Factor.
Diff inTemp.
between Hut
Body and Air.
3 51 3.78 408 4.42, 4.77 5.15
3 68 3.97 428 4.64 501 5.40
387 4.12 4.48 4.87 5.26 5.67
4.10 4.32 461 5.12 5.33; 6.04
1 1 l
iS° Fah.
36 "
54 "
72 "
90 "
108
126 "
144
162 "
O.94
I.I I
1.22
I.30
'•37
1-43
1.49
i-53
158
1S0 0 Factor.
Diff. in Temp.
between Hot Factor.
Body and Air
Fah.
198 "
216 "
234 "
252 "
270 "
288 "
306 "
324 "
I.62
1-65
1.68
1.72
1-74
1-77
1.80
1.83
1.85
342° Fah.
360 "
378 "
396 "
4H
432 *'
450 "
468 "
..87
1.90
1.92
1.94
1.96
1.98
2.00
2.02
The use of these tables may be illustrated by referring once
more to the example iu radiation already given. To find the
amount of heat lost by convection by the same pipe we proceed
as follows : According to Table No. 3, a pipe 2 iuches in external
diameter would lose 0.728 of a heat unit persquare foot of surface
per hour for a temperature difference of one degree Fah. The
corresponding number for a pipe 3 inches in external diameter
is 0.626. Hence we infer that a pipe 2 11-32 inches in outside
diameter would lose about o 693 heat units per square foot of
surface per hour, for one degree of temperature difference. (For
the difference between .728 and .626 is .102 and 11-32 of .102 is
.035. Then .728 — .035 = 0.693.)
The area ofthe pipe has already been found to be 6.14 square
feet. Hence 6.14 x 693 = 4.26 heat units per hour would be
lost by convection by the whole pipe if its temperature were i°
higher thau that of the air. As a matter of fact, its temperature
exceeds that of the air by 323°; hence the total loss per
hour by convection would be 4.26 x 323 = 1,376 heat units, if
the convection loss were strictly proportional to the temperature
difference. As it is not so, we must take the proper correction
factor from Table 4. We find this factor to be 1.85 •
hence 1,376 -4- 1.85 = 2,546, which is the number of heat units'
we may expect the pipe to lose, in oue hour, by convection.
Hence, finally, we have—
Total loss of heat = total radiation loss -f total convection
loss.
=2,627 -f 2,546 = 5,173 heat units per hour.
As a final example of the calculation of the loss of heat by
steam pipes let us find the amount of heat lost in one hour by
a naked steam-pipe 2 11-32 inches in external diameter and one
foot long, conveying steam at a pressure of 55 lbs. by the gauge
the temperature of the air and surroundings being 8o° Fah
The temperature of the pipe will be found to be about 302°
Fah. We have already found the surface of such a piece of

October, 1892.] ENGINEERING MECHANICS. 265
pipe to be 0.614 of a square foot. The calculation, then, is as
follows :
Temperature difference X 302 0 — 8o° = 222°.
Radiation loss per hour by Newton's law =
0.614 (area X -64 (see Table 1) x 222 = 87.2 heat units.
Same reduced to conform with Dulong's law of radiation =
87-2 X 1.98 (see Table 2) = 173. heat units per hour.
Convection loss per hour (considered proportional in temperature
difference) =
0.614 (area) x .693 (see Table 3) x 222 =94.6 heat units.
Same reduced to conform with Dulong's law of convection =
94-6 X 1.70 (see Table 4)) = 160.S heat units per hour.
Then the total loss of heat per hour — loss by radiation +
loss by convection.
•73-0 + 160.8 = 333.8 heat units per hour.
It is not claimed that the results obtained by this method of
calculation are strictly accurate. The experimental data are
not sufficient to allow us to compute the heat-loss from steam
pipes with any great degree of refinement; yet it is believed
that the results obtained as indicated above will be sufficiently
near the truth for most purposes.
THE Babcock & Wilcox boilers were selected by the Electrical
Engineering Company of Ireland for the Dublin Central
Electric Lighting Station, located in Fleet Street of the Irish
Capital. The steam generating plant consists of four ofthe Babcock
& Wilcox type of water-tube boilers, each capable of
evaporating 8500 lb. of water per hour, at a pressure of 150 lb.
per square inch. The total heating surface in each boiler is 510
square feet. They are set in two batteries of two boilers each,
each battery being provided with a steam receiver having outlets
for the connections to the maiu ranges of steam pipes. Each
boiler is composed of fourteen sections of slabs, each section
being composed of eight best lap-welded wrought-iron tubes,
4 in. in diameter and 18 ft. long, connected at the ends by continuous
staggered headers or " up takes " and " down takes," the
tubes being fastened therein by being expanded into tapered
holes. The several sections are connected at each end to two
steam and water drums, and at one end with a mud drum, by
means of lap-welded wrought iron tubes, 4 in. in dimeter and of
suitable length, expanded iuto cored holes. The steam and
water drums are 36 in. in diameter and 32 ft. 7 in. long, made of
steel, A in. thick, and have longitudinal seams double riveted,
and they are provided with a manhole at one end and two nozzles,
oue for a safety valve and one for taking off steam, 5 in. diamter,
with an 11 in. flange, faced and drilled. Each boiler is fitted
with two safety valves of 5 in. diameter, set to blow at 155 lb.,
and there is a steam pressure gauge in front. In close proximity
to the boilers are erected three Worthington steam pumps, each
capable of supplying water to two of these boilers when fully
loaded. There is also all the requisite wrought iron piping for
the connections between the pumps, boilers and water tanks, the
latter being erected in front of boilers, over the coal bunkers.
Close to the large chimney shaft are the three feed-water heaters,
each heating a sufficient quantity of water to feed two of
the boilers. They are connected with the main exhaust steam
pipe, and are fitted with bye-passes and a complete arrangement
of stop valves to enable the exhaust steam from the engine to be
sent through any of the feed-water heaters or past them. The
exhaust pipes are carried from the heaters up the chimney to
within a few feet from the top.
THOSE who are using low pressure steam boilers will find
something worth examining in an automatic feed water apparatus
manufactured by John R. Hanlon of Pennington, N.J.
The arrangement consists of a tauk furnished with two
valves; one, an automatic float valve connected with the water
main and regulating the supply of water to the tank, while
another small float valve is fastened to the bottom of the tank
and connected therefrom directly with the boiler. This last
mentioned valve is governed by the flow of water into the
boiler and by steam pressure from the boiler. When the steam
pressure is off or very low, aud the height of water in the
boiler is below the pre-established level, the water in the tank,
seeking its proper level in the boiler, forces the valve from its
seat and the flow into the boiler begius. The supply valve
maintaining the same level of water in the tank, the flow
through this valve in the bottom of the tauk will continue until
there is a corresponding level of the water in the boiler. Wheu
this point is reached, the downward pressure upon the valve
ceases and the valve in virtue of its floating quality is lifted
against its seat and closed, thus preventing the possibility of
backward pressure from the boiler forcing the water back into
the tank; in fact, the stronger the pressure, the tighter this
valve binds to its seat.
MODEL LOCOMOTIVE ENGINES.
The Baltimore & Ohio Railroad has just p'aced in service on
its Chicago Division three new passenger engines, built at the
Baldwin Locomotive Works, after new designs furnished by
the General Superintendent of Motive Power of the B. & O.
Company. The engines weigh 113,000 pounds, have driving
wheels six feet six inches in diameter, cylinders 19 by 24
inches, and are without doubt the finest passenger locomotives
running into the city of Chicago to day. Companions of these
new engines have developed wonderful power and speed in
hauling the famous Royal Blue Line trains, which run between
New York, Philadelphia, Baltimore and Washington, over the
Philadelphia Division of the B. & O. Railroad. The B. & O.
has added over forty new, high class engines to its motive
power equipment within the last sixty days, and others are
under construction. While constantly adding engines of approved
design aud highest grade to its motive power, and passenger
coaches of Pullman standard to its rolling stock, the
B. & O. is also expending large amounts for additional second
aud third tracks and sidings, and improved facilities at terminal
points. By the time the World's Fair is opened for the reception
of visitors the B. & O. will be well equipped to handle expeditiously,
the large volume of passenger traffic which will
naturally seek this picturesque route from the Atlantic seaboard
to Chicago.
THE TITAN OF CHASMS.
A Mile Deep, 13 Miles Wide, 217 Miles Long, and Painted Like a Flower.
THE Grand Canyon of the Colorado River, in Arizona, is now
for the first time easily accessible to tourists. A regular stage
line has been established from Flagstaff, Arizona, on the Atlan­
tic & Pacific Railroad, making the trip from Flagstaff to the
most imposing part ofthe Canyon in less than 12 hours. The
stage fare for the round trip is only $20.00, and meals and com­
fortable lodgings are provided throughout the trip at a reason­
able price. The view of the Grand Canyon afforded at the
terminous of the stage route is the most stupendous panorama
known in nature. There is also a trail at this point leading
down the Canyon wall, more than 6000 feet vertically, to the
river below. The descent of the trail is a grander experience
than climbing the Alps, for in the bottom of this terrific and
sublime chasm are hundreds of mountains greater than any of
the Alpine range.
A book describing the trip to the Grand Canyon, illustrated
by many full-page engravings from special photographs, and
furnishing all needful information, may be obtained free upon
application to Jno. J. Byrne, 723 Monadnock Block, Chicago,
111.
THE annual meeting of the American Society of Mechanical
Engineers takes place in New York City Nov. 14th to 18th.

266 ENGINEERING MECHANICS. [October 1892.
SOME English writers take the view that as long as the protective
tariff policy prevails in this country they need have no
fears of competition in neutral markets from this side of the
water. The conclusion is not logical. Industries observes,
"The American people are aiming at two hitherto irreconcileable
things—that of having the cake of protection, and yet eat­
ing the fruits of unfettered trade. Whether this difficult achievement
will ultimately come to be reckoned among the many
wonderful things that the Americans have already done, time
alone cau show."
It draws comfort from the fact that our skilled labor is 75
to 100 per cent, higher than in Englaud, aud that this fact increases
cost of products to a point that will probably bar us out
of foreign markets. The point is overlooked that this very fact
increases the efficiency of labor, and that as measured by a unit
of time the difference in cost is much less, very much less, thau it
appears to be. Whether the increased efficiency of high-priced
American labor can altogether compensate for the cheaper per
diem labor of foreign workmen is the problem now under solution
The multiplication of labor-savingdevices, ofthe expansion ofthe
volume of work done by improved machinery was never as great.
There is a race between labor and labor-saving appliances on
this side that foreign employers are only slightly acquainted
with. An equalization is in progress, through immigration and
through improving machinery, and employers abroad should be
careful iu drawing conclusious based merely upon cheaper per
diem compensation of their workmen.
THE Northern Railway of France has lately announced some
results achieved by two uew compound engines built last year.
The running has never been paralleled in France in any regular
services. These engines have taken 120-ton trains from Paris
to Amiens—82 miles—in 1 hour 30 minutes = 54.6 average, and
from Paris to St. Ouentin, 95 miles, in 2 hours = 47.0 average.
In regular service with ordinary trains they have, in the
course of three months, given an average of 46 miles per hour
between Paris and Amiens. Between Lille and Paris the best
speed has been 49.2 for 157 miles. Between Paris aud Mons
have been the lowest of all records - 42 miles.
On a dead level, with trains of 206 tons, it has been 56. On
grades of 1 in 200 continuous for 12 miles, it has averaged 47,
with trains of 196 tons—engine not included of course—and 50
and 53 for trains of 138 tons weight. Betweeu Amiens and Paris
the runs have been made over the inequalities throughout at a
nearly continuous rate. To the summit of a gradient 1 iu 125
soon after leaving Calais, the speed has averaged 43 miles per
hour with a train of 140 tons.
The boiler is of iron, A in- I single lap joints ; telescopic rings ;
smallest rings between the forward drivers ; pressure 182 pounds.
Low-pressure cylinders are cast in one piece with the saddle,
which forms the reservoir or receiver. Their valve chests are
placed at an angle with the top and side, a position very accessible,
aud largely adopted in Belgian practice for this reason.
The small cylinders are situated outside the frames at the
centre of the eugine, and receive steam from the dome by the
outside pipes. The exhaust from the high-pressure cylinders
enters a three-way passage of T plan. A hollow cock or shield
covers either the direct passage to the cylinders or the rightangle
junction leading to the chimney exhaust. These threeway
cocks are actuated by a very small steam cylinder placed
beneath the boiler, thus avoiding a number of levers from the
foot-plate. With this appliance the full tractive force of nearly
10 tons can be applied in starting without changing the receiver
pressure of 7S lbs. In case of accident to either group of cyl­
inders, it permits either pair to be worked alone. The maximum—theoretical—effort
in the large cylinders with steam
taken direct from boiler to the receiver is 5 tons, and 4.7 tons in
the small cylinders at boiler pressure. This power combined
means au adhesion of j!;, which is scarcely possible with the
steam sand jet, aud out of the question with the coupling-rods
taken off, as has been tried. Valves and cylinders are fitted
with automatic greasers.
The lap on high aud low-pressure ports is 'g in. inside and
r
English electricians are averse to any general introduction of
new terms in electrical nomenclature at preseut. The degree of
electrical resistance developed in wire under different conditions
is unascertained. The operation of winding wire increases
resistance as diameter of bobbin decreases. Alloys containing
manganese are preferable to those containing zinc. Electricians
find it difficult to obtain a substance with a constant resistance
to use in establishing electrical standards. The British
Association has after patient investigation adopted the following
units of resistance :—(1) That the resistance of a specified
column of mercury be adopted as the practical unit of resistance
; (2) that 14 4521 grammes of mercury in the form of a
column of uniform cross-section, 106.3cm. in height, at o° C. be
the specified column; (3) that standards in mercury or solid
metal having the same resistance as this column be made and
deposited as standards of resistance for industrial purposes ; (4)
that such standards be periodically compared with each other,
and also that their values be redetermined at intervals in terms
of a freshly set up mercury column.
7 ,; in. outside. The valve gears of the two groups are Walschaert's
patent.
The inside cranks have round nuts; pressure on bearings
outside, 12.9 tons. Against this difference the weight under
the forward drivers is 440 lbs. more than the rear wheels connected
to the outside cylinders. Instead of the four cranks
being arranged at right angles with each other, or at 180 deg.
individually, they are set at angles of 162 deg., and thus at
least one of the cranks is always off the dead centre, and the
delays of starting common to two-cylinder engines is avoided.
The reversing screws are twins, actuated simultaneously by
one hand wheel for the ordinary working as compound. The
wheel is mounted on the low-pressure screw shaft, but instantly
ungeared to act only on the high-pressure valves. The mechanism
is very simple. A trigger is placed on the periphery
of the hand wheel, and keys or uukeys the wheel from the
screw shaft. Fixed rigidly on this hand wheel is a pinion
whicli gears into another that is fixed on the end of the outside
or high-pressure screw. When this wheel is keyed to its
shaft, it actuates the two screws together, or, if it turns loose •
on its shaft, only the second shaft of the high-pressure cylinders
is moved. A second stationery trigger keys into the
wheel shaft to prevent its turning when only the secondary
shaft is to be worked. Consequently, if the wheel is locked to
its shaft and the stationary trigger locks the shaft in its bearing,
no movement is possible in either direction by either
screw. The usual graded scale has two index fingers, and if
these start from zero together, the admissions to the two cylinders
are kept equal. But when under way, the- high-pressure
cylinder valves are worked independently of the low by unkeying
the hand wheel.
The frames are lis in. thick, and strongly stayed inside between
the two outside cylinders by a cross piece 27 in. long.
The tender holds 4 tons coal, 3300 gallons water, and rests on
6 4S-inch wheels ; loaded, 33 tons. Coal consumption is 32
pounds per mile against 35 in older engines. Water evaporated
7)2 pints per mile, per square foot of grate area.
There are 202 tubes, 12 ft. 9 in. between plates. Heating surface,
fire box, 116.9 sq. ft., tubes 1065.2 ft. Boiler capacity, 205.7 cubic
ft. Stroke, 25X in. drivers, 6 ft. 11 in. weight, loaded 47 tons.
THE MOUNTAINS OF COLORADO.
Denver, Estes Park, Colorado Springs, Manitoe aud Gleuwood
Springs may be reached from Chicago or St. Louis via.
the Burlington Route fast vestibuled express trains, handsomely
equipped with every modern improvement. Write
P. S. Eustis, Gen'l Pass Agent, Chicago, for particulars.

October, 1892.] ENGINEERING
THE water route between Montreal and Lake Erie is as fol­
lows : through the Lachine Caual (8% miles), five locks, depth
of water on sills, 9 f. to 10 ft.; Lake St. Louis (15A miles) ; the
Beaucharnais Canal (u# miles), nine locks, depth of water, 9
ft.; Lake St. Francis (32A miles); the Cornwall Canal (11)2
miles), six locks, depth of water, 9 ft. ; Farran's Point Canal
(A mile), one lock, depth of water, 9 ft. ; Rapids Flat Caual (4
miles), two locks, depth of water, 9 ft.; Gallop's Canal (7 A
miles), three locks, depth of water, 9 ft.; and after Lake Ontario,
the Welland Canal (27^ miles), 27 locks, depth of water,
14 ft., to Lake Erie. Thence, via Detroit River, Lake St. Clair,
St. Clair River, Lake Huron, and Mackinac Straits, to Lake
Michigan, on which there is plain sailing in navigable waters
to Chicago.
A CERTAIN Mons. Deloncle has started the idea that a monster,
or rather a monstrous, telescope shall be constructed for
the Paris Exhibition to be held in the year 1900. The telescope
is to be a reflector with silvered glass mirror with a focal length
of about 130 ft. The mirror is to be 9ft. 10 in. indiameter, and
will weigh 9 tons. All sorts of things are expected of this telescope.
Those who have had any experience iu telescope work
know, however, that these promises caunot be fulfilled. Granted
that the instrument is perfect, its immense area will be none
the less useless. The utility of a telescope depends on the
aerial conditions, aud years might elapse before it was possible
to use such a telescope with advantage. Even the great Lick
telescope with an object-glass nearly 3 ft. in diameter placed
under presumably the best possible atmospheric conditions has
proved thoroughly disappointing, and it is said that better work
is done with 8 in. refractor at the same observatory.
THE Council of the British Institution of Civil Engineers in.
vites original communications ou the subjects included in the
following list, as well as on any other questions of professional
interest. This list is to be taken merely as suggestive, and not
in any sense as exhaustive. For approved papers the Council
has the power to award premiums, arising out of special funds
bequeathed for the purpose.
The Council will not make auy award unless a communication
of adequate merit is received, but will give more thau one
premium if there are several deserving memoirs on the same
subject. In the adjudication of the premiums no distinction
will be made between essays received from members of the Institution
or strangers, whether natives or foreigners, except in
the cases of the Miller and the Howard bequests, which are
limited by the donors.
1. Standard Forms of Tests for Materials used iu Engineering
Construction.
2. The Methods and Cost of Converting Limestone into Lime.
3. The Design and Constructiou of Railway Passenger Car­
riages, having reference to (a) strength and safety ; (b) ease and
smoothness of motion ; (c) durability ; (d) moderate deadweight
; (e) facility for entrance and exit; (fi) lavatory accom­
modation ; (g) provision for refreshments; and (h) sleeping ar­
rangements.
4. The Cost of working Electrical Tramways, taking account
of Interest on capital, and of a sinking fund for depreciation.
5. Ship Canals, and the Canalization of Rivers.
6. The Design and Construction of Ship Railways.
7. The Failures of Reservoir Embankments and Dams, aud
the Causes to which they may be ascribed, with suggestions for
avoiding or remedying them.
8. The Disposal of Towu Refuse by Burning, and the appli­
cation of the heat thereby generated.
9. The Action of Weirs in times of Flood.
10. The Working of Inclined Retorts in Gasworks.
11. The Design and Construction of Modern Gasholders of
large size.
MECHANICS. 267
12. The Carburetting of Gases for Illuminating Purposes.
13. The most suitable form of Electric Light Mains, having
regard to durability, economy of conducting material, and
facility for making and laying house connections.
14. The Risks of Electric Lighting to life and property, with
the means to be takeu to prevent or lessen them.
15. Plant for the Construction of Sea Works.
16. The Methods of and the Machinery for Tunnelling.
17. The various Systems of Mechanical Ventilation for Mines,
Long Tunnels, Underground Railways, Sewers, &c.
18. The Design of Lofty Iron and Steel Structures.
19. The Laying-out of Engineering Workshops.
20. Modern Machine Tools and Workshop Appliances.
21. The Continuous Running of Steam and other Engines,
with details of construction.
22. The best Arrangement of Engine for any given Electric
Light Station.
23. The various Systems of utilizing Compressed Air, Water,
and Liquefied Gases for Motive Power.
24. The recent developments of Mechanical Refrigeration.
25. Coal Shipping and Discharging Apparatus.
26. The Method of Trans-shipping Grain, and its Classification
and Storage in Granaries.
27. The Structural and other Defects of Iron aud Steel Ships,
aud their Causes.
28. The most Recent Types of (a) Passenger and Mail Steamers
; (b) Cargo Steamers ; (e) Warships; and (d) Ferry Steamers.
29. The Comparative Efficiency of Different Types of Marine
Engiues.
30. Electrical Motors for (a) Inland Navigation ; (b) Ocean
Vessels.
31. Mechanical Propulsion for Lifeboats and for small Undecked
vessels.
32. The Raising of Wrecks, with a Description of the Plant
employed.
33. Mining Operations, including the Sinking and Timbering
of Shafts, Fixing Pumps, &c.
34. Coal-winning in seams situated at great depth below the
surface.
35. The Surface Arrangements of Collieries, including those
for banking, cleaning, sorting, screening, and shipping the coal.
36. The best means of Utilizing the Slack of Non-caking
Coal, including Briquette-making.
37. Recent Improvements in Pumping Machinery.
38. Quarrying Operations and the Plant Employed.
39. Recent Blast Furnace Appliances, with reference to temperature
and pressure of blast, &c.
40. The Modern Practice in the Manufacture of Finished
Steel, having regard to increase of output aud diminution of
cost.
41. The Present Position of the Manufacture of Basic Steel.
42. The Manufacture of Aluminium and its Alloys.
43. The Influence of the Minute Admixture of Metals on the
properties of Metallic Alloys for Engineering Uses.
44- The Concentration and Sizing of Crushed Ore and other
materials.
45. Tin Dressing as practiced in Cornwall.
46. The Manufacture of Lead aud the Extraction of Silver.
47. Smelting processes as applied to the Extraction of Precious
Metals from their Ores.
48. The treatment of Gold and Silver Ores in the United
States.
49. The Electro-deposition of Copper.
50. On the applicatiou of Water Power aud its Transmission
to a distance by Electricity.
51. The Design of Electric Locomotives.
52. The Practical Working of Multiphase Alternating-current
Motors.
53. The Design and Manufacture of Small Arms aud of Quickfiring
Ordnance.

268 ENGINEERING MECHANICS. [October, 1892.
ENGINEERING enterprises of great magnitude are multiplying.
The example of the construction of the Manchester Ship
Canal has stimulated a number of somewhat similar enterprises.
A 22 mile cog-road is projected in Switzerland across the Simplon
Pass, a portion of which involves the construction of a five
mile tunnel. The estimated cost of the undertaking is six million
dollars. The commercial and technical societies of Holland
have petitioned the Government to advance the work upon the
draining of the Zuyder Zee as fast as possible. The estimated
cost of the work is $76,000,000. It requires the erection of a
dyke 26 ft. high and tweuty-five miles long, and involves the
removal aud reconstruction of the coast defenses.
IN the recent discussion on Portland cement by members of
the Institution of Civil Engineers, Mr. H. K. Bamber remarked
that cement was often stored for some weeks aud turned over
to lessen its tensile strength with the mistaken notion of making
it safer to use. The high tensile strength now realized is
obtained by using a larger quantity of lime than formerly, and
the object of exposure to the air is to weaken the excess of
lime. Wheu Portland cement was less finely ground thau it is
at present, it was well to keep it some time before use, because
then most of the larger particles were reduced to powder, but
ground so that the whole passes through a sieve of 2500 meshes
to the square inch, and 90 per cent, through one of 5625 to the
square inch, it is not only useless, but detrimental to keep it
for more than a month.
IN the Technograph, Mr. E. S. Keene describes some experiments
made to determine the relative efficiency of different cutting
augles in lathe tools. The apparatus used was a spring
dynamometer attached to the face-plate of a lathe. This dynamometer,
iu its essential features consisted of two blocks
screwed into the face-plate, the left-hand block having one end
of a spring coil fastened to it. A pin, parallel to the axis of the
spring, passed freely through holes in both blocks, so as to
receive the thrust ofthe dog driving the piece operated upon.
This pin in turn compressed the spring. A roll of paper was
also arranged on the face-plate to give a continuous record of
the spring pressure. The angles of the tool were measured by
a bevelled protractor. The angle of forward inclination of the
tool is called " clearance," aud that of the side of the tool " side
rake," and the angle made by the upper cuttiug face of the
diamond point is called "top rake." A\\ angles were measured
from vertical or horizontal planes. The angles of " top rake "
ranged from o deg. to 20 deg., of " side rake " from 10 deg. to
20 deg. With tools of 25 deg. " side rake " the average increase
in the efficiency of cutting for each 5 deg. of " top rake " was
18.73 P er cent. With 20 deg. " side rake" the increase was 23.8
per cent, and with 10 per cent, "side rake" it was 38.63 per
cent.
AT the last prize contest instituted by the City of Paris for
the best electric meter the prize of 5000 f. was awarded to Professor
Elihu Thomson. With the desire that this sum should
serve for the development of the theoretical knowledge of electricity,
he has requested M. E. Thurnauer, General Manager for
Europe of the Thomson-Houston International Electric Company,
to offer a prize for the best work on a theoretical question
in electricity, and to organize a committee who should propose
the subjects, examine the productions, and decide the prize.
The committee has decided that the prize should be giveu for
au investigation ou one of the following subjects:—[x) The
heat developed by successive charges and discharges of condensers
under different conditions of frequency, nature of dielectric
and quantity of charge. (2) It has been shown theoretically
that wheu the two surfaces of a condenser are connected by a
conducting body, the condenser becomes the source of alternatiug
currents as soou as the resistance ofthe conducting body
decreases below a certain limit. The formula that permits cal -
culating the period of this oscillation has not yet been completely
verified. This period of oscillation should be investigated
experimentally under conditions such that the exact
measure of resistance, capacity and coefficients of self-induction
may be possible, in order to arrive at a complete and precise
verification of this formula. (3) When a condenser made with
an imperfect insulating material has been charged and then left
to itself, the charge is gradually dissipated. The time necessary
for the charge to be reduced to a giveu fraction of its initial
value depends only on the nature of the insulating material. It
is proposed to investigate whether, as certain recent theories
would seem to indicate, analogous phenomena do not present
themselves in metallic conductors, and whether these can be
shown experimentally. (4) It is proposed to arrange and systematize
our present knowledge of the graphical solutions of
electrical problems, and deduce from them some general methods
as iu graphical statics. The theses presented may be written in
English, French, German, Italian, Spanish or Latin. They may
be in manuscript or printed. The papers must be seut before
the 15th September, 1893, to B. Abdank-Abakanowicz, Consulting
Engiueer, 7, Rue du Louvre, Paris.
THE whole subject of canal building across the narrow territory
connecting North and South America is now up for thorough
engineering consideration. That one or more watercourses
must soon be opened up for Pacific commerce is a
recognized fact and necessity. Much as the matter has been
considered, there is yet doubt in the highest engineering circles
as to the best route considered from commercial, military,
financial and engineering points ; for engineering talent has to
take cognizance of all factors. In connection with this, much
exploration has been done, and resources of great value and
diversified character have been discovered in contiguous territory.
English engineers acting for and under British capitalists
representing large ship building and commercial interests,
have made and still, are making exhaustive explorations and
investigations as to soil, climate, mineral aud timber wealth,
all with a view of not only building a canal, but also opening
up some of these resources as fields of future investment.
German enterprise is by no means asleep, and ship lines are
projected which will help much in the development of the
Central American region. With the construction of a canal
comes the building of railroads in Honduras, Nicaragua and
adjoining territory. The construction of railroads may not be
so long coming as Americans imagine ; in fact, well-considered
plans for an inter-oceanic railroad in Nicaragua show these
advantages over the Panama routes :
1. On the Pacific Coast the harbor at Corinto is perfectly
land-locked, with deep water and best facilities as to space and
depth for constructing wharves for handling freight direct.
2. Fifty miles of line already constructed.
3. Route crosses an already populous portion of the Republic
where the cities are situated, thus securing a large local business
for railway.
4. Light grades over nearly the whole extent of the route
with the exception of a few miles at the summit, where a gradient
of 2.5 per cent, may be used.
5. Cheapness of cost of construction of greater part of the
route, which would uot exceed 25,000 dollars per mile.
6. Sixty-five miles of natural inland navigation where largest
ocean steamers could penetrate at a comparatively small cost
for deepening Blewfields River bar. Steamers drawing 12 ft.
have now no difficulty in entering.
7. The security of both terminal harbors for both sail and
steam vessels.
S. Abundance of fresh provisions and water at both harbors.
9. A large and valuable land grant.
10. Salubrity of climate at both ports and in interior.

October, 1S92.] ENGINEERING MECHANICS. 269
THE RAILWAYS OF THE GLOBE.
At the Railway Congress now being held iu St. Petersburg, a
statistical tableau showing the lines open in different quarters
of the world was presented, and this tableau shows that their
total length at the beginning of this year was 385,803 miles, of
which 167,755 are in the United States, 14,082 miles in Canada,
and 5,625 miles in Mexico and the Argentine Republic. In
Europe, the German Empire comes first with 26,790 miles,
France second with 24,310 miles, Great Britain and Ireland
third with 22,685 miles, and Russia fourth with 19,345 miles.
Wurtemburg and Denmark are the countries which have made
the least progress in the construction of railways since 1886;
while in Asia, apart from the 16,875 miles of lines in India, the
Trauscaspian line recently constructed by the Russians is 895
miles in length, the Dutch colonies have S50 miles of railway,
the French 65, and the Portuguese 34, while there are 125 miles
of Hues in China, aud 18 in Persia. In Africa, the colony of
Algeria and Tunis comes first with 1,940 miles, the Cape Colony
second with about i.SSo miles, Egypt third with 965 miles, and
Natal fourth with 341 miles ; while the Orauge Free State has
150 miles.
THE experiments made in the application of electrical energy
to the supplanting of steam on war ships are progressing favorably.
The contest betweeu the mechanical aud the electrical
engineer is a good-natured oue and each learns from the other.
One point made by the mechanical engineer is that iu case of
flooding of compartments the electrical devices would cease to
work and might even bring the branches of main circuits into
communication with one another and thus threaten grave consequences.
Electro-motors, they also argue, are not suitable
for deck work where rains and heavy seas might attack them,
cor for working rudders or auchors in which the resistance to
be conquered might suddenly change and be beyond the power
of the motor. It is fouud advisable to have at least two dynamo
generators and that both be kept moving in order to secure
as much as possible the continuous action of the working
machinery. As ship machinery must be small because of limited
space, the revolutions of motors must be faster and this
requires that the peripheric velocity of their framework should
be high.
By dynamo-electric machines of compound coil, well regulated
to supply at a constant velocity a variable electric current
with a constant potential, and employing also a compound coil
motor, placed derivatively on the main circuit, tbe working
machinery can even now be moved at a constant velocity,
whatever be the resistance to be conquered and at the will of
the manipulator, without the action of these motors influencing
that of the others or changing the movement of the
generatrix. And this essential condition becomes so much
easier of attainment on board ships, where the circuits being
short, they can be effected with very little resistance. With
proper contrivances the velocity ofthe working machinery cau
also be varied, although not so very extensively as by other
systems of transmission.
Nabre Soliani, Chief Engineer of the Italian Navy Department,
gives his conclusions as follows : I am inclined to think,
that upon the whole the area of electric application on board
vessels is not so extensive as it might at first sight appear, and
that improvements must be made before electricity supersedes
those other means which are now used for the transmission and
distribution of power. I do not mean to say that these improvements
will never be attained. On the contrary, in all probabil­
ity, if not certainty, this will be done, and perhaps the day will
come when even the main marine engines will become electromotors
; I mean when we shall be able to store up on board
ships electrical power, in the same way we now store up coals,
or rather, wheu we shall succeed in transforming directly into
electricity the power contained in coal. I must now say a few
words about the results of the system. All authors agree that
for short distances the result of power of this system is
very high. If the dynamo generators and motors are well
proportioned aud act upon proper conditions, it is admitted
that the economy of power is not below 75 per cent, between
the engine of the dynamo generator of the current and the
motors ; or rather between the work of the steam on the pistons,
and that ofthe electric power on the shafts ofthe motors.
We may admit without being much mistaken that this latter
corresponds with the work brought on the pistons iu ordinary
compressed air or water motors, and therefore the said result
may be compared with their results. If, as for such cases, we
suppose the actual power result from the dynamo engine is
0.60, the entire power result from the electric system of power
transmission and distribution is : 0.60x0.75=0.45, say 45 per
cent., which little differs from the result given by the other
indirect systems, viz, by compressed air, or by hydraulic
apparatus.
THE WM. CRAMP &. SONS' SHIP AND ENGINE BUILDING
COMPANY
THIS plant covers 25 acres in the city of Philadelphia, and has
a water front of 1229 feet. Between 3600 and 4000 men are
employed. Total tonnage under construction 43,698 tons.
Marine engines under construction 76,000 horse power, laud
engines, 25,000. Value of five ships under construction,
$ 14,526,000. The dry dock is 462 feet long, cost f 500,000,
capacity, 5,400,000 gallons, pumping capacity, 120,000 gallons
per minute. The floating crane has a lifting force of over 100
tons.
This firm has built: 18 war vessels ; 2 lighthouse tenders ; 6
steam yachts; 68 ocean steamers ; 22 steamboats ; 54 tugs and
towboats ; 7 ships; 1 bark ; 7 brigs ; 13 schooners; 11 vessels
lengthened and rebuilt ; 58 vessels, such as sloops, lighters,
barges, floating docks and caissons. Total 267.
The machinery, tools and shop appliances are all of extraordinary
size and capacity, befitting such an establishment. The
plant is in fact an exposition of machinery. In the engineering
department thirty-six draughtsmen are constantly employed, in
the construction department, thirty-five. Total number of men
now at work, 3621. The largest engine yet made at these
works had a capacity of 12,000 horse power. The boiler shop
is equipped with two 50 ton electric cranes. The vertical bending
rolls are used to bend metal up to 1 }4 inches thick, and
plates 11 feet wide can be handled. The hydraulic motor has a
swing of 11 feet and cau be used in a boiler 22 feet long and 17
feet diameter. The five war vessels now under construction
are the U. S. S. New York, 8150 tous displacement, 16,000 horse
power ; cruisers Nos. II, 13 ; 7475 tons displacement, 21,000 horse
power; U. S. S. Indiana aud Massachusetts, 10,298 tons displacement,
each 9,000 horse power. The Cramps are making
triple expansion engines, superior to the best engines of
English yards. The work they are putting in Cruiser No. 12 is
designed to excel auy achievements on record as to engine
power and work. Older shipbuilders are more content to build
on old models and wait for the pressure of new requirements to
stimulate them to exertion. The Cramps make every new ship
as a whole and as to every part and detail of it, a study. Experiments
and tests and observations are always perfecting and
furthering work in hand. A spirit akin to that of enthusiasm
inspires all work in this great plant. Present results are
regarded merely as good enough for the present, but the Com­
pany, its engineers, draughtsmen and constructors all vie with
each other in a struggle to do the very best in their respective
departments. It is in American ship building yards that the
greatest progress in ship building will be made in the future
aud for the best of reasons.

270
THE Rue Manufacturing Co., 116 North 9th St., Philadelphia,
have entered upon their early winter work with a marked in­
crease in orders.
THE contract for pumping machinery, including Compound
Duplex Pumping Engines, Deep Well Steam Pumps, Boilers,
Heater, etc., for Wyoming Water Works, Wyoming, Ohio, has
been awarded to the Laidlaw & Dunn Co. of Cincinnati.
OLD bolts and nuts make a costly scrap heap, because the
vibrations to which they are subject, loosen them and wear the
first and second threads. J. C. Saxton, 52 Broadway, New York,
is selling a nut lock which renews the bolt by means of an
eccentric jam-nut. It is so arrauged that the force of gravity
tightens it. This nut lock is particularly good on railroads.
THE Hartford Steam Boiler and Inspection Co. report for
June, 6,438 inspection trips, 11,688 boilers visited, 5,280 internally
and externally examined, 707 subjected to hydrostatic
pressure. Whole number of defects, 9,74°, of which 800 were
dangerous; leakage, 1,662; defective riveting, 1,65s; incrustation,
1,361 ; sediment, 737; defective settings, 297 -, blasted plates
219; defective pressure gauges, 481. There were 13S cases of
dangerous defective riveting reported as "dangerous."
THE Simonds Patent Rolled Forging Process produces forgings
uniform in size, aud they have no equal in this respect. Their
forgings being all made from stock of a diameter equal to the
largest part, and all collars, heads or shoulders formed by
reducing instead of upsetting the metal, they obtain stronger and
better articles thau by any other known method. In many
instances the forgings are used without machinery. Among
the articles so used, are monkey-wrench screws, Baxter wrench
screws right and left-hand, fish-plate bolts, whiffletree hooks,
piano stool screws, etc.
THE Tobin Bronze made by the Ansonia Brass and Copper
Co., can be welded by the Thompson Electric Welding Process.
Its non-liability to give forth sparks makes it invaluable for
Gunpowder machinery aud Gunpowder Tools of every descrip­
tion.
The Navy Department have specified its use for certain pur­
poses in the machinery of all the new cruisers constructed and
in the course of construction.
The Associated Factory Mutual Insurance Companies have
designated Tobin Bronze as the Standard metal for piston rods
for the so-called " underwriters' pattern for steam fire pump."
THE Yale & Towne Manufacturing Co. are now operating the
Bran ford Lock Works.
The Branford products include a full line of medium grade
Locks and Hardware, and when the use of Yale goods is inadmissible,
the Branford products are recommended as the next
best available.
All Branford products are marked either " B. L- W." or
" Branford ; " Yale goods invariably bearing the name " Yale "
or the Trefoil trademark, the products of the two establishments
being kept entirely distinct and separate.
The united line of products enables The Yale & Towne Mfg.
Company to meet any conditions, e.ther of price or quality, for
hardware of every grade.
A full line of Branford goods will be carried at the offices of
The Yale & Towne Mfg. Company, aud all orders promptly and
carefully filled.
The Company has four branch offices: New York, 84-S6
Chambers St.; Chicago, 152-154 Wabash Ave.; Philadelphia,
1120 Market St. ; Boston, 224 Frankliu St.
ENGINEERING MECHANICS. [October, 1892.
THE Clayton Air Compressor Works, 43 Dey Street, New
York, furnish some new and interesting information in their
recent Catalogue No. 7.
This Catalogue is the most complete one of its kind ever
issued, aud describes in detail the various styles of Steam and
Belt Actuated Air Compressors for use in Mining, Tunneling,
Railway and Bridge Building, Pumping Natural Gas, Supplying
Pneumatic Tubes, Operating Pneumatic Riveters, Tools
and Cranes, Aerating Water, Elevating Water, Acids and other
liquids, Submarine Work, Operating Oil Fuel Burners, Refrigerating
and Ventilating, Charging Automatic Sprinkler Systems,
Stripping Rubber Hose in Rubber Factories, Testing
Tinware, Agitating Liquids of all kinds, Finishing Silk Ribbon,
etc. It also illustrates and describes the new Clayton
High Pressure Compressor, suitable for air or carbonic acid
gas.
The field of usefulness for Compressed Air is constantly
broadening, and as they devote attention solely to the construction
of Air Compressors, they are able to furnish a Compressor
especially suited to the peculiar requirements of each
of the above duties, and this catalogue shows several new
designs representing the latest and most enlightened features
of air compressor practice ; it also contains Testimonials, In­
formation and Data of interest to users of Compressed Air,
Illustrations, Tables and Price Lists, not only of the Clayton
Air Compressors, but of the Clayton Steam and Belt Actuated
Vacuum Pumps, of the Clayton Fly-Wheel Steam Pump, especially
suitable for pumping coal tar, and also of Air Receivers,
Boilers, Rock Drills, Smiths' Tools, Hose, Couplings, etc.
Copies of this catalogue, estimates aud general information
will be furnished upon application.
PROFESSOR WM. H. BURR, who has recently been appointed
to take charge of the department of Engineering in the Lawrence
Scientific School of Harvard University, graduated from
the Rensselaer Polytechnic Institute in the Class of 1872, and
during the following three years occupied positions with a
wrought-iron bridge company in New York City and on the
water supply and sewerage system of Newark, N.J. He was
then called to the faculty of the Rensselaer Polytechnic Institute
as Assist, in "Rational and Technical Mechanics," which
position he held for one year, and was then made the head of
that department. He filled that chair for eight years, and
during that period published two books, "The Stresses in
Bridge and Roof Trusses, Arched Ribs and Suspension Bridges,"
now in its 7th edition, and "The Elasticity and Resistance of
the Materials of Engineering." While teaching at Troy, he
also acted as consulting engineer at various times to the
Northern Railroad Dept. of the Del. & Hud. Canal Co., the
water works and sewerage system of Lansingburg, N Y., and
on other similar works. In the spring of 1884, when the formation
of the Union Bridge Company caused the organization
of the Phoenix Bridge Company, lie accepted the position of
Engineer of Construction of the latter, and subsequently became
General Manager. It was under his supervision that the
large bridge structures of that company (among them the
Ches. & Ohio bridge at Cincinnati, the Red Rock Cantilever,
the Pecos Viaduct, etc.) were designed and executed. In
April, 1891, he became Vice Prest. of Sooysmith & Co., consulting
and contracting engineers for bridges, bridge foundations,
and pneumatic subaqueous work, tunnels, etc. He has
also been associated with Mr. Alfred P. Boller, consulting engineer
of New York City on the large bridges now being built
by that city across the Harlem river. He has contributed to
the papers and discussions of the Am. Soc. C. F,. A recent
paper by him, i. e., "The River Spans of the Ches. & Ohio
Bridge at Cincinnati, Ohio," secured the Rowland Prize of
that society at its annual meeting in January last.

Ociober, 1892.J ENGINEERING MECHANICS. 271
HERCULITE, a new French explosive, is a yellowish gray
powder, composed of sawdust, camphor, nitrate of potash, and
several substances that are kept secret. It cannot be fired by
sparks, flame or detonation. At a trial, a half-pound charge of
the compound was inserted in a blast hole abont 4 ft. in depth,
tamped with sand and earth, and fired by a special igniter. A
block of stone of about 30 tons was, it is said, displaced.
ASSUMING that irou is constituted of a system of little magnets,
and with possible assumptions as to the size of these magnets
and their strength, it is found by Professor Fitzgerald that
their natural rate of vibration may be one hundred millions per
second. Unless the period of vibration propagated through the
iron approximates to this, the wave lengths would, he says, be
very small ; while quicker vibrations, with periods like those of
light, would not be propagated at all.
ARTICLES of incorporation have been filed by the Lodge &
Shipley Machine Tool Co., Cincinnati, Ohio, with a paid-up
capital of $ 100,000. The new company succeeds to the plant
aud business of the Ohio Machine Tool Co.,William Lodge,
proprietor, and with Mr. William Lodge as President and General
Manager and Mr. Murray Shipley Jr., Vice-President and
Secretary.
They propose, in addition to the specialties they are now
producing, to manufacture a line of turret lathes of new design,
and enbodying a number of the patented features contained in
the motor gear lathe recently put on the market by the Ohio
Machine Tool Company.
Iu addition to the above the Lodge & Shipley Machine Tool
Co., will manufacture a complete line of machinery for bordering
and turning pulleys, couplings, friction clutches, etc., from
twenty inches to six feet in diameter.
Since the announcement of the organization ofthe company
on August 31, work has been crowding in to a degree that has
necessitated additional facilities which have been promptly
added. The company is now in shape to execute all work
ordered, on short notice.
THE MAGNOLIA ANTI-FRICTION METAL CO. has achieved ex-
traordinary success in the sale of Anti-Friction metal, and the
latest statements of the company exhibit an expansion in
demand that is a surprise to the managers. The fact that additional
capacity has been recently added is a strong evidence
of the growth of the business. Some things sell well because
well advertised, but this well-known product, which is unusua'ly
well advertised owes its solid standing to the recognition of its
superiority from mechanics, professional engineers, who have
carefully watched it in practical working, and to hundreds of engineering
proprietors, who, until this metal was put upou the
market, tried successively a number of products of greater or
less merit. The tests which this metal has passed, and is passing
through in thousands of workshops every day, are better
than the mass of testimonials, good as they are in their place.
The metals to reduce friction to a minimum have had to encounter
much prejudice and still worse stubbornness, but despite
all open and hidden opposition the Magnolia people
have placed their metal upon a footing that cannot be disturbed.
The mechanical engineers have warmly welcomed the
Magnolia after having subjected it to every manner and degree
of trial. A recent circular of this company very fairly says :
" Mechanics as a rule are eminently practical, and an article
of this kind cannot be juggled into success, but must pass the
trying ordeal of practical every day use. If it possesses unique
qualities they will certainly be found out and appreciated ; but
if the article does not possess value, no amount of persuasion
cau change the opinion thus formed.
"We claim that Magnolia Metal is the best metal that has
ever been devised for Steamships, Railroad, Dynamo, Rolling
Mill, High-speed and Heavy Engine, Saw Mill, Cotton Mill,
Paper Mill, aud for every other class of mechanical bearings,
and the enormous trade in this commodity that has been developed
during the few years since this metal was first put on the
market is a logical confirmation of our claims. In other words,
machinists, engineers and manufacturers know a good thing
when they get it, and will have it again.
" This company makes only the Magnolia Metal, and only
one grade of the metal, and that shows a lower co-efficient of
friction, lasts longer, runs cooler and requires less lubrication
than auy known metal."
This circular states:
" We do not ask you to believe any statements we might
make in regard to qualities of this metal, nor even to credit the
hundreds of testimonials we have from first class sources ; but
we do ask that you will accept the logic of the above facts to
such an extent as will induce you to prove in your own way
whether or not Magnolia Metal is the very best metal in the
World for your machinery."
Offices at 74 Cortland St., New York : 75 Queen Victoria St.,
London, E. C; 41 Traders Building, Chicago.
The accompanying lines show the expansion of sales from
year to year. This year's sales will reach thirty times greater
than the sales of the first year.
1891 m^BBn^HBHIB
Estimate for
1 12 - B H H B B H ^ ^ H n n i
Based on first seven months' sale9.
A GREAT deal of attention is being paid by Messrs. Schneider
& Co , of Crensot, to the perfecting of armor plates and turrets
for the protecttiou of guns, either on laud batteries or on board
ship. In the design of these turrets much ingenuity has been
displayed, and their efficiency is so far recognized that a large
number of armored cupolas have been ordered by the French
Belgian and Roumanian Governments. The latest improvement
in ordnance is the outcome of some experiments that were made
at Chalons in 1888, when it became evident that something had
yet to be done to render disappearing guns thoroughly efficient.
Accordingly, Captain Galopin set himself the task of designing
a turret in which the total duration of movement should not
be more than six seconds, at the same time that the whole
operation should be performed without the aid of motive power
Such a turret has been constructed at Creusot to the order
of tbe French Government. It weighs 150 tons, and is easily
manipulated by hand power. A commission was lately appointed
to experiment with this new turret, and to ascertain
its efficiency as an engine of war. The turret was mounted upon
a solid structure of masonry, and was armed with two guns of
155 mm. The results of the experiments are reported to be in
every way satisfactory. The operation of raising, firing the
two guns, and lowering, only occupied four and a half seconds,
and it was found possible to repeat this charge every minute.
Precautions have been takeu to insure free ventilation without
at the same time allowing any admission of gases caused by explo­
sions ofthe enemies' projectiles. As the result of these experiments,
Messrs. Schneider are likely to have placed with them
a number of orders for this new class of war materiel, and in
view of the heavy contracts that are now in hand for cupolas
and guns, it is evident that the enormous works at Creusot will
be in full activity for some years to come.

272 ENGINEERING MECHANICS. [October, 1892.
THE Schuylkill Foundry and Machine Works, situated at
Conshohocken, on the lines of the Pennsylvania and Reading
Railroads, was established over 26 years ago by John Wood, Jr.,
the second son of Hon. John Wood. It is the largest and best
equipped concern of the kind in this part of the Valley. The
works when running to their fullest capacity find employment
for several hundred skilled mechanics and their helpers, as well
as employing many men at various points erecting machinery
and putting up boilers. Mr. Wood started the works at the
age of 19 years in a small way, and, by a thorough knowledge,
close attention and perseverance brought the business to its
present magnitude and high standard. It is well to mention
that he is the inventor and patentee of the celebrated Wood's
Water Tube Safety Boiler, together with other kinds of boilers,
heavy castings and machinery. Many of the largest rolling
mills, carpet, woolen as well as hundreds ol* electric light and
railway plants throughout the country have been supplied with
boilers and machinery from these works, among the more
prominent of which are the Pottstown Iron & Steel Co.; John &
James Dobson Carpet and Woolen Mills, Phila.; Hughes &
Patterson's Rolling Mills, Phila.; Duncannon Iron Co., Dun-
cannon, Pa. ; J. Woods & Bros. Co.'s Iron & Steel Works, Conshohocken,
Pa. ; Reading & South-Western Railway Co., Read­
ing, Pa.; Pottsville Iron & Steel Co., Pottsville, Pa.; Valley
Rolling Mills, Coatesville, Pa. ; Windsor Lock & Steel Co.,
Bridgeport, Conn. Offices for the sale of these boilers are being
located as fast as possible in many of the principal cities of the
country. The main office is at the Schuylkill Foundry and
Machine Works, Conshohocken, Pa
The advantages claimed for these boilers are, the large amount
of efficient heating surface, the small space occupied for the
power required, rapid and economical steam generating, easy ac­
ment and consideration needed in selecting a boiler, combining
economy in fuel with increased power, than in the choice of an
engine. The Wood Tube Boiler is specially constructed to
meet these requirements, and in advantages over the majority
of water tube boilers they are as accessible for cleaning or re­
pairing as any ordinary tubular or cylinder boiler.
The boiler is contructed of two end tube cylinders, varying
in dameter according to the power ofthe boiler required, but in
no case to exceed 3 feet long, which leaves ample room for a
man to work in, and with all the facilities provided in an ordi­
nary cylinder boiler. The end plates of the cylinder are
flanged and single riveted. The outer end plates are made
convex, to give them additional strength, the inner plates being
stayed by the tubes. In the centre and on the outside plates of
each cylinder a man-hole is provided; which permits easy
access to all the tubes, for the purpose of cleaning or repairs.
The inner tube plates consist of a circular flanged plate %
in. in thickness, in which there are a number of holes drilled in
a staggered form. The back cylinder, and tube end is an exact
duplicate ofthe front, and the two are connected together by a
cessibility for cleaning to all parts, externally and internally, great inch neck, double riveted at their flanges, and made of best
strength and durability from disastrous explosions, construction,
freedom from cast-iron headers, manifolds and numerous joints,
made throughout of the best soft open-hearth wrought steel,
more valve and steam space than possessed by any other boiler,
perfect circulation of water, producing remarkably dry steam.
Economy of fuel should be one of the chief considerations of
all steam boilers. Even a small saving per day will amount
to a considerable sum per year. There is, in fact, more judg-
number of 4 to 4!^ in. tubes ; these are all expanded and beaded
on the inside of each tube head. At certain spaces there are
i^-inch stay rods passing through the tubes and riveted to the
outer or disked head by means of wrought iron crow-feet ends.
These act as braces or stays, while each tube acts in the same
capacity, and each tube being of greater strength than the stay-
rods, although the pressure on the tube sheets almost equalize
the pressure outside or disked ends. Hence it will be seen
there is an additional amount of strength over any pressure
desired to carry. The shells of these tube cylinders are made
of best plates, full A inch thick and double riveted, and each
connected on the top to a steam drum of sufficient size, by a 16
plate j\ inch thick. These necks are capable of allowing a
perfect and constant circulation. The drum being 30 to 36
inches in diameter, and about 2 feet longer than the boiler,
ample storage room for water and steam is provided. The
drum also being accessible at the front end by means of a manhole,
allows every part to be explored. The boiler is supported
either by side brackets riveted to the shell of the tube cylinders,
or is suspended from the top by means of side columns and

October, 1892.] ENGINEERING MECHANICS. 273
girders, or saddles, to yokes riveted to the top of the steam
drum directly under the saddles, and thus is entirely free from
the brickwork.
This boiler is constructed entirely of one kind of metal, and all
its parts are well proportioned and subjected to about the same
heat, the exposure will be equal and throw no strain on the
joints, as there are none exposed. This is of great importance,
and one that should be taken into consideration, as this unequal
expansion causes boilers to become weak, and often results in
explosions. Then again, it is much more accessible for clean­
ing than most boilers of this type, as all that is required when
cleaning is actually necessary (which is seldom) is simply to
remove the man-hole plates at each end of the tube sheets, and
ample access can be had to all tubes at once, while on other
boilers, hundreds of small caps or plugs have to be removed,
thus losing time and causing much annoyance and expense.
Again, when repairs are required, it can be accomplished by
any ordinary boiler maker. This is a consideration that all
steam users will appreciate. The capacity of the boiler will
also be 30 to 50 per cent, greater than any tubular or flue
boiler occupying the same space. And as to safety, durability
and construction it has no equals, and has the very best circu­
lation of any boiler made.
It should be mentioned that recent tests, both as to evapora­
tion and capacity have been made by Professor Jay M. Witham,
consulting engineer, 131 South Third Street, Philadelphia, and
Professors Frank C. Wagner and J. R. Allen, ofthe University
of Michigan, and the results showed most points ahead of any
competitive list. This has encouraged Mr. Wood to issue a
supplementary circular containing all data relating to these
tests, which can be had on application in person or by letter
to the Schuylkill Foundry and Machine Works, Conshohocken,
near Philadelphia.
MR. E. H. WOOD recently read a paper on electric locomotion
before the Mechanical Section of the British Association which
has been condensed as follows :
The electric motors were placed vertically, so that the driving
wheels were horizontal. The necessary adhesion was to be
obtained by springs pressing the driving wheels against each
side of the central rail. An advantage claimed was that the
motors could be kept constantly running, even wheu the train
was stopped ; the driving wheels being thrown out of gear by
mechanism under the control ofthe driver. The engine can be
constructed of any reasonable size ; and the deadweight would
be less for the power than in a steam motor. The difficulty with
points and crossings was met by an arrangement of working
the central rail. The pieces of rail of similar section to that
used for the central rail, are curved to a suitable form, and
coupled together by a special casting near each end ; the two
sections of rail are not in the same longitudinal plane, and each
cross-piece is provided with a roller working upon a horizontal
axis; at the centre of the length of the two portions of rail a
casting is fixed, which is common to both, and is so formed that
it rides freely upon a vertical pivot which is fixed to a sleeper,
or other suitable part of the permanent way. The two sections
of rail, which thus form a kind of rocking cradle, are free to
move upon the centre pivot, and the rollers at each end travel
upon paths of a segmental form when looked at in the plan ; in
elevation the segmental paths are so formed that one section of
the rail can be moved into position with, say, the main line
track, but when the rocking cradle is swung sideways the second
rail, which, as previously described, is in different plane, is
caused to rise during its swing, and complete tbe middle rail for
the branch, or cross over line. Owing to the different level of
the two sections, the portion which is uot in use at any given
time lies below the horizontal plane passing through the top of
that which is in use. The engine was provided with ordinary
flanged wheels, being designed to meet the case of a railway
where it is desired to haul ordinary stock, and where the curves
are not sharp ; but in the case of lines like the City and South
London Railway, where the grades are steep and the curves very
sharp, the carrying wheels need have no flanges, and the stock
cau be made to take very sharp curves—indeed up to 50 ft.
radius—without difficulty. This becomes important in cases
where it is desired to pass under streets which diverge at right
angles, and also at termini, where a balloon-ended station will
do away with the necessity for shunting operations, or breaking
of electrical connections.
MR. ALEXANDER SIEMENS read an interesting paper before
the British Association on the South London Railway. Iu the
locomotives of 100-horse power capacity, the efficiency of the
motors under widely varying conditions was practically constant
at about 92 per cent. The armature speed to secure these
results on the brake was varied from what would correspond to
twelve miles per hour of the locomotive to about thirty miles
per hour, and the brake horse-power under these different
speeds was no-horse power and 49-horse power respectively.
After being put into actual service, the locomotives were
thoroughly tested, the average speed being about thirteen miles
per hour. Each locomotive, which, fully equipped, weighs not
far from 13^ tons, when drawing a load of 21 tons exclusive of
passengers, required, under ordinary running, a current of not
over 50 amperes, although in starting as much as 140 amperes
were used. The fluctuations of voltage at the generating station
are shown to be not coincident with the fluctuations at the
terminals of either one ofthe locomotives.
A BUILDING ou the corner of State and Madison Streets,
Chicago, is to be plated outside with aluminum and glass. It
will be four stories high. Each window, extending from floor
to ceiling, will have two sheets of plate-glass n feet long joined
at the centre with a line of aluminum, making one plate practically
22 feet long.
A FRENCH commission has been making numerous experiments
with passenger vehicles passing around railroad curves
to determine the resistance encountered. Engineering, in condensing
some of the results arrived at, says:
One of the most important points to be settled by an investigation
of this character is to what extent sharpness of curvature
should be compensated for by decrease of grade in locating new
lines. Owing to the great variations which atmospheric conditions
make in the resistance of a curve, this point cannot be
easily settled, but it may be noted that a slippery state of the
rails, which lessens the adhesion of the locomotive, also reduces
the resistance on the curve, and consequently a curve that is
properly compensated for fair weather, as compared with the
tangent, will be over-compensated when the rails are greasy.
As a fair practical estimate, however, M. Le Chatelier concludes
that the extra resistance on a curve of 656 ft. radius is equal to
slope of o 4 per cent., and on one of 492 ft. radius to a slope of
0.6 per cent. These figures are materially higher than the
actual experimental resistances found would appear to warrant,
and thus include a factor of safety.
The commission have also made experiments on a curve of
245 ft. radius, and the general results obtained have been
summed up by M. Le Chatelier as follows: (1) Every type of
engine, carriage, and wagon used in the every-day working of
French railway lines, can pass freely over a curve of 328 ft.
radius, or even of 245 ft. radius of standard gauge line without
requiring any widening of the track. (2) Such widening is of
no advantage, and may cause instability and increase of resistance.
(3) The use of a tangent between reverse curves is useful
only in point of view of action of the buffers, and need not
exceed 33 ft. to 66 ft. in length. (4) Superelevation can be
entirely omitted without compromising the safety of the train
even at comparatively high speeds. Excessive superelevation
may become a cause of instability by favoring the displacement
of the axles towards the inner rail. (5) The resistance of all
kinds of vehicles, as well as of locomotives of different types
in curves of 328 ft. radius is on an average about 18 lb. a ton.
This figure may be reduced to 11 lb. or 14 lb. a ton without the
use of complicated devices. In curves of 245 ft. radius the
average resistance does not exceed 22)/z lb. per ton.

iii ENGINEERING MECHANICS. [October, 1S92.
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F. H. WHITING, DENVER, COL.

November, 1892.J ENGINEERING MECHANICS. 273
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering.
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia.
London Office, 270 Strand, D. NUTT, Agent.
Two search lights have been erected on the World's Fair
grounds of six foot parabolic ground glass reflectors, weight two
tons each. Another will be erected May 1 which will have a
solid ground glass y] feet in diameter, 12 horse power and equal
to 25,000 candle power.
A REVOLUTION in the art of enameling has been effected,
whereby cast or wrought iron, or steel, or marble, or almost any
hard surface cau be enameled. Shade upon shade, delicately
blended, can be added. The illusion is said to be absolute. This
opens up possibilities for a wide industry.
THE first of twelve guns lately ordered for the new battle-ships
will be forty feet long, diameter at breech four feet, twenty-one
inches at muzzle, weight i5S,ooo pounds, powder charge 500
pounds, weight of shot 1100 pounds, speed of shot 2100 feet per
second, distance 12 to 13 miles, power of penetration in solid
steel armor, 21J inches at one mile, 26;3' inches close at hand.
A RATHER common mistake in mill managers is to run too
tight belts. Engineers who have made a study of it say the lots
of power from friction alone in some ofthe best equipped mills
in the country is from 22 to as high as 39 per cent., which should
not be over 15 per cent. A fair average of loss in coal is three
pounds per day, per horse power. Iu using shafting and belting
errors of alignment are the first and easiest fallen into; next,
the spacing and hanging of pulleys. Other errors are often
committed in the adjustment of bearings, in the size of the
pulleys and in the tension of the belts.
FUSION of metals has been relied upon by chemists and metallurgists
to make alloys and many would not think of any
other process. A new process has received some endorsement,
viz., compression, first suggested by cold rolling of shafting.
This field is rather new, but experiments are being made and
tests show much progress in making valuable alloys, if the term
be admissible, by compression of metals under powerful pressure.
Zinc and copper have been actually united by repeated
compressions. Most remarkable properties can and probably
will be developed by compression, and there may be a field
opened in this way for the production of a better armor plate.
ONE ofthe ugly difficulties of founders is that of fracture due
to unequal cooling. Certain pieces of work are very hard to
cast, for instance, screws for naval engines. To avoid unequal
contraction, the mold containing the model of the screw is
placed in a furnace when temperature is right. The screw is
cast and annealed in the furnace. Pieces too large for the cru­
cible and too small for the Martin furnace can be advantageously
dealt with in this way. Small converters will probably be soon
more generally used for large castings. The use of steel castings
is destined to drive out iron castings where iron has been ex­
clusively used.
THE English iron trade is threatened with serious complica­
tions from the increasing cost of coal and coke due to labor or­
ganization. The fear is that continental mill products may be
imported more largely in consequence. The grip of trades-
unionism is getting stronger and stronger in England and the
demands and threats of Socialism and kiudred isms are becoming
Entered at the Post-office in Philadelphia as Second- Class Mail more Matter. serious on the continent. American employers may con­
SUBSCRIPTION RATES.
gratulate themselves that labor questions are no worse among
them thau they are, and that the spirit of discontent is less
Subscription, per year $2 00 rampant. Agitation for better conditions and greater results is
Subscription, per year, foreign countries 2 50 a necessary and creditable element of human nature, high or
low, aud no enlightened community need expect freedom from
PHILADELPHIA, NOVEMBER, 1892.
the struggles of the wage workers for more of the wealth produced.
IN the Braine Electric Tramway System the slot difficulty is
practically surmounted by making a wide slot which is covered
with a steel rail flush with the surface of the roadway. An ar_
rangement in the car raises the "cover" from its seat by rollers
which pass underneath the rail. The cover rail is two inches
wide, seven-sixteenths of an inch thick and weighs under three
pounds per foot. The " collector " raises this rail one and a half
inches as the car passes over and it falls back into its seat by its
own flexibility. The speed of the car is 660 feet per minute, and
the power absorbed in raising the cover is less than one-tenth
horse power.
THE subject of crystalization or the tendency of certain products
to crystalize when they are supposed to keep still is coming
up before the attention of engineers, builders, chemists and
others. In a former number reference was made to the cement
bacillus. Since then experimenters have entered on the work
of finding out for themselves what the new enemy to cement is
able to do. The present objective point is to make such a mixture,
by use of gypsum or sulphuric acid as will increase density
to a point that will give room for the crystals to comfortably
stretch themselves when they feel like it. If the ceiling is too
low they will push through the roof, so to speak, and make a
leak.
BOAT building economy on the lakes may very easily cross the
danger line, as was the case with the builders of the steel steamer
" Western Reserve," a shell of steel. Builders and insurance
agents have suddenly awakened to the fact that rules are needed.
The agents say they need them to know how to insure, and
the builders say they need them to know how to bid on new
work safely. Rules are as imperative on the lakes as on ocean
ship building. Lloyd's rules are the outgrowth of a century of
experience and competition. Some wise rules and regulations
on lake boat building will save a great deal of trouble and loss.
The " go as you please " sort of construction that has been going
on in lake yards is fraught with something more than mere loss
of vessel.
A PRACTICAL inventor, speaking of coal cutting machinery,
says : I find that the most convenient machine, and a better one
for all-round work than either, is one having a cylinder at each
end, with the cutting wheel in or near the middle. By this
arrangement a comparatively light machine will keep the rails
without extra fittings iu working, and is capable of cutting
either coal or fire-clay ; and the power can be varied to suit the
material to be cut by making it run from 3 to 1 to 12 to 1 be­
tween the crank shaft and cutting disc, and its total length
need not exceed seven feet. The discussion of the question
has developed much dissatisfaction with coal cutting machines
abroad, and especially because of the loss of time caused by
applying motive power, whether steam or compressed air.
English mining engineers take a rather gloomy view of applying
power in coal cutting, and lean to the Longmad system.
Another drawback in English mines is the lack of skilled labor
to work machines. On this side we are several slips ahead.

274
ORDINARY prices of labor and coal on English railways have
stimulated locomotive superintendents to construct locomotives
in a way to keep longer out of the repair shop and burn less
coal. The cost of coal for fifteen great companies rose from
111,585,000 in 1889 to $17,450,000 in 1891.
THIS is the way an English critic puts it; There can be little
doubt that marine engineering in the British Navy is to a great
extent a farce ; and why ? Simply because engines and boilers
are expected to do the impossible. They are cramped up in
every direction, and altogether too small for the power which
their engineers try in vain to force out of them.
Some day these facts will be brought home to the minds of
those responsible for the design of our men-of-war with terrible
emphasis.
AN English engineer [suggests as a means of carrying off
sewer gas, the erection of iron shafts either open at the top or
provided with combs which might take the place of street
lamps placed on the line of curb aud connected with the sewer.
The periodical flushing by automatic chambers is strongly
urged in conjunction with ventilating posts in preference to the
ordinary street openings.
THE importance of a more extended system of canalization in
this country is emphasized in many ways, but one which can be
seen without special argument, is that when the Erie canal
closes freight rates fall in competing railroads to less thau half.
THE frequent and often unaccountable breaking of chilled
rolls has given mill men a great deal of trouble. Discussions
as to remedies fail, and about the only conclusion reached is to
move the housings farther apart, and by proper gradations of
form, to reduce the unequal expansion betweeu the neck and
body of the roll.
AN alloy of great density, hardness and durability can be
made for tools by using pig iron as a base into which is introduced
tungsten alone, or a combination of two or more of the
following metals:—Tungsten, lead, zinc, uranium, titanium,
copper, nickel, cobalt, chromium, molybdenum, or alloy or
compounds of thesame in such proportion as is found suitable.
Pieces of wrought iron or steel may also be introduced, but not
to the extent of lowering the carbon in the resulting alloy to
the point at which it occurs in the hardest forgeable steel, so
that the nature of the material shall remain the same as pig
iron in point of carbon.
PROF. CARPENTER'S work, "Text Book of Experimental
Engineering," published by John Wiley & Sons, has met with
a good reception at the hands of engineers, students, professors
in colleges, and others directly and indirectly interested in engineering
work. It is an expansion of older editions. The
added matter rounds out the work and gives it a symmetry
which makes it very valuable as an aid in research. There is
necessarily considerable elementary matter, but there is also
much that is uot properly so classed, and which advanced
students and experienced engineers will find of value. If the
students who use it in the class room and laboratory and machine
rooms of colleges will continue to apply its teachings in
after life, the)- will increase the value of their services to those
by whom they will be employed.
The work is of course not exhaustive, but if students will
cover the foundations laid with enlightened practice they will
be all the better engineers for it. The chapters on "Testing
Machines," "Testing Materials of Construction," "Measurements
of Pressure," "Methods of Testing Steam Boilers,"
" Methods of Testing Steam Engines," are all written with a
clear understanding of practical requirements, and are espe­
ENGINEERING MECHANICS. [November, 1892.
cially fitted to open the way for students to enter into the
broader fields they will find opening up when they enter upon
practical work. I'rof. Carpenter has rendered a valuable service,
not only to the younger portion of the engineering fraternity,
but to the older as well. This work is being welcomed
as it deserves to be, and no doubt it will be followed in time, as
it ought to be, by an appendix containing the results of further
experimentation.
MCKINLEYISM has done more to stimulate doubts in the
minds of Englishmen as to the correctness of Cobdeuism than
anything else that has come up for forty years. These doubts
are very well expressed by a writer iu The Engineer, London,
Oct. 7, iu which he says : It seems to me that the whole science
of political economy as stated by the Free Trader, is based on a
multitude of assumptions which are not facts. In this it is
possible that I am mistaken, but I cannot find that books ever
take cognizance of what is going on around us. For example,
we are told that a country with a heavy tariff cannot have a
population living iu comfort, or growing in wealth. But France
has a heavy tariff, supports au enormous army aud navy, and
is, in spite ofthe tremendous sum paid in 1871 and 1872, enormously
wealthy at this moment. Belgium has a pretty stiff
tariff, and yet it is for its size one of the richest countries in the
world, supports a huge population, and its wealth is well distributed.
Look at the sums its mill owners spend ou palatial
engine houses and machinery !
Again, I am told that a high tariff runs up the cost of living;
why is it that I cau live better in a French or Belgian town for
less than two-thirds of what it costs me to live in Free Trade
England? Why is it that a Belgian workman is better off with
3s. a day than au Englishman is with 5s. a day?
Finally, I must ask oue more question. Is it demonstrably
true that it is better for a country to have a considerable portion
of its population steeped to the lips iu penury, and another
portion earning a very precarious livelihood while it buys commodities
cheap, thau it would be fully to employ the greatest
possible number of its population in producing commodities
for itself at a slightly dearer rate ?
When I see a country daily becoming richer like France
under the pressure of a heavy tariff, I doubt whether our political
economists quite understand what they are writing about;
and when I see capital and talent migrating to the protected
country, as English capital and talent have gone to Spain and
Italy, and are now going to the United States, to build up vast
industries, I begin to rub my eyes and doubt whether Protection
is really after all an unmixed evil, aud to ask myself how
it happens that John Bull is really the only wise man in the
civilized world—the only man who thoroughly understands and
profits by the laws of political economy.
LOCOMOTIVE construction is receiving more than ordinary
attention under the rapidly growing demands for greater speed,
power, endurauce and general efficiency. In a new engine
recently introduced on a French railway Serve tubes are used
and the working pressure 215 pounds per square inch is the
highest yet used. There are four coupled driving wheels aud
the trailing axle is under the after end ofthe fire box. The two
high pressure cylinders are outside aud drive the trailing
wheels and the two low pressure cylinders are inside. All the
slides cau be reversed with one motion. The tubes are only 10
feet long and hence a shorter boiler is possible. Ninety
engines are now being fitted with them, as a result of long and
exhaustive experiments. The principal dimensions of the
engine refered to are :
High-pressure cylinders, diameter 13.4 iu.
Low-pressure cylinders, diameter 21.25 i n -
Stroke 24.4 in.
Diameter of driving wheels 6 ft. 6.75 in.
Heating surface, total 1620 sq. ft.

November, 1892.J ENGINEERING MECHANICS. 275
" OUR English engines are grand engines but they require
grand roads," is the epigrammatic maimer an English railroad
superintendent summarizes his experience in Brazil with Bald­
win and British locomotives. His conclusions are these : The
English engines, when erected, would uot run out of the siding
until extensive alterations had been made without getting off
at each curve, either on forward gear or back, and after the
alterations, when all had been done that I could do, it was not
until the road had beeu thoroughly relaid by first-class men
that they could be run on the main line ; before this was done
they constantly ran off, breaking tender bogie pivot centres,
axle-boxes, etc.
As to the Baldwin engines, they had only one fault and that
was the centre Hue of boilers was too high. Notwithstanding
this, they were the type most suited to the road, and perfectly
safe in the hands of a competent driver. Everything about
them wore remarkably well, and did, I feel safe in saying, more
work during the construction of the road, than all the English
engines combined—omitting the tank engine—and cost much
less than any oue of the nine English engines. Iu fact, if I—
as locomotive superintendent—was at any time required to go
out with a special train, I took care to let it be a Baldwin, in
case I wished to drive myself, which I often did. The Ameri­
can type of locomotive is so much easier to handle, oil, aud
ride upon, for a driver. This was my first experience with
American locomotives, aud oue I can never forget. Our Eng­
lish engines are grand engines, but they require grand roads.
THE use of oil tempered crank pins in locomotive aud other
work requiring unusual streugth and elasticity will be greatly
extended. Specimens Ai m - i' 1 diameter and 2 in betweeu
marks, cut longitudinally from the pins after treatment show
these results :
Tensile strength 112,0401b.
Elastic limit 61.1701b.
Elongation 20.55 P er cent.
Contraction of area 45-53 per ceut.
The chemical composition ofthe pins tested was :
Carbon 0.50
Manganese 0.60
Si'icon 0.15
Phosphorus 0.035
THE essential requirements of a safe and economic steam
boiler may be enumerated as follows :
(1) The application of heat to the internal flue or other heating
surface should be as uniform as possible.
(2) The heating surface exposed to the most intense zone of
combustion should be covered with active currents of a welldefined
direction, and of such an erosive character as to absolutely
prevent the settled deposition of calcareous or other
matters of a heat non-conducting character.
(3) The structural characteristics of the heating surface just
described should be of a flexible character, so that the maximum
metallic dilations shall be easily compensated for in the
range of flexibility.
(4) The structural character of the heating surface should be
such as to promote a distinctive direction of circulation so as
to avoid the clashing of the currents.
(5) The arrangement of parts should include the provision of
a foreign substance-depositing vessel, quite removed from the
zone of heat, and such as to be easily accessible for examina­
tion.
(6) There should be no metallic part of the structure so
rigidly formed that the expansion or dilating influence of heat
to which it may be subjected shall produce dangerous stress.
(7) The form of construction should be such as to permit pres­
sure up to 300 lbs. per square inch to be obtained, without ne­
cessitating an abnormal thickness of shell plate.
(8) The steam generator should be accessible for examina­
tion ou all sides.
(9) The chemical action of combustion should be thoroughly
under control, so that absolutely perfect combustion shall be
possible.
(10) Both the rate of producing combustible gas from the
solid combustible and the supply of the volume of air for its
oxidation or combustion should be under control.
(11) The external or outer shell radiation should be reduced
to the lowest limits.
Many horizontal internal-flued boilers would not come up to
these requirements. The water tube type shows what progress
cau be made when old ideas are set aside.
As heretofore remarked, no satisfactory system of disposing
of sewage has been devised. Progress is being made however.
A recent suggestion is to employ microbes to feed upon sewage
matter, and to specially cultivate these organisms for that pur­
pose. It has been done successfully, as all know, under the
Massachusetts Board of Health. A late writer on the subject
is W. E. Adeney, who read a paper on the subject in Dublin
before the British Institute of Public Health, The preferable
method is to first remove the solids and then turn the microbes
loose upon the sewage to be purified. Sewage is a question of
oxidation, not filtration. The process has been tested at Dublin,
and is as follows:
After passing a preliminary straining chamber, the liquid
flows into the first of a series of tanks 7 ft. square and 16 ft.
deep, being conveyed to the bottom and spread uniformly over
the floor. In rising to the surface the fine particles are caught
in the gelatinous matter, and a large proportion of the suspended
nutter is thus removed by a purely mechanical process,
aud without the addition of any chemicals whatever. The partially-
purified effluent from this tank is carried through a mixing
race to a second aud similar tauk, receiving in its course a
dose of manganate of soda, two to five grains to the gallon.
The manganese effects the oxidation of a considerable part of
the organic matter, and becomes converted into the brown oxide
of manganese, which falls to the bottom, carrying with it
the lighter particles that had escaped from the first tank. The
liquid is then conducted to a third tank, where nitre (two to
three grains to the gallon) is added in order th it such of the
constituents that were not amenable to the manganate of soda,
or which escaped its action, may be broken up by the saprophytic
organisms. As to the time required for this action, the
tank capacity at Dundrum is completely filled and emptied
every twenty-four hours, but it is believed that less time would
be sufficient. The effluent is clear and bright and absolutely
non-putrefactive.
Mangauate of soda and nitre are therefore the materials
used to effect precipitation aud purification. The manganese is
recovered from the tanks at one half original cost. This method
is more promising thau any other, because natural agencies
are utilized, viz., vibrionic or aerobic organisms, which reduce
waste organic matter to gases and nitrates.
THE Calleudar pyrometer, lately introduced, is an electrical
resistance pyrometer, based ou the same principle as the instrument
introduced by the late Sir W. Siemens. In this the action
depends on the variation with temperature of the electrical resistance
of a wire. The wire, in Mr. Callendar's arrangement,
is wound on a plate of mica and contained iu a porcelain tube.
The pyrometer does not occupy much space, and could be
adapted to the measurement of local temperatures as easily as
M. Le Chatelier's instrument. It appears certaiii that a reliable
form of pyrometer has been brought within the range of indus­
trial practice, and we may expect to see, at no distant date,
pyrometers as familiar accessories of steel works as are now the
analyst's test-tube and balance.

276 THK CONSTRUCTOR. [November, 1892.
Translated by Henry Harrison Suplee.
The levers c' and c" have a common axis at 5, and when
separated by a wedge at 6, they press upon the ends of the ring
at 3' and 3". A pin at 7, keeps the levers from sliding iu the
direction 7 . 1, as well as the ring b' b".
The coupling shown in Fig. 944 c, acts both ways, as au internal
aud external strap brake, and is used on a shaping machine
by Prentiss. * The steel strap b, is covered with leather. When
the arms c' c" are drawn together it acts as an external strap
on the pulley a", and when they are forced apart it becomes an
internal strap iu the pulley a'. The arms c' c" are carried on
sleeves and are rotated to or from each other by a screw action.
CHAPTER XXIII.
PRESSURE ORGANS CONSIDERED AS MACHINE ELEMENTS.
I 30S.
VARIOUS KINDS OF PRESSURE ORGANS.
In distinction from the various kinds of tension organs which
have been considered in the four preceding chapters, there
exists another group of machine elements of which the sole or
principal characteristic is that they are capable only of resisting
forces acting in compression. This group includes fluids,
both liquid aud gaseous, whether limpid or viscous, such as :
Water, oil, air, steam, all pasty substances, clay, molten metals ;
also granular materials, all kinds of grain, meal, gravel, etc.
In all these materials the principal feature lies in the fact that
the particles are subdivided to such an extent that they cau be
separated from each other by a very small force, while on the
other hand they are capable of opposing more or less resistance
to compression, this resistance in many instances, as, for example,
in the case of water, almost equalling that of metals. These
materials may be used as machine elements in a great variety of
ways, and in the following discussion they will be included
under the general title of Pressure Organs. Like their counterparts
the tension organs already discussed, they are used
largely for the transmission of motion in various manners, but
are of still greater importance on account of the great variety
of physical conditions in which they appear.
I 3°9-
METHODS OF USING PRESSURE ORGANS.
The distinction which has been made between tension and
pressure organs enables various points of contrast and comparison
to be made as regards the methods of utilizing them, and
pressure organs may be divided in the same manner as tension
organs (see js 262) into standing and running organs. These
divisions have but little practical application in this instance,
but the three following subdivisions in j 262, viz. : Guiding,
Supporting (i.e., raising or lowering), and Driving are here
applicable also. We may therefore distinguish pressure organs,
when considered as machine elements, into the following
classes :
1. For Guiding.
2. For Supporting (including raising and lowering).
3. For Driving.
These various methods of action may be used either separately
or in combination, aud are found iu most varied forms in many
machine constructions. The great variety of possible combinations
makes it desirable for a general view of the entire subject
to be taken before discussing details.
Translation Copyright, 1890.
force" of the pressure organ serving to retain it within the
desired limits. Canals are merely conduits of larger dimen-
FiG. 945-
sious, as at e, and natural streams of water often serve the purpose.
Driving Organs, Pistons and Cylinders.—The bodies by
means of which the pressure organ is connected with the external
forces aud resistances with which it is intended to act
mechanically may be called generically, Driving Organs, and
are very varied in character. Among these are movable receptacles,
also moving surfaces or moving conduits (as in turbines),
and also moving pistons in tubes or cylinders. A piston serves
to oppose the stress in the pressure organ in the direction of its
motion, while the walls of the tube oppose their resistance at
right angles to the direction of motion. The inclosure in which
a piston acts is called, in general terms, the cylinder, and details
of construction will be given hereafter. The principal types
will here be considered briefly.
A complete working contact between piston and cylinder can
only be obtained wheu both surfaces are alike, and this is only
geometrically possible with three forms of bodies ; i. e., prismatic
bodies, bodies of rotation, and spirally formed bodies. Of
these the prismatics are most useful, aud among the prismatic
bodies the form most extensively used is the cylinder.
The fit of a piston in its cyliuder, entirely free from leakage,
is very difficult of attainment, and is rarely attempted in practice.
In steam indicators the piston is very accurately fitted directly
into the cylinder, but in most cases a practically satisfactory
result is obtained by the use of some intermediate packing
device.
A
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1
1
1
•—111—
1
!
s -JjL.
1
i ! <
-iii— 1
i
1
p a s JL. rA—1
i ! ;
'" " j ' '
1
L
—II—*
FIG. 946.
In many cases a soft packing of hemp or leather is used, Fig.
946. At a is showu a piston with external packing, at b ati
internal packing. In these cases oue eutire end of the cylinder
is open, the piston filling the entire cylinder and acting upou
the inclosed pressure organ on one side, this constituting a
single-acting positiou. At c and d are similar double acting
pistons. Pistons of the forms shown in a and b are sometimes
called plungers, aud the shorter inclosed pistous, as c or d are
2 310.
also called piston-heads. At e is a double acting pistou used in
connection with a rod and stuffing box, the rod being connected
GUIDING BY PRESSURE ORGANS.
with external mechanism, and the stuffing box made either with
In order to use a pressure organ for guiding, /'. e., to compel a external or internal packing, as indicated at 1 and 1'. In many
more or less determinate succession of motions, it is necessary instances pistons are made with openings which are fitted with
to use also two other machine elements formed of rigid mate­ yalves, and hence may be called " valved " pistons, while those
rials. These latter are for the purpose :
here shown are termed closed or solid pistons.
The tightness of the packing is usually produced by the appli­
a, Of resisting the internal forces of the pressure organ
cation of some external force, but in the so-called forms of self-
and keeping it within the desired limits.
acting packing the necessary pressure is supplied by the con­
b, Of connecting the pressure organ with the external forces
fined fluid. This is shown in the following illustrations.
to be received and opposed.
a
Tubes, Conduits, Canals.—The tube a, Fig. 945, limits the b
boundary of the particles of the pressure organ, and retains it
in the desired form and controls its direction. A bend iu a
m
tube corresponds to a pulley around which the pressure organ
is bent, and thus has its direction changed. Even wheu no
change of direction is made, the tube is necessary to oppose resistance
to the particle of the pressure organ, and hence at
every section it must offer resistance to tension as well as compression.
Conduits, or channels, as at b, are tubes with one
side left open, the force of gravity or the so-called "living
FlG. 497-
•See Mechanics, Feb., 18S4, p. 140.
Fig. 947 a aud b, Cup packing for piston or stuffing box ; metal
_J
i~^

November, 1892.J ENGINEERING MECHANICS. 277
packing, usually for pistons, but also used in stuffiug boxes.
The fluid in all three cases enters behind the packing rings and
tightens the joiut in proportion to the increased pressure.
In the class of self-acting packing may also be included the
various forms of liquid packing, some of which are given in
Fig- 948. The forms at a and b are practically plungers, while
FIG. 94S
in many cases an ordinary packing has its tightness increased
by a layer of water or oil upon the pistou, as shown at c.
FIG. 949.
These are among the oldest forms of transmission organs,
but are practically true pistons in principle and action. At a is
a single diaphragm, known as the monk's pump : b is the socalled
"bellows" form ; e angle of change of direction is 180°.
At c is a combination of case a with case b. The plungers
bx, b.,, b3, are of the same diameter, and the load Q is supported
on these columns. These three cases correspond iu principle
with the similar cases ab cot Fig. 7S4. Since the three plungers
^1. bt, b3, of case c all exert the same force, they may also be
made to give the same result when made as showu at d, or if
the three plungers are combined in one, form e is obtained.
The latter form is well known iu practice as the hydraulic
press. The principle involved in all these devices is the same
as appears in the various pulley systems of tension organs.
A comparisou of Fig. 951 a with e shows that the same principle
exists in both, and case a may be considered as a waterlever
of equal arms, and case casa lever of unequal arms.
FIG. 952.
The water-lever has been used in more or less complete devices
for balancing the weight of pump rods in deep mine
shafts. Fig. 952 shows Oeking's water counterbalance.! The
t Zeitschrift Deutscher Ingenieure, 1S85, p. 545. Oeking incorrectly calls
the device a b an accumulator.

27S ENGINEERING MECHANICS. [November, 1892.
pump rod is carried on the two plungers d1 d.,, and its weight in metres. The flow between the various reservoirs is controlled
counterbalanced by the weighted plunger aud cylinder a-b. by suitable valves.|
In the Emery scales and testing machines water-levers of Small tanks are iu very general use at railway stations ; and
unequal arms are used iu connection with metallic diaphragms. the various ponds and mill dams used iu connection with waterwheels
are other examples. In many cases the water ways are
large enough to serve as reservoirs also, as iu the case of canals.
• -
Natural reservoirs are found in the case of many mountain
lakes, the Swiss lakes affording many numerous instances.!
Such basins are also formed artificially by constructing dams
across narrow outlets, and so storing the water for use. Note­
• • '•••• — • - • - ~ — —
worthy examples found in France, the basin at St. Etienne,
formed by damming the river Fureus, being over 164 feet (50
metres) deep.?
Water may also be stored iu accumulators at high pressures
from 20, 50, as high as 200 atmospheres, and cau then be used
for operating hydraulic cranes, sluice gates, drawbridges, etc.
These accumulators may be considered as a form of releasing
FIG. 953.
ratchet mechanism (see (J 266). To this class of mechanical
action also belongs the system, used in the Black Forest, by
Fig. 953 shows a combination of two hydraulic levers, each of which the streams are temporarily dammed and then suddenly
the form of Fig. 951 a. The weight O travels in a straight line, released iu order to float the logs down with the sudden rush of
being kept parallel by the four equal plungers bfjif^, and
the current.
crossed pipe connections. This construction is similar to the
Iu using high pressure water transmission it is sometimes
cord parallel motion of Fig. 784 d.
desirable to transform a portion to a lower pressure in order to
In all ofthe devices described the rigid body is guided by the
operate a lower pressure mechanism, or by a reversal of the
motion of the pressure-organ. It must be remembered that
same principle, to convert a lower to a higher pressure. This
motion is merely a relative term, and the rigid body may move
can be done by means of the apparatus devised by the author,
through the fluid. An example of the latter is the rudder of a
aud shown in Fig. 956. ||
vessel, wliich acts in oue plane ; or iu the case of the Whitehead
torpedo several rudders are used, guiding the torpedo in any
direction.
?3i2.
RESERVOIRS FOR PRESSURE ORGANS.
Reservoirs are used in connection with pressure orgaus in
order to enable a number of applications to be operated collectively,
and also to enable the pressure to be stored for subsequent
service, and in this respect they correspond to the various
forms of winding drums used with tension orgaus, and shown
in Fig. 7S7. The following illustrations will show the use of
such reservoirs.
Fig. 954 shows a tank for use with petroleum distribution, as
.
Tl !
• J 1
C J|C
L
This is a form of hydraulic lever of unequal leverage, but
is different from those shown iu Fig. 951. Referring to Fig.
95617, the high pressure water is delivered at a, and connected
with the lower pressure water al by means of the plungers b, blt
the latter being in one piece of two different diameters. The
difference iu pressure, neglecting friction, will be inversely as
FIG. 954.
the areas of the two plungers, or if they are of circular section,
inversely as the squares of their diameters. Iu this case the
used in the American oil fields, and more recently in the oil lower pressure then acts in the cylinder c upon the plunger d.
district of Baku. The oil wells are at a1} a.,, a3, and the oil is The action of this arrangement may be considered as if the
forced to the elevated reservoir at c by pumps. From the reser­ plungers b aud bl were upon the same axis and rigidly convoir
the oil flows to the point of shipment d, and the supply is nected, and the leverage compounded in a manner similar to
gauged by the fluctuations of level iu the tank.*
that of the rope craue of Fig. 792 a ; this comparison being
The reservoirs used in connection with the water supply of more clearly showu by referring to Fig. 956 b, This device may
cities are similar in principle. Where the configuration of the also be used as a supporting hydraulic lever, similar to Fig. 951 c.
land demands it, the pipes are ruu in inverted siphons connect­ If a communication is made between the two different water
ing intermediate reservoirs. An illustration of this arrange­ columns, as showu in Fig. 956 c, the pressure will be equalized.
ment is given iu Fig. 955, which shows the waterworks system This gives a differential hydraulic lever similar in principle to
of Fraukfurt-am-Main designed by Schmick.
the Chinese windlass of Fig. 790 a, or the Weston Differential
Block of Fig. 796 e.
A
\\
' .
!'
0
11
a ,
j;
i]
ji
ji
t A large inverted siphon is formed by the new Croton Aqueduct, which
passes under the Harlem River at a depth of 150 feet below the surface ofthe
131...1I1 1.5U1
river, and a tunnel of 10*4 feet in diameter driven through the solid rock
See Mechanics, Nov., 1SS6, p. 241.
X This is examined in detail in a memorial on the better utilization of
water, published at Munich in 1883 by the German Society of Engineers and
FIG. 955,
Architects.
'i For further discussion of this subject the following references may be
The highest spriug is at a„ Vogelsberg, and the next at a.,, consulted : Jaubert de Passa, Recherches sur les arrosages chez les peuples
Spessart. These both deliver into the reservoir r,, c.u at Aspeu- anciens, Paris, 1846; Ditto, Memoire sur les cours d'eau et les canaux
hainerkopf. The next reservoir is at c3, Abtshecke, from which d'arrosages des Pyrenees orieutales; Nadault de Bnffon, Cours d'agriculture
the water flows through b., to the reservoir ct and cb, from which et d'hydrauhque agricole, Paris, 1853-1858; Ditto, Hydraulique ag?icole ap­
the city is supplied. The elevations above sea level are giveu plication des canaux d'irrigatiou de l'ltalie septentrionale, Paris 1861-1862 •
Baird-Smyth, Irrigation in Southern India, Loudon, 1856 ; Dupuit Traite de
la conduite et de la distr. des ean\, Paris, 1865 ; Scott-Moncrieff Irrigation in
* A system of this sort was built in 1887 from Baku to Batoum ou the Southern Europe, London, 1868; Linant de Bellefonds Bey, Memoire sur les
Black Sea. The length of line is 1005 kilometres (603 miles), 6 in. diameter, pnneipaux travaux d'utilite publique en Egypte etc., Taris, 1873- Krantz
and the reservoirs 3000 feet above sea level.
Etude sur les murs de reservoirs, Paris, 1870 ; F. Kahn, Ueber die Thalsperre
der Gileppe bei Verviers, Civil ingenieur, 1879, P- 1; also an article bv
Charles
" Ueber I See
Grad
das Glaser's Wasser,"
111
Aunalen,
" la
Berlin,
Nature,"
1885, 1876.
1S76,
Vol.
p.
XVIL,
55 ; also
p. 234.
a brief article bv the author

November, 1892.] ENGINEERING MECHANICS. 279
The opposite extreme to a high pressure accumulator is found
in those pools or receptacles of water far below the natural sea
level, such as are fouud iu mines, and in the polders or drainage
pools of Holland, Lombardv, and parts of Northern Germany.
Reservoirs are not confined to use with liquids. Examples of
other fluids are found iu the gasometers of gas works, in the
receivers for compressed air, so extensively used in mining aud
tunneling, and in making the so-called pneumatic foundations.
Smaller reservoirs are found iu the air-chambers on pumping
machinery, aud the like.
The sewage system of Berlin, designed by von Hobrect, consists
of ten drainage pits, with the water level below the natural
level, arranged on the so-called radial system. The sewage is
pumped from these pits and delivered by means of pipes to
sewage farms at a distance from the city.
Negative receivers, so-called, may be used for air, as in the
case of the coining presses ofthe English mint, where a vacuum
chamber is used to receive the air already used for driving the
machines, and kept pumped out by steam power. The ventilating
apparatus for mines also often contains such negative
reservoirs for air.
Reservoirs are also used for granular materials, such being
extensively used in connection with grain handling machinery.
A steani boiler may be considered as a physically supplied
reservoir, as well as a physical ratchet system (see \ 260). A
combined physical and chemical reservoir is found in the electrical
accumulator, which may properly be called a currentreservoir.
4V combined physically and mechanically operated
negative reservoir is found iu the various forms of refrigerating
machines
A modern application of pressure organs, and one which is
rapidly extending in use, is that of the distribution of power in
cities. I ? ollowing the impulse giveu by the introduction of the
high pressure water system of Armstrong, the use of gas in
motive power engines by Otto followed, and many other methods
of meeting the problem have been applied.
Iu long distance transmissions of this sort, special reservoirs
are often used, iu which force may be stored, so to speak, and
from thence distributed iu a manner similar to the ring transmission
system for rope (see \ 301). In this method the pressure
organ after use is returned to the reservoir to be compressed
and used again, or it may be used as in the line transmission
and allowed to escape at the end of the line*
The following cases are given as applications of pressure
organs iu long distance transmission :
1. The Loudon Hydraulic Power Company distributes 300
H. P. by means of water at a pressure of 46 atmospheres (675
pounds). A similar and earlier installation is in use at Hull.
2. The General Compressed Air Company distributes power
by means of air at a pressure of 3 atmospheres (45 pounds) in
Leeds and Birmingham. The system is au open line, aud iooo
H. P. are used in Leeds, and 6000 H. P. in Birmingham.f In
Paris the Compagnie Parisienne de Pair comprime, precedes
Victor Popp, distributes power from three stations in quantities
varying from a few foot pounds up to 70 or 80 H. P., a total of
some 3000 H. P. The use of compressed air appears to be
destined to a widely extended use for this purpose.
3. The distribution of power in New York by means of steam
mains is extensive and well known.
4. The vacuum system is used also in Paris by the Societe
anonyme de distribution de force a domicile. This is an open
line transmission, operating in 1885, about 200 H. P.
5. Transmission by highly superheated water has been used
in Washington, by the National Superheated Water Co., distributing
heated water at pressures from 26 to 33 atmospheres
(400 to 600 pounds), the water beiug converted into steam at the
point of utilization.
6. The distribution of power by means of gas holders has
already been referred to, and the distribution by electric currents
is rapidly being developed.
5 3'3-
MOTORS FOR PRESSURE ORGANS.
The methods of applying pressure organs to the development
of motive power are even more varied as iu the case of tension
organs. For this reason a general view of the subject will be
takeu in order to obtain a classification which will simplify the
discussion. The main distinctions are those of the character of
the motion of the mechanism, and of the method of applying
the pressure organ to the motor.
The great difference iu the character of the motion of the
mechanism lies in the fact that it may be either continuous or
intermittent, so that the motor may be either :
A running mechanism, or
A ratchet mechanism (compare \ 260). The ratchet pawls for
pressure organs are the various forms of valves (see Chapter
XXVI).
The various forms may also be classified according to the following
important distinctions based on the method of driving.
The pressure organ may drive, or
It may be driven, or
The impelling mechanism may itself be propelled.
There is also a third distinction to be made, namely, whether
the pressure organ acts merely by its weight, or whether it acts
by its living force of impact. This last distinction cannot be
sharply observed in practice, but is especially to be considered
in discussing the theory of action of the various machines.
In the following pages the various applications will be shown
iu a manner similar to that employed in ji 262 for teusion organs,
following the system of classification outlined above, and beginning
with ruuuing mechanism as the simpler of the two
great divisions.
A. RUNNING MECHANISM FOR PRESSURE ORGANS.
I 3M-
RUNNING MECHANISM IN WHICH THE PRESSURE ORGAN
DRIVES BY ITS WEIGHT.
With a few unimportant exceptions the motors of this class
are operated by liquids, which at moderate velocities practically
follow the laws of gravity.
Iu Fig. 957, a is an undershot water-wheel, and b is a half-
FiG. 957-
breast water. The water is guided in a curved channel and the
buckets are radial, or nearly so. The wheel is so placed that
the buckets pass with the least practicable amount of clearance
over the curved channel. At c is shown a high breast wheel,
and at d an overshot wheel (compare I 47). In these latter
wheels the buckets are so shaped that they retain the water in
the circular path, being closed at the sides also, while on
account of the moderate pressure they are left open above. At
e is shown the side-fed wheel of Zuppinger.
Fig. 95S, a is an endless
chain of buckets, and b a
similar arrangement, using
disks running with slight
clearance in a vertical tube.
In the wheels shown in
Fig- 957 the water acts ou
the wheel much in the same
manner as a rack acts when
driving a pinion, and iu this
sense a water wheel may be
considered as a gear wheel.
When the water acts only
by gravity these constructions
are only practical when — ^A
the wheel cau be made ««»JM».
larger in diameter than the pIG g^g
fall of water, and where
small diameters must be used the arrangements of Fig. 95S are
available. Very small wheels acting under high pressures may
be employed by making use of the so-called "chamber wheel
work," f of which some examples are here given.
FIG. 959-
Fig- 959" is the Pappenheim chamber wheel train. In this
the tooth contact is continuous, the teeth being so formed that
* See a paper by the author in Glaser's Anualen, 1885, Vol. XVII., p. 226. the continuous contact' of the teeth at the pitch circle prevents
t See Lupton and Sturgeon, Compressed Air vs. Hydraulic Pressure, Leeds,
1886; Sturgeon, Compressed Air Power Schemes, London, 1886; also ihe X See Berliner Verhandluugen, 1S68, p. 42.
Birmingham Compressed Air Company, Birmingham, i88«.

28o ENGINEERING MECHANICS. [November, 1892.
the water from passing, while the points aud sides of the teeth
make a close contact with the walls of the chamber. The
downward pressure of the water enters into the spaces between
the teeth and drives both wheels. The axes of the wheels are
also coupled by a pair of spur gear wheels outside the case,
thus insuring the smooth running of the inner wheels. This is
the oldest form of chamber train mechanism known, and cau
also be used as a pump, operating equally well in either direction.
Fig. 959 b is Payton's Water Meter, with evolute teeth.
The flow is intermittent, but one contact begins before the
action of the previous one ceases.
Fig- 959 e is Eve's chamber gear train. The ratio of teeth is
I to 3, and the flow is also intermittent. The theoretical volume
of delivery for all forms of chainber gear trains, whether continuous
or intermittent in delivery, is practically equal to the
volume described by the cross section of a tooth of one of the
two wheels for each revolution.
Fig- 959^ is Behren's chamber train. In this case each wheel
has but one tooth, as is also the case with Repsold's train (described
hereafter), and the gears belong to the class of disc
wheels or so-called " shield gears " (see j! 211). This arrangement
possesses the great advantage of offering an extended surface
of contact at the place between the two wheels where, in
the previous forms, there is but a line contact. This permits a
sufficient degree of tightness to be obtained without requiring
the parts to press against each other. Behren's chamber gear
makes an excellent water motor if the impurities of the water
are not sufficient to injure the working parts.
The flow of water through chamber gear trains is not uniform,
and the inequality of delivery increases as the number of
teeth in the wheels is diminished, hence they should be driven
only at moderate velocities when used as motors, in order to
avoid the shocks due to the impact of the water.
g 315-
RUNNING MECHANISM IN WHICH THE PRESSURE ORGAN
DRIVES BY IMPACT.
In driving running mechanism by impact, fluid pressure
organs, both liquid and gaseous, may be used, as will be seen
from the following examples.
FIG. 960.
Fig. 960 a is a curreut wheel, or common paddle wheel. The
paddles are straight, and either radial, or slightly inclined
toward the current, as in the illustration. The working contact
iu this case is of a very low order.
Fig. 960/} is Poncelet's wheel. The buckets run in a grooved
channel, and are so curved that the water drives upwards aud
then falls downwards, thus giving a much higher order of contact.
At c is shown an externally driven tangent wheel. The
buckets are similar to the Poncelet wheel, but with a sharper
curve inward. The discharge ofthe water is inwards, its living
force beiug expended. At d is an internally driven tangent
wheel, similar to the preceding, but with outward discharge.
The form shown at e is the so-called Hurdy-Gurdy wheel. The
water is delivered through curved spouts, and this form is practically
an externally driven tangent wheel of larger diameter
and smaller number of buckets. This wheel, from a crude
makeshift, has become one of the most efficient of motors.*
Wheels with inclined delivery as made in the forms shown in
streams as a simple expedient, but of low efficiency; b is the
Borda turbine, consisting of a series of spiral buckets in a barrel
shaped vessel; c is the so-called Danaide, the spiral buckets
being in a conical vessel, this form being mostly used in France.f
Iu the wheels which have been shown in the preceding illustrations
from Fig. 958, the living force of the water acts by
direct impact through a single delivery pipe.
The following forms differ from the preceding, in that the
water acts simultaneously through a number of passages around
the entire circumference of the wheel. This form gives the socalled
hydraulic reaction in each of the inclosed channels, and
hence wheels of this class are commonly called reaction wheels,
or reaction turbines.!
Fig. 962 a is Segner's wheel, the water entering the vertical
axis aud discharging through the curved arms ; b is the screwturbine,
entirely filled with water ; c is Girard's current turbine,
with horizontal axis, and only partially submerged ; d is Cadiat's
turbine, with central delivery, and e is Thomson's turbine with
circumferential delivery and horizontal axis, the discharge being
about axis at both sides. In all five of these examples the
column of water is received as a whole, and enters the wheel
undivided until it enters the wheel; in the following forms the
flow is divided iuto a number of separate streams.
FIG. 963.
Fig. 963 a is the Fourneyrou turbine, acting with central
delivery ; the guide vanes are fixed and the discharge of the
water is at the circumference of the wheel; b is a modification
of the Fourneyron turbine, the water beiug delivered upwards
from below, and sometimes called Nagel's turbine ; c is the
Jonval or Henschel turbine, the guide vanes c being above the
wheel, which is entirely filled by the water column ; d is Francis'
turbine, with circumferential delivery through, the guide
vanes c* ; e is the Schiele turbine, a double wheel with circumferential
delivery aud axially directed discharge. Iu the latter
three forms a draft tube may be used below the/wheel, to utilize
that portion of the fall, as indicated in forms c and d.
FIG. 964.
For gaseous pressure orgaus, of which wind is the principal
example, some forms are here given. Fig. 964 a is the German
windmill, with screw-shaped vanes ; b is the Greek aud Anatolian
windmill, with cup-shaped vanes. Both forms are similar
in action to the above described pressure wheels. At c is shown
the so-called Polish windmill, with stationary guide vanes ; ||
fl* is Halladay's windmill, made with many small vanes, which
place themselves more and more nearly parallel with the axis
as the force of the wind increases, the rudder

November, 1892.] ENGINEERING
\ 316.
RUNNING MECHANISM IN WHICH THE PRESSURE ORGAN IS
DRIVEN AGAINST THE ACTION OF GRAVITY.
Running mechanism for the purpose of elevating liquids, and
especially for lifting water, are of very early origin, and the
various machines for this purpose form the very oldest of
machine inventions.
FIG. 965.
Fig. 965 a is a bucket wheel, the vessels on the circumference
lifting the water ; this is driven by the power of men or animals,
or in many instances by a current wheel (as iu Fig. 960.;).* At
b is the Tympauou of Archimedes, used down to modern times,
the sections deliver the water through openings into the axis;
c is a paddle wheel, only adapted to raise the water a small
height, much used in the polders of Germany, Holland aud
Italy. The paddles are made either straight, or curved, or
sometimes slightly crooked at the end.f At d is the Archimedian
screw, which, when placed at an angle as shown, is well
adapted to elevate water. The Archimedian screw is exten­
sively used in all positions for the granular and pulverized
materials, in which cases the outer cyliuder is omitted and a
stationary channel substituted, as shown at e, in Fig. 965 e, and
if the transportation of material is iu a vertical direction the
screw is entirely surrounded by a stationary tube. A still later
form is made with a wire spiral, by Kreiss of Hamburg.
FIG. 966.
MECHANICS. 281
there is uo necessity for distinguishing in classification between
them as pumps for liquids or for gaseous fluids. Fig. 967 c is
FiG. 967.
Fabry's ventilating machine for mine ventilation, consisting of
a double-toothed combination chamber train, with unequal
duration of contact. Root has also used the form shown at d,
which has unequal contact duration, and which has since beeu
made by Greindl as a pump.'S
FIG. 968.
Greindl also makes the form shown iu Fig. 968 a, with gears
of one and two teeth, and rightly claims it to possess the advantage
of a greater freedom from leakage. The form shown at b
has been used by Evrard as a blower, but it does not differ in
principle from a. Baker's blower, shown at c, is a triple chamber
train, also used by Noel as a pump.
It has already been stated tbat Behren's pump, F*ig. 9$gd, has
also been used as a steam engine. As long ago as 1S67 a steam
fire engine has been constructed by putting two of these
machines on thesame axis, one beiug driven by steani. the other
forcing the water.
Chamber gear trains may also be used to be worked in connection.
F*ig. 969 shows an arrangement iu which the chamber
A, 1 B i
i/„l./,...;,'„.,.„' :....;...., ,,:
Fig. 96612 is the spiral pump, iu wliich the screw of Archimedes
is replaced by a channel formed in a plane spiral. In
this form the inclosed air becomes compressed by the speed of
revolution of the mass, and the water can be forced quite a considerable
height.! Fig. 966 b is a conical spiral pump called
after its inventor, Cagniard Latour, a Cagniardelle. The Cag
uiardelle is usually placed entirely in a trough, but the illustration
shows how the end of the spiral may be modified so as to
require uo enlargement ofthe delivery channel. The diameter
of the cone is adapted to the height to which the water is to be
lifted. The Cagniardelle may also be used as a blower, the inclosed
water driving the entrapped air before it.
The chain and bucket devices already shown in Fig. 958 as
motors are also well adapted to drive the pressure organ, and
are in practical use in numerous modifications. Fig. 958 a is
extensively used iu dredging machinery, grain elevators and
the like, and Fig. 958 b is much used for lifting water.
The various forms of chamber gear trains already described,
give by inversion corresponding forms of driving mechanism,
some examples of which are here given.
Fig 9°7 a FIG. 969.
train A delivers water to a distant one B, driving the latter and
receiving the discharge water from B through a return pipe to
be used again. The combination forms a transmission system
of the second order (see \ 26), and is similar to a belt or chain
transmission. The loss iu efficiency in this device is not an unimportant
consideration.
Au important class of machines consists of those made with
tension orgaus for transporting granular materials. For this
purpose belts, chains, etc., are used, and when the transmission
is horizontal, or nearly so, grain is successfully transported on
wide belts.|| Another application is that of Marolles, using an
iron belt, 40 in. wide, 0.06 in. thick, for transporting mud.
Twelve such machines were used on the Panama Canal work,
the distance being 200 feet, and the speed of the band 12 to 40
feet, accordiug to the nature of the material. Similar apparatus
at the Suez Canal handled material at a cost of 7.6 cents per
cubic yard.
is Repsold's pump ; each wheel has one tooth, the
I 3'7-
RUNNING MECHANISM IN WHICH THE PRESSURE ORGAN IS
profiles being formed as described in ''/, 207 ; b is Root's blower,
DRIVEN BY TRANSFER 01 LIVING F'ORCE.
the wheels having two teeth each, and the action being the
The method of driving pressure organs by a transfer of living
same as the Pappenheim machine, Fig. 959 a. This device has
force is one wliich admits of numerous applications, as the fol­
been very extensively used as a blowing machine. Since the
lowing examples show.
actiou * Large of wheels these of machines this sort in have drawing been in air use against in Syria for pressure many centuries, is simi­
Fig. 970

282 ENGINEERING MECHANICS. [November, 1892.
many instances are made iu one piece with the wheel itself, this
adding to the efficiency. These pumps have been most successfully
made by Gwynne, Schiele, Neut and Dumont among
FIG. 970.
others.* Centrifugal pumps have beeu successfully used as
dredging machines for lifting wet sand, gravel and mud, iustances
among others being the North Sea Canal at Amsterdam,
and the harbor at Oakland, California.
Fig- 970 b is the well kuown fan blower used everywhere for
producing a blast of air, and acting by centrifugal force. When
used "is exhaust fan this is widely used in connection with
suitable exhaust pipes for removing foul air, sawdust, and other
impurities in workshops, as well as for the ventilation of mines.!
At c is shown a form of spiral ventilator, known as Steib's ventilator
; it is similar to some of the preceding forms, but is of
limited application, aud is better adapted for lifting water, a
service to which it has been applied in the polders of Holland.
At rf is a centrifugal separator, a device of numerous applications
for separating materials of different specific gravity by
centrifugal force. A notable example of this machine is the
centrifugal separator for removing cream from milk.
Another variety of machines for driving pressure organs by a
transfer of living force, is that in which another pressure organ,
either liquid or gaseous, is used instead of a wheel as the impelling
mechanism. To this class belong the various jet devices,
injectors, etc.
FIG. 971.
Fig. 971 a is Giffard's injector in the improved and simplified
form made by the Delaware Steani Appliance Co. Iu this case
steam is used to drive a jet of water into a vessel already containing
water under pressure. The jet of steani rushing through
the nozzle bi draws the water in by the suction tube b.L, and both
pass through the mixing tube b3, and are discharged through
the outlet tube bt; the outflow at bb provides for the relief of
the discharge at starting, before the jet action is fully established.
The regulation of the flow of steam is effected by a
steani valve attached above bx. At b is Gresham's automatic
injector, which is so made that should auy interruption occur
in the supply of water at b.,, the suction action is automatically
started, and the entering column of water is lifted again. This
is done by the introduction of a movable nozzle b6 between b3
and b„ which adjusts its position with regard to b3 according to
the variations in pressure above and below.
Fig. 972 is Friedmann's jet pump. The mixing tube b3 is
divided iuto a number of sections, which permits a very free
entrance to the water, and gives au excellent action ; b is
Nagel's jet pump, used for lifting water from foundations by
means of another jet of water. The entrance jet is at b1: the
FIG. 972.
suction tube at b.lt and the mixing tube at* A 3; the regulation is
effected by a valve at the end of b3.
Steani jets are also used to produce a blast of air, or compressed
air may be used for the same purpose, as can also water
under pressure. A reversal of the last mentioned arrangement
occurs in Bunsen's air pump, in which a jet of water is used to
produce a vacuum. Receut devices for utilizing jet action are
numerous. Among others, a jet of air has been used to feed
petroleum into furnaces as fuel. Dr. W. Siemens proposed to
carry the petroleum in the hold of a vessel in bulk, aud substitute
sea water, as it was consumed, in order to maintain the
ballasting of the ship undisturbed. Granular materials have
been handled by means of jet apparatus, usually impelled by
compressed air, sometimes by water jets.
An especial feature of jet pumps, and one which should not
be overlooked, is that they act either by guiding the pressure
organ stream, or that the driving action of the pressure organ
stream itself produces a guiding action, and that the existence
either of a reservoir or some external means
JCJ|\ if=^ of driving must be presupposed The use of a
'•-'•: •
"3 pressure organ in motion for driving mechanism,
is in this respect similar to the so-called
inductive action of an electric current.
An example of pure guiding action is
II ;\\ c| ' found in the "Geyser Pump" of Dr. W.
Siemens, Fig. 973. The water is to be raised
from a depth H, and the tube b is prolonged
downward to a depth //, below the sump 6'.
H The prolonged tube bl is open at the lower
-*- ^3 end, and in the bottom opening T an air tube
•s c is introduced, and air is admitted at a pressure
slightly under that of a column of water
of height equal to Hv
The air mingles with
the water and forms a mixture in ax which is
lighter than water, and the air pressure is then
capable of forcing the light mixture up to the
surface. The lifting action is assisted by the
expansion of the ascending air. Siemens
•Y
found that it was possible to produce this
action when //was equal to If, that is, the
FIG. 973. specific gravity of the mixture of air and
water = 'A.
* A recent installation of magnitude is that of five centrifugal pumps built
FIG. 974.
by Farcot, of Paris, in 1887, for supplying the Katatbeh Canal ill Egypt.
The wheels are 12 ft. 6" dia , and each deliver 17,660,000 cubic feet in 23 hours,
Fig- 974 a is the so-called " flying bridge," the current flow­
the lift varies from 1 to 12 feet.
ing in the direction of the arrow, causing the boats to swing
f Fans lor these purposes are made in great variety by J. B. Sturtevant.
across the stream, describing an arc about the anchor to which
Boston, Mass.
j I
RUNNING MECHANISM
I 318.
IN WHICH THE
PROPELLED.
MOTOR ITSELF IS
The third division, in which the motor itself is propelled in
the liquid pressure organ, contains fewer varieties than the preceding
ones but is of the greatest importance since to it belongs
the entire subject of marine propulsion.

November, 1892.] ENGINEERING MECHANICS. 283
they are held by a chain ; b, is a sail-boat, the sail being the
driving organ transferring to the boat a portion of the living
force of the current of wind. At c, is a steamboat with side pad­
dle-wheels, and d, a stern-wheel boat; e, is a screw propeller.
A screw driven by a. steani engine pressing the water backward
and the reaction of the water impelling the boat. At fi is a
so-called jet propeller, the reaction being produced by jets of
water forced through tubes at the side of the boat, the water
being driven by centrifugal pumps.* Atg, is shown a current
wheel motor. The side paddle wheels are caused to revolve by
the action of the current, and by connection with a cable or
chain gearing (See Figs. 787 aud 794) the boat is propelled up
the stream.
Direct acting reaction jets have been used for torpedo boats,
using carbouic acid gas, but this method has been superseded
by twin screw propellers driven by compressed air. Rockets
and rocket shells are examples of direct acting pressure organs.
£. RATCHET MECHANISM FOR PRESSURE ORGANS.
I 319-
FLUID RUNNING RATCHET TRAINS.
The pawls iu a fluid ratchet train are the valves. The}' may
be divided into two great classes,! similar to those existing iu
ratchets of rigid materials, viz.
Runniug Ratchets, or Lift Valves, aud
Stationary Ratchets, or Slide Valves.
In the first class we have flap valves, also conical and spherical
valves, aud iu the second, the various torms of cocks, cylindrical
and disc valves and flat slide valves. In both kinds of
valves there exists an analogy to toothed and to friction ratchet
gearing, since by use of contracted openings the effect of
friction is produced, and with full openings it is obviated.
This gives a division which does not exist in the case of friction
and toothed ratchet gearing.
Viewed according to the preceding classification, pistonpumps,
and piston machines are properly ratchet trains.!
This idea does uot seem to offer any practical difficulties, since it
can be made to include all the numerous variations without creating
more confusion than the former methods of classification.
It is not practicable to distinguish between the devices acting
by gravity and those acting by transfer of living force, since
both are frequently combined.
The oldest devices are those using air, and the oldest piston
is the membrane piston, (Fig. 949) iu the form of a bag of skin
used as a bellows. In this primitive device the earliest valve
was the human thumb, and in the larger bellows the heel of
the operator, these being followed at a later date by valves of
leather.') The working part of the bag was next strengthened
by a plate, (See Fig. 949 a.) and developed into the common
bellows, next followed the disc piston, a very early improvement
|| and later the plunger, from which the numerous modern
forms have grown. The following examples will illustrate.
Fig- 975 a, is the common lift and suction pump, a ratchet
train similar to Fig. 749 ; a, is the pr-ssure organ stream (corresponding
to the ratchet wheel a) b2, the holding pawl iu the
form of a valve, c2, is the receiver or cylinder for the water and
piston, c-i, is a pawl-carrier in the form of the piston, b,, the
other pawl, or lift valve. The water here overflows at the top
of the cylinder, and if it is to be lifted to a greater height the
cylinder may be prolonged upward and the rod proportionately
lengthened. Iftherodisto be kept short, the form shown at
b, is used. The top of the cylinder is closed and the rod
brought out tlirough a stuffing box, and the discharge tube
only is prolonged. At c, is the so-called force pump with a
disc piston, and at d, the same form with plunger. In these
the discharge valve is iu a separate chest. The water column a,
is divided into two divisions a1 and a.,, the lower being impelled
in the up stroke, and the latter ou the down-stroke of the piston.
A blow or shock is produced at each stoppage of the
motion ofthe water column and to reduce this action the speed
of flow must be kept down, and also the shock cushioned by
means of air vessels. At d, air vessels are shown both on the
suction and force pipes.
The preceding pumps are all single acting, discharging one
cylinder of water for each complete double stroke of the piston.
By cylinder of water is here meant the product of the piston
area by the length of stroke.^ The space between valves and
piston is not included, this being merely clearance or water space.
The piston may be so constructed that it remains stationary
and the cylinder slides upon it, this forming an inversion ofthe
common form and possessing many applications.
Fig. 976(7 is Muschenbrceck'spump (1762) for moderate lifts,
b, is Donnadieu's pump for deep wells, especially adapted for
FIG. 976.
artesian wells.** This latter form possesses the peculiarity that
cylinder and discharge pipe move, and the piston is stationary
while action is not changed. (See Fig. 749 ) At c, is Althaus
so-called telescope pump, which does not differ from Fig. 975 a,
except that the piston is longer aud is operated by two side
rods instead of a single central one.!! The form at d, is a modification
of c, with external packing.
In the pumps shown in Fig. 9752, b, and Fig. 97617, the piston
rod plunges into the water ou the downward stroke and
hence acts as a piston, lifting water by its displacement. On
the upward stroke the water flows into the space again,
and so the volume of delivery is not altered but a slight portion
of the delivery takes place on the down stroke. This action
can be utilized, however, as was very early done in mine
pumps, by increasing the diameter ofthe rod, or forming it into
a plunger so as to cause the delivery to be divided equally
between the two parts of the stroke. This form may be called
a double delivery pump, or briefly a double pump, since it is
practically two pumps, using the same set of .valves. Some
examples follow.
Fig- 977 a, the plunger

2S4 ENGINEERING MECHANICS. [November, 1892.
By making the suction valve also a moving 'piston, both the
water columns may be kept in motion for both movements of
the rod. This is a double actiug ratchet mechanism (Fig. 750,)
and hence also a double acting pump.
FIG. 978.
Fig. 97S

November, 1S92.] ENGINEERING
WIRE-ROPE TRANSPORTATION AND TRANSMISSION,
Wire rope will always be an important factor in mining operations,
and its widest application is to be found in its adaptations
to the surface and underground haulage of coal and ores as
embraced in hoisting, inclined planes and haulage. On inclined
planes no rule can be given for determining the least angle of
inclination that can be worked by gravity. For planes up to
500 ft. in length, the minimum grade may be assumed at about
5 per cent. For longer planes, from 500 up to 2,000 ft., it varies
from 5 to 10 per cent, being greater in proportion to the length
of the line and less in proportion to the load. The profile of
the plane should be concave if possible, with the steepest inclination
at the top. Where grades are so slight that gravity cannot
be utilized as a motive power, a continuous system of wire
rope haulage is commonly applied either by a "tail rope," or
an " endless rope."
In long spans, intermediate supporting wheels are frequently
used, and it is usually sufficient to support only the slack side
of the rope, but, whatever the span, the driving side of the rope
will require a less number of supports than the slack side. The
sheaves supporting the driving side should, in all cases, be of
equal diameter in the driving wheels; for it makes no difference
whether the rope laps half way around or only a quarter, the
tension induced by bending is the same. With the slack side,
however, smaller wheels may be used. The actual horse-power
transmitted approximately equals 3^ times the square of the
diameter ofthe rope in inches, multiplied by the velocity in feet
per second.
As for the limits of span it has been found in practice that
when the deflection of the rope at rest is less than 3 in. the transmission
cannot be effected with satisfaction, and that shafting
or belting is to be preferred. This deflection corresponds to a
span of about 60 ft. The maximum limit depends somewhat
on the contour of the ground and the height of the tower. There
is an instance at Lockport, N. Y., of a clear span of about 1,700 ft.
All wire rope tramways are practically transmissions of power
of this kind, in which the load, however, instead of being concentrated
at one terminal, is distributed uniformly over the entire
line, and the actual horse-power transmitted approximately
equals 434* times the square of the diameter of the rope in inches,
less six millionths the entire weight of all the moving parts, multiplied
by the speed of the rope in feet per second.
THE governments of Great Britain, France, Belgium, Prussia
and Austria several years ago directed that commissions of mining
experts make a thorough investigation into mines and mine
management, with a view to the greatest possible prevention of
accidents and loss of life. All these commissions have completed
their arduous labors in a most creditable and exhaustive
manner. A British mine inspector, Mr. W. N. Atkinson, condenses
some of the conclusions from the Austrian report as
follows :
That in the working of mines, provisions be made for two
shafts or outlets, and if the shafts are close together, the surface
arrangements should be such that a fire cannot destroy the
means of access to the mine by both shafts. These shafts should
be of sufficiently large area to carry the full volume of air required
at a velocity not exceeding 20 ft. per second. If the
shafts are used for ventilation only, the velocity may be greater,
but it should not exceed 33 feet per second. The return air
should be calculated as exceeding the intake in volume by 15
per cent. If existing shafts do not meet these requirements,
more shafts should be sunk or the output be reduced to comply
with them. The sectional area of the roadways should be sufficient
to convey the required amount of air at a velocity not exceeding
20 feet per second, and ample allowance should be made
for the space occupied by mine cars in transit.
MECHANICS. 285
Ventilation should restrict fire-damp to not more than I Ai P er
cent , and carbonic acid ^ per cent. Hence the air should
range from 70 cubic feet per man per minute to 140 feet. The
air should be split to supply 100 men in each split. Fans and
the assensional system of ventilation are recommended instead
of furnaces, and all fans should have recorders, governors and
water gauges. The most accidents are found to come from the
shot-firing, especially when black powder or its derivatives are
used. The danger is reduced by judiciously placing the shot
holes, and careful tamping with damp sand. The greatest care
is necessary in causing explosions to prevent contact with firedamp.
Black powder and its derivatives are condemned except
where there is very little fire-damp.
If the proportion of gas in the air current rises to 2 and 2)4
per cent., shots may still be allowed on condition that they are
fired by a method incapable of igniting gas, and that fire-damp
dynamite of the prescribed composition is used. When the
proportion of gas attains 3 to 3A per eent., shot-firing should
be stopped, and also when explosive mixtures can be detected
in holes in the roof, although the air current does not contain
3 A per cent, of gas. The use of inflammable material as stemming
should be rigorously forbidden, and shots should be fired
at times when the fewest possible number of men are in the
vicinity.
It was fully proved that dry coal dust in suspension is very
dangerous, but the reason is not known why some coal-dust is
easily ignited while other dust ignites with difficulty. Shot firing
is the chief danger in dusty mines, and it is recommended that
that method be forbidden except when soda-dynamite is used.
The following precautions are recommended in the working
of fiery and dusty mines :
All the seams or parts of seams where dust is plentiful should
be divided into working districts of small extent, separated by
safety barriers, and ventilated separately, in order to localize any
possible explosion of fire-damp or coal-dust; galleries connect
ing such districts should be carefully closed or freed from coaldust
; haulage roads should also be freed from dust, either by
dampening the floor, or injecting water by small pumps. When
a seam is being opened out, the area should not be enlarged by
useless galleries, or by exposing too great surfaces. A superfluous
amount of air should not be allowed to circulate, on
account of its drying action on the dust. If coal dust is found
to accumulate in any district, shot-firing with high explosives
should only be allowed after the place—within a radius of 11
yards—has been freed from dust by watering, and if this cannot
be done, shot-firing should be prohibited, except with safety
explosives such as soda-dynamite. If fire-damp is present to
the extent of yi to 1 per cent, in conjunction with dust, then
shots should only be fired by Lauer friction-caps, or other central
percussion caps, or by electricity. If the air contains 2 to
2^ per cent, of fire-damp, shot-firing should be prohibited
altogether. The shots should always be fired by competent
officials.
Mr. Atkinson thinks that the Austrian experts err in stating
that shot-firing may still be allowed when the greatest precautions
are taken, in places where there is 2^ per cent, of firedamp.
Such a proportion can be detected by an ordinary safetylamp,
and in his opinion, the only safe rule to go by is not to fire
shots where any gas can be detected within 20 yards of the shot.
In commenting on the experiments made with shot-firing in
the presence of coal-dust, he states that the conclusion drawn
requires further elucidation. While the fact that the drier the
dust the more inflammable it becomes is self-evident, the important
thing to know is " How damp must it be to be harmless
? " He also expresses an opinion that the physical condition
of coal-dust as to dryness, purity, and fineness will be found to
be more important factors than its chemical composition.

286 ENGINEERING MECHANICS. [November, 1892.
OUR naval engineers have boldly liberated themselves from
the nest of difficulties encountered in maintaining forced draft,
by resolving to use ioo port smoke-stacks on armored cruiser
No. 3. Though No. 3 may look like a stovepipe hat on a dwarf,
yet the advantages secured, and the vexing difficulties overcome,
will fully compensate for " looks." Smoke and gas will thus be
disposed of. There is more room to get away from conventional
methods and ideas in marine engine and ship construction.
THE average artesian well in the west gives enough water in
one month to cover six acres to the depth of one foot. There is
no economic and practical method of constructing reservoirs to
contain the supply, and hence only a small degree of water
power or flow is actually utilized. Here is a great opportunity
to devise some cheap and practical method for enabling the
farmer to store water and use it economically as required. The
latest official figures show that there are or were 8,097 artesian
wells doing service on 51,896 acres, with an average depth of
210 feet, and average cost of $245.58. The average discharge
is 54*4 gals, per minute and surface irrigated 13A acres. This
is an insignificant result. Irrigation from streams is of course
the cheapest and preferable method, but there is a vast area
beyond the reach of such methods. Only iA per cent, of the
land irrigated is served by wells, the figures for stream irrigation
being 3,631,381 acres. Both systems will be rapidly developed,
but it would be well if some system could be devised to meet
the pockets and needs of the agricultural communities remote
from streams, and whose dependence is almost exclusively on
artesian well supply.
MR. THEO. T. ELY, superintendent of motive power P. R. R.,
Mr. Axel Voght, mechanical engineer, and Charles Lindstrom,
chief draughtsman, have presented to the railroad world a sam­
ple of engineering designing in a locomotive that may well be
watched with unusual interest. It is expected to make a speed
of 100 miles per hour. It is a two cylinder compound and
weighs 72A tons, or, with tender, 112 tons; four drivers, 7 feet
diameter; boiler pressure, 200 pounds; cylinders, 19^2 and 31
inches. Pistons of both cylinders have a 28-inch stroke. Train
is started from the low pressure cylinder. The boiler is 5 feet
in diameter, 27 feet long; fire-box 9 feet long, 40 inches wide,
inside grate measurement. Height to top of cab, 14 feet; top
of stack, 1 5 feet; distance from bottom of boiler to rail, 6A feet.
Slide valves are between cylinders instead of on top. Piston
valves, 12 A inches diameter. The brake cylinder is under the
cab and at the back of it, and the brakes are suspended in front
of each of the four driving wheels. The cross-head hangs from
an upper guide. The sand is distributed through covered valves
by compressed air. Another new feature is that the engineer
can start the engine with about as much twist of the wrist as he
uses the air-brake. The engine truck has a side-sliding motion
of 1A inches, as well as a central motion, and while under high
speed can go straight around a curve while the wheels are con­
forming to the irregularity, powerful springs bringing the engine
into the direct lines as soon as straight road is reached. This
will, it is estimated, save a tremendous amount of wear and tear
on the machinery, and enable the engine to run round curves
at the highest speed, reducing the danger of such a performance
to a minimum.
"This locomotive," said Mr. Ely, " is not intended for climb­
ing grades or for doing any local work, the large wheels being
adapted for long and rapid runs. It was built to serve a pur­
pose which no locomotive in existence has yet done. The tender
is equipped with three pairs of wheels, instead of eight wheels
on two trucks. They are of the same pattern as the forward
wheels of the engine, and each pair is equipped with equalized
brakes. The tender is equipped with spring buffers."
Mr. Ely says: "It is too early to talk of results. It takes
from nine months to a year to get an engine in a condition to
make or break a record. That will be our position in regard to
our own new engine, the 151 5. We desire to build a locomotive
that will haul a paying train between New York and Jersey City,
or between other principal points on our system, at a very high
rate of speed.
"When I say a paying train I mean the heaviest trains that
are run on our lines. We have engines, of which the Class P
is a fine type, that could haul a light train of four or five cars at
very high scheduled speed. The Empire State express train on
the New York Central Railroad, runs at very high speed, but it
is a light train, weighing probably 190 tons, or 380,000 pounds.
A good average of our heavy trains is 300 tons, or 600,000 pounds.
That is quite a difference.
" The idea is to get the time between Jersey City to Philadel­
phia down to 90 minutes, a maintained schedule speed of 60
miles an hour. This we desire to do with the new locomotive
under all conditions, no matter how unfavorable, taking con­
siderations of delays, slow running stretches, etc. This, of
course, requires that the engine shall make up time lost, and
bring the train over the road at an average of a mile a minute,
including everything. We hope that under the best conditions
after our engine is thoroughly in trim that as high a speed as
100 miles an hour may be maintained. I will not say that I
expect it, because I will have nothing to take back if I do
not."
This engine is a more radical and complete departure from
former ideas than has ever before been shown, and in making
this departure Mr. Ely has done as the first Napoleon did when
he laid aside much of his military book knowledge. These are
the largest driving wheels ever used, and the engine affords the
largest boiler pressure ever had. The Pennsylvania Limited,
without passengers, weighs 395 tons, and one train, the Western
Express, when heavily loaded weighs 500 tons. This train main­
tains a speed of 45 miles on the New York Division, and fre­
quently makes spurts of a mile a minute. In talking about his
new engine Mr. Ely said: "It is largely an experiment, and
until the locomotive has peiformed the work it was designed for
we shall so regard it. This engine was built not for economy,
but for a gain in power. You can get power as well in a straight
engine as you can in a compound, but the purpose of building
the engines of which No. 151 5 is the first type, is to draw our
heaviest trains at high and continued speed over the New York
division, between Philadelphia and Jersey City—in fact, to get
engines which can maintain under all conditions and in all sorts
of weather a speed of 60 miles an hour without the slightest
difficulty.
" Now, the boiler limits the capacity of an engine to make
steam, so we make the boiler as large as we can to start with.
The next thing to do is to get more steam, and we argue if the
compound engine is economical for fuel it must also be economi­
cal for steam. Instead, therefore, of trying to save money in
fuel, we try to get a more powerful locomotive by the economical
use of steam. There is more steam used in a simple cylinder
than there is in a compound. The compound engine weighs
more than a simple one, because the extra weight goes into the
cylinders. My idea in constructing this engine was not only to
get results but to add cylinders. I selected the two-cylinder
type of compounding as being the most simple of the class."
While our English cousins are wasting Arnold's writing fluid
recklessly, and publishers abroad are running up unnecessary
composition bills about locomotive building, our practical men
are quietly upsetting their favorite theories in practical work.

November, 1S92.] ENGINEERING MECHANICS. 287
ONE effect of the Zone tariff system, says Dr. Weckerle, the
Hungarian Minister of Finance, is to entail a very heavy expenditure
for extra rolling stock and new stations. He says
they want 10,000 new freight cars, 100 locomotives and 500
passenger cars. Including the widening of old tracks and the
laying of new ones needed, the estimated total cost of all this
is about $15,000,000. In view of this expenditure it would seem
that the Zone tariff system is not an unmixed blessing to the
Hungarian taxpayer, but good for the shops.
THE condemnation of aluminium vessels for domestic use by
the German chemists has been upset by the experiments of M.
Balland, communicated to the Academie des Sciences, in
Paris. From -experiments extending over several months he
concludes that this metal is not so easily attacked as iron, copper,
lead, zinc or tin by air, water, wine, beer, coffee, milk, oil,
butter, gas, urine or saliva. Vinegar and salt attack it, but not
to such an extent as to render its use undesirable. This report,
coming from a French source, is interesting, as bauxite, the
chief aluminium mineral, is found chiefly in France.
SOME peculiar experiences have been gained in connection
with the asphalt pavements in the streets of Frankfort-on-the
Main. Shortly after they had been put down, in 1885 and
1S86, cracks of varying lengths and from 0.8 in. to 1.2 in. deep
were formed in the asphalt, resembling those sometimes formed
in earth under great heat. The cracks were found to extend
mainly along the lines of the gas mains in the streets, and
odors of illuminating gas were freely given off from them.
Removing the asphalt surface showed that the beton foundation
layers immediately underneath were also cracked, permitting
the gas leaking from the mains to come in direct contact
with the asphalt. The latter, it appeared, absorbed more or
less of the gas elements, principally benzine, and through their
action lost all its cohesive properties, finally cracking in the
manner referred to. Why the material on either side of these
gas-pipe lines should separate by cracking in consequence of
the supposed action is not stated. Is it due to contraction or
tension caused by slight upheaval ?
SOME FAMOUS SHIPS.
The outcry which has been raised against the destruction of
Nelson's old flagship, the " Foudroyant," makes it interesting to
trace the end of other famous vessels. The "Shannon," which
fought and captured the " Chesapeake," was broken up at Chatham,
parts of her hull being sold at a fancy price ; Sir Francis
Drake's "Golden Hind" came to a similar end at Deptford, a
chair made out of her timbers being one of the treasures of
Oxford University; the " Resolute," which went in search of Sir
John Franklin, and, after being abandoned in an ice waste,
was picked up by an American whaler, and returned refitted
by the United States Government to this country, was moored
in the Medway for some years afterwards, but ultimately taken
in dock and pulled to pieces, a suite of furniture fashioned from
her oaken timbers being sent as a memento to the American
President; the "Sovereign of the Seas," the first British threedecker,
built in the time of Charles I, " to the great glory of the
English nation, and not to be paralleled in the whole Christian
world," was accidentally destroyed by fire at Chatham after
seeing much and long service. Of Captain Cook's "Endeavor"
not a trace is left, though several of his scientific instruments
have been preserved ; nor is there any trace of the " Victoria,"
which made the first voyage round the world. The " Betsy
Caius," which brought William of Orange to England in
1688, was cast away 138 years later. Several English and foreign
warships which have been sold to the Norwegians are
now carrying timber .from port to port; the "Marlborough,"
which conveyed so many thousands of our troops to India, is
now moored at Gibraltar as a coal-hulk; and the "John Bertram,"
the American racing tea-clipper, foundered some years
ago while struggling along towards England with a cargo of
petroleum.—Standard.
A NEW FRENCH ARMORED CRUISER.
The Dupuy de Lome, built at Brest from the plans of M. de
Bussy, was launched so long ago as October 27th, 1890, but is
only now approaching completion. She differs from all previous
ships of her class in that she is fitted with three screws,
and from all modern ships of her class in that she is covered
with what is practically a complete coating of armor; and, since
there are now being built five other cruisers which partake of
some of her leading peculiarities; since, moreover, she is of a
type which cannot but prove exceedingly formidable, a description
of her can scarcely fail to be of interest to all who follow
the development of navies. Constructed entirely of steel, she
is 374 ft. long and 51.5 ft. broad, and she has a depth of 35.7
ft. With a draught of water aft of 24.6 ft. and a mean draught
of 23.4 ft., she displaces 6300 tons of water, and she is therefore
a good deal smaller than our new unarmored cruisers of the
Edgar class. Her great length, in proportion to her beam, is
especially noticeable. The length of ships of our Orlando class
is only 5.33 times their breadth; of ships of our Blake class,
only 5.77 times their breadth ; and of ships of our Edgar class,
only 6.0 times their breadth ; while the length of the Dupuy de
Lome is 7.26 times her breadth. Her proportions indeed are
almost like those of a torpedo-boat catcher, and they are calculated
greatly to assist her speed. With engines indicating in
the aggregate 14,000 horse power, when worked under forced
draught, she will do her 20 knots; and, working with natural
draught, she will do her 17.5 knots.
The arrangement of the Dupuy de Lome's armament is
peculiar. Just forward of amidships on each broadside there
is on the upper deck a sponson supporting a 7.46 in. 11-ton
breech-loading gun—model 1887 — of 45 calibres. Each is
covered by a revolving 3.94 in. armored turret that is moved
by hydraulic machinery. Between these turrets, and along the
greater part of the upper deck, runs a light superstructure,
which is very sharp forward, and at its extreme end, slightly
raised above the superstructure deck, is a 6.2 in. 6.5 ton quickfiring
gun of 45 calibres. Two more guns of the same model
are placed on a somewhat lower level, in such a manner that
one commands each bow. All these guns are in separate turrets,
as before. At the stern the arrangement is similar, save
that the three 6.2 in. quick-firing guns are all on the superstructure
deck. In consequence the ship can fire simultaneously,
either right ahead or right astern, two 7.46 in. and
three 6.2 in. guns ; and on either beam, one 7.46 in. and four
6.2 in. guns.
There are two large military masts of steel, and in the interior
of each is a winding staircase, which leads to the lower top.
These masts, which are pierced, will serve in action as conning
towers. Each carries in its lower top two 3-pounder quickfiring
guns, and in its upper top an electric search-light projector.
A little abaft of the forward group of 6.2 in. guns there
is on each quarter a six-pounder quick-firing; on the bridge
there are two Hotchkiss one-pounder revolving cannon ; and
on the superstructure forward there are two more guns of the
same kind, so that when chasing the cruiser can bring to bear
two 7.46 in., three 6.2 in., two six-pounder, two three-pounder,
and four one-pounder guns. All the pieces have an initial
velocity of 2400 foot-seconds or upwards, and possess, therefore,
great power in proportion to their calibre. The 6.2 in.
quick-firing guns are converted breech-loading guns, model
1887.— Times.

288 ENGINEERING MECHANICS. [November, 1892.
GRAPHICAL STATICS and Its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
The pressures that it exercises on its supports are also equal to
pr and tangent to the arc at A and B. Let A B = 2 a be the
bearing of the arc and IH =fi its'versed sign. If A E = pi­
ts the pressure which the support A undergoes, the vertical com­
ponent A b of this force is giveffby the'relatiou
Ab_ _A^_
AH" A C
whence
A b=pa.
The horizontal component or thrust is giveu by the proportion
Eb _ HC
or
or
now
whence
Eb = - P -
AE~~ A C
Eb=p X HC
Eb=p(r-f),
AH = a''=f(2r—f),
Pf
A f ) ~ * \A
\fi 2
which gives the thrust iu function of the bearing and the versed
2
The first O w is constant, whatever be the radius considered
O m, and equal to the polar distance counted parallel to the
chord of the arc ; it is therefore also the same for the extreme
sides of the polygon or for the extreme elements of the arc ;
hence it represents the thrust exercised on the supports.
sign.
Hence the thrust which a polygon or an arc suspended or
the relation — / is very weak, i. e., if the arc is very elliptic,
supported and subject to vertical weights exercises on its sup­
a
ports is represented by its polar distance estimated parallel to
we
may omit the unit before -= and write approximately for the
thrust
Eb
pd>_
AT
§84.
CASE OF VERTICAL WEIGHTS ; THRUST.—When (Fig. 19) the
forces which act, whether ou an articulated polygon, or on a
flexible arc fixed at its extremities, are vertical, let their number
be limited or not, the polygon of these forces is represented
(Fig. 19) by a vertical a b. Let O be the pole of the polygon or
of the curve of equilibrium. The tension of a side of the
polygon is represented by a radius O m parallel to this side, like­
wise the tension at a point of the arc, if it is a question of au
Fig. 19.
— — -**
arc, is represeuted by a radius O m parallel to the tangent to the
arc at the poiut considered.
This force O m can be decomposed into two components, oue
O o parallel to the chord A B ofthe arc, the other u m vertical.
Fig. r9.
Fig. 19'.
->0'
Ihe chord of the arc.
This distance represents also the pressure or tension of the
arc at the point where its tangent is parallel to the chord.
If the supports are level, the thrust is represented by the
polar distance properly called, which represents also the tension
or pressure, according as the arch is suspended or supported, at
its lowest or highest point.
I 85.
POLYGON OF BRIDGES SUSPENDED OR SUPPORTED.—The
cable of a suspended bridge is bound to the platform which it
supports by vertical bars (suspension bars) equidistant, and it is
proposed to arrange the cable in such manner that the total
weight of the platform be distributed equally amoug all the
bars. Consequently (Fig. 19), the acting forces i.I / , 2.2-*, 3.3', . . .
are here all vertical, equal and equidistant and the question is
to find the form to give to the cable in order that it remain in
equilibrium under the action of such forces.
Generally the versed sign of the cable is given which it is of
interest to take large, so that it will follow from the solution
likewise if we wish to diminish as much as possible the tensions
which the cable supports ; but, in each case, the versed sign is
limited by the circumstances in which we are.
THEOREM.— The funicular polygon formed by a cable of a
suspended bridge is inscribable in a parabola with a vertical
axis.
In fact, let (Fig. 19) A and B be two points of suspension of
the cable ; 1,2,3,4,5 the equidistant suspension bars of the
platform, i. e. the lines of action of the acting forces, and (Fig.
19) 1,2,3,4,5 the lengths equal to one another borne end to end
and forming the force polygon.
Let us draw a parabola with a vertical axis passing through
the points A and B and any others ; we shall thus determine by
their intersections with the bars the points 1,2,3,4,5 ; it is required
to show that the polygon A 1.2.3.4.5 B remains in
equilibrium under the action of vertical forces equal to one
another, acting at its apexes.
To this effect, with any point 0 draw radii
Oa, Out, On, Op, Og, Ob,
respectively parallel to the sides

November, 1892.] ENGINEERING MECHANICS. 289
A 1, 1.2, 2.3, 3.4, 4.5, 5 B
of the polygon and cut this group of lines by any vertical ab
which will determine the segments of it.
am = 1, mn = 2, up = 3, pa = 4, qb = 5
Vertical forces equal respectively to these magnitudes applied
to the five apexes of the polygon will keep it in equilibrium by
reason of the theorem of Varignon.
The whole question is therefore to show that these forces are
all equal to one another.
.In effect, let us trace the parabola with two rectangular axes
Oay, O0x, the one vertical, the other horizontal.
Its equation will be of the form
We should have likewise,
H p -BA- C (2X a).
the bearings — which are whole numbers.
a
It is, consequently, easy to draw the funicular polygon which
the cable forms and which is subject to pass through the given
points A, B, C without having recourse to the general method of
I 45. We can also draw it directly (see note III. bis) which furnishes
the apexes of the inscribed polygon A 1.2.3. . . .
In order to have the tensions, through a point O we shall
draw the parallels O a, O m, ... to the sides of the polygon,
and we shall cut this group by any vertical a b. We know that
all the segments 1, 2, 3, . . . will be equal to one another; ab
represents the total weight wliich the platform bears and, as
this weight is given, we can deduce from it the scale of the
forces. Let Q be this weight reckoned in tons, we conclude
from it that a length — is a ton.
According to this scale, 0 a will be the tension of the side
A 1, O m that of the side 1.2, etc.
§86.
y = A + Bx+ C-.
THRUST OF A PARABOLIC ARC BEARING A UNIFORM VER­
TICAL WEIGHT.—If the suspension bars approach one another
indefinitely or if the weight ofthe platform is spread uniformly
2
over the whole cable instead of being so, by equal parts, ou
Let us call xu yx the co-ordinates of the point 1; x2, y2 those equidistant verticals, the funicular polygon is blended with the
of the poiut 2, . . .; xi , yi those of the point bearing the parabolic arc in which it is inscribed. Hence, a parabolic arc
n°i. If a is the equidistance of the bars, we shall have, for -with a vertical axis bearing a weight uniformly distributed
example :
according to the horizontal (platform of bridge) or, what
x r
x = - 3 + ",
amounts to the same thing, a weight uniformly distributed ac­
y3= A + Bx3+C*\
cording to its chord, whatever be its inclination, and fixed at
its two extremities, remains in equilibrium, even if it is perfectly
flexible. It forms a funicular curve or a curve of pressure
l-r3 yt = A + B (x3 + a) + C
+ a?
(in other terms, it is stretched or compressed), according as it
presents its concavity upwards or downwards ; iu the first case,
whence,
it can serve as cable to a suspension bridge ; in the second, it
can form an arc of a metallic bridge supported (save the pre­
y\ Ba-^-(2a.v3+ai),
cautions to be taken to avoid instability).
In order to have tensions or pressures at its various points,
aud the tangent of the angle which the side 3.4 makes with through a point O', we shall draw parallels O' a, O' b to its ex­
the horizontal will be
treme tangents ; for that it is sufficient on the vertical I C oi
the middle of the chord to take a length I C double I C aud
——— = B + — (2X3 + a).
the right lines C A, C B are the tangents to the extremities of
tbe arc ; we shall cut the angle a O' b by a vertical a b.
Now the radius 3.4 or Op is, by hypothesis, parallel to the This vertical will represent the total weight of the platform.
side 3.4; therefore, if O H is the polar distance,
Let p be the weight per metre according to the chord A B
and A B = 2a ; the total weight will be ab —• 2 pa, which will
give the scale of the forces, since, Up is expressed in kilograms,
it will follow from this equality that a length —— represents a
kilrjfgram.
The tension (or pressure) at a point AI of the arc will be, according
to this scale, equal to the radius-vector let fall from O'
whence, by eliminating member by member,
aud parallel to the tangent to the curve at DI.
The tensions (or pressures) supported by the extreme ele­
5., — C (xt — x3) = Ca = const.
ments, are represented by the extreme radii a O' and 0' b.
The one a O' is decomposed into a vertical component o> a
According to that, in order to draw the polygon, through the and a component 0' u parallel to the chord A B.
middle of A B draw a vertical on which we shall take a length The one 0' b, into a componentu O' parallel tothe chord and
/ C equal to the given versed sign/.
a vertical component " b.
The parallel Cx to A B is tangent to the parabola, and, if The fixed points A and B are generally placed at the apexes
we draw the curve to the axis Cx and the vertical Cy, its equa­ of abutments in masonry ; the thrust O'u tends to throw these
tion will be :
abutments inward or outward, accordiug as the arch is suspended
or supported.
Let us take the usual case where the points A audi? are level.
Then the point a is iu the middle of a b ; b a = a o represents
since it is to pass through the points A aud B and through the
half the total weight of the platform, let it he pa; then the
point C.
thrust is
We can therefore determine exactly the co-ordinates of each
0't.i —pa: tan b O'u.
of the apexes 1, 2, 3, knowing the abscesses of the bars, i. e.,
Now O'b is parallel to the tangent to the parabola at B ; hence
tan b O'o is the angular coefficient of this tangent, since the
axes Cx, Cy are rectangular. Now this angular coefficient
IC 2/
= —, as it would follow moreover from the equation of
IB a ^
the curve; hence the thrust is
n a p aA
0u-yax- = *-T
(To be continued.)

290 PUMPS AND PUMPING. [November, 1892.
BY WILLIAM KENT, M.E
A serious impediment to the use of these pumps is the wear
of their valves or leathers, whicli are soon destroyed by sand
and gravel. To renew them, the pump rods of 50 to 100 feet
length have first to be removed by drawing them up and disconnecting
the sections, one at a time.
Belt Driven Reciprocating Pumps.—Piston and plunger
pumps driven by a belt from a rotating shaft are commonly used
for feeding boilers and similar uses, their chief advantage being
that the power used is obtained at a small fraction of what it
costs in an ordinary direct acting pump. Iu a works in which
the power is geuerated by a high class engine, a horse power
FIG. 66. BELT DRIVEN PUMP (Stewart Heater Co.).
may be obtained from about 15 to 20 lbs. of steam per hour
while the ordinary direct acting pump uses not less than 100
lbs., which is largely increased by the leaks, stoppages and slow
speeds to which small pumps are liable. In taking power from
a belt it costs the same per horse power as that delivered to any
machine driven by belt from the main shaft. The mechanical
FIG. 68. BELT-DRIVEN BOILER FEED PUMPS.
feeding the quantity of water is 100 lbs. x 144 square inchesX A*
foot lbs. per hour= 120 foot lbs. per minute = JJ^TJ = .0036 H.
P., or less than T 4 0- of one per cent, of the power exerted by tbe
engine. If a direct acting pump, which discharges its exhaust
steam into the atmosphere, is used for feeding, and it has only
one-tenth the efficiency of the main engine, then the steani used
by the pump will be
equal to nearly 4 per
cent, of that generated
by the boiler.
Nearly all th
prominent manufa
turers of direct act
ing pumps also niakt
belt driven pumps
for wliich reference
may be made to theii
catalogues. Cuts
some of the be
known forms E
giveu below, Figs.
to 70 inclusive, which
are taken from th
catalogues of th
Stewart Heater Co
Buffalo, and Th
Gleason & Bailey
Manufacturing Co.,
of Seneca Falls, N.Y.
FIG. 6 7. BELT-DRIVEN PUMP (Gleason & Bailey Mfg. Co.). FIG. 69. BELT-DRIVEN PUMP.
work needed to feed a boiler may be estimated as follows:—If
the combination of boiler and eugine is such that half a cubic
foot (say 31 lbs.) of water is needed per horse power, and the
boiler pressure is 100 lbs. per square inch, then the work of
F*ig. 71 shows a belt driven pump made by W. & B. Douglas,
Middletown, Conn., for paper makers' use. It is especially
adapted to work on the suction boxes, in connection with the
Fourdrinier Paper Machine.

November, 1S92.] ENGINEERING
The cylinders are six inch bore aud twelve inch stroke, the brass- surplus must pass iip through the discharge pipe ; so a conlined
and brass valve seats, each pump being double acting. stant stream is kept flowing through the discharge pipe with
FIG. 70. BELT-DRIVEN PUMP.
The valves are easy of access for repairs, as it is only necessary
to remove the nut and take off the cap to get at every valve.
Figs. 72 and 73 show the Nagle Power and Boiler Feed Pump,
made by the Phenix Iron Foundry, Providence, R. I. The construction
is clearly shown in the cuts.
Hand Pumps.—Our limits of space will not allow of any extensive
treatment of the many varieties of hand pumps that are
ou the market. Reference must be made to the catalogues of
the manufacturers and especially to those of W. & B. Douglas,
of Middletown, Conn, (established 1832), and the Goulds Manufacturing
Co. and Rumsey & Co., both of Seneca Falls, N. Y.
These catalogues contain illustrations of many hundred different
varieties.
The Buckeye Force Pump.—A style of hand pump which has
recently come into extensive use is shown in Fig. 74. It is made
by Mast, Foos & Co., of Springfield, Ohio. The upper part of
the cylinder is the smallest, being one-half the capacity of the
lower part. The cylinder is provided with two plungers, connected
together with an iron rod. As the plungers start ou the
up stroke the upper plunger makes room for one-half of the
water in the cylinder, aud the other half is forced out through
the discharge pipe. Ou the return stroke the upper plunger
forces the water in that part of the cylinder down again, but as
the water is rushing through the valves in the lower plunger
MECHANICS. 291
FIG. 72. THE NAGLE POWER AND BOILER FEED PUMP.
The Chain Pump.—The chain pump is au ancient form of
pump or water elevator, which is still used to a considerable extent
for domestic purposes.

292 ENGINEERING MECHANICS. [November, 1892.
It consists of a chain carried over two sprocket wheels, one set
below the water level iu the well, and the other in the "curb "
F*IG. 73. NAGLE POWER AND BOILER FEED PUMP.
box, or framework at the top. The chain is provided at intervals
with rubber or metal buttons, of nearly the diameter ofthe tube
FIG. 74. THE BUCKEYE FORCE PUMP.
of metal or wood which is placed in the well, in which the
ascending part ofthe chain runs. Fig. 75 is an illustration of a
chain pump from the catalogue of Messrs. W. & B. Douglas.
Fig. 76 shows two forms
of button used for chain
pumps, from the catalogue
of Comstock & Coose, Indianapolis,
Ind.
The Jet Pump.—The simplest
form of jet pump was
shown in Fig. 7, in the first
article of this series. In it
a small quantity of water was
raised from a low level by
the suction of an induced
curreut caused by water flowing
through a pipe from a
high level. This principle
is sometimes used for draining
cellars and like purposes,
where a supply of water
under pressure is available.
Au application of this kind
is shown in Fig. 77, representing
L- Schutte & Co.'s
" Eductor." The eductor, or
water jet pump is the casting
showu above the strainer in
the cut, which contains a
nozzle for the delivery of the
high pressure water in the
direction of motion it is desired
to give the water to be
raised.
Substituting steam for the
high pressure water column,
and making the nozzle correspondingly
smaller gives
us the steam jet or water
ejector. Simple forms of
such an apparatus are the
FIG. 75. CHAIN PUMP.
jet pumps made by Van Duzen & Tift, of Cincinnati, O., Fig. 78.
The figures iu the last column of the following table are given
in Van Duzen & Tift's catalogue, but at the same time they say
that it would be impossible to state, even approximately, what
FIG. 76. BUTTONS FOR CHAIN PUMP.
size of boiler is required to operate the different sizes of pumps ;
or, in other words, the quantity of steam consumed by auy size
of a jet pump would so vary under different conditions as to
make it impossible for auy calculation to be made as to what that
quantity might be. The quantity of steam required will depend
upon size of pump ; pressure of steam ; temperature and character
of liquid ; height, length, size, and direction of both suction
and discharge pipes; size and length of steam pipe.
(To be continued.)

- November, 1892.J ENGINEERING MECHANICS. 293
ELECTROTECHNICS.
A Compilation ofi Rules, Tables and Data.
BY CHARLES M. SAMES, ELECTRICAL ENGINEER.
Where .Pis the pull in pounds and A is expressed in sq. cms.
When A is in sq. in.,
_ B _!_v A

294 ENGINEERING MECHANICS. [November, 1892.
THE extent to wliich and the manner in which aluminum can
be profitably and even safely used in a foundry has not yet
beeu experimentally or scientifically verified. It is in unskilled
hands liable to do more harm than good. Small quantities
properly used help to make sound castings, but it makes the
slag brittle aud it is apt to break and get into the mould.
THE Builders' Iron Foundry of Providence, R. I., has recently
shipped for test at Sandy Hook, the first of the eight 12-inch
Mortar Carriages for which they have a contract with the
United States Government. These carriages are large and
powerful pieces of mechanism, and are to be used for coast defence.
The total weight of each is about forty-two (42) tons.
THE American Institute of Mining Engineers held a four
days' session at the Neversink Mountain Hotel, near Reading,
Pa., beginning Oct. II. The members met, not so much to read
and listen to the reading of prosy papers, but to renew friendly
relations, form acquaintances aud to enjoy their trip, a method
which the members of other associations might adopt to some
extent with advantage.
NAVAL engineers are calling for a smaller and hardier class
of war ships, with greater speed, more coal-room and lighter
draft than those that mistaken zeal and skill have sent to do
service. Spain is now constructing eight vessels to meet the
present requirements. The " Barfleur " is the latest English
ship of this sort. She is 360 feet long, 70 feet beam, 10,500 tons
displacement, 13,000 H. P. Speed, 18 knots. Her draft is
small. She can go into shallow harbors, and her quick-firing
guns cau presumably do more destruction than the heavier and
more unwieldy guns of heavier ships.
THE electrical transmission of power from Lauffen to Frankfurt
has suggested and stimulated schemes of like character iu
many localities ; one ofthe latest is a scheme to supply Madrid
with water and electric power and light, as well as to irrigate
the intervening country. The project is to dam up two streams
where a water fall of 200 feet can be secured, then build a fivemile
canal which will increase the fall to 1100 feet. The power
retained will be utilized to ruu dynamos and it will be transmitted
to Madrid by wire. The scheme is a great one, evidently
feasible, aud highly advisable.
La Nature says that MM. Olivet, of Geneve, have brought
out a new system of electric heating applied to conservatories.
A dynamo worked by some motor, sends the current into receivers
of special metallic composition, which become rapidly
heated, but without exceeding a certain temperature. A heated
air current is set up as with steam-heating, but with the advantage
of absence of all unwholesome gas or vapor which might
injure the plants, simplicity of construction in the parts conveying
the energy, perfect safety as regards heat, which can be
regulated at will, convenience and rapidity in starting and extinction,
and cleanliness. Cost is not mentioned.
A WRITER in the Ironmonger expresses the opinion that
steel is liable to be changed by the actiou of time, unaided by
any external mechanical or chemical influence, and in support
of his view that time alone appears to be sufficient to produce
these changes, he cites several examples of failures which have
occurred w'thin his own experience, some flat steel plates
cracking spontaneously, and others on being tested by dropping.
Mention is made of numerous boiler plates that cracked
after the boilers had been at work for years, and weeks after
the steam pressure had been reduced and the water run out,
and this, too, in face of the fact of every boiler being tested to
double its workiug pressure when new.
A DIFFICULTY is experienced in casting small articles of steel
to obtain sufficient heat and fluidity in the converter at the time
of pouring. Experimenters have found that a superheating of
the metal for pouring may be obtained by so working as to ensure
the presence of silicium in the metal after the removal of
the bulk of the carbon. In blowing, at the time when the flame
falls, silicium in the form of a suitable alloy is added to the
metal in the converter. Such flame as there was at the time of
the addition at once disappears, but the temperature rises from
the combustion of the silicon and the formation of a non-volatile
product—i. e., silica. When the carbon flame again appears,
the blow is finished. Silicium is not only the material which
may be employed ; thus, in the basic operation, fluidity may be
given to the metal wheu overthrown by the addition of an alloy
rich in phosphorus, the blow being continued until the phosphorus
is continued.
GALLOWAY'S boiler has been improved a little by the original
inventor and maker. The present invention is designed to promote
and render more positive the circulation of water. According
to one arrangement the inventor fixes within the upper
part of the tube a circular plate of less diameter than the tube
at that place, so that there is an annular passage around its
edge for the ascending current of water, while the plate prevents
the descent of water at or near the middle of the tube. Or
the plate may be placed at a little distance above the upper
mouth of the tube, allowing the descending current to issue all
round from under its edge. Instead of a plate thus placed
within or above the tube, a dish may be employed which serves
to collect and retain impurities deposited from the water ; the
same dish may be made of considerable depth so as to constitute
a tube with its lower end closed suspeuded within the Galloway
tube and of smaller diameter, so as to leave all round it
an annular passage for the ascending current.
4
IT was the favorable opportunity which made the "Monitor"
what it was, and which brought the revolution in naval warfare.
There is our "Vesuvius," hanging arouud "like a bound boy
at a husking," waiting for a chance to show it is as far beyond
the " Monitor " iu destructiveness as the " Monitor " was ahead
of the old modern hulk "Cumberland." The three 15-inch
caliber guns of the "Vesuvius" no doubt could do all that is
claimed for them. It is permitted to prowd around without a
DR. A. BUCHAN, in recently describing the circulation of cur­ defender among those who ought to be its friends. The "Vesurents
in the North Atlantic, said that these currents were lost :t vius " is 246 ft. 3 in. long, 26 ft. 6 in. beam, aud 14 ft. 1 in. deep;
at a depth of only 500 fathoms, below which depth the ocean u the displacement is 805 tons, with a mean draft of 9 ft. 3 in.
had always a constant temperature at all depths. The same e The free-board is thus low, being only about 5 ft. She has two
condition was reached at 1500 fathoms in the Pacific Ocean. 1. three-bladed screws, each driven by a triple-expansion engine,
He traced the course of the warm dense salt water issuing bej-
having high-pressure cylinder 21'i in., intermediate, 31 in., and
low the surface from the Mediterranean through the Straits of )f two low-pressure cylinders each 34 in. in diameter ; all being 20
Gibraltar. This, he said, traveled northwards, skirting the e iu. stroke. There are four locomotive boilers 9 ft. diameter and
west coast of Europe, and thus warming the water even to the e 19 ft. S iu. long, with a grate surface of 200 sq. ft. In addition
north of Norway. He considered that the current was suffii-
to the propelling engines she is furnished with an electric-light
ciently warm and strong to prevent the entrance of icebergs js plant and with powerful air-compressors for workiug the dyna­
into the North Sea.
mite guns. She can carry 140 tons of coal.

November, 1892.] ENGINEERING MECHANICS. 295
ENGINES AND BOILERS IN THE NAVY.
It is a matter of common observation that very different results
are obtained from the engines aud boilers iu various ships
of war, under apparently reasonably similar conditions. Thus,
for example, we have, say, two cruisers of about the same dis­
placement and intended to attain like speeds. The power re­
quired is about the same for both ships. One entirely fails to
get steam enough without resorting to a forced draught pressure
which runs the boilers. The other does all that is expected of
her, and more, without the least trouble, and with a draught
which scarcely deserves to be called forced. At first sight the
anomaly seems to admit of very simple explanation. The ship
which has done well has more boiler power than that which has
done badly. This may be true in certain cases, but it is very
far from being true in all, and we are driven to find a different
solution. Unfortunately, however, it is difficult to obtain the
requisite data. Yet it is extremely important that they should
be accessible, and it may serve a useful purpose to direct attention
into the proper channel for obtaining that which is so desirable.
It appears to us that nothing has more effectually stood in the
way of progress than the assumption that in all cases where a
cruiser or a battle-ship has come to grief the boilers are in fault,
and that all successes are due in turn to the merits of the boilers.
It is quietly taken for granted that so long as the engines run
without getting hot bearings or breaking down, one engine by
au eminent maker must be as good as another engine by a different
but still eminent maker. Thus, for example, we have
already heard it stated that the fine performance of Her Majesty's
ship Sappho, was due to the boilers, and to them alone.
Until some proof is given to the contrary, we must hold the
opinion that this is a mistake, and that her success is due as
much to her steam engines as to the boilers that supplied them.
To pass from the particular to the general, however, we may,
without further preface, say that much of the trouble met with
in certain ships is due to the way iu which the steam is wasted
by uneconomical engines. The last thing to be tested in a manof-war
is the weight of steam used per horse-power per hour.
Let us suppose that we have two vessels, one of which uses 20
lb. of steam per indicated horse-power per hour, and the other
30 lb., and that in each case the power developed is 5000 horses.
The boilers in the first case must make 100,000 lb. of steam, and
in the second 150,0001b. of steam per hour. Let us further suppose
that each square foot of grate is equal to 14 indicated
horse-power ; then in the first ship it must produce 280 lb., and
in the second 420 lb. of steam per hour. If a pound of coal is
equivalent to 8 lb. of steam, then in the first ship 35 lb., and in
the second 52.5 lb. of coal must be burned on each square foot
of grate per hour. The first can easily be done with a forced
draught of little over half an inch water pressure, the second
will need at least 2 in. In the former case the boilers give no
trouble whatever, in the second they break down. We have
taken an extreme case. We do not suppose that conditions are
often met with in which one set of engines uses 50 per cent.
more steam than another set. But our readers can easily allow
for this ; and extreme cases make the most forcible illustrations.
It may furthermore be pointed out that while a boiler is per­
fectly safe if driven up to a certain point, it may break down if
pushed but a little further. A couple of feet make all the dif­
ference between a safe walk and a fatal fall over a precipice;
and so it may readily happen that a little extravagance in the
use of steam by the engines may prove calamitous to the boilers
which supply them. It is for this reason among others, we
think, that much more general success has been attained in the
use of forced draught in the merchant service than in the Navy.
A case in point is supplied by the latest addition to the Peninsular
and Oriental Company's fleet, namely, the Himalaya, a
splendid vessel of some 10,000 tons displacement, and indicating,
we believe, about 9000 horse-power. The single-screw
triple-expansion engines are by Messrs. Caird, and the boilers
have been fitted on Howden's system. There are three doubleended
boilers with 2^ in, flue tubes, and three single-ended
boilers, or in all twenty-seven furnaces. Ample steam is ob­
tained with about A in. water pressure at the furnace bars. Now
there are very few ships in the Navy which will give 9000 indicated
horse-power with twenty-seven furnaces, with less than
1^2 in. of air pressure at the bars. We believe that the larger
proportion of naval boilers are as economical as boilers in the
merchant service, or even more economical, because they have
flues smaller in diameter, and the coal is certainly better. But
we do not think that the engines are as economical, and this is,
we suspect, a hitherto unrecognised, or at least unstated, cause
of boiler failure. Whether it is or not can only be definitely
settled by forming something like an accurate estimate of the
quantity of steam used per indicated horse-power per hour, and
this could be done by employiug donkey feed pumps in good
order, and taking the number of strokes with a counter. In
this way, while it might in a man-of-war be impossible to secure
minute accuracy, there ought to be little difficulty in obtaining
figures of very great value.
We do not think that there is any reason to doubt that naval
marine engines are less economical thau those in the merchant
service. A good deal of correspondence has recently appeared
on the subject of Navy boilers, and it will be remembered that
Mr. Howden expressed himself as confident that he could do in
ships of war what he has done in such vessels as the City of
Dundee. We venture to think that in saying this he has reckoned
on au engine economy that does not exist, and that the
demands made by the engines on the boilers will be found to be
far heavier than he expects. Mr. Melville, Chief of the Bureau
of Steam Engineering in the United States, has been very outspoken
on this subject. An authority on coal consumption in
men-of-war, gives highly suggestive figures of results obtained by
careful experiment on board the Newark, the Concord, and the
Bennington. They are, so far as we know, the first trials of the
kind ever made in a man-of-war; and we find that the Newark,
indicating in round figures, 9000 horse-power, burned 2.43 lb.
The Concord, indicating 3500 horse-power, burned 2.76, and the
Bennington, 3500 horse-power, burned 2.6 lb. per horse per
hour. These figures are considerably in excess of the consumption
in the merchaut service. Thus, for instance, Mr.
Dalrymple got down below 1.5 lb., with engines indicating over
2000 horse-power, and we are convinced that the consumption
seldom exceeds 2 lb. per horse per hour. Even in the racers it
must be very small. It has beeu authoritatively stated that the
City of Paris runs with 12 tons per hour, or 288 tons per day.
This corresponds to less than 1.5 lb. of coal per horse per hour,
and even if we admit that the boilers, since they have been
" Howdenized," evaporate 10 lb. per pound of coal, the engines
must be very economical, using but 15 lb. of steam per horse
per hour, and in the racers speed is the first consideration, coal
the second. Iu our own Navy, the very few rough experiments,
the results of which have beeu made public, go to show that
the consumption is at least 3 lb. per horse per hour. The cause
of this want of economy is a very large question, which would
scarcely admit of being discussed here within reasonable limits.
Many conditions, some of which are unavoidable, contribute to
it; one is, no doubt, that the engines are as much too small for
full-power work as they are too large for general cruising speeds.
Another is that the stroke is too short, aud the loss by clearance
large. It was not unusual, on full power trials, to run
with the auxiliary starting valve open, so that steam of
boiler pressure goes straight into the valve chest of the intermediate
cylinder. In any case the ratio of expansion is reduced
in order to get the utmost possible power out of the machinery
Anything like economical workiug, in the fullest sense of the
term, is in such a case impossible. It may, of course, be urged
that engines are only driven for short periods at full-power.
This may be quite true, but it does not affect our argument.
Boilers break down when called upon to develope full power iu

296 ENGINEERING MECHANICS. [November, 1892.
the engines. We suggest that this is largely due to the work of
economy in the engines. If these used less steani, the boilers
would have to supply a smaller quantity in a given time, aud
less forcing would be needed. But it is impossible to maiutaiu
this argument with confidence in tbe absence of all information
as to how much steam the engines of such a ship, let us say, as
the Royal Sovereign or the Barham, which have boilers of a
very different type, really do use per indicated horse-power per
hour. We have suggested the application of the method so
well worked by Mr. Dalrymple as a means of obtaining the required
data. Until some information has beeu got concerning
the weight of water actually evaporated iu Navy boilers worked
to their full power, it is, we think, scarcely fair to say that the
boilers are alone to blame. In any case, what we have said
may help to explain why it is that some engineers are far more
successful iu their practice than others. We have heard it said,
" take care of your boilers, and your eugiues will take care of
themselves." There is a certain amount of truth in this ; but
the converse of the propositiou is, we think, even more applicable
in the case of the ships of our Navy.— The Engineer.
IN all metalliferous mines large quantities of useful color
could be wrested from products at small expense. Iron ores
give many shades in yellow, brown, red and purple. Copper
mines would give green oxides fit for paints. This is a neglected
field, and ought to be looked into.
MINING engineers engaged in the subterraneous explorations
at the Flem-les-Mons, Belgium, have peculiar difficulties to
overcome at a depth ranging from 3600 to 3900 feet below the
surface. Coal will soon be raised from those depths. At 3762
feet a headway was driven through a hard mass of rock, where
water at 122 feet was encountered. Two shafts are now used,
but when new winding engines aud an immense rope are made
for the new and direct shaft, they will be left. Many roofs have
fallen from explosions of fire damp.
BAKER & Co., 40S-414 N. J. Railroad Ave., Newark, N. J. have
issued a neat pamphlet giving valuable data concerning platinum.
Tables give the weight per foot of wire iu Troy and
French weights and of sheet and foil, also table giving fractional
parts of an iuch expressed in thousandths, also numbers
of wire gauges expressed in decimal parts of an inch together
with a comparison of Troy, Avoirdupois and French weights.
ELECTRICAL engineers, and engineers generally, will watch
the behavior ofthe new Liverpool Overhead Railroad, which is
to be operated electrically. It is six miles in length, and cost
$4.00,000 per mile. At first trains will run every five minutes,
and later on every three minutes. Time, including stops at 14
stations, 30 minutes. The electricity will be conducted by a
steel wire on porcelain insulators, supported on cross timbers
between the rails. Cast iron hinged collectors, sliding upon
this conductor, will make the connection between the motors
on the traiu and the dynamos at the generating station. Automatic
signals will be electrically worked by the trains themselves.
THE culm ofthe Edgerton Coal Co.'s breaker at Jtrmyn, Pa.,
is now discharged by air pressure through a pipe 300 feet long,
which has a total beud equal to 28 degrees. The air pressure
is 4 pounds per square inch. The culm does uot strike the sides,
as the air acts as a cushion. The cost of labor and oil is $1.50
per day. A positive blast blower, 5 feet 6 long by 3 feet 9 diameter,
revolved 75 revolutions per minute, and was operated by
a pair of direct-acting engines, 13 in. by 16 in., 125 revolutions per
minute. Leading from the blower is a line of io" cast-iron
flanged pipe, which run under the dirt chute, aud out the opposite
side of the breaker, and thence on a pitch of 22° to the top
ofthe bank no feet vertically above the dirt chute. Under the
dirt chute is a hopper from which the culm is drawn by means
of a worm into the 10 in. pipe. Here it is struck bv the blast
from the blower and instantly conveyed in a continuous stream
to the top of the culm pile. The blower exerted a pressure of
4 lbs. per square iuch against the culm, and it mattered not
whether it was fine or mixed with pieces of slate or rock, it had
to go. The culm is forced out of the end of the pipe line with
sufficient force to throw it from 60 to 200 feet further. There is
an entire absence of the dust oue would expect to see.
PROF. H. B. DIXON, M.A., F.R.S., recently read a paper on the
progress of mining before the members of the Federated Institution
of Mining Engineers (England). Prof. Dixon said:
The rapid act of chemical change, which follows the kindling
of au explosive mixture of gases, has of late years attracted
the interest both of practical engineers and of theoretical
chemists.
To utilize for motive power the expansion force of ignited
gases ; to minimize the chance of disastrous conflagrations of
fire-damp in coal mines ; to follow the progress of chemical
changes under the simplest conditions, are some among the
problems presented in industry or science, demanding for their
solution a knowdedge of the phenomena of the explosion of
gases. Experiments have shown that the explosive wave is a
specific constant for ever)'gaseous mixture; that it has been
shown that the rate of explosion depends upon the occurrence
of the primary reaction, and that the determination of the rate
may throw some light on what is now so obscure—the mode in
which chemical changes are brought about; and, finally, that it
does not seem impossible that a connection between the rate of
the molecules and the rate of the explosion may be worked out,
which will give some definite information on points of high in­
terest in the theory of gases.
E. H. SANITER finds that by using a mixture of lime (90 per
cent.) and calcium chloride (10 per cent.) sulphur in iron can be
more readily removed than by present methods. The iron is
kept molten in plumbago crucibles. The results show (1) that
lime alone removes a considerable quantity of sulphur from
iron if the contact is sufficiently prolonged. (2) That a mixture
of calcium chloride and lime in the short space of half an hour
completely eliminated the sulphur. A mixture of calcium
chloride and lime is prepared, which will fuse readily at the
temperature of the iron to be operated upon. The desired combination
is made by grinding calcium chloride and lime together
iu a mill to thoroughly mix them, and also to bring them
to a moderately fine powder. About equal parts of each are
required to give the desired fusibility. This mixture is then
placed in a ladle or receiver, and consolidated by heat or kept
iu positiou by other suitable means. The heat may be applied
in the first instance by means of a blowpipe arrangement using
blast furnace gas, but when in continuous use the heat of the
ladle itself is quite sufficient. The receiver is then filled with
iron, which may be drawn direct from the blast furnace, the
heat of which melts the mixture, which, rising up through the
metal, removes the sulphur very completely. Appliances are in
course of constructiou which will deal with the whole output of
the furnace as the metal is run. The plant required is of a simple
and inexpensive character, consisting of ladles or receivers
on wheels. The cost of materials at present prices is about 6 d.
per ton of iron treated, and this will be less when a more efficient
receiver is used. It is also very probable that should a
demand arise for chloride of calcium the price would go down.
Against this extra cost may be set the cheaper production and
enhanced price of the pig iron produced. This process can be
adapted to a considerable number of uses, such as: (1) The
purification of hematite, basic, and common (1.5 per ceut. P.)
irous as they ruu from the blast furnace or cupola, thus producing
these qualities of iron low in sulphur and silicon, after which
they might be used for direct steel-making or cast into pigs.
(2) The purification of steel in the ladle after it leaves the fur­
nace or converter.

November, 1892.] ENGINEERING
THE rapid progress being made in lake transportation is seen It is a matter of surprise to me that the Owings Building
in the recent record of power and cost of an average vessel. should have been referred to in a paper designed to show the
The speed maintained was 11.85 miles per hour, loaded ; 12.72, weakness of Chicago foundations, for the following reasons: A
unloaded. Coal burned per mile, loaded, 226; unloaded, 209. combination foundation of concrete and steel was laid, and
Margin in this case, 174 net per day while at work. Boat- upon this dimension stone walls and piers occupying almost
builders and investors note this fact, and the lake ship yards the entire basement story were constructed, and upon these
have now quite a large amount of tonnage under construction walls and piers a fireproof building of solid masonry was
to profit next season by these exceptional margins.
erected 13 stories high, exclusive of the gable roof and the
IT is rather late in the day for limestone to be assuming such
important airs over steel as to propose to take the place of
steel pillars under sky-scraping Chicago buildings. The steel
columns set up a great laugh when they first heard it, and
treated it as a joke; but when the limestone pillars said they
meant all they claimed, and that unless they were allowed to
take their claimed place, the big buildings of Chicago would
go down until it would take a spy-glass to see the top of
them, Mr. Ossian Guthrie, who thinks he knows stone from
iron, took up the question, and disposed of it in his way
saying:
" From a careful study of the geology of Chicago, with some
experience in foundations and many years (of perhaps, well
improved) opportunity, I have reached the conclusion that the
foundation upon which Chicago rests is of remarkable uni­
formity, and ample for any load within the bounds of reason.
In support of this conclusion I beg leave to call your attention
to the following proofs :
In 1847 I assisted in laying the foundation for the old Bridge­
port pumping works. This foundation was the first effort
worthy of mention at foundation laying in Chicago, and ante­
dated its successor by several years. This foundation was
made of 12 X 12 oak timber, carefully imbedded on the clay,
and covered with close jointed plank, and upon it the masonry
was laid, and the ponderous machinery rested and operated for
23 years without showing a crack in the superstructure. For
20 years this foundation has supported the Danville elevator
with equal success. Coming down to modern times, we find
so much convincing proof that I only deem it necessary to call
your attention to a few of the many modern structures of which
Chicago may justly feel proud.
The Monadnock Building, which is built of solid masonry, is
nearly 200 ft. high, fireproof, and one of the heaviest buildings
in the United States, compared with the area covered by its
foundation, upon every square foot of which there is a load of
3,750 lbs. This building has settled uniformly about 5 ins.,
where an allowance was made for 6, and not a single crack is
visible in the entire structure. A dealer in building material
said to me that the builder, during the process of erection,
seemed to be striving to find places to add weight.
The foundation of the Western Bank Note Building was laid
on the quicksand overlying the clay. This building, which is
eight stories high, solid masonry, and fireproof, settled uni­
formly 2A1 ins.
The Home Insurance Building only settled A i n -. *»vith the
addition of two stories. The new Fair Building, ten stories
high, combination of steel and masonry, with all its load, only
settled 1 in.
In a recent article, evidently published for the purpose of
showing the weakness of Chicago foundations and the necessity
for going down to rock, reference was made to the Post Office
and Owings Building, neither of which can be considered as
fair criterions by which to judge. In relation to the Post Office,
everybody who knows anything about foundations, and who
saw that foundation in process of construction, knows that it
was not suitable for a substantial six-story office or commercial
building.
MECHANICS. 297
story devoted to foundation, and yet this building has settled
so little as to be imperceptible to a careful observer, and the
adjoining 9-story building, also of solid masonry, has suffered
but little from the settling of its massive neighbor.
, In so far as the publications referred to tend to discourage
the erection of other "sky scrapers," they are all right; but if
the object is to furnish a pretext for going to the rock for the
foundations ofthe future structures of Chicago, or effect a sub­
stitution of limestone piers for steel or iron columns, in my
opinion they are not only needless, but reprehensible.
1 repeat, the clay underlying Chicago is wonderfully uniform
in carrying capacity, and ample for any future structure erected,
with a proper regard for the interests ofthe public."
Pmgineers regretfully recognize the fact that the foundation
in the busiuess section requires careful haudling. If the fact is
beyond dispute that the foundation is only 12 to 20 feet thick,
resting on a bed of softer clay 40 to 80 feet deep, then it would
be a pertinent inquiry to ask : What will be the probable effect
of covering this square mile of crust (the business center of
Chicago) with a comparatively solid mass of brick, stone and
steel on a 12 to 20 foot shell of stiff clay ? Engineering journals
prefer to extract precarious comfort from the rather unwarranted
conclusion that the latest information, to use the language of
one journal, "seems to indicate that the foundation problem is
not really so grave as it seemed ; that there is really a fairly solid
bed all the way down to rock and that the rock itself, or the hard
pan overlaying it, cau be reached almost everywhere at no great
increase of cost over the present rather expensive foundation."
The present expensive foundation consists of a steel rail and
I-beam foundation invented to spread the load evenly over as
much of the area of the building as possible. This is not the
point. The real question is involved in the ability of the 12 to
20 foot crust as a whole. The possibility of having to go down
through the substratum at the resulting great expense is gently
hinted at and it is believed by very competent engineers that
the commercial necessities of that metropolis will yet compel
the adoption of this view of the problem.
THE inventor of the Stone Flexible Shaft, Nelson Stone, received
the suggestion whicli led to the discovery of the flexible
shaft while watching a workman straightening whalebone for
whips. He noticed that the bone which was long and slightly
curved when turned at one end turned also at the other, no
matter how small a circle was described. The idea entered his
mind that power could be transmitted through the curved
whalebone. He secured a patent in 1S71 and soon the mechanical
world began to appeciate the tool which he was not slow in
improving. The company use a slow speed motor of oue to two
horse power whose speed can be geared from 220 to 1200 to suit
requirements. For heavier work the company uses a motor
specially designed by T. H. Dallett & Co., of Philadelphia. They
also have a tool of use to foundrymen and machinists for grinding
out inequalities in castings and also in glass fractures.
The company is extending the adaptability of the tool and is
receiving many orders for special designs. The field for the
flexible shaft is widening constantly aud much ofthe new work
coming in is for special requirements. The distance to which
the tool in any case can be carried in order to reach the work
required is limited only by the length of wire transmitting
electricity to it.

298 ENGINEERING MECHANICS. [November, 1892.
FOR reasons which upon careful examination will prove to
be very shortsighted and unbusiness like, the business managers
of American railways have persistently fought and opposed
water lines aud canals as well as caual building. This opposition
to canals and water routes has been a mistake from the start, and
will be a greater mistake in the future. A very great expansion
of canalization in the Uuited States is a commercial necessity,
which will assert itself in the near future. luiropean governments
long since became converted to this great necessity, and
European railway managers long ago learned that in the greatest
possible expansion of canalization lay their greatest prosperity.
The same truth will ere long dawn upon the minds of
our American railway managers. One error many make who
talk and write without examining the facts and statistics connected
with our railway development is that railway earnings
are declining and investments less profitable. Such is not the
case ; the reverse is true. American railway managers imagine
and believe they must oppose caual and water lines lest competition
deprives them of a part of their usual traffic. What are
the facts? Iu 25 years the freight rates on 7 trunk lines fell
from 2 cents 9 mills per ton per mile to 6.8 mills or over 75 per
ceut. Yet the income on these roads, after paying operating
expenses, increased from 29 per ceut. of the gross receipts in
1865 to 32 per cent, in 1S90. In other words the low freight
rates have not resulted iu loss to investors iu railway securities.
There is an exception to the general rule that improved
canalization is not injurious to freight traffic, and that is in the
case of the lines competing with the Lakes and the Erie Canal.
But even in this case, the lower water and resulting lower rail
rates, stimulates agriculture in the great northwest to a much
higher point thau it would otherwise reach.
This competition will be intensified when the channels connecting
the different lakes will be increased to 20 feet. To
meet this competition, which water carriers say, will reduce the
present cost by lake aud canal one-half, the railroad will have
to devise some means by which they cau haul freight at lower
than the present rates.
The poiut to be made, however, is, that canalization on an extensive
scale will work not only to the advantage of the general
public but to the railroad interests as well. Freight rates in our
general railway system have gone as low as they are likely- to.
Railway managers are devoting their attention to the best
means of bringing about a general advance. The coming advantage
is uot in lower freight rates ou existing tonnage but iu
so cheapening cost of transportation through a wide-spread canalization
that industries will multiply and present undeveloped
resources be developed, and through this result a much greater
diversification of industries aud dispersion of population. The
same results which have been achieved in Europe can be
achieved on a much larger scale here. The problem is uot only
a commercial aud industrial one, but au engineering problem as
well. Ship canals iustead of remainiug on paper merely 011 the
civil engineer's table should be written ou the face of the country.
The engineers have already indicated the possibilities.
Railroad managers great aud small should take up this questiou
in a broad, patriotic and truly enlightened spirit, and co-operate
as citizens in the building up of a public sentiment that will
make such a broad policy of cheaper transportation facilities a
success.
THE frequent failure through cracking of cast iron car
wheels ou mountain roads due to brake pressure has led to
very careful experimeuts, the results of which iu part were
codified by Mr H. J. Small, superiutendeut of motor power of
the .Southeru Pacific Road, iu a paper read before the Master
Car Builders' Association. Faulty aud dirty iron at the junction
ofthe wheel plates is the cause of numerous breaks aud it
is caused in this way. When the iron is poured iuto the mold
it goes to the bottom and spreads to the rim, and finally fills
the upper or outside plate. The metal which form this plate is
almost the first that enters the mold, and which has been
cooled by contact with mold and chill. The metal whicli forms
the lower plate, such as the ribs and the inside plate, comes in
contact with surfaces already heated by the first metal passing
over these surfaces ; the consequence follows, that the outer
plate is about the first part of the body of the wheel which
solidifies ; the metal in the ribs and the inner plate being in a
still liquid state, arrests the dirt in an attempt to work out, and
causes it to adhere to the metal forming the solid outside plate,
aud likewise affects the gases forming the blow holes in a simi­
lar manner.
The tests showed conclusively that the cracking of the
wheels is mainly due to the difference of temperature betweeu
rim and hub. The tests also showed that the cracks started iu
the same place, the outer plate. The fundamental question to
solve is what is the direction of the stresses causing these cracks
and how cau they be counteracted ? The stresses come in so
many ways that the only remedy is to put the metal iu a position
to have the stresses due to the expansion of the rim act
uniformly throughout the plates and not at one point in the
plate.
The first way which suggests itself is to put less metal in the
ribs, either by decreasing the number of ribs, or else their size ;
and, second, to use the " S" form of bracket, as it takes less
force to extend the length of these thau of the straight curved
brackets. A third way of resisting the action would be to
extend the single plate nearer to the outside of the rim of the
wheel.
To avoid cracking the concave form of outside plate is better
thau the convex because it does not present the sharp curve at
the junction of the plates. The choice of the experimenters
fell on a wheel registered JN. It has thirteen small brackets,
^•j-iu. inside plate (full of blow holes) and ^53-in. outside plates,
the latter beiug of a concave form.
The wheel which gave the best results, JN, was carefully
compared with the Sacramento wheels to find the relative excellence
of the metal in the two wheels. Rectangular sections
cut from each showed an average tensile strength of 20,596 lbs.
per sq. in. for the JN wheel and 22,190 for the Sacramento
wheel. By the Pennsylvania drop test a wheel of the same
make as the JN wheel cracked on the seventh blow aud broke
on the fifteenth. The average of a large number of .Sacramento
wheels broken by the Pennsylvania test during the past six
months is : cracked at 7 2 3' blows ; broke at 1173 blows. These
two sets of tests indicate that the materials of the best wheel,
JN, aud the Sacramento wheels were nearly alike.
The advantages of the JN wheel have beeu summarized as
follows : the pressure exerted on the journal is transferred to
the wheel plates in radial directions parallel with the center
line of pressure, running through point of contact between
wheel aud rail. A wheel subjected to vertical pressure alone
should have the contour of its outside plate conform as much
as possible to this center line of pressure, or, in other words,
the straighter and nearer the outside plate is to this center line
the better results can be expected, for the reason that the
strains will largely be borne by the outside plate alone, as
would be the case in the JN wheel, whereas, in the case of the
old Sacramento pattern wheel the outside plate deviates considerably
from the center line of pressure, and consequently
brings the greatest pressure to bear at the junction of both inside
and outside plates. This defect, when takeu in connection
with the expansion and contraction of the metal at the junction
of wheel plates, as previously referred to in this report, may be
considered as one of the causes of the frequent cracking of
wheel plates.
The results of these tests proving conclusively that the JN
design of wheel is the best to resist effects of heating, patterns
after this design were made, increasing weight of wheel to 600
pouuds, distribution of metal being practically the same.

November, 1892.] ENGINEERING MECHANICS. 299
C. H. LlNDENBERGER, explains a very good method in The
Technic, for obtaining the strain on continuous girders, es­
pecially in their application to continuous revolving drawbridges.
AT Toronto 500 horses were sold to make room for electricity
ou street cars. The trolley in the annexed district of New York
sent 325 to pastures green. Such things are calculated to make
a horse laugh.
BY this time the capital of the Western Union has been increased
$13,800,000 to make it $100,000,000. The added capital
is to build new lines aud additions. During the year 23,514
miles of new and additional wire were added.
IT requires no very brilliant intellect to recognize the increasing
possibilities of a European conflict of arms. The ex­
traordinary activity at shipyards, arsenals, gun works, foundries,
etc., poiuts to this possibility. East of Europe governments
have, during the past few months, placed orders for
large quantities of war materials. The Sultan of Turkey will
soon place au order for 24 gun boats. Military engineers in
Great Britain and on the continent were never busier, and
each government is vieing with its neighbor to secure the
greatest efficiency in every department of warfare.
THE British Consul at Jerusalem, in his last report, refers to
the progress of the Palestine railway, whicli has now been in
course of construction for the last two years. The concession
was granted by the Porte in iSSS to a company styled " Societe
Anonyme Ottoniaue," having its headquarters at Paris, and the
works, which were calculated to cost about ,£240,000, but which
will probably exceed that sum, are beiug carried out by a firm
of French engineers. The line has now been constructed. The
line from Jaffa to the foot of the mountains is iu a fairly good
condition, but it has not yet been opened to traffic. The part
to be finished is that which lies between the Jaffa plain aud
Jerusalem, and which will follow one ofthe valleys leading up
towards Jerusalem from the southwest. The work will be difficult,
but it offers no insurmountable obstacles. The length of
the whole line will be fifty-four miles, or seventeen miles longer
thau the present carriage road. When the line is completed a
branch will be made from Ramleh to Gaza, possibly with the
object of forming a junction with a line from Egypt.
PROF. SHORT has devised a gearless motor, especially for
street cars in which the following wearing parts of the double
reduction motor are avoided: Two high speed shafts, two pinions,
two gears, four brass bearings, four oil cups, four bearing
caps, sixteen cap bolts, motor pans, side curtains, aud all the
attending fixtures, bolts, nuts, etc., that go to fasteu these
things in place, while about half of these parts are saved wheu
comparison is made with the single reduction motor.
Its entire weight is supported on spiral springs and there is
uo hammering. The degree of economy secured is a disputed
point. The company making the improved gearless motor is
now furnishing them for 30 in. wheels and they weigh only 2,300
pounds. It has 13 field magnet cores cast integrally. Two
brushes are used aud the machine is water proof. Copper wires
of large carrying capacity reduce heating due to wire resistance
to a minimum. Efficiency ranges from 75 to 90 per cent. With
ordinary loads on level track a speed of 10 miles an hour can
be made ; when in parallel, 20 miles can be done. The capacity
of the present machine is 20 h. p. to 25 h. p. Stronger motors
will soou be constructed.
MUCH is yet to be learned ofthe laws of thermo-dynamics as
they relate to the compression aud expansion of air under various
conditions. Can a gas expand without doing work ?
Steam entering a cylinder expands and in a way that does no
work at the instant of that expansion, ft is generally admitted
that if a gas expands without doing work il will not fall in
temperature, and the explanation is that the work done during
au expansion of gas is expended or absorbed iu producing fric­
tion among the molecules of air. The resulting heat restores
the temperature lost by expansion. As a theory this reads
nicely, but the question arises, Is there sufficient friction among
the molecules to restore the lost temperature? This theory is
not acceptable to all. Rankine disposes of the question in this
way:
" Wheu the expansion of a gas takes effect, not by enlarging
the vessel in which il is contained, aud so performing work on
external bodies, but by propelling the gas itself from a space in
which it is at a higher pressure p1 a portion of energy repre-
sented by / v dp is employed wholly iu agitating the parti-
J fit
cles of gas ; and when the agitation so produced has entirely
subsided through the mutual friction of those particles, an
equivalent quantity of heat is developed which neutralizes the
previous cooling, wholly if the gas is perfect, partially if it is
imperfect."
Clerk Maxwell says: " In the more perfect gases, the cooling
effect due to expansion is almost exactly balanced by the heating
effe.ct due to the work done by expansion, when this work
is wholly spent in generating heat in the gas." "No change
of temperature occurs when air is allowed to expand in such a
manner as not to develope mechauical power." "The temperature
remained unchanged wheu a gas expands without deling
work." The laws underlying expansion have certainly not beeu
ascertained in all their relations.
AT the Charities Hospital, Paris, there is now in progress a
series of experiments of the greatest interest to the scientific
world, and offering a most astonishing experience to the intelligent
observer. Dr. Luys is experimenting ou the exteriorization
of the humau body, and a reporter was to-day allowed
to be present to witness what was done.
Exteriorization is the transference of human sensibility to
an inanimate object; it is the hypnotizing of a human subject
so that the sensitiveness is made to leave the physical body of
that subject and enter into any object that may be decided upon
by the scientists. In the experiment to-day so completely was
this done that Dr. Luys transferred a woman's sensibility iuto a
tumbler of water.
The tumbler was then taken out of sight of the subject and
the reporter was invited to touch the surface of the water. As
his hand came iu contact with it the woman involuntarily and
shriukiugly started as if in paiu. This experiment was repeated
several times, care being takeu upon each occasion that the
hypnotized subject should not see the contact between the hand
aud the water. The water retained the sensibility for a considerable
time and previous experimeuts in the same line show
that the water being drunk before the sensibility eutirely leaves
it the hypuotized subject falls into a deadly swoon.
In addition to this wonderful discovery Dr. Luys has likewise
confirmed another great experiment by Colonel Hoche, the administrator
of the Fjcole Polytechnique, who found it was possible
to trausfer the sensibility of the hypnotized subject to the
negative of a photograph of the patient. When a scratch was
drawn across the face of the negative a sensation of pain and
shock was evident ou the subject, and a few minutes later a
mark would appear upon the same spot as had already been
made on the negative.
Dr. Luys tried this experiment, as he did that of the tumbler
of water, several times to-day, having an unusually sensitive
subject, aud each time the experiment was a success. The
room to-day was well filled with the most scientific men in
Paris and they evinced the greatest concern iu all that was done.

300 ENGINEERING MECHANICS. [November, 1892.
QUARTZ mines rich in gold have been developed near the
head waters of several streams in Nicaragua.
AN electric railroad to the summit of Popocatapetl volcano,
Mexico, is projected over wliich to transport sulphur from the
crater, 17,784 feet above sea level.
FREE gold to a depth of 180 feet, and quartz of high grade is
being taken at the rate of $4000 per mouth, with a 12-stamp
mill, from old mines in Columbia, which have been purchased
by an English syndicate.
MINING engineers in the interests of the Pennsylvania Railroad
Co. have estimated the deposits of bituminous coal near
the summit known as the Bluebaker coal district at 200,000,000
tons, which will be brought within reach of the market by the
construction of three or four small spurs from the main line.
The veius of this district show 14 feet of good coal or about
14,000 tons per acre available for shipmeut.
FARMERS AND CANALS.—The President of the Vienna Corn
Exchange, in a recent speech, said that grain growing in
FjUrope has ceased to be remunerative, owing to the development
of new agricultural regions, and to the lowering of railway
rates. The only chance he could see for the European
farmer was in the construction of a uetwork of canals in Central
Europe. Cheap water transportation would help the
European farmer against the competition of the United States,
Iudia, and Australia.
SIXTY per cent, of the moisture of a large section of Russia
which was formerly available for nourishment of vegetation is
now lost because of au alteration of climate resulting from the
disappearance of large forest areas. One remedy sought is to
make a radical change in the manner of dealing with rivers,
which too generally are so used as to permit a rapid drain of
water from the higher altitudes and to be thrown disastrously
upon the lower areas in overflows. The excess due to spring
rains is rapidly carried off and wasted. Engineering talent has
the problem under consideration. It is no easy one. Famines
will be repeated until the violated laws are respected. General
Annenkoff has charge of the subject but has not yet suggested
the adoption of any remedial ageucies.
TOOLS OF THE PYRAMID-BUILDERS.—A two years' study at
Gizeh has convinced Mr. Flinders Petrie that the Egyptian
stone-workers of 4,000 years ago had a surprising acquaintance
with what had been considered modern tools. Amoug the
many tools used by the pyramid-builders were both solid and
tubular drills and straight and circular saws. The drills, like
those of to-day, were set with jewels (probably corundum, as
the diamond was very scarce) and even lathe tools had such
cutting-edges. So remarkable was the quality of the tubular
drills and the skill of the workmen, that the cutting-marks in
hard granite give no indication of wear of the tool, while a cut
of a tenth of an inch was made in the hardest rock at each revolution,
and a hole through both the hardest and softest material
was bored perfectly smooth and uniform throughout. Of
the material and method of making the tools nothing is known.
—London Exchange.
THE "greatest silver-lead" mining district in the world has
THE Allhouse Automatic Coupler is the latest. The coupler
consists of a double winged arrow having its shaft journaled
in one car to one side of the center of the coupling, so as to
beeu developed at Slocan, British Columbia. Some of the ore
runs from 1,500 to 2,000 ounces in silver, but the average is 200
to 500 ounces silver, and from 50 to 70 per ceut. lead. While
wagon roads are being built 500 mules are pressed in the ser­
turn in a horizontal plane, exactly as auy shaft turns in its
journal, and a slot formed by two vertical bars beveled on their
outer edges, which are set in the coupling to the other side of
the center of the coupling. The center of the slot is the same
vice of carrying over 20 miles.
distance to one side of the center ofthe coupling that the hook
or arrow is to the other. Then the edges of the wings of the
arrow are twisted, so that as the point of the arrow enters the
THE fact that the five armor perciug projectiles were crushed slot on the next car the arrow is turned about one-quarter way
when coining in contact at a velocity of 1700 feet with Bethle­ round and the wings pass into the slot and back of the bars
hem armor plate establishes the superiority of these plates over forming it. The arrow is weighted on one side so that after the
English or French plates. Two of the five penetrated only a arrow wings are in the slot a sufficient distance it automatically
few inches and did not crack the plate. The tempering of turns so the wings are in a horizontal plane behind the bars of
curved plates for turrets was a complete success.
the slot.
RAILROADS in Palestine, according to a contemporary, will be
so common soon that no notice will be taken of them. A new
line has been begun, starting from the old castle at Acre, passing
north of Mount Carmel, across the plains of Esdrelon—
with a station at Nazareth—and crossing the Jordan near Bethsham.
Thence it will proceed with an easy gradient to Damascus.
Already the laffa railroad is workiug transformations.
" Villas " are springing up at Jerusalem along the Jaffa road. A
large hotel has been built near the Armenian convent, and the
station for Bethlehem, predicted two generations ago by the
author of " Eothen," is actually in hand. As if to emphasize
the substitution of the modern for the ancieut spirit, it is now
announced the quarrymen of Jerusalem have gone on strike.
Whether the walking delegate is kuown in that remote region
the despatch does not say. Just as soon as the march of improvements
created a demaud for more stone, the quarrymen
demanded more pay, which the contractors and builders refused
to grant. Thereupon the stone workers "went out" iu regular
western fashion.
THE influence of continuous and discontinuous electric light
upon the structure of trees was recently the subject of a Paris
Academy of Science paper by M.Gaston Bonnier. Out of three
lots of plants, one was submitted to a constant electric illumination,
another to au illuminating alternation with twelve hours'
darkness, and the third was left to develop in ordinary daylight.
The experiments were carried out in the electric pavilion of the
Central Markets at Paris. The temperature was pretty constant—between
13 deg. and 15 deg.; the light was giveu by arc
lamps in shades, and the trees—pines, beeches, oaks and
birches—were surrounded by glass, the air being gradually renewed.
It was found that continuous electric light produced
considerable modificatious of structure in the leaves and shoots
of the trees. The plants breathed, assimilated, and secreted in
a continuous manner, but they appeared as if encumbered by
this continuity, and showed a simpler structure. The shoots
were very green, the leaves more open, less firm, and smaller.
Differentiation was less decided in every respect. In the specimens
exposed to intermittent illuminatiou the results were
similar to those obtained under normal conditions.

November, 1892.] ENGINEERING MECHANICS. 301
" How to Push a Post in the Ground " covers 43 pages ofthe
August number of the Transactions of the American Society of
Civil Engineers. Even under this liberal and able treatment
much remains to be said on the subject of pile driving. J. Foster
Crowell, C. E., endeavors to disturb some of the accepted
formula? on the subject and is vigorously answered by Mr. A.
M. Wellington, John C. Trautwine and others. Five formulas
were under discussion, as follows:
Sanders :
_ V2Wh
L--s — -
Wellington : L = 4
Crowell (a) : L
X2wh
7+1
\2-vh
s + 0.3
Crowell (b) : L
s+ 0.1 +
A 40,000
.s ,- + 11'
wh
$ow -Of h
Trautwine : L -= (J to r's)
s+ <
in which,
L = the safe load ou one pile ;
zo = the weight of the ram ;
/* = the height of the fall in feet;"]
5 = the penetration per blow under the final blovvs,-iu inches;
11' = a term varying from o. 1 to 1.
As thus written, the (numerical) fractional coefficient is the
factor of safety, and the other factor is the extreme load R ou
one pile.
I and zo to be measured in oue and the same unit as both iu
pounds or both in tons.
In the long discussion which took place the fact was recognized
that many conditions and accidents arose or happened to
nullify the formula in greater or less degree, but the conclusion
was reached that while the formulas were mathematically correct
and approximately exact iu their results, the difficulty of
obtaining all the data to be embodied in the formula would remain
as au obstacle to their absolute acceptance under all con­
ditions.
Mr. Trautwine says : "The elements atteudiug the operation
of those principles (formulas) are so uncertain and so numerous,
and the experimental data at hand are.so uucertain and so few,
that the wonder seems to be, not that we are without established
and reliable rules, but rather that any one has ventured
to formulate any rules at all.
What the civil engineer aims to accomplish is to determine
how much load can be safely carried under a given penetration
of pile. He is making an effort to establish a formula by which
the penetration of a pile under a falling ram affords the data
for a mathematical determination of its value in the support of
given loads. No such formula has been satisfactorily deduced.
It is noted some piles which penetrated several iuches to the
blow while being driven, resisted the same weight and fall without
any perceptible penetration after the pile had beeu permitted
to rest, thus affording a restored equilibrium to the mate­
rial through which the pile had been driven. Upon the other
hand, piles which were driven home with difficulty, have settled
down under seemingly inadequate loads, which would indicate
that the material failed to find adherence to the pile, thus permitting
the percolation of water tending to soften the material
which sustained the pile.
It is evident, then, that if the penetration of the pile, after a
succession of blows, is taken for a basis of calculation as to
what the pile will support in service, no formula, no matter how
accurate, can be relied upon ; for the last blow of the ram, iu
the process of driviug, occurs when the material surrounding
the pile has been disturbed in the act of driving, whereas the
effects of such disturbances have generally disappeared by the
time the piles are loaded. Manifestly, the bearing capacity
must be determined from data corresponding to conditions of
service. This at once suggests that such tests should be made
by dropping the ram on the driven pile after affording it some
period of rest. Thus it would be comparatively easy before
moving the driver, to test on Monday moruiug the pile last
driven Saturday evening, and the penetration of the pile observed.
The penetration due to the last blow each afternoon
could always be compared with that resulting from the first
blow on the mornings following, aud, if deemed necessary,
other tests could be made after longer intervals of rest. But
little time would be lost iu following this practice, and at the
same time the data so obtained could be used with uo small degree
of accuracy to determine by means of formula the bearing
capacity of piles iu service.
Mr. Bouscaren called attention to the fact that the resistance
of the soil is often greater wdien the pile is being driven
than it is after the pile is driven. Mr. Chas. B. Brush showed
the danger of brooming piles after they had been driven home
and of driving too little or too much. The force exerted to
drive a pile is a very uncertain factor in determining its bearing
power. The weight of ram aud the height of fall may indeed
be determiued with reasonable exactness, and the product of
these gives us, no doubt, quite approximately, the energy
stored in the ram at the instant when it comes into contact
with the head of the pile; but in estimating how much of this
energy is utilized in driving the pile, we are obliged to remem­
ber that the mass of the pile has yet to be set in motion ; that
the direction of the blow can seldom be more thau approximately
in line with the axis of the pile ; that the vibration of
the pile under the blow will vary with the length of the pile
projecting from the ground ; that according to circumstances
this vibration may facilitate or impede the driving, and that to
an unknown extent; that the pile, even at its best estate, is
more or less compressible, and that the head must become more
or less crippled by the blows delivered upon it, thus further increasing
and rendering still more uncertain the amount of the
useless consumption of energy in the delivery of the blow.
The disposition to theorize aud to deduce formula from insufficient
data sometimes leads to unimportant conclusions.
IF the cholera scare has done no other good it has served to
emphasize the importance of immediate attention to scientific
sanitary devices with reference to sewage. The municipality
of Providence has decided to no longer leave protection from
cholera to Providence, but to construct a sewage system wliich
involves the carrying of the product a proper distance from the
city aud there subjecting it to well tried chemical methods before
discharging it into the bay.
IN manufacturing tubular rivets the practice has been to form
them in one of two ways, by striking the blank from a length
of wire and boring out the tubular shank, or by striking from a
plate a blank of circular form for the head and two side pieces,
which when bent down and formed in dies will serve as a tubu­
lar shank. The first method is costly, and in the latter the rivets
are of little use when great strength is required. A recent inventor
takes a disc of thin steel which he submits to the actiou
of a pair of dies so as to form a shallow cup. This cup is then
submitted to the actiou of a second pair of dies, and, if necessary,
to a third pair, iu order to draw out the tubular portion to
the required length. The tube'so formed and closed at one end
is submitted to another pair of dies, by which the closed end is
flattened down and a head formed of any suitable size. The
rivet is theu submitted to the action of a reaming too], bv
wliich the edge of the tube is bevelled off inwards and the
rough edges removed.

3°2 ENGINEERING MECHANICS. [November, 1892.
BOLTE AUTOMATIC TIME-KEEPER.
The Bolte Automatic Time-Keeper is a new device for keeping
accurately a record of the time of arrival and departure of
employees.
No. 1.
Cut No. 1 shows the complete detail, with clock and dial, and
the hand making the registration.
VI 1
t 50 55 60 3 10 13 20 2530 33 40 43 30 55 60 3_ 10 15 Z0 ZS .10 35 40 1550 55 60 5 10 15 2
r 1 "i") •[ 1 • i 1 1 1 i i 1 "i r 1 "i 1 1 i I 1 1 1 I~T~^
r 1
) ::
' 1 3
. 5 "I
1 •
1 i
/ 3
\. ..... L....... - '.
/'" "i
10 1
L.:::.: A..:A:AJ
W
No. 2.
Cut No. 2 shows a section of the upper part of the record
sheet. The cylinder arouud which this record sheet moves turns
in time with the hour hand, making one revolution every twelve
hours. The heavy line marked 7 o'clock indicates the hour at
wliich the workmen are expected to arrive. The numbers recorded
on the left of this line are early,
whereas those on the right are late. Each
of the light colored lines indicates five
minutes, therefore any oue registering
three lines to the right of the 7 o'clock
line would be fifteen minutes late, and as
the proprietor enters his establishment in
the morning one glance at the clock will
indicate just those employees who are
late or absent, and how many minutes
they are behind time.
Cut No. 3 shows a section of the key
rack, through the openings of which the
registrations are made.
Cut No. 4 shows the registering key,
full size. Each workman draws his pay
accordiug to a certain number, and iu this
case the one shown is No. 75. This number
appears in raised letters on each end
of the key ; the eud marked "iu " being
nickel, the end marked "out" being of
copper. The indication of an employee
registering "out" is shown by a star (*)
being placed after the number, thus 75*.
The value of this device is self-apparent.
Each workman makes his own registra­
No. 3.
tion and cannot complain of the timekeeper.
No collusion is possible between time-keeper and employees.
By actual use it has demonstrated the fact that employees
are much less liable to be late, as by the use of the
No. 4.
Bolte Automatic Time-Keeper not only the workmen themselves
are able to inspect the record, but their employers are able each
day at a glance to ascertain the numbers and names of those
who are arriving on time, or others who are habitually late or
absent. The device will be placed on the market by the National
Time Recorder Co., 361 and 363 East Water Street, Milwaukee,
Wis.
• • ; • , '
BINDERS are furnished from this office at 50 cents each similar
to illustration.
THE Philadelphia Blue Print Co., 41 North 7th Street, has extended
and enlarged its borders and is now in shape to meet any
demand likely to be made upon it with despatch.

November, 1892.] ENGINEERING MECHANICS. 303
THE accompanying cut shows the corroding action which
often occurs from damp ashes on the space between the fire-box
and the grate bars, and which becomes packed betweeu the
plate and the bars. This corrosion is the subject of remark.
If there is the slightest leakage or dampness these ashes begin
at once to corrode everythiug in contact with them, aud in a
short time the boiler becomes unsafe. The piece shown in the
cut was taken from a furnace about two years old and fully onequarter
of an iuch thick. It was taken out just against and
above the grate bars, and in places it was only f. to ,',; of an
inch thick. This same state of things extended entirely around
the fire-box. _
AN improved method of castings in brass, bronze or alum­
inum reproduces the finest details of the engraving and chasing
work so fully that it is difficult to distinguish, even with a magnifying
glass, the difference between the original and the copy.
The metal is forced into every fine line of the matrix by increasing
the pressure in the rear and decreasing the pressure in
front of the molten metal which is forced from the bottom of
the holder to all the cavities and depressions. The process has
not yet been applied to iron or steel. Among these castings
were plaques, medallions, grilles, backs of hand mirrors and
brushes for toilet sets, statuettes, card receivers, ash trays, table
ware, picture frames, name plates for machinery, fine gear
wheels, pieces of surgical apparatus, aluminum bronze dies for
stamping sheet metals, or for forming or embossing plastic
materials, such as celluloid, papier mache, leather, etc., aud
numerous ornamental and decorative castings. Wm. Kent,
M. E., 35 Warren St., New York, is general manager.
THE advantages proven for the Fire Felt covering made by
the H. W. Johns Mfg. Co. are :
" First. It is superior to hair felt, as a non-conducting ma­
terial.
"Second. It is composed entirely of asbestos fiber, and is
practically fire-proof, it having deteriorated slightly after an
hour or more, in a furnace.
" Third. It is a felt-like fabric capable of being shaped aud
fitted to any irregular surface. Shocks from blows and from
being walked ou will not injure it.
" Fourth. The Fire Felt is slightly heavier than the hair felt
of equal thickness.
" Fifth. The fire and water-proof material which forms its
exterior jacket was not injured by hammering, it is cheaper and
lighter thau the lead or sheet-iron casting now used, and is
easier to supply or remove. So taken as a whole aud compared
with the hair felt with its lead or iron covering, it is a great
deal lighter.
"Sixth. The non-conducting material is neat in its appear.
ance, and can be applied without the exterior jacket, while the
latter can be used with any other pipe or boiler covering.
AN Allis-Corliss eugine, lately erected for the Narragansett
Electric Lighting Co., of Providence, R. I., is of very novel
design. The engine is cross-compound, 19 and 36x48 inches,
condensing. There is no fly-wheel, but instead ofthe fly-wheel,
and in the same place as the fly-wheel, is the armature of the
generator, this armature beiug 16 feet in diameter, and weighing
about 40,000 pounds. By this arrangement all belts and
counter-shafts are dispensed with. The arrangement looks like
an ordinary fly-wheel made in two sections and bolted together,
except that the rim of the fly-wheel is about 30 inches thick,
and is the armature of the generator, while the dynamo field is
erected about the armature iu such a way as to practically inclose
it. Some idea of the size of the machine will be obtained
from the following dimensions : The foundation space occupied
is 42 feet by 21 feet 6 inches. The outside diameter of the
field is 19 feet J A inches, while the diameter ofthe fly-wheel is
16 feet. The weight of the armature aud of the field complete
will approximate 90,000 pounds. The armature makes 90 revolutions
per minute, and delivers current to the circuit at 7200
alternations per minute. The current is collected by means of
brushes bearing upou large ring collectors mounted upon the
shaft. Nearly 60,000 thin sheets of irou make up the magnetized
part of the dynamo. The machine is good for 500 electrical
horse-power continuously and an efficiency of 92 per cent.
FASTEST TIME EVER MADE.
One of the Royal Blue Line trains of the Baltimore & Ohio
Railroad, ou a recent run between New York and Washington,
covered a mile in 39A seconds as recorded by a mechanical indicator.
At this rate the train traveled at the phenomenal
speed of a trifle over a mile and a half a minute, or over ninety
miles an hour, whicli surpasses all previous records of fast time.
If the speed were maintained the time between New York and
Washington would be reduced without stops to two hours aud
a half and with stops to three hours. Five hours is now the
fastest time between the two cities, and it is made daily by the
Royal Blue Line only.
THE Thomson-Houston Company are making a marine incandescent
dynamo set, which occupies 40 inches by 24 in. It
is 27 inches high, weight 900 pounds, h. p. 3/2 to S. The armature
shaft of the dynamo and the shaft of the engine are connected
by a flexible coupling.
PROF. FORBES, the English Consulting Electrical Engineer
of the Tunnel Power Company has visited this country twice
this year to pass upon plans for utilizing the Niagara Falls
water power. A small tunnel is now being constructed to furnish
2000 horse power to run the power house of the electric
railway on the Canadian side. A tunnel 6700 feet long lined
with brick is now completed on the American side, which it is
expected will develop 120,000 horse power. The Canadian company
will develop 100,000 horse power. Work on that side will
be begun next spring.

iii ENGINEERING MECHANICS. [November, 1892.
KEYSTONE LUBRICATING GREASE.
ECONOMICAL, PURE,
CLEAN, SAFE.
One pound guaranteed to go
further, and do better, than three
gallons of any other lubricating
oil. It is used by thousands of
the largest firms in this country.
BRASS AND IRON CUPS FUR­
NISHED FREE OF CHARGE.
Keystone Lubricant
CAN BE OBTAINED
ONLY FROM THE MANUFACTURERS.
THE KEYSTONE LUBRICANT CO., 209 N. Third St., Philadelphia,
THE NATIONAL FEED WATER HEATER.
A BRASS COIL HEATER delivering Water to the
Boilers at 212° Fahrenheit.
400,000 HORSE POWER NOW IN USE
PRICES LOW. SATISFACTION UNIVERSAL.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE.
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
HARRISON SAFETY BOILERS
COMBINE IN THE HIGHEST DEGREE:
ABSOLUTE SAFETY FROM DESTRUCTIVE EXPLOSION.
ECONOMICAL AND RAPID GENERATION OF DRY STEAM.
DURABILITY, LOW COST OF MAINTENANCE, GENERAL EFFICIENCY.
MEEITS PEOVE1T BY T - W r EZSTT-Y--I'I-V-E YZE-A-ES SEE,"VICE.
First Cost Moderate, owing to Simplicity of Construction and Inexpensive Setting.
New pamphlet, describing latest improvements ol setting, together with drawings and specifications of boilers
of any size, from 4 H. P. to 240 H. P., promptly mailed upon application.
HARRISON SAFETY BOILER WORKS.
Germantown Junction, Philadelphia, Penna.
New York, N. Y., 41 Dey Street. Atlanta, Ga., 9 North Pryor Street.
Chicago, 111., 187 L,a Salle Street.
THE BALL & WOOD ENGINE,
SIMPLE, COMPOUND AND TRIPLE, HORIZONTAL AND VERTICAL,
-AS BUILT BY-
THE BALL & WOOD CO.,
Office, 15 Cortlandt St., New York,
[Is superior in DESIGN, FINISH and WORKMANSHIP. In REGULA­
TION and ECONOMY it has no equal. Built with new tools, from
new patterns, and after long experience, it should and
DOES mark tbe latest step in steam engineering.
REPRESENTATIVES:
W. B. PEARSON & CO., Home Ins. Building, . . . .CHICAGO ILLS
W. A. DAY, No. 128 Oliver Street BOSTON ' MASS
HYDE BROS. & CO., Lewis Block PITTSBURGH PA
W. M. PORTER, Hodges Building, DETROIT MICH '
I IF H' WH?T,N S r° N ' •' •' H0UST0N '' TEX * S -
'IF. H. WHITING, DENVER, COL.

December, 1S92.] ENGINEERING MECHANICS. 305
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering,
Published by JOHN M. DAVIS, at 430 Walnut St., Philadelphia
London Office, 270 Strand, D. NUTT, Agent.
All Subscriptions for Great Britain should be sen! to London. Price, las. yearly.
Entered at the Post-office in Philadelphia as Second-Class Mail Matter.
IN six or seven mouths there will be launched from the Ches­
SUBSCRIPTION RATES.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
PHILADELPHIA, DECEMBER, 1892.
IT is probable a tunnel will be cut under the Duluth ship
caual, at an estimated cost of $600,000, rather than a draw
bridge, which would cost $400,000.
ENGINEERS are devising a system of connecting, by an
electric belt line, the cities of Buffalo, Cleveland and Pittsburgh,
with power obtained from Niagara Falls.
To cut off iS rapids in the Columbia River, Oregon, it is pro­
posed to build a ship canal 60 miles long, and thus shorten the
route 100 miles from the head waters to Grand Canon.
THE hydraulic mining engineers of California have gained a
victory in Judge Gilbert's recent decision that operations can
be conducted so long as the velocity of the stream to carry off
the debris is not lesss than two miles per hour.
THE earning power of electric roads as compared to cable
roads is as 4 to 3, while the cable road costs double the electric.
Continuous rails are recommended to avoid the disadvantage of
joints, and a standard rail head is also urgently suggested.
ELECTRIC conduits in Paris must hereafter be under the sidewalks,
except in very narrow streets, and private companies
must leave 3 ft. 3 in. for municipal wires next the houses. Each
company has to pay for the relaying of the pavement before it
is disturbed.
ALL telephone wires in Cincinnati now ruu under instead of
over street crossings. Distributing poles will catch the ioo and
over wires and gather them into five cables aud carry them
under the street and up the pole to a distributing ring equipped
with 104 insulators.
THE Colorado river is being harnessed by irrigating engines
to rescue a desert. It lies 100 to 120 feet above the sea, 90 miles
from it, and has a fall of a foot per mile. The land can be
cheaply irrigated, and steps are being takeu to transform a vast
arid region into a garden.
DAVID BAKER, M. E., of Sparrow Point, Md., has devised au
ingenious and practical mounting for a steam drill to do away
with hand drilling at the furnace front at the time of casting.
The power drill used by Mr. Baker works quicker aud better,
describes a true circle and saves much labor.
ALL European governments are interested in the trials of
projectiles and armor plates. The next competitive trial is to
take iplace very soon at Ochta, near St. Petersburg, when the
Harvey, Tresidder, St. Chamond and Schneider plates will be
tested in a strictly competitive way by 6 inch forged steel
Holtzer projectiles fired with about 2,000 feet velocity.
AND now comes Stephen II Emmons to upset previous no­
tions as to what constitutes a correct unit of fuel gas measurements.
Mr. Emmons makes a recomputation of fuel-gas heat
units, aud points out, iu the first place, the perplexing incon­
stancy of constants. It is painfully evident that the prevailing
theories and standaids of measurement of heat must be radi­
cally modified.
ter, Pa., ship yards a steamer for the Sound Service that will
surpass any thing ofthe kind ever constructed. The length will
be 440 feet, depth of hull 20 ft. 6 in., constructed of steel, 58
water tight compartments and absolutely fire proof and unsinkal.le.
The horse power will be 8000 ; ten Scotch boilers ; speed,
22 knots; carrying capacity, iooo tons; cost, $1,250,000.
M. A. GREEN, of .\ltonua, Pa., has designed au engine governor
which overcomes "racing." To keep the governor stable,
there is introduced a device which automatically regulates the
overbalancing of the centripetal force. When the governor is
so arrauged that the centrifugal and centripetal force balances
the governor becomes unstable because the centripetal force
increases faster than the centrifugal force. This action is held
in check by the automatic device referred to.
THE veutilating plant of the Baltimore and Potomac Tunnel,
at Baltimore, is operated by electricity through a copper cable a
half mile distant, with a 45 H. P. motor. The air is changed
every five minutes ; velocity 32% ft. per second. The length of
the tunnel is 3600 feet, 22 feet high, and semicircular arch. The
Davidson wheel has a diameter of 15 feet aud velocity of periphery
of 658 feet per minute. One-half the power ofthe motor
is required to overcome the inertia of the air, the rest is availa
ble for friction of tunnel and force and suction of passing trains.
THE recovery of by-products in the manufacture of coke for
blast furnaces has reached a high state of perfection in German)'.
The yield with dry coal has beeu increased from 67 to 75 per
cent., due in part to air-tight ovens, necessary for the recovery
of b)'-products. A coke plant of 60 ovens mentioned, yields
24,000 centimeters of surplus gas daily, capable of heating
boilers with a surface of 375 sq. ft. meters, which is equivalent to
21 tons of coal. This plant on 48 hour coke, running 30 da} s a
month will coke 5625 tons of dry coke per month. The profit
on the by-products by the Hoffman-Otto coke oven here used
is sufficient to lead to a more general adoption of the system.
THE long telephone line between New York and Chicago will
probably be soon extended to Boston ou the East, Minneapolis
iu the Northwest aud St. Louis in the West- The success of
this undertaking has imparted a stimulus to long distance telephoning.
One uniform size of carbon granules is used, aud au
improved battery is used, the Puller, and consists of a solution
of bichromate of soda and sulphuric acid as follows : Water,
10 gallons; commercial sulphuric acid, 25 pounds; bichromate
of sodium, 8A pounds. Three cells are used. Copper used,
826,500 pounds of No. 8 ; wire, 42,750 ; poles, 35 feet high and
45 to the mile ; charge for five minutes' conversation, $9.00.
THE Cresson system of transmitting power through buildings
by vertical shafting is a great improvement over old methods,
and deserves consideration. This system secures a perfectly
true bearing of the step between the revolving and stationary
faces and the entire bearing is filled with oil, which penetrates
the step bearing, notwithstanding the enormous pressure on its
and prevents heating from friction. A system of guide pulleys
or idlers reduces the strain on the belt which is guided truly in
line with both driving and driven pulleys. The Cresson Com
pany (Philadelphia) have simplified some ofthe annoying diffi­
culties incident to the transmission of power, and their efforts
will be appreciated by those who adopt their improvement.

3°4 ENGINEERING MECHANICS. [December, 1892.
THERE is much need of uniformity in street rails. Width of
wheel tread varies from x)2 to 5 inches, and depth of wheel
flanges vary from six-seventeenths of an inch to IA inch. If a
2 '4 inch tread and a three-quarter inch wheel flange could be
adopted it would greatlv simplify matters. T rails, girder rails
and a section of girder rail deep enough to be spiked to a tie,
are both used. Width of rail head and depth of flange ought to
be agreed upon. Mr. John F. Ostrom says of this kind of rail :
Its adoption by the association would materially simplify both
the track aud wheel questions. It would give to manufacturers
a clear idea of what street railway requirements are likely to
be, aud enable them to have such rails as may be desired ready
for next spring's business ; aud it would be of incalculable
JOHN PLAYER'S compound locomotive tried for several mouths
on the Lake Shore and Michigan Southern Road accomplishes
two objects not heretofore accomplished by locomotive builders
as well : First, to automatically reduce the pressure ofthe live
steam admitted to the low-pressure cylinder, so that the mean
effective pressure on the low-pressure pistou at starting may be
equal to that on the high-pressure piston or be regulated in any
desired ratio, and to automatically regulate this supply of live
steam at reduced pressure to the low-pressure cylinder, aud to
prevent this pressure from working against the back of the
high-pressure piston ; second, to automatically cut off the supply
of live steam to the low-pressure cylinder at a period when
the pressure in the high-pressure side of the receiver is the
same as that ou the low-pressure side, and to simultaneously
open connections between the two ends of the receiver so that
the exhaust steam from the high-pressure cyliuder may flow
direct through the receiver into the low-pressure steam chest
and act upon the low-pressure piston ; third, to provide
benefit in enabling the many new companies to avoid the mis­ means whereby the engineer can at all times obtain comtakes
of inexperience to work with us toward a higher standard plete control of the engine iu the same manner as a simple
of excellence in street railway work.
engine when switching, running ou turn tables, &c. With this
improved combination live steam at a suitable working pressure
THE natural gas region of Indiana continues to attract atten­ is permitted to act upon the low-pressure piston at all times
tion of manufacturers. All English concern is about to erect iu starting, and the steam at this pressure is maintained in
six 25-ton open-hearth steel furnaces, 20 trains of rolls besides the low-pressure side of the receiver and prevented from work­
cold roll and machine shops to make tin plate. The total iug against the high-pressure piston until such time as the
outlay will be $1,000,000. Mine factories zxxd mills are pro­ high-pressure end of the receiver becomes charged with exhaust
jected at Gas City. A hub and block company are in this lo­ steam from the high-pressure cylinder at approximately- the
cality, compressing blocks of wood for carriage and wagon same pressure, whereupon the intercepting valve, acting in
work to destroy intercellular tissue. The Bonney Rapid Vise combination with the pressure-regulating valve, permanently
Company is here, and the Akron Steam Forge Companv is cuts off any further supply of live steam to the low-pressure
coming. The Whitely Harvesting Machine Company which cylinder, and permits the direct passage of the exhaust steam
controls 350 patents in this line, and wliich emplovs iooo men from the high-pressure into the low-pressure cylinder. This com­
is moving from Springfield, Ohio, to Muncie, Ind. Several bination also prevents live steam admitted through the pressure-
other large Ohio industries contemplate an early removal to regulating valve from passing into the high-pressure end of the re­
this favored locality ; correspondence is going on with a large
number of manufacturers to induce them to locate in this gas
ceiver, and thus acting upon the back of the high-pressure piston.
field. Tin plate manufactories are working in that direction,
MAYOR WM. G. ROSE, of Cleveland, in his address of wel­
and it is probable the manufacturing activity of that portion of
come to the American Street Railway Association, made a
Indiana will be greatly increased during the next vear or two—
statement that the extraordinary demands of corporations for
provided confidence is maintained in an inexhaustible supply
monopolistic privileges in municipalities would lead to muni­
of gas. There are symptoms of exhaustion in other older gas
cipal ownership of street railways as water works and gas
fields more or less marked, but the temptations of abundant
plants are owned, aud, he might have added, public schools.
aud cheap and pure fuel seem to be sufficient to overcome
A public sentiment is rapidly growing which demands a return
doubts as to the permanency ofthe natural gas supplv.
to the public treasury of part of the profits resulting from the
To obtain the maximum thrust for a given expenditure of use of liberal franchises. This sentiment commands scant re­
power for a screw propeller is the objective point of all cognition or respect among those who have become accustomed
mechanical engineers who are wasting time on this elusive to buying aud profiting by franchises. While there are but one
problem. Au ideally perfect screw is one whose thrust effort in or two systems, aud while there are only a few competing cor­
pounds, multiplied by the ship in feet per second and divided porations for these franchises, everything will move along
by 33,°oo would equal the indicated horse power less 10 to 12 smoothly with and for the corporations owning the street rail­
per cent, on account of engine friction. Those who are trying way systems. But inventions are the order of the day, and
to increase the efficiency of the screw propeller, have only 10 improvements in the application of power are of daily occur­
per cent, increase to work ou before realizing a theoretically rence. Capital is seizing every improvement that is new and
and practically perfect screw. To accomplish this thev have good, buying up competing devices and patents wherever pos­
three things to work on after starting with sufficient blade sible and shelving them. But a day of reckoning must logically
area, viz., to reduce the work expended in driving the water come. Competing corporations for municipal privileges must
astern, to reduce the skin friction of the blade and'to make the necessarily arise. Franchises will be sought for as they be­
edgeways resistance as small as possible. The engineers have come more valuable, and out of this competition will come
all along made the mistake of assuming that a propeller could profit to cities. It is an error to suppose that with the multipli.
be designed that would suit any and all ships, all speeds and all cation of methods and systems aud improvements with their
loads. The truth i-, that the propeller must be constructed with resulting economies that corporate ownership of methods of
refereuce to three factors, ship, speed and displacement, there transportation cau remain in its present positiou.
fore there must be as many designs of propellers as there are The engineer is the disturbing factor in the case. His cease­
different conditions. The point to be kept in view is to design less energy is devising something new aud better, and the
a propeller that will drive astern the largest quantity of water anxiety of capital for more profitable employment will lift each
at the lowest velocity. But engineers are working in the dark improvement from the blue print to the black board of the
because they lack the fundamental knowledge as to how and Stock Exchange. Propositions have been frequeut of late in
why a propeller produces a thrust.
the direction of municipalities, assuming the ownership of electric
plants, roads, etc. The logic of events, the laws of competition,
the tireless euergy of the human brain, will bring
about these results without the help of the theorist or socialist.
When they come public opinion will be up aud ready for them
and the only wonder will then be why municipal ownership
had not been thought of and adopted sooner.

December, 1892.]
Translated by Henry Harrison Suplee.
Pig/ 9S3 is Norton's so-called V shaped pump. Iu this device
the pistons c2 and ct form a single stationary piece, aud the cylinder
and valves bl and b3 is
the moving part. It will {CA:
readily be seen how easily I j
the lift pump may be made
double-acting. j i
A double-acting lift pump
as used for a steam engine
air pump, by Watt, is showu
in Fig. 984. This is practically
a combination of two
different pumps. It has three
valves, the foot valve b2, piston
valve bl and upper valve
b3. On the downward stroke
the mixed air, water and vapor
passes through the piston
from the lower to the upper
part of the cylinder, ami on
the up stroke this is discharged
through b3 aud a
fresh cylinder full drawn in
through b... This pump is
double acting, since the piston
valve acts both in the up
and down stroke. This works
the same whether pumping
liquid or gaseous fluids, the
action being the same as if
two valves only were used.
The upper valve is required
for other reasons, i. e. to con­
trol the discharge, as for
boiler feeding, etc.
THE CONSTRUCTOR.
FIG. 9S4.
The preceding examples will serve to illustrate the application
of fluid ratchet trains with running ratchets. It is important
in all cases, and especially with the higher velocities, that
provision should be made to have the valves close without
shock, or in other words, that the engagement of the pawls
should be quiet. This problem has already appeared in some
forms of ratchet mechanism (see \ 240) and here offers still
greater difficulties, especially when heavy moving masses are to
be controlled. The question is daily being considered in practical
problems of construction * and a great variety of valves
has been designed. The present indications appear to be leading
toward the use of valves operated mechanically by the
pump, instead of those operated by the fluid itself, but. a final
solution of this problem has not yet been reached.
\ 320.
FLUID RATCHET TRAINS WITH STATIONARY RATCHETS.
As already shown in fj 255, it is necessary, in ratchet trains
with locking teeth, to effect the engagement and disengagement
of the pawls by some additional mechanism. This is also the
case in those fluid ratchet trains which used stationary pawls,
i. e., sliding valves. An example is found in the case of the
simplesingle-actingair pump used in physical laboratories, which
since its invention by Otto von Gerike f has been made with
stationary pawls, and is shown in a crude form in Fig. 985.
The "receiver" d',
and its pipe connection
forms a negative
reservoir, the pump
a c d [ b., a ratchet
train for the propulsion
of the column
of air a. The suction
valve is at b.,, and the
discharge valve at bt, both being in the form of stop cocks.
The suction valve b., is operated by hand when the piston is
drawn out, and when the end of the stroke is reached the valve
* See Fink. " ^Construction der Kolben-und Zentrifugalpumpen," Berlii
872; also Bach, " Konstruction der Feuerspritzen."
+ This name is spelled as given above in the earliest records, and not
' Guericke," as is often given.
305
Translation Copyright, ibt,u.
blt which had previously been closed, is opened, and the first
one closed, anil the air expelled on the return stroke.
cock, b3, is also placed close to the receiver.
There is but little difficulty iu applying
slide valves to single-acting pumps,
A stop
and they are also readily arranged
for double-acting cylinders. By examining
the arrangement of flap valves
iu the compress double-acting pump,
Fig. 986, it will be seen that the valves
b, aud b, open and close simultaneously,
and that the same is true of b2 and b3,
aud that the two actions alternate with
each other. The operation of the valves
is such that the four spaces I to IV are
connected alternatelv iu the order /-//
and III-I V, and I-I 11 and II-IV.
From this it will be seen that if sliding
valves are used they may all be connected
together, or united in the same
construction. This may be done as
shown in Fig. 987 a, which represents
the so-called "four-way " cock. As here
shown, all four Of the passages are
closed, this position corresponding to
the eml of the piston stroke. When
Fio 986.
the plug is turned 45°, as shown by the dotted liues, /and ///
are connected, and also //aud II' and if it is turned the same
amount in the other direction, /and // aud /// and IVaxe
FIG. 987-
connected. The portions ., and b, may be omitted, as in Fig.
987 b, and the passages //, /f'and ///brought closer together,
as shown at c. From this form it will readily be seen how the
passage /can be converted into a mere delivery pipe, and the
radius of curvature of the bearing surfaces, made of infinite
length, giving the well-known slide valve, Fig. 987 A. Iu like
manner other forms may be developed. It must not be forgotten
that this device really consists of four valves combined iu
one, and in fact recent forms of steam engines contain the four
valves made separately, these often again being lift valves.
A iioteworth v peculiarity in the forms shown in Fig. 9S7 a and
d must be considered. Iu hoth instances the valve overlaps
the port ou both sides, this beiug technically known as "lap."
It is also apparent that the lap ou the two sides of one port may
differ, and that different laps may be used for different ports.
By use of this expedient the opening aud closing of the ports
need not be simultaneous, but may occur successively.
From the preceding considerations the following propositions
may be laid down ; the latter applying to all, and the former to
nearly all, lift valves :
The application of slide valves iu all fluid ratchet trains depends
upou two principles:
1. The combination of several valves into one piece.
2. The control of the time of action of these valves by means
of the lap.
The application of a slide valve to a pump is shown in Fig.
988 a. In this case /is the discharge outlet, and 'IVthe suction
connection. In such pumps it is necessary to provide some
mechanism to operate the valve, and such mechanism is termed
the " valve gear." This valve gear may be arranged in a great
variety of ways.
A simple form of gear is that shown in the figure, 9SS a, in
wliich an arm 6, attached to the piston rod, moves the valve by
striking against tappets 5' and 5" on the valve stem. This

3°6 ENGINEERING MECHANICS. [December, 1892
arrangement is similar to the locking ratchet of Fig. 753. It
has the defect, however, of requiring the piston to move rapidly,
or else the valve will not be carried past the middle position,
and the pump will stop. This defect can be met by using a trip
gearing device such as showu in Figs. 742 and 743, to continue
the condition of the valve when started by the impulse of the
pistou rod.
A somewhat simpler method is that in wliich the reciprocating
motion of the pump rod is used to revolve a shaft by means of
a crank, Fig. 988 b, from which the valve may be operated by
means of a return crank or eccentric. This arrangement is
often used, especially for blowing engines, etc. ;: ' It will be
apparent that a four-way cock device. Fig. 987, maybe arrauged
so as to be operated by continuous revolution, instead of a
reciprocating motion, and hence the eccentric may be omitted
and a rotary valve device substituted.
In Fig. 9886 the crank and crank shaft are used merely for
the purpose of actuating the valve gear. It is practicable,
however, wheu a crauk is once admitted, to use it still further
as oue of the parts of the pump, such as iu chamber trains.
Many such devices haae been proposed,! although but few of
these have been put to practical use. The three following devices
will illustrate.
L 1 ,
Fig. 989(7 is Pattison's pump, a form of chamber-crank train.
The crank a here assumes the form of an eccentric, the rod /<
becomes a llat pistou, the edges of wliich form a tight joint
with the ends of the cylindrical chamber d. In the position
shown in the illustration the spaces //and /and ///and /('
are in communication. In the dotted positions /// is couuected
with /, followed again by //and /anil ///and IV. This trans
fer of communication is produced by the action of the crank,
and hence no other valves are necessary.
The form shown at Fig. 989 b is made with an oscillating
cylinder. The piece c. which plays au inconspicuous part in
Fig. 9S9 fi, is now used for the chamber, and its oscillating
motion with regard to b supplies the necessary- valve action.
Oscillating pumps are used in a variety of forms.
When the pump is used for pure water, as for drinking supply,
the question of wear upou slide valves is not so important as
with pressure pumps. A fair comparison can hardly be made,
however, betweeu pumps with slide valves and those with lift
valves, as the former have been but little used and also not
practically designed.
It is a matter of surprise that when occasional applications of
slide valves are made in pumping machinery, that such devices
should be considered as something new The difference between
the action of water and air is well known, aud yet even
with the slight weight of an air column the shock in blowing
machines is most apparent. It can hardly be supposed that the
other form would remaiu uninvestigated.
The pumps shown in Fig. 989 a and c are commonly known
as rotary pumps, which title is manifestly incorrect, since in
form a there is au oscillating pistou which does not rotate,
while in form e, notwithstanding the rotary motion the action
is similar to form a. Other so-called rotary pumps have been
devised with curved piston action, some of these being as early
as the 17th century. In some designs a radial slide acts in the
pump case as a ratchet, and is drawu in and out by a cam of
appropriately curved profile. A large number of rotary pumps
have been made on this principle, many of which will be found
in Poillon's treatise. These pumps are usually made with
metallic packing only, and are used iu Italy and France for
pumping wine aud olive oil ; they are also adapted for brewery
pumps.
The undeniable predilection in favor of rotary pumps on the
ratchet train principle is worthy of consideration. It is claimed
that they have a higher efficiency, but this remains to be established
; also the rotary motion gives a continuous uniform motion
to the wat r column, but this is equally accomplished by the
forms shown in Figs. 982 and 9S9. This uuiform flow can only be
approximately attained, as must be the case from tbe nature of
the mechanism. The principle is that of a ratchet train whicli
is intermittent iu principle, and hence differs from a continuous
running movement. The idea that such pumps give a continuous
and uniform discharge is due to the fact that the column of
water is operated directly from the part which is driven continuously,
but this by no means follows. This combination of
a continuous running motion, with au intermittent ratchet
action whicli is uot apparent to the eye, will be showu in other
cases hereafter.
? 3 21 -
ESCAPEMENTS FOR PRESSURE ORGANS.
Ratchet trains found with pressure organs also include
escapements as completely as is tbe case with the preceding
forms of rigid ratchet mechanism. The ratchet of 'i 25S, showu
again iu Fig. 990 may be considered as au escapement if we
assume the checking of a by b to be uniformly opened and
closed.
If now, iu Fig. 991, the checked member fi is made a pressure
organ, such as water, iu communication at H with a pressure
reservoir, or with a negative reservoir at /", or both, the
Fig. ifr3c)c is Beale's gas exhauster, made with a so-called
regular lifting and closing of the valve b produces au escape-
"sliding crank " e, which acts at the same time as crank and
piston. Without the use of special valves, the spaces // and
///interchange with /and /''by the revolution of tl. Beale's
exhauster is in successful and extensive operatiou in various
gas works.
In the examples cited and in the numerous modifications of
them, it will be noticed that the checking or ratchet action of
the liquid is invariably performed bv slide valves.
()ne of the objections to the use of slide valves for ordinary
water pumps is the wear upon the surfaces due to impurities
in the water. When the water is free from such objectionable
impurities, it is to be considered whether slide valves might not
be much more generally employed than has hitherto been the
case. If this form of valve were given the benefit of practical
FIG. 990
study and experience, it ought to be possible to avoid the
shocks due to concussion existing in pumps made with lift
valves when operated at high speeds.i
ment acting in a similar manner to Fig. 990. By means of
A great number of valve forms have been designed, j) using such a device the pressure organ a can be constrained in per­
combinations of single valves on the principle of the multiple forming mechanical work. The range of such au escapemeut
ratchet (see '>, 242), the action of the valves being assisted bv is not determined by the teeth of a wheel, but ou the contrary,
weights, springs, etc., but these have not completely attained is similar to a friction ratchet, and can be varied at will.
the desired end. ||
The applications of escapemeuts with fluids are in principle
the same as those formed of rigid bodies, but in practice their
* See Zeitschrift Deutscher Ingenieure, tS35, p. 929; also Herrmann's
nature is very different. We have already distinguished between
Weisbach's Mechanics, Vol. Ill . Part 2, p. 1089.
watch escapements aud power escapements, aud iu the present
t See the author's "Theoretical Mechanics," in which over 90 chamber instance the power escapemeuts are by far the most important.
crank trains are described and analyzed.
For this reason the latter will be considered first. Unperiodical
X Poillon refers t

December, 1S92.] ENGINEERING MECHANICS. 307
of volume. To these we mav add the adjustable escapements
on the principle of those described iu \ 259, and we have the
following classification :
a. Unperiodical Power escapements.
b. Periodical Power escapemeuts.
c. Adjustable Power escapements.
d. Escapements.for measurements of volume.
A. UNPERIODIC POWER ESCAPEMENTS FOR PRESSURE
ORGANS.
2 322.
FLUID ESCAPEMENTS FOR TRANSPORTATION.
One of the simplest practical applications of the principle of
Fig. 991 is Felbiuger's Postal Tube, shown in diagram in Fig.
992. The line tube d is connected with a reservoir of compressed
FIG. 992.
T
reversal of 180°. This may be accomplished either by the use
of tension organs or pressure organs.
Fig 994 shows a double canal lift constructed by Green for
air at H, and at T with a similar negative reservoir. At b is a
the Grand Western Canal in England in 1840, the connecting
sliding pawl, here shown opeu ; the piston, or carrier c, in the
mechanism being tension organs in the form of chains. The
form of a leather box containing letters, telegrams, etc., being
boats are carried in tanks e, e,, the ends of which are closed by
driven through the tube. A valve b' enables the end of the
valves or gates

308 ENGINEERING MECHANICS. [December, 1892.
pulleys, and the plunger operates the valve automatically by
means of the rod />', when the highest
position is attained. This form of lift has
been much used, sometimes of very large
dimensions. The great passenger elevator
of the Hamilton St. Station ofthe Mersey
Tunnel has a plunger l8 // in diameter,
with a lift of 87'/,' feet, the car holding 50
passengers.*
A practical objection to direct-acting
lifts of this form lies in the heavy counterweights
required, and also in the depth to
which the cylinder must be sunk. A
different form has therefore been designed
in which a piston travel of moderate length
is multiplied by use of a tension organ
system, such devices being extensively
used for passenger elevators, notably by
the Otis Elevator Company.
Hydraulic cranes are also forms of high
pressure escapements, first designed by
Armstrong, and since used by many others,
especially in connection with Bessemer
Steel plant, in which hydraulic cranes
have proved most valuable.
F'g- 997 shows the mechanism of a
hydraulic crane by Armstrong. The piston
is double acting, and there are four valves
^n ^s. ^.1. bt, ofthe type shown in Fig. 9S6,
the external connections also being neces
FIG. 996.
sary in order to complete the escapement.
The high pressure water enters at H, and
FIG 99S. FIG. 999.
The preceding apparatus resembles the hydraulic press. It is
in fact quite different, being a genuine ratchet train, capable of all
the modifications of such mechanisms as to speed, distance, and
arrangement. Ou account of these points the applications of pressure
organ escapemeuts are becoming rapidly more important.
5 324passes
through the pipe /, and is discharged to the atmosphere
PRESSURE ESCAPEMENTS FOR MOVING LIQUIDS.
at /('. The rod ... is made of half the area of the piston e The use of unperiodic pressure escapements for moving
liquids in machine construction has
been practiced from an early period,
and at the present time improved devices
for this purpose are much used.
An almost forgotten device of this
kind is Brindley's boiler feeding apparatus.
Fig. 1000, this being based
upon the principles already given in
Fig. 991.
The necessary opening of the valve b
is made by the float c, and the closing
by the counterweight e, (compare Fig.
950). This apparatus was first applied
to Watt's boilers, the feeding of the
boilers of Newcomen's engines being
FIO. 997.
effected by a cock operated by the
attendant.
(compare Fig. 946 c). When b, and b3 are open, as in the illus­ Fig. 1001 is Kirchweger's steam trap
tration, the forward stroke is made with one-half the full force ; for the removal of water of condensa­
when fi, and b, are open, the forward stroke is made with full tion. The escape valve b is opened by
force. By opening 6., and /*>,, the return stroke is made bv the the float c, which, in this instance, is
pull of the load upon the chain. At b' is a safety valve which open at the top, so that the water flows
comes into action should the load descend too rapidly, by the over the rim until it sinks, and thus
opening of b3 alone.*
opens the valve, This valve motion is
—k
\ 323-
HYDRAULIC TOOLS.
in itself a ratchet train, checked and
released by the action of the float.
When the valve is opened the water iu
Hydraulic escapements, similar to those used for lifting loads the float is forced out by the pressure of
are also applicable to machine tools. Among these may be
the steam, ji
noted the devices of Tweddell, for riveting, punching, bending,
The slow moving float device, as in
etc. (see \ 54).
Fig. iooo, has also beeu advantageously
FIG. iooo.
Figs. 99S and 999 show the arrangement of Tweddell's rivet­
used for operating steam traps, by
ing machine ; ct is the piston, 0,, b., the valves, one of which
Tulpin, of Rouen ; Handrick, of
connects with the pressure reservoir at H, and the other with
Buckau ; Piischel, of Dresden:
the atmosphere at sl. When b, is opened by the lever e, the
Dehne, of Halle, and others.
hydraulic pressure enters above the piston d, and the stroke is
Similar escapements have been
made. The return stroke is effected by means of the auxiliary
designed to separate air from
piston ./,. which is fast to d, ami under which the water pres­
steam, or air from water, as in
sure is acting at all times. Closing o,, anil opening b2, enables
the devices of Andral, Kuhl-
this to act and lift the main piston. This gives practically a
mann, Klein and others. ||
hydraulic lever of unequal arms, the shorter arm always being
Otner examples of escape­
loaded with //, and the load on the longer arm varying between
ments of this kind are found iu
H and A. The lever mechanism tl', d", d'", controls the
the so-called Montejus, used for
length of stroke of the die, by means of the tappets d" and
elevating syrup iu sugar refiner­
d'", which are connected with the lever e. This is also used
ies, in the return traps of steam
on the lift of Fig. 996, and shows the complete escapement.
heating systems, and in various
The arrangement of valves is shown in detail in Fig. 9994
other forms of boiler feeders,
FIG. IOOI.
such as those of Cohnfeld, Rit­
* See Robinson.
ter & Mayhew, and others, *fl
t See Weisbach-Hcrrman, III., 2, p. 240 ; Colyer, p. 11 ; Robinson, p, 52. 'i This form of trap is made in many varieties, the one shown beiug by
\ For fuller descriptions oi Tweddell's machine see: Proc. Inst C. E. Losenhausen. of Dusseldorf. A similar one by MacDougal is much used in
LXXIIL, 1S83, p. 64 ; Engineer, July, .885. p. 88; August, p. 111 ; Revue Indus­ England, and a feed pump on this principle is made by Korting in Hanover •
trielle, 1S84, p. 5; 1885, p. 493; Mechanics, 1885, p. 272; also Robinson, as German Patent No. 36, 332.
above, and Zeitschr. Deutscher Ing., 1886, p. 4^2.
I For illustrations of these devices see Scholl's Fiihrer des Maschinisten
10 Edit., p. 493. *j See Scholl, p. 235.

December, 1892.] ENGINEERING MECHANICS 3°9
B PERIODICAL PRESSURE ESCAPEMENTS.
in communication with the discharge, and since b2 is larger than
I 325-
/',, the pressure between them moves them iuto the position
PUMPING MACHINERY.
bf bf. This puts the main cylinder in communication with the
Periodical fluid escapement trains have a wider application discharge, and the piston sinks by the weight of the load upon
thau unperiodical trains, since it is practicable, as already shown, it. At the close of the stroke the tappet 6 moves the arm cf
to use a fluid ratchet train to operate the valves in a simple into the position cx again, and places the auxiliary valve in the
manner. This makes it possible to produce the opening and first position and a new stroke is made. |
closing of the valves in a periodical succession mechanically, This machine constitutes an escapement of the second order,
instead of by the fluid column. In this construction the fluid since the small and large escapements alternately release each
column may therefore drive the piston, instead of being driven other ; the lever device 5-6—r, forms a third mechanism, so that
by it. This idea seems very simple, and yet pumps had beeu the machine, as a whole, is of the third order
known for two thousand years, and had occupied the inventive
energy of the preceding centuries before the simplest forms of
the modern steam engine were devised. It is therefore all the
more important in the study of machine design to investigate
the fundamental principles involved.
It is impossible, in the limited space wdiich can here be given,
to go into this subject in its entirety , the-arrangement of the
valve gear ofthe Newcomen engine with tumbling bob gear, is
an instructive example.
In Fig. 1002 is shown Belidor's single acting water pressure
engine.*
In the cylinder it is a piston ; a, is the entrance of the water,
FIG. 1004.
a, the discharge outlet. The valves bl aud l'2 are united in a
Fig. 1004 shows the double acting water pressure engine of Roux A/
three-way cock (see Fig. 987). This valve is operated from the
The double action is obtained by combining the four valves in one,
piston rod c by a tumbling-bob gear (see Fig. 742). The tum­
and by communicating the admission aud discharge alternately
bling lever E el e.,, weighted at E, is connected with the piston
with both sides ofthe piston In this case the lever connection
rod at Cj, and moves about its axis independently of the lever fi.
cy is replaced by an escapement. The small pistons bf bf are
When the end of the piston stroke is nearly reached, the lever
acted on at the outer ends by the pressure water through the
E passes the middle point, and tips over, when the arm/, strikes
small passages kf, k.fi This gives an escapement of the third
the lever/* and carries it to the position fi', moving the lever of
order. The cup-shaped ends c2, e3, of the main piston c form
the three-way cock from b to b'. The arm t\ is behind E. The
the pump plungers. This machine should operate satisfactorily.
return stroke of the piston moves the arm e, of the tumbling
It is readily apparent that the piston steam engine may also
gear towards the right, and as the end of the stroke is reached,
be considered as au escapement. The valve gears differ from
the tumbling bob is again tripped, and the three-way cock
the preceding forms only on account of the conditious of ex­
moved again into the position b. A cord secured at the ends to the
pansion and condensation. These are reducible to a limited
points e3 and e,, and fastened to E, limits the travel of the latter.
number of simple cases.
The piston rod is connected directly to the pump to be operated, t
It will be observed that this machine is a ratchet train of the
second order, the piston and valve forming au escapement, and
the valve gear a releasing ratchet train each operating the other
Fig. 1003 is the single
acting water pressure engine
of Reichenbach. Iustead
of using a tumbling
bob gear to operate the
valve, Reichenbach uses
a second water escapement,
operating the valve
by a piston, the valve
being itself a piston valve
The double piston valve
b3 b, of the second escapement
is operated by the
main piston rod, the tappets
5 and 6 striking the
lever c, as each end of the
stroke is reached. The
water under pressure enters
at a{ and is discharged
at a,. The tappet 5 moves
the auxiliary valve into
FIG. 1003.
the position bf bf, wliich
places the space above b,
*• Belidor, Architecture hydraulique, Paris. 1739, Vol. II., p. 238.
t The above described machine, designed by Belidor in 1737, for the water
works at the bridge of Notre Dame, does not appear to be altogether practi
cable. It has been here given on account of the valve motion, which is historically
interesting and doubtless good, and has been reinvented several
times since. It was not new in 1737, having been m Newcomen's steam
engine, as was already known to Belidor, since it is described by him in the
same volume of his treatise.
FIG. 1005.
Fig. 1005 is a single acting high pressure engine. The steam
% See Weisbach-Herrmau, CI, 2, p. 53b; also Ruhltuaun, allgeru. Mas
uien Chre., I , p. 348.
i; See Revue Industrielle, 1S84, p, 114. Built by Crozet et Cie.

ENGINEERING MECHANICS. [December, 1892.
enters at at, and the discharge to the atmosphere is at a.,. The the main piston to the left, as indicated by the arrow. Just
opening of the valve o, permits the steam to enter, forcing the
pistou c down, and raising the weight G. The valves , and b2
are operated by a ratchet train released by the tappets 5 aud 6
on a rod moved by the main piston. The pawds are double
acting, and are of the form shown in Fig. 671. When e reaches
the bottom of the cylinder the tappet 5 releases the ratchet 7,
before the end of the stroke is reached the seat b0 is moved as
much to the left of the centre as it now stands to the right. In
and closes the valve fi, by means of the connections /, ey The
release of 7 opens the valve b., by means of the connections e.f.,,
aud permits the escape of the steam from below the piston.
This equalizes the pressure above and below the piston, from
which the valve b., is called the equalizing valve. The upward
stroke of the piston causes the tappet 6 to reverse the ratchet 7
and operate the levers f,/",, closing the equalizing valve aud its
connections.
The device differs from the preceding in that the principal
escapement a b, b2 c d changes iu character with the stroke.
The two ratchet trains can be seen iu principle in the double
l : ... ' _S ____^^^
acting tumbling gear of Fig. 1002. The mechanism, when lifting
the valve, is of the third order, and when closing, of the
FIG. 1007.
second order. The gear as shown is Farey's ; Fig. 779 shows
this principle in a rigid escapement train, the corresponding
the seat 60, as shown in the figure to the right, there are additional
valves formed, P2, /?„ /34, which act to operate the auxil­
form in siugle-acting train is the chronometer escapement, Fig. iary pistons b2, bs, under which latter the small steam passages
769.
cau be partly seen. When b0 is moved to the left, a small post
If the engine is a condensing one, a condenser valve b3 is is uncovered by f32, and live steam enters the cyliuder L behind
added, this being opened by the closing of b.2, as is also a jet b2, while at the same time fi4 connects R with the exhaust. This
valve in the condenser. When the steam is to be expanded, the causes b.2, b, b3, to move to the right and reverses the pump.
lever c, is so arranged, the closing of b, is produced earlier (see The reverse action takes place at the other end of the stroke,
the smaller diagram) by the positiou of the tappet 5, and the
corresponding counterweight lifted. This only operates the
ratchet 7, and /, is released by a second train 8, which is
effected by the tappet rod or by the so called cataract A,
released by a tappet 9, see ji 260.
The condenser is a negative reservoir, and was the principal in­
the whole forming a combination of the third order.
vention of Watt. It involves the use of two fluid ratchet trains ;
the air pump, and the cold water pump, and also usually includes
a boiler feed pump.
collection of ratchet trains.
The entire engine is composed of a
Steam pumping engines are by no means always made with
lift valves, and a great number of more receut designs are made
with slide valves \see Fig. 987). Rittenger has applied slide
valves successfully to single-acting engines, and they are especially
applicable to double-acting non-rotative engines. In the
last decade especially have valve motion for steam pumps with
slide valves been multiplied, and some illustrations are here
given.
Fig. 1006 is Tangye's direct-acting steam pump. The steani
FIG. 1008.
FIG. 1006.
entrance is at /, and the exhaust at //'. The slide valve b is
the so-called E form, combining the four valves of Fig. 986 m
one; b2 and b3 are the auxiliary pistons lo move the valve, and
form part of an escapement of which the valves b" and b'" are
operated by the main piston c at each end of its stroke. The
latter valves communicate with the cyliuder posts // and ///.
Wheu b'" is lifted by the piston, the space R is in communication
with the exhaust, aud the pressure in / throws the valve
over, equilibrium being soou after established through the aperture
k.2. The reverse action occurs on the return stroke. This
is a steam escapement ofthe second order, with au independent
starting lever, the whole forming a combination of the third
order. This has been much used by Tangye for steani pumps.
Fig. 1007 shows the valve motion of the Blake pump, which
is very extensively used in the United States. In this case there
is a movable seat b0 under the valve b, the opening through the
seat always beiug in communication with the posts //, ///, IV,
although ba is moved a short distance at each end of the stroke
by tappets ou the piston rod. Iu the position of the parts
shown the steam entering at /will pass through ///and move
Fig. 1008 shows the valve gear of Deane's steam pump, which has
also been extensively used. The main valve is moved by means
of auxiliary pistons, as in the preceding instance. The auxiliary
pistons are controlled by a separate valve b', which itself
is operated by lever connections with the main piston rod.
This combination b', b 2 , b, forms again a mechanism of the third
order.*
If the last three devices described are compared with the
Reichenbach water-pressure engine, it will be seen that the
fundamental principle is the same in all. The coustructive
arrangements which may be adopted are clearly shown in the
preceding examples, which may be modified in a variety of
ways. Among other widely used arrangements, that of Knowles
may also be mentioned ; in it the action ofthe auxiliary pistons
is controlled by a slight twisting motion given to the valve stem.
FIG. 1009.
Fig. 1009 shows Pickering's steam pump.f Iu this design the
main piston c acts also as the valve for the auxiliary pistons
fi,, b3, so that the spaces R and L are placed alternately in com-
* See Am. Machinist, Feb. 17, 1883, p. 4. For an excellent steam pump by
Dow, see Mining and Scientific Press, 1885, March, p. 169, and May, p. 313.
f See Poillon.

December, 1892.J ENGINEERING MECHANICS. 3 11
munication with / and IV The whole forms a steam escapement
of the second order.
Fig. 1010 shows Harlow's valve gear, also used for pumping
machinery.* This is also a steam escapement of the second
order, similar to the preceding. The valve action for the
auxiliary pistous is formed in a prolongation of the piston rod,
the grooves c, aud e, placing the spaces R and L alternately in
communication with //'.
FIG. IOIO.
59 *
By comparing the precediug designs with the water pressure
engine of Roux, Fig. 1004, the similarity will be apparent. All
the examples given show the fuudameutal relation existing between
these devices and the mechanical escapemeuts of watch
movements. The escape wheel is replaced by the fluid column ;
the anchor, by the valve ; the vibrating member, whether pendulum
or balance wheel has here not a free movement but a
determinate one against an external resistance. Similar
arrangements include steam hammers, also hammers and rock
drills, usually driven by compressed air, these latter consisting
of mechanism of the second, rather than the third order. An
example will serve to illustrate the general arrangement of such
devices.
FIG. IOII.
Fig. ion shows the arraugement of Githeu's rock drill.f
The curved valve b, is operated by the actiou of the curved
outline formed in the piston c. The middle position of the
valve is a dead point, but this is overcome by the momentum
of the heavy piston.
* See Engineering and Mining Journal, Oct., 1884, p. 23
tSeeEng. and Mining Journal. March, 1887, p. 107. Also Halsey s rock
drill, Trans. A. S. M. E-, 1884-5, p. 71.
The devices ofthe third order are capable of a very important
modification whicli can be considered by examining for instance
the Deane gear, Fig. 1008, or either of the two preceding
it. An inspection will show that it is entirely practicable to
use the auxiliary piston to operate a pump cylinder, as independently
of that operated by tlie main piston d. It is only necessary
to make it larger in diameter and of proper length of
stroke ; and there is nothing to prevent making it of the same
diameter and stroke as the main piston.
The valve of each cylinder will then be operated by lever
mechanism connected to the rod of the other piston. This
arrangement involves the replacing of the E valve by the common
D valve, which is not important, but is nevertheless an
advantage. The two escapements are conveniently placed side
by side for constructive reasons, and the double arrangement is
known as a "duplex " machine, this term being given to two
combined cylinders, of which the valve of each is operated by
the pistou movement ofthe other. This type is now frequently
met, having been made for small apparatus very early, in
France by Mazelline and yet earlier, in 1859, i' 1 t,le United
States by Worthington.
FIG. 1012.
Fig. 1012 shows a duplex pump by Mazelline.1: The illustration
shows oue piston .,, at mid-stroke with its valve b,, at the
end of its travel, and connected to the rod ofthe other cylinder
by the lever e.,.
The work is divided into two portions which is provided for
by the doubling of the parts. If the two piston escapements
(cylinders, pistons, valves, steam, etc.) are indicated by [1] and
[3], and the valve movements by [2] and [4] the action will be
as shown in the following lines,
whence we have
['] [2] [3]
and [3] 14] [1].
both being of the second order.
FIG. 1013.
Fig- IOI 3 shows a perspective view of Worthington's Duplex
Pump, the arrangement of which is apparent from inspection.
The duplex steam cylinders are at the right, and the double
acting pump cylinders on the left.
The advantages obtained by using this form of pumping
machine practically outweigh the objections which might be
made against the duplication of parts. In double acting pumps
ofthe forms shown in Figs. 1006 to 1010, the motion of the
water columns is interrupted, at low speeds, at each reversal of
t See Poillon, Plate IX.

312 ENGINEERING MECHANICS. [December, 1892.
the piston, while with the duplex pump the discharge is practically
continuous, because each cylinder begins its stroke just
before the other comes to rest.
An objection to all the other forms of direct acting pumps
already described lies in the fact that to obtain uniform pumping
action it is necessary to carry the initial steam pressure for
the entire stroke of the piston, or in other words, the best action
ofthe water end is obtained by means of the least economical
action of the steam cylinders.
This defect was overcome in the earlier pumping engines,
such as the Cornish mine engines, by using the steam to lift
heavy weights, pump rods, etc., the living force of the mass
permitting an early cut-off and high expansion, and the uniform
desceut of the weight being used to force the water. By
this method the Cornish engines attained a high degree of
economy. This method being single acting, caused the entire
column of water to come to rest during the time required for
the up stroke of the pump rod, and hence the Cornish type of
pumping engine gives a most economical action of the steam at
the expense of a defective action of the pumps.
In the larger sizes of Worthington pumping engines the expansion
of the steam has been for a long time effected by using
compound cylinders, and excellent results attained in steam
economy. The efficiency, however, was by no means so high
as was desired. In 1886 the so-called Worthington equalizer
was introduced with a view of enabling the desired high duty
to be attained.
FIG. 1014.
This device, shown in Fig. 1014, is a ratchet train of the tumbling
type, similar to that shown in Fig. 743, the springs being
replaced by water pressure from a high pressure air cham­
ber* The air chamber forms a periodical storage reservoir.
The plungers/, / are attached to a cross-head connected to
the prolonged piston rod, and the cylinders are carried on
trunnions 7, 7. During the first half of the stroke the plungers
are forced into the cylinders the latter swinging about the centres
7, 7 ; and during the second half they are forced out by the
action of the stored euergy.f
The resistance and assistance which the pistons/give to the
steam piston is shown by a curve of the form of Fig. 1014 b, as
has also been obtained by the indicator.
P
FIG. 1015.
If in Fig. 1015 a, we make P equal the component ou each
portion of the pressure Q ou the main piston rod, we have :
Q 2 /'sin /3 = yjftary,
in which
This
0
tan ,i = -
P
{'AT?
*Au equalizer ot this type was patented iii Germany, by the Berlin
Anhalt Works in 1885.
fin kinematic notation this action is expressed by (CP+CP-J-) as shown
bv b See Theoretical Kinematic*, pp 522, -*•;*'-;,
or if we make 0 the ordinatey, of the desired curve
2 Px
vV-f b*
and substituting c for 2 Px
we have
y x
c s/f^TlA
(3'7)
which equation is readily expressed graphically.
If this curve is drawn upon the rectangle which represents
the resistance of the water, as in Fig. 1015 0, we get the actual
resistance curve fig h, and this resembles closely the expansion
line for a high degree of expansion, or in other words, the impelling
force and the resistance are practically made equal to
each other throughout the stroke. The dotted curve abede,
is that of an actual indicator diagram.j This shows that with
the Worthington high duty pumping engine the most efficient
action of the steam is obtained at the same time as the best
action of the water end.ji
FIG. 1016.
Fig. 1016 shows a longitudinal section of a Worthington high
duty pumping engine. The equalizing cylinders and their air
chamber are seeu on the right; the dotted lines e., show the rod
of the second cylinder, which operates the valve l\.
As it has already been seen that rnanv forms of the third order
can be reduced to the second order, it may be inquired as to
the possibility of obtaining a pumping mechanism of the first
order. This has already been accomplished by uniting the
steam escapement with a water ratchet train. The device is the
Hall Pulsometer, shown in diagram iu Fig. 1017.
The steam enters at a, at b, is the anchor shaped pawd, and d,
is the vessel corresponding to the framework
of a rigid escapement, (compare
Fig. 775)- If the vessel d is closed as
shown by the dotted lines and a volume
of water e, iucluded, we obtain an action
ofthe first order. The efficiency is very
low ; about % to *, that of a pistcu
pump, but the simplicity and convenience
is so great that this may often be
neglected.
Another escapement of the first order
is Montgolfier's hydraulic ram, which is
a water checking-ratchet train, the efficiency
of which is low. A more recent
device is the application of a water
ratchet train to drive a pneumatic ratchet
train, first used on a large scale by
Sommeillier in the construction of the
Mont. Cenis tunnel, and by means of
whicli the efficiency was brought up
nearly to 50 per cent.|| Pearsall has recently
improved the hydraulic ram and
raised its efficiency to nearly So per
FIG. 1017.
cent., either for water or for air, but this
X See Mair, Experiments on a direct-acting steani pump. Proc lust C E
London, 1886. • Je-The
Worthington equalizer accomplishes an end sought by designers of
steam pumps for the past 200 years, for since Papin's first machines in Cas
sel (1690) the desired aim has been to combine the action of a variable elastic
driving medium, and a uniform, non-elastic resistance.
I, See the author's paper, Ueber die Durchbohrung des Mont-Cenis
Schweiz. polyt. Zeitschr, 1857, p. 147.

December, 1892.] ENGINEERING MECHANICS. 313
has been done by the introduction of a valve gear, making it a
device of the second order.*
\ 327.
I 326.
ROTATIVE PRESSURE ENGINES.
FLUID TRANSMISSION* AT LONG DISTANCE.
AH effective method of obtaining an advantageous action of
the steam is to substitute for the reciprocating mass of the
When the motive power is intended to operate the piston
Cornish
of
engine a rotating mass. This is accomplished by
using the reciprocating motion of the piston to operate a crank
a pump situated at a distauce, some connecting mechanism
shaft upon which a fly-wheel is placed. Since it is practicable
must be interposed betweeu the two cylinders. Formerly this to give the rim of the fly-wheel four to six times the velocity of
was accomplished by using long rod "connections ; instead of the crank pin, the magnitude of the moving mass can be much
this a pressure organ transmission may be employed. When smaller, aud since the value varies as the square of the mean
water is used as the medium for transmission, this may be velocity, the mass is reduced at least 16 times. It is therefore
termed a " water rod " connection. This is used in connection possible by this means to give even small pumps an efficiency
with water levers (see j) 311 I.
equal to that of large pumping engines, j
It is not practicable to construct single-acting pumping
engines iuto fly-wdieels, because the piston speed v is too variable.
If we draw a curve representing v, the ordinates being
the positions of the piston, we have for a connecting rod of
infinite length a circular curve, as in Fig. 1021 a. When the
FIG
Fig. 1018 shows three devices for this purpose. At a is shown
a closed system with pistons of equal diameter ; b is a similar
one with unequal pistons; aud c is a form with combined
pistons. Such water-rod connections are adapted for use in
mines, and the following example will illustrate.
FIG. 1019.
The arrangement of transmission in the Sulzbach-Altenwald
is shown in Fig. 1019, which represents the engine above ground,
while Fig. 1020 shows the mechanism in the mine.
F\s--—4.
4«f, *>». -4~r~-
AsJO. ---V 1 -
::y:..
V ;
'•A '*,
l\ •
FIG. 1021.
\fm \
~VAy
V \
i i
i i
AA
W4 _
length of the rod is taken into account these curves are mo
fied, as shown in Fig. 10210, which is drawn for a rod four
times the length of the crank. This curve also shows the ratio
of the tangential force on the crank pin to the pressure on the
piston, ji
The variations in the value of V, which ofteu differ widely
from the mean value Vm, must necessarily be communicated to
the mass of water, and hence great variations occur in the
stresses. For this reason the Velocity of the column of water
must be kept within moderate limits, notwithstanding the use
of air vessels. These variations become much less serious
when two pumps are connected by cranks set at right angles
with each other. The corresponding velocity curve is shown in
Fig. 1021 c, and many pumping engines are now so made. More
recently triple cylinder engines are made with cranks 120°
apart. The velocity curves in this case are shown at d. It is
evident that both these forms involve complications in construction
which compare unfavorably with the direct-acting
pump with equalizing cylinders (see ji 325).
Instead of using a revolving fly-wheel, the mass of metal may
be arranged to swing in an arc of a circle of large radius. An
ingenious application of this principle has been made by Kley,
in his water works engine with auxiliary crank motion. The
proportion between the steam pressure and the vibrating mass
is so arranged that the auxiliary crank conies to rest either a
little before, or a little beyond the dead point, so that the return
stroke in each case can be effected by the action of a
cataract. In the first case, the fly-wheel swings backward after
| The Gaskill pumping engine i* a duplex pump with fly-wheel, aud
cranks at right angles, and has given excellent results. See Porter's " Re­
di f d,
FIG. 1020.
port of the Gaskill Pumping Eugine at Saratoga."
i Referring to the designations in Fig. 1022, we have
cos Since I'd-. =
sm to + tan
The arrangement is of the same form as Fig. 1018 b The /" rtic and Pv= P
steam piston c operates the two plungers », b.t, which in turn
operate the plungers c, ef, and c2 cf in the mine, the pump
plungers ex e, being placed in the middle.f
*See Engineering, Vol. XLL, 1886, p. 47, also H. D. Pearsall, Principle of
the hydraulic ram applied to large machinery. London, 1886.
t See Zeitschrift fur Berg, Hutten und Salinenwesen, XXII. p. 179 ; XXIIL,
p. 6; XXIV., p. 35. The depth is 820 feet, the speed from 6 to 16 double
strokes per minute, with a pause of one second, giving about 420 feet piston
speed per minute. This engine, built by the Bayenthal Machine Works at
Cologne in 1858, has operated regularly for 29 years without any interruption
worth mentioning.
1 c,
• P •
the ratio — is also
equal to the same expression.
Hence the
curves above given
also show the ratio of
the force in the path
oi the crank-piu to
the pressure on the
piston.
In Fig. 1022 a and b. P aud c are represented by 1 . :
in Fig. d, bv 2' . 1 ; in c and d, the ratio of connecting rod to crank is again
taken as infinitely great. The curves are adapted lor double-acting pumps.
When two single-acting pumps connected to right-angled cranks are used.
Ibe second half of the curves of Fig. b become the same form as the first
• " \

314 ENGINEERING MECHANICS. [December, 1892.
the pause, and in the second case, forward.-" The valve motion
of this form of engine is considered in the following section.
2 328.
VALVE GEARS FOR ROTATING ENGINES.
Rotative engines are distinguished from pure reciprocatiug
pressure organ escapements in that they deliver their effort in
the form of rotary motion adapted to be used for driving running
machinery. Between the two forms there is also the
intermediate kind, with merely auxiliary rotative mechanism,
such as have been already referred to. The translation of
reciprocating and rotary motion may be accomplished in a
variety of ways, but by far the most useful and best known is
that by which the rectilinear motion of a piston is transmitted
to the shaft by crank connection.
The variations in the tangential component of the pressure
P' on the crank pin, Fig. 1021, becomes still greater when the
pressure P, on the piston also varies by reason of the expansion
of the steam. For this reason some form of equalizer is
required in the form of a fly wheel. This latter becomes a
reservoir for the storage of living force. Extreme examples of
this action are found in rolling mill work in which within a
brief time a 1000 H. P. engine may be called upon to deliver
2000 H. P., a demonstration of action of the fly wheel as a
reservoir of power.
The valve gearing for rotative engines is an important and
extensive subject. In the preceding sections a series of valve
gears have already been described, These have all been based
upon the principle of operating the valves by a direct reciprocating
motion, taken either from the piston or piston rod.
With rotative engines another method is used, the motion being
taken from the revolving portion of the machine, and this
method may also be adopted for pumps with auxiliary crank
action. We may then distinguish between :
Reciprocating valve gears, aud
Rotative valve gears.
Rotative valve gears are desirable even for direct acting
pumps, but in a still greater degree are they desirable for rotative
engines. Watt's rotative engine was made wdth a reciprocating
valve gear.f aud this form has one advantage in that it
is adapted for rotation in either direction.
Hornblower, the inventor of the compound engine, also used
a reciprocating valve gear. The slide valve, invented by Murdock,
in 1799, led the way to the introduction of the rotative
valve gear in 1800, but the old reciprocating gear still contiuued
to be used, and is even re-invented at the present time. The
later direct acting steani pumps with auxiliary rotative mechanism
are almost always made with rotative valve gear. Kley's
pumping engine, referred to in the preceding section, is made
with reciprocating valve gear, since its motion is both before
and behind the dead points of the crank.
The use of the slide valve, combining four valves iu one member,
enables a very simple valve gear to be made for the ordinary
double acting escapement, as the diagram of a plain slide valve
engine, Fig. 1023, clearly shows.
Fig. 1023.
The use of an ecceutric r, and rod /, to operate the valve b,
is not the earliest form of gear, the first method being the use
of au irregularly shaped cam which brought the valve to rest
except at the time of opening or closing.} A feature of the
slide valve which was long overlooked was the fact that the
time of closing the steam ports //and /// could be regulated
so as to effect the proper expansion of the steam. In order to
accomplish this result without impeding the exhaust of the
steam, the eccentric r, must be given the so-called angle of
advance 2 0 1 . 2' beyond the mid-position. The direction of rota-
* For a fuller account of this interesting engine (German Patent No. 2345),
of which more than fifty are in operation, see: Berg-u. Huttenm. Zeitung
Gliickauf, 1877. No. 18, 1879, No. 98 ; Mouiteur des int. materiels, 1877, No. 20;
Compt. rend, de St. Etienne, 1S77, June ; Berggeist, 1879, No. 85; Z. D. Ingeniure,
1879, p. 304, ISSI, p. 479, 18S3, p. 579. Dingler's journal 1881, p. 1, 1882,
tion of the crank is then governed by this angle, the arrangement
above giving rotation to the left, and the position 1 2"
for rx, giving right-hand rotation.
The actiou of the slide valve may readily be represented
graphically.? The angle of advance and lap being given the
point of cut-off can be determined by the following method.
FIG. 1024.
Fig. 1024. The circle 1 Ca represents the circle of the eccentric
aud may also be taken as the crank circle on a reduced
scale. C" and C" are two symmetrically placed positions of
the piston at which it is desired that the cut-off shall take place.
Through these points with a radius 1.3 = / describe arcs from
centres 3" and 3'" ; their intersections E., and E3 with the circle
give the angles at which the expansion C0 C" and C C"
occurs, in this instance ,'0 of the stroke. We now select the
point ?'., ofthe crank circle at which the admission shall begin,
join V.t E2 and draw the equator 2.1.2' parallel to it, and the
angle 2 . 1 . C wull be the angle of advance S, and the distance
of 2 . 1 from E„ I'.,, the outside lap e2 for the port //. The
width of port a must also be chosen, and must be so taken that
it is less than i\ —• e2, aud is represented by the parallel A.,.
When the crank reaches /,, in this instance at , 9 „ R 0 ofthe stroke,
the exhaust begins, and tlie distance r, i, of the parallel A, I2
from the equator is the inside lap.
The construction is similar for the other half of the stroke.
The angle o* is already known, and hence the parallel E3 V3
from E.., cau be at once drawu, and the admission point V3 determined.
The outside lap e3 is somewhat less than e,, thus
giving a correspondingly wider port opening. The inside lap
i, is made equal to /'.,, and the bridges o, and b2 are made equal,
thus giving a symmetrical valve seat. A certain amount of discretion
is permissible in the selection of b., = b3; care being
taken that there is sufficient bearing at the extreme valve stroke
to insure tightness. The points // and // are also of importance,
as they determine the closing of the exhaust. The corresponding
piston positions Or aud Crare not symmetrical,
because / = •'._., but the inequality in the compression is not
serious.
The above method of considering the influence of the ratio
— is very simple. It is easy to substitute any desired ratio —,
r r,
but the variation is slight. It must be noted that the distance
1 . 3 must be laid out to the actual scale of construction.
1 The application of
Zeuner's diagram to
the same case is made
in the following manner,
Fig. 1025. The
circle 1 C0 represents,
as before, the eccentric
circle and the crank
pin path. The angle
c,. 1.2 = a. 1.2 =
90 — tt. With 1 as a
centre, describe circles
with radii e and •', here
made alike for both
ends of the valve, also
Fir 102=;
p. 349; Maschinenbauer 1881, p. 63 ; Oesterr. Ztg. f. Berg-u. Hiittenwesen 1882 ;
Kohleninteressent (Teplitz) 1882, No 34 ; Revista metalurgica (Madrid) 18S3,
No. 968.
t See Farey, Treatise on the Steam Engine, London, 1827, p. 524. Engines
with slide valves were only made by Boulton aud Watt, after James Watt
retired
X See
to
Farey,
private
p 677.
life.
one of radius e + a.
, .f' 5 ' Upon 1 . 2 and 1.2 as
diameters, describe circles, valve called ellipses the " were valve used circles. : since
rj-'H,! ( :se, To see be Zeuner, continued.) Schiebersteuerr
Englehardt, I Formerly first the so-called published ' in Civil Ingenieure, Vol. 2, 1856
1 .!*-^!"?^^ Schiebersteuerungen, Freiburg,

December, 1892.] ENGINEERING MECHANICS. 31
PROOEEDI2NTO-S
OF I'HE
AMERICAN SOCIETY OF MECHANICAL ENGINEERS,
New York Meeting, November 29th to December 2d, 1892.
N E W PROCESS OF CUTTING CAMS
Bv W. A. GABRIEL, ELGIN, III. (Member of the Society).
The writer of thi.4 paper is engaged in the work of designing small
and intricate machinery for the manufacture of parts of watches, and in
the course of his experience found it necessary to produce cams of
greater accuracy than could he obtained in old and well-known ways.
As a result of this the following method of laying and cutting such
cams was devised by the writer, and is made the subject of this paper.
The following is a description of the cam cutting machines and
manner of laying out the forms used therein. It is hoped that the dia
grams that form part of this paper will give the reader a clear idea of
the scheme.
To commence with, a chart of all the cam motions in a machine is
laid out, similar to a sample diagram shown at Fig. II, and a position
line is drawn across it. Prom this chart the forms for the cam-cutting
machines are made. Figs. 12 and 13 were laid out from the chart al
Fig. II. The position line is located on them in its proper place, so
that when the form is in the machine the line can be marked on tincams
after being cut. The use of this line makes it possible to place all
cams in a machine in their proper place at ..nee. The line is marked
on the cams from the form while in the machine, after the cam has been
cut. A pointer is put in place of the cutter, and another pointer in Ihe
place of the roll acted on by the form (Figs. 8 and 9). When the position
line marked on the form is brought around to the pointer at thai
place, the pointer in place of the cutter is made to mark a line on the
cam. When all the lines marked on the cams in a machine are in line
parallel with the cam shaft, they are ready to be secured to it. It will
be noticed by referring to the drawings of the machines that the levers
transmitting motion from the form to the cutter are multiplying. An.i
FIG. 10. Fio. II
01" workmanship in making the form will be reduced 111 the cam, ami
more perfect work produced.
In some cases the form is laid out on a board covered with paper, and
is then sawed out, taking care not to run over the line. It is then trued
up with a file, and is ready to use in the cam-cutting machine. But in
cases where great accuracy is necessary, the form is laid out on sheet
brass ibout jL inch in thickness, and as metal will keep it-, form unchanged
tor any length of time, a cam can be reproduced the same as
the original at any time
An instrument to facilitate the laying out of forms on metal is shown
by Figs. 16 and 17. It consists of an ordinary tubular beam compass,
vith strong points to scratch a plain line on the metal, and an attach
ment at the adjusting end that will enable it to be set to jfg-„ of an inch
of any required distance. The large sectional view, Fig. 17, shows the
construction ot the adjusting nut. A steel scale with inches tenths and
hundredths on it is used in connection with the compass. To operate
it the point on the sliding head is run out to nearly the distance required,
and the points are set in the divisions on the scale. A magnifying
glass is used to see that the points rest in the centre of the lines,
the adjusting nut being used to bring that about. The part of the nut
carrying the divisions can be turned independently of it. It is then set
to /.ero, and if the distance calls for several one-thousandths of an inch
more or less, it can be obtained by turning the nut to the right division.
The compass is then set ready to mark a line on the form.
The sheet metal on which the form is laid out is first pit-pared by
drilling a hole near its center, the size of the center pin in the spindle
in this case it is five to one, and the form, of course, must have a rise or on which the form turns in the machine. The hole is then tilled with
throw five times that of the cam being cut. This is done so that errors a small brass plug, having a line center point in it. This insures the

3i6 ENGINEERING MECHANICS. [December, 1892.
hole being in the right place when the form is finished. After the form
is outlined on the brass plate it is sawed out with a band saw fo. metal.
Fio. 10.
and is then placed upon a small table ami finished with a tile. A fixture
is attached to the table for holding the file perpendicular to the
edge of the form. It is then ready to be put in the cam-cutting machine.
I will now proceed to describe the machine that cuts a groove in the
side or face of a cam.
This machine is shown by Figs. 6 and 7, and consists of a strong bedplate,
on which are placed two upright spindles, to carry the cam to be
cut and the form. Over them, and pivoted at one end, is a strong lever,
so placed as to make a proportion of live to one between the cam and
form. .
At one end is a roll to act on the form. Over the cam spmdle is the
cutter spindle, with its driving gears. Adjustment is provided up and
down. The cutter spindle is driven through bevel gearing by a counter
shaft and universal couplings. This allows for all necessary movements
of lever and cutter.
Both cam and form spindles are turned by worm gears with the same
number of teeth in each, and are turned in the same direction by worms
which are made tapering, so that side shake can be taken up.
The worm shaft can be turned either by hand or power, as is clearly
shown by the drawings. The form for this machine must be just the
shape of the space inclosed by the groove in the cam, and must be five
times actual size. This is necessary on account of the roll and cutter
being mounted on the lever. The roll should be just tive times the size
of the finishing cutter. A small slide in the end of the lever, marked
(a) on plan Fig. 7, provides adjustment so that the sides of the groove
can be finished with a tine chip, or trimmed up after being worn so badly
as to require it.
The lever carrying the cutter and roll is held up to the form by a
weight suspended at the end of a cord, which passes over a pulley
swiveling at the top of a column, and attached to lever, as shown on
plan Fig. 7. It can be seen that the machine just described is quite
simple and will do excellent work.
The machine for cutting a groove in a cylinder cam, shown in Figs.
8 to II, is more complex, but will do work as perfect as the former. In
this machine the cam, being cut, is moved endwise by the form as it
turns and whatever shape the form has is given to the cam, as perfectly
as in'the other machine. The roll acted on by the form is carried by a
bar which moves parallel with the spindle carrying the cam to be cut.
Motion is transmitted from the bar to the cam spindle by a lever, which
is pivoted so as to give tbe same proportion of movement as in the former
machine. The worm shaft can be turned by hand or power.
Means are provided lo take up any side shake between worm and gear.
The cutter and its driving gears are mounted on a compound slide, so
that it can be adjusted to position with ease. A support is provided for
the outer end of arbor carrying the cam, to prevent chattering when
taking heavy cuts.
The spindle (a) is free to move endwise in the outer spindle, of which
the worm gear is a part, and also in the back bearing (b). The driving
pin (c) is fast in the worm gear spindle; and passes freely through a
disk (d), which is keyed fast to the sliding spindle (a), A ring (e)
which cannot turn encircles the disk (J)t and in it are pins pivoted in
small slides in the lever. Adjustment is provided to take up any shake
in pins or slides. This arrangement is necessary on account of tbe
foreshortening of the lever. In this machine it is not necessary to have
the form just live times the size of the space inclosed by the groove, as

December, 1892.] ENGINEERING MECHANICS. 3^7
in the former machine ; but the rise or throw must be. The form ought
to be as large as convenient in order to avoid having too steep a rise
for the roll to overcome. A number of holes are provided in the bar
carrying the roll, to assist in adjusting it properly. A weight at the end
ef a cord, attached to the bar, keeps the roll up to the form while cutting
the cam. Means are provided to enable the form to be turned
independently of the spindle. This is useful in starting to cut the cam.
Fio. 6.
Ft... 7.
A hole is first drilled in the cam blank, to start the cut. The hole is
brought opposite to the cutter by turning the blank on its spindle, then
the form is turned to adjust endwise. The machine is then set ready
to cut the cam. The position line is marked on the cam after being
cut, to avoid any chance of error from its slipping on the arbor.
In many cases the pin working in the groove of a cam is secured in
the end of a lever working on a fulcrum. If the radius of the lever
be short, and the throw of the cam be great, a serious cramping of the
pin may take place, on account of the foreshortening of the lever. On
Figs. 14 and 15 is shown a way whereby the cutter may be moved in
cutting the groove in a cam, in the same way that the pin itself would
move, on account of the foreshortening of the lever. In order to
simplify this problem, the pin should not work below the center line of
the cam. To set this device the cam blank and form should be
turned to exactly the center of the throw, and then, with the rock-shaft
(a) in the position shown, the adjustable arms (bb), Figs. 14 and 15, are
moved up to contact with the blank, one on each side. The bar (d),
on which arms (bb) slide, is supported at each end by yokes (cc) which
in turn slide on round bars (ee). At the outer end of bar (d) is a stud
(/) to which is pivoted a connecting rod (g). One end of this rod is
adjustable in a slot in a curved arm which is pinned fast to the rockshaft
(a). At the opposite end of the rock-shaft, and within the vertical
slide (A), is a short rocker arm carrying a flatted pin (j) which slides in
a suitable slot in slide Ih). As the cam is being cut, its movement
endwise causes motion to be imparted to the mechanism just described;
and that in turn causes the vertical slide (A), carrying the compound
slides and cutter spindle, to move up and down. In order that the
amount of motion up and down shall equal the foreshortening of the
lever and pin which is to work in the cam, it is first found by measurement
of the drawings of the machine in which the cam is to work.
Then, by means of a micrometer screw at (/), and the adjustment of
the connecting rod in the slot in the curved lever, the machine is set to
an equal amount, and then is ready to cut the cam.
The writer of this paper does not think ^hat, practically, this foreshortening
of a pin working in a cam cuts much of a figure, as in most
cases it can be corrected by rounding the pin a little. But some might
think it ougln to lie provided for in a cam cutting machine, and for this
reason the writer thought best to describe a way by which this objection
might be overcome.
Two machines, on the principle of those described in tins paper,
have been in successful operation for the past three years, which produce
work giving entire satisfaction.
It would be a source of pleasure to the wiiter of this paper il anything
in this method of cutting cam, should lie of
use to any member of this Society.
STRAINS IN THE RIMS OF FLY-BAND
WHEELS PRODUCED BY CEN­
TRIFUGAL FORCE.
Bv JAMES B. STANWOOD, CINCINNATI, O.
(Member ofthe Society.)
The strains developed in fly-wheels and pulleys
are of an extremely complex nature, so that the
numerous rules and formulae employed for proportioning
them are almost entirely empirical in charac
ter. Experience and judgment have dictated largely
the thickness of the rim, while the eye has played
an important part in determining the shape and
taper of the arms.
In text-books on machine design are found analyses
of the strains in pulley arms due either to the pull
of belt, the inertia of the rim, or the centrifugal pull
on the anus due to weight of rim, etc. These textbooks
also state that the strength of the rim is not
affected by its thickness as regards centrifugal force;
for with an increase of thickness there goes an increase
of weight with a corresponding increase of
centrifugal force and area of cross-section to resist it.
From this reasoning, wheels of good metal, perfectly
true and in good running balance, are only limited
in speed by a periphery velocity, roughly assumed at
about a mile per minute, or 88 feet per second; a
speed giving a very low strain per square inch of
rim—to wit, about 800 lbs. per square inch of rim
cross-section.
Yet in view of these statements we find wheels
l.ursting at low speed, others running safely at high
speed.
In saw-mill practice, where belts travel at high
speed, bursting pulleys have given so much trouble,
that heavier rims and arms for this service have
become common when cast iron wheels are used.
Sometimes even solid disk wheels are employed.
In electric lighting plants many receiving and
UXJ tightening pulleys have failed, causing serious or
casual disaster, according to circumstances.
Within a few years very large fly-band wheels
with wide thin rims have taken the piace of fly-wheels with square rims
and have also been operated at very high speed. The writer hnows of
one case where the periphery velocity on a ly'-t)" wheel is over 7,500
feet per minute.
In band saw-mills the blade of the saw is now operated successfully
over wheels 8 and 9 feet in diameter, at a periphery velocity of 9,000 to

318 ENGINEERING
IO,000 feet per minute. These wheels are of cast iron throughout, ol
heavy thickness, with a large number of arms Who would dare to
operate an ordinary 9-foot pulley at this speed ?
In shingle machines and chipping machines where cast iron disks
from 2 to 5 feet in diameter are employed, with knives inserted radially,
the speed is frequently 10,000 to 11,000 feet per minute at tin
periphery.
In view ofthe disasters so common of late to large band fly-wheels
running at slower speed than these, it seems probable that the strains
set up in wheels by centrifugal force have not been fully considered.
Last spring the writer was one of three experts, called in to decide
upon the cause of a serious fly-wheel accident. From the testimony
submitted by a well-known builder of large wheels, he was led to investigate
a special strain developed by centrifugal force in band-wheel
rims. This strain is due to the fact that all materials have elasticity,
and stretch when under strain. The wheel in question was 22 feet in
diameter, 50 inches face, and had a periphery speed of 5,000 feet per
MECHANICS. [December, 1892.
minute. It was built in sections, as so many large wheels usually are
(see Fig. 107). The segments were secured to arms in such a manner
that the segmental joints lay half way between the arms. This construction
was criticised by the aforesaid builder, who indicated by a
Fio. 108.
sketch (see Fig. 108) a better method. This formed the starting point
for the investigation, which the writer wishes to submit for discussion.
A thin annular ring (Fig, 109) I inch wide and t inches thick, revole
ving about a central axis A, is subjected to a simple tensile strain, similar
in every respect to that found in a boiler shell, its amount per square
V
inch 7"being — , when Fequals velocity of rim, in feet, per second.
This can be shown as follows :
Let r — radius of ring in inches.
R = " " " feet = —
V =. velocity " " "
12
per second.
The tensile strain T in pounds per square inch of rim section, due to
Fio. 109.
bursting pressure per square inch/ with a ring thickness/ in inches, is:
pr
T= A
t

December, 1892.] ENGINEERING MECHANICS. 3 : 9
Each pound weight of ring exerts a bursting pressure due to centri
fugal force =
V-
(2)
32.2 A
01 for each inch in length of ring ii will bt
r-
X
(A
When wheels are made in halves or in sections, the bending strain
FIG. IIO.
may be such as to make / gTeater than that given above. Thus, when
tlie joint comes half way between the arms, the bending action is similar
expanded ring into its original diameter at the arms. It will
to
then
a beam
have
supported simply at the ends, uniformly loaded, and / is 50
the form diagrammatically exaggerated, as shown by Fig. I IO.
percent, greater Then the formula becomes
Under these conditions what will be the strain upon the ring? The
ring between each arm resembles now a uniformly loaded rectangular .71 zd
A'
V
beam fixed at both ends ; it is also under a tensile strain of — pounds.
10
The greatest strain in pounds per square inch F to which any fibre is
subjected, can be expressed generally, thus
2
('""' IO (12)
J
or for a fixed maximum rim velocity of 88 feet per second, and /** =
b.ooo lbs.,
.fill V
F ' 2/ ~.A + A
2
AA)
where /represents in inches the distance from center to centei of arms,
p the uniform load in pounds per square inch on the length /, and / =
thickness of rim in inches. The width is assumed to be unity.
This formula can be expanded by substituting for / its value
X — X .261 / (from 3) where d = diameter of ring in inches
32.2 d
= 2r and foi /its value — (6) where 7v"= number of arms.
. jtii
Then
3.14V 2 V 24
F = — n~ X - - X -7 X .261/
N 32.2 d |__
~~YA •" 10
±**21 A- 'A
N 2 t 10
(6)
(7)
11 / (tU-
.95,1
\r~To)
32.2
X ,261 / p
But tilt ends of the arms do not remain rigid : the arms themselves
expand longitudinally under the influence of their own centrifugal force,
substituting in (t) we have
and they are also elongated by the strain outward imposed upon them
by the expanding ring. In fact a compromise is effected; the arm
V
X
32.2
T:
X .261 / x
/
yi
10
(-1
stretches out to the ring, the ring yields in towards the arm, and the
Lending action of the ring depends upon this undeterminate amount.
It appears, therefore, that the strain F cannot equal the value as derived
by equation (8). By a careful comparison of rim thicknesses, as determined
by equation (9), with good practice / is found to be too large.
Under this strain the ring expands. If C he taken as the modulus of
,t, yr-d
elasticity, this expansion will amount to — in the circumference
On the contrary, — gives consistent results, and reasonably for
roughly the arms can be assumed to expand one-half of the amount
that the ring expands diametrically. When the arms are few in num­
ofthe ring.
ber, and of large cross section, the ring will be strained transversely to
It arms are inserted in the ring, and are supposed al first to have no
a greater degree than with a greater number of lighter arms. To illus­
weight and to be rigid, with no elasticity, theit eflect will be to pull the
trate the necessary rim-thicknessea for various rim velocities, pulley
diameters, number of arms, etc., the following table is submitted, based
upon the formula.
(10)
"AA)
_-475_f.__.
Thi;? is half the value given by (9), and the value of / is taken at
6,000 lbs. per square inch.
THICKNESS UI KIMS IN SOLID WHEELS.
Diameter of pul- Velocity of rim in Velocity of rim in
ley in inches. ' feet per second feet per minute.
24
24
48
io8
108
5°
88
184
184
1,000
5,280
5,280
11,040
11,040
No. ui arms.
6
6
6
16
36
Thickness in
inches
H
if
2*,*
(8)
(9)
If the limit of rim velocity for all wheels be assumed to be 88 feet
per second, equal to I mile per minute, F=- 6,000 lbs; the formula
becomes
•475''
.67N 2
d
7 Tn ( ll )
l.Os./
'= m W
It is a fact that wheels do spring out at the joint when cast in h
or sections; for the writer has frequently tested them when they have
shown this state of affairs. F'or this reason the construction for segmental
whee's, shown by F'ig. 10S, is preferable to that shown by
Fig. 107.
Wheels in halves, if very thin rims are to be employed, should have
double arms along the line of separation (Fig. III). Compare the
thickness of the rim of a wheel made in segments or in halves, the joint
half-way between the arms (Fig. 107), with the thickness of the rim as
constructed in F'ig. 108. For example, take a 20-foot wheel at S8 feet
rim velocity per second, with lo arms. When constructed according to
Fig. 107, t must be 2J^ inches; according to Fig. 108, ij *, inches.
Attention should be given to the proportions of large receiving and
tightening pulleys. The thickness of rim for a 48-inch wheel (shown
in table) with a rim velocity of 88 feet per second, is J*} inch. This
should be carefully noted. Many wrecks have been caused by the
* These are the calculated thicknesses for a band saw-wheel 9 feet in diameter with
390 revolutions per minute. The actual thicknesses as made were found to be 2*^
inches with 16 arms, and % inches with 36—i*/jj inches steel arms.

32° ENGINEERING MECHANICS. [December, 1892.
failure of receiving or tightening pulleys whose rims have been too
thin.
A word of caution should be given to engine builders and engineers.
Wheels may be specified to be made too light in weight; for with a
given diameter and weight there is a minimum safe-weight dependent
upon the principles already set forth, Fly-wheels calculated for a given
coefficient of steadiness are frequently lighter than the minimum safeweight.
This is true especially of large wheels.
A rough guide to the minimum weight of wheels can be deduced from
our formuke. The arms, hubs, lugs, etc., usually form from one-quarter
to one-lhird the entire weight of the wheel. If b represent the face of
the wheel in inches, the weight of the rim (considered as a simple
annular ring) will be
w = 82 dth lbs (14)
If the limit of speed is 88 feet per second, then for solid wheels
t=°-7 '' (")
fX L
For sectional wheels (joint between arms)
t= -•°5' / 03)
Substituting in (14) we have: weight of rim for solid wheels,
ry
•57
Total weight of wheel : for solid wheel,
.76 ,1' !• . .86 d' h . , , .
1 1 = 1 to in pounds 17)
.\"' A"'
For segmental wheels with joint between arms :
„. 1.05 J'- li , 1.3 il' 1 b • , ,0,
XV ----- -* to -* _ in pounds 15)
y-i jtr'i ' v '
This investigation has not the advantage of extreme accuracy, but it
tends to show a relation which ought to be observed. The constants
used may be modified by further experience.
The value of /•'= 6,000 lbs., is taken at one-sixth of Rankine's ultimate
breaking strength of cast iron when under transverse strain. The
factor of safety is, therefore. 6. It should be remembered that in wheels
this factor can be rapidly diminished ; thus the strain varies nearly as the
rim velocity squared, and if the velocity is doubled, the strain is quadrupled,
and the factor of safety is reduced from 6 to less than 2.
PUMI'INO STATION,
NANTICOKE WATER COMPANY.
Arranged for either Suction or Pressure Feed.
FIG. 55.
Wilkes-Barre, Pa., Sept., 1892.
Main.* »ip/>fv.
ing Town.

December, 1892.] ENGINEERING MECHANICS. 321
TESTS OF A PUMP RECEIVING SUCTION WATER
UNDER PRESSURE.
BY K. VAN A. NORRIS, WH KESBARRE, PA. (Member of the Societj ).
'1 HE following experiments were made in April, 1S92, with the view
of determining the advantages of the plan of feeding water under pres
sure to a direct-acting pump over that of drawing the water from a receiving
well. The circumstances were as follows :
The borough of Nanticoke, Pa., is supplied with water from Harvey's
Creek, a small stream tributary to the Susquehanna, the water being
conducted through mains from a dam some two miles up the creek, and
reaching the Nanticoke Water Co.'s pumping station with a piezometric
head of about 60 feet when the pipe is flowing about 1,000,000 gallons
per day. Up to the above date the water had been discharged at the
pumping station into two receiving wells (Fig. 55), and thence pumped
into the town mains by two duplex Gordon and Maxwell pumps, 22inch
steani cylinders, I2*/2'-inch plungers, l6*4-inch actual stroke. It
was suggested by Mr. J. H. Bowden, the chief engineer of the company,
that the pressure of water in the mains could advantageously be used in
feeding the pumps. Accordingly one well was thrown out of use, and
the connection shown in Fig. 55 put in, consisting merely of an 18-inch
pipe connecting the suction ofthe pumps to the inlet from the main and
extending across the No I well, with a 10-foot length of 18-inch pipe
standing vertically as an air chamber, tt. obviate any danger to the
pumps from water ram. In this air chamber, and extending to the bottom
of the tee to which it was connected, was a movable screen fenremoving
any floating material from the water. This screen is readily
removed from the bottom for cleaning.
Both pumps, it will be seen, were arranged to draw from either well,
so that no stoppage was necessary in making the change; and when it
was desired to change from suction to pressure, or vice versa, all that
was required was the opening of one valve and the closing of another.
The pumps are supplied with steam from the Susquehanna Coal Co.'s
boilers at their No. 2 shaft, distant about 150 feet, through a 6-inch
wrought pipe, and just before the pressure was turned on they were both
making 25 single strokes of each plunger per minute, sucking their
water from'No. 2 well. As soon as the valves were changed their speed
increased to 33 strokes, without change of steam valves, and they appeared
to run much more smoothly.
The accompanying indicator cards were taken on April 9th by Mr.
Bowden and the writer, and the results in following table calculated
from them. Four cards were taken from each end of each cylinder
under each condition, and the results in the table are averages from
them. The pressure in the "suction" pipe was determined by a pressure
gauge in the position shown, read at time of taking each card. Cards
were taken under the following conditions ;
.Suction from well, 50 strokes of each plunger, cards I .V. and 1 W.
Suction from well, 25 strokes of each plunger, cards 2 S. and 2 //'.
Pressure from main, 50 strokes of each plunger, cards 3 6". and 3 //*•
Pressure from main, 25 strokes of each plunger, cards 4 5. and 4 //'•
They seemed to show that about 90 per cent, of the gauge pressure in
the main was utilized, and that the resulting saving in steam calculated
from the cards was about 20 per cent.
No measurement of the water pumped under the two conditions was
attempted, as it went directly into the supply pipes; but the pumps appeared
to work more smoothly and to keep the stand-pipe level more
constant under pressure than when sucking.
The suction valves of the pump were provided some years ago with
springs to make them seat promptly, and these were not altered by the
change in method of feed.
TESTS OF NAN'IICOKL WATER CO.'S PUMPS, APRIL 9. 1892.
Pumping from welh and direct from snpply main. Tested by I. II. Bowden and
R. Van A. Norris.
(J'-r.lon and Maxwell
Duplex Plunger
Pumps.
22-inch steani.
1 A 2-inch plungers
i6J^ inches strok
Left-hand pump
2 £
.£ ft
Suction
Pressure.
50
50
36 i It.s 3,156 lbs 93-5 —3 TO
24.75 'bs . ,.-.-•. lbs 99 6 430
Difference , . 1j.35 lbs
3* f
736 lbs
Suction
Pressure .
Difference
25 33.4 lbs
25 23.1 Ibs
. . 10.3 lbs
1,358 lbs
1,060 lbs
298 lbs
Suction 50 33.9 lbs 2,912 lbs
Pressure. 50 ' 25.25 lbs 2,369 lbs'
Difference . . 8 65 lbs 543 lbs
Suction 25 32.4 lbs 1,314 lbs
Pressure 25 23.3 lbs 1,060 lbs
Difference . . u.i lbs 254 lbs
p-> p,.&
ux v a
Ml cC M)
•U J- CJ
< "; <
9' 9 -3-rt!
97-3 +32
0 M
J= §
\f =
<
25in
**9rV
v - -
" U.
V CM
a,
85-Ar*
9*t
These experiments were made simply for our own satisfaction, and
while not carried far enough to be of exact quantitative value, it is hoped
that they will be of some interest, sufficient to elicit discussion.
VARIABLE SPEED POWER TRANSMISSION.
BY H. C. SPAULDING, EXETER, N. H. (Member of the Society.)
If such an estimate could be made with any approach to exactness,
it would be most interesting to know how many pairs of step pulleys are
to-day in operation in the United States alone Surely there are few
mechanical contrivances more generally accepted and incorporated into
FIG. 56.
Mains EachL
Connected to
t>vth Pump*
every class of machinery for affording a simple and ready means ot
changing the speed either of the entire driven mechanism, or of one or
more parts of it, independently of others. Vet their inherent defects
are so well known as to call for hardly more than bare mention in
order that they may be borne in mind while considering the device presented
below. Inability to produce speeds other than those predetermined
by the ratios of corresponding steps ; the limited number of such
speeds except as obtained by large and unwieldy cones with an excessive
number ot radii, at a corresponding expense in stock and finishing
cost; inconvenience of shipping belts except as applied to light work
and without stopping the machine, or at least depriving it of driving
power while the change is being made; enforced parallelism of driving
and driven shafts;—all are considerations so thoroughly appreciated by
practical engineers and designers, as to call for no extended comment.
The demand lor something which should offer the same advantages
with fewer attendant drawbacks, has been partially met by a number of
devices which have become more or less well known, in connection
with various classes of machinery.
In spinning apparatus, speeders and fly-frames allow the use of continuous
element cones, the shafts being conveniently placed near together
and parallel, while a continuous and gradual change of speed is obtained
by slowly and automatically shifting the belt from one end of the

cones to the other. Were the required range of speed greater, however,
or the change more rapid, the device would evidently not produce
such satisfactory results.
In woodworking machinery the use of a wheel so arranged that it
may traverse a driving disk, its edge thus attaining a -.peed corresponding
to that of the disk at varying distances from its center, has been
tried with more or less success, but the frictional contact (theoretically
a line only) is so slight that saw-dust or dirt of any kind, on wheel or
disk, is liable to interfere with uniform action, while the axis pressure
of both parts must be excessive, and the driven shaft varies its position
with every change of speed, necessitating an extra link in the mechani
cal transmission, with a consequent friction loss.
The Evans friction cone has recently been applied to a number of
problems of this character, but is open to the objections inherent in all
continuous cones, while the shafts must be close together, and expert
opinions differ as to the durability of the belting used, owing to tlie
peculiar and rapidly recurring stresses to which it is subjected when in
operation.
Without dwelling upon other devices for obtaining the desired results,
we come to a type of apparatus which seems to the writer to overcome
most of the difficulties noted, in a simple and effective manner, the invention
of Mr. E. F. Gordon, Mechanical Engineer of the John A
White Company, of Dover, N. H. In the opinion of those most interested
in its development, it is worthy of more extensive trial and investigation
than has been or can in the immediate future, be given it in the
line of machinery to which it is now being applied, and in presenting it
to the Society it is hoped that its possibilities and limitations will
thereby be more clearly brought out by actual demonstration.
Simply stated, the device consists of a deeply grooved pulley, split by
a plane perpendicular to its axis, and dividing it symmetrically, with
means for varying the distance of the two parts one from the other,
(iiven a belt adapted for the purpose, it will, in running on such a
pulley, He nearer the center as the two parts are more widely separated,
and recede as they are brought nearer together. Such a pulley may be
used on either the driving or driven -.haft, or both, and it is evident
that the shafts may be at any practical distance apart, also that the
greater the pull on the belt, the greater it.*- hug and consequent freedom
from slip. Tn some cases it is desirable to place a loose pulley between
the two parts referred to, making a compact arrangement tor starting,
stopping, and varying speed, in the space ordinarily occupied by a
single pulley of the usual style.
Fig. 181 shows such an adaptation of the device, with one ot" the
Fio. [81.
many available arrangements for varying the working radius ot the
pulley. In the illustration, .-/ is the shaft, BC the two halves of the
pulley, /> the idler, E the belt, FG hand wheels, // a collar fast on the
shaft. By the action of the belt, />' and C 'end to separate from each
other, and since B is fasl on the shaft, ./(', which is splined on the
shaft, and hence must turn with it, although free to move along it, is
forced against E. 1 he hand wheel-., /'and G, arc ircc to turn on the
shaft, but may be held at rest whenever desired. Ihe hub of one
carries a male screw, and the other .1 female, so that by altering the
position of f>ne on the other, they increase or decrease the distance between
the collar, //, .md the half "f the pulley, C, thereby allowing (
to recede to a greater or les-, distance from />', and determining the
position of the belt, E, and its consequent -.peed relative to that of the
shaft, A. It will lie evident that in this construction, when used as a
driving shaft, the belt speed will become less and less as /-'is screwed
into C\ until Chas so far receded from /•' as to allow the belt to drop
on the idler, /', when the driven mechanism will come to a standstill,
to be gradually .started again by the adjustment of /and G.
Fig. 182 shows a still simpler form, applicable when the pulley is
located on the end of a shaft. In this case the loose pulley is omitted,
it being assumed thai only .1 speed adjustment is necessary, one part of
ENGINEERING MECHANICS [December, 1892.
the pulley being fast on the shaft, the other free, but loosely pinned to
the first so as to rotate with it, the working being determined by the
adjustment of a hand screw.
KM. 182.
The belt may be either round or nearly square iu section, though for
the most of the experiments so far made a narrow double ply leather
belt has been used, with the edge beveled to correspond with the angle
of the pulley's face.
The construction shown in Fig. 182 has recently been applied to the
feeding rolls of a 48'' band resawing machine in a way which illustrates
its simplicity and adaptation to this class of work.
Fig. 183 shows the arrangement of parts, A being the split pulley,
its shaft being driven by a link belt from a continuation of the lower
band wheel shaft, and supported by an arm, /?, swinging from this as a
center. The belt, C, drives the pulleys, DD, on horizontal shafts
worm-geared to the axes of the feed rolls, the swing of the arm, />,
compensating for the varying length of the belt, C, owing to changes
either in position of the feed rolls, E, with reference to the saw, or in
the working radius of .-/, (he latter being determined by the position of
a hand screw.
The diameter of the split pulley is I2 /V , the minimum working radius
3 // , giving a linear speed to the surface of the feed rolls of from ten to
thirty per minute. A double ply belt l // wide is used, and its power is
such that if the stock be held firm, the -.lip occurs between it and the
feed rolls (four in number, all geared, iS inches long, 3 inches diameter),
and not -it the belt, as in the case of the usual style cone pulley
formerly used with a machine of the same capacity.
No dynamometric tests have yet been made, but a pulley six feet in
diameter is now nearly ready for careful investigation as to efficiency
under widely varying loads and speeds. Should the results be satisfactory,
the simplicity, compactness, reliability and cheapness ofthe device
would apparently warrant its extensive use by the engineering fraternity.
AN ANALYSIS OF THE SHAFT GOVERNOR.
BY F. M. RlTES, PITTSBURGH, I'A., (Member of the Society).
Considering the amount ot labor which has been spent upon the
theory and method of steam distribution and the mechanical design of

December, 1892.] ENGINEERING MECHANICS. 323
steam engines, it is strange that so little work has been done towards
perfecting the governor.
While the subject ofthe steam engine proper is certainly an interesting
one, that of the governor is not less so; yet technical literature
shows no lack of treatment of the former, to a practically complete exclusion
of more than a mere reference to the latter. It is true that the
patent records are proof of a reasonable activity on the part of inventors
in this subordinate branch of steam engineering; but the claims for novelty
have almost invariably been restricted to structural features rather
than indicative of radical departures from the original design of 1839.
However, disregarding the mechanical improvements, it is a fact that
not a single complete work of such a character, either of description or
ol a scientific nature, has ever been issued. A credible explanation of
this condition is that the average consumer does not fully realize the
importance of the subject, and the manufacturer does not care to part
with the information which it has cost him dearly to acquire; while
there is a curious want of comprehension among scientists as to the requirements
and possibilities of shaft governing. It is to clear up the
general uncertainty, awaken a well-deserved interest, and indicate the
splendid opportunity for research in a practically unexplored mechanical
held that this paper is presented.
With the advent anel development of the electric industries has grown
a demand, continually more exacting, for better service from this hitherto
much neglected mechanism; but it should be noted, however, that
competition among manufacturers in general has been confined to the
question ofthe degree of regulation, and that, with a few exceptional
cases, the subject of rapidity of adjustment has been regarded in silence
so that even yet the importance of this function of a governor as a fac
tor in the service of a power plant is not sufficiently appreciated.
(in account of the peculiar duty imposed upon the engines of an
incandescent electric light plant, in which those already partially
loaded must receive occasional considerable accessions of power, the
ability ofthe governor to *' catch the load" is especially valuable in a
commercial sense in preventing momentary variations of voltage and
consequent fluctuation in the lights. On the contrary, the effect of a
sluggish governor is especially annoying to both producer and consumer,
and the evil is more apparent during the period of greatest capacity,
when the increasing load is continually shifted and returned to
the engines in operation, and the entire plant with its output is more or
less influenced, to its detriment.
In the same manner, but in far greater degree, the entire equipment
of an electric railway is reliable and durable, other things being equal,
in proportion to the power of the governor to meet continual and instantaneous
changes of load over wide ranges without surging or permitting
a variation of speed greater than the legitimate amount of the regulation,
while the character of the service resultant from a governor retarded
in its action gives every indication of its uneasy search for a
position of stability wdiich continually eludes it, but which it passes and
repasses without finding. In this most recent industry the governor
also first appears prominently as a factor in the economy ofthe engine.
If the governor be not equally prompt to adjust for the new position
corresponding to a violent change of load, a vibratory action or a racing
eflect may very easily be generated, which shall cause the reverse of
an economical distribution of the steam. In such a case the steani con
sumption approaches moae or less closely the limits represented by the
extremes of cut-off. The evil is, of course, more marked in the case of
multiple expansion engines, where the range of economy is greater, so
that an imperfect governor often condemns by association an engine of
highly efficient steam distribution, when regulated to suit the load,
although the loss is not so great with engines whose efficiency remains
more nearly uniform over their range of power.
Even though the actual variation of the load may be an insignificant
amount, and the corresponding change of speed be imperceptible, or
the real change in speed not beyond the limits of the regulation, so that
the average revolutions per minute as read over an extended period of
time are perfectly normal; yet the average efficiency of the steam distribution
may be far from the efficiency ofthe average and perhaps perfectly
proper steam distribution.
There is no intention to detract from the value of a well-regulated
governor, but it is a certain fact that rapidity of regulation should hold
a far more important position in its influence on the constancy of both
speed and economy. The two terms " degree of regulation " and "rapidity
of regulation " are often confounded and misapplied, but the
properties of the governor they represent are so distinct that they maybe
varied independently even in die same governor. The degree of
regulation may be defined as the percentage of variation of speed
necessary to maintain a unity between the centrifugal and centripetal
forces in governor adjustments, corresponding to variations of load or
steam pressure. The rapidity of regulation implies its own definition
as the speed of adjustment to meet the varying conditions of load or
steam pressure. The degree of regulation depends on the rate of variation
of the centrifugal force at constant speed with respect to that of
spring tension ; while the rapidity of regulation depends on the effect of
the inertia of the masses that compose the governor.
The degree of regulation is a variation of speed as measured over a
considerable interval of time, during which the adjustment of the governor
is maintained constantly ; while the rapidity of regulation deals
only with momentary demands upon the governor.
It is perfectly possible to adjust the relation between the centrifugal
force and that ofthe spring to such refinement that perfect isochronism
is attained, and yet be so slow of adjustment as to possess no stability
even under moderate changes of load, and the resultant racing will lie
even more violent with a supersensitive regulation.
I In the other hand, a governor may be designed to utilize its entire
inertia for rapid regulation, without the power to do so on account of
the low degree of regulation, so that a governor perfectly designed with
respect to its inertia eflect will not alone guarantee good regulation, nor
does close regulation necessarily imply rapidity of adjustment; on the
contrary, it is perfectly possible in a poorly designed governor to oppose
the increment of centrifugal force by that of inertia ; and for the same
reason (opposition to the effect of inertia) the many ingenious devices
for increasing the possible degree of regulation are of doubtful Utility,
by acting as obstructions to a rapid adjustment.
The problem of inertia becomes still more complicated by the necessity
of distinguishing between the eflect of moment of inertia of the
weights considered concentrated at their center of gravity, and hereafter
to be termed ''tangential inertia," and that due to the aggregation
of moments of inertia, caused by angular acceleration about thecenter
of support of the particles composing the mass of weights, and hereafter
to be termed '* angular inertia."
The action of these two forces of inertia are here distinguished anil
described probably for the first time, and it is of the utmost importance
that they should be thoroughly understood, to be fully appreciated in
their application as governor forces. They are both of inertia origin,
but the first is generated by the momentary tangential effect about the
center of revalution of the shaft, and the other by a varying angular
velocity about its center of support and rotation. In other words, tinone
is a moment of inertia of the concentrated mass about its center of
revolution reduced to a secondary moment about its center of rotation
and support. The other exists only as a primary moment about its center
of support. Again, these may assist 01 oppose each other, or together
unite with or in opposition to centrifugal force. In short, it is
possible to ring all the changes of combination ofthe three forces according
to the design of the governor.
Mathematically, it is possible to combine the two inertia forces in
their effect on rotating the weight about its own center into one force
applicable at the center of oscillation, located with reference to the center
of revolution, and which is resisted by the moment of inertia of the
weight with reference to its own center of support.
If mr, z be the moment of inertia about the center of revolution where
mr, 2 .
;-, is the radius of gyration (see Fig. 18), then is the correspond­
ing inertia force exerted at the center of oscillation, where r2 is the
radius of oscillation, and — r3 is the moment of this inertia about
the weight's supporting pin to produce angular movement, where r3 is
the distance of the center of oscillation as referred to the center of revo-
FlG. 18.
lution, while mrf represents the moment of inertia of resistance to
rotation about the supporting pin where ri is its radius of gyration about
this pin ; so that the ratio
is the eflect in angular displacement about the supporting pin due to an
angular acceleration about the center of revolution, and is independent
of the mass of the weight.
If 1:, — o, then -i-A o, and the supporting pin is either identical
with the center of oscillation or situated on the normal to the radius of
oscillation through that point, and there is no inertia effect, but the governor
has reverted to a purely centrifugal type.
(Fo be continued.)

324 ENGINEERING MECHANICS. . [December, 1892.
SMOKE PREVENTING DEVICES.
Sinuett seems to have struck the right idea and method for
preventing smoke. He uses an injector at the furnace mouth
to supply air, well mixed with steam. Steam is the active
agent by which a complete or almost complete combustion of
the gases is effected This is certainly a novel explanation,
though not altogether a novel suggestion. Steam has been
long used at furnace doors, but more with the idea of increasing
the air supply. The explanation is now made by Mr. Sinuett
that the cause of smoke is due to the fact that there is not
sufficient hydrogen,—the fuel consumed—to effect perfect combustion.
Smoke represents resulting non-combustion. Now
he simply proposes to introduce steani in such way in furnaces,
by a simple and cheap device, as will furnish sufficient
hydrogen to effect perfect composition, and thereby prevent
smoke.
Numerous and satisfactory tests, it is said, have beeu made
showing uot only a smoke-preventing combustion, but an
economy amounting to io per cent, in fuel, with less ash aud
clinker by use of the steam-mixed air.
Laboratory experiments also prove the same action. Dried
powdered charcoal sealed up in a tube of dried oxygen will uot
fire at red heat, but when filled with moist oxygen, there is
active combustion.
Another proof of the power of steani-mixed air to prevent
smoke through perfect combustion of the gases is shown in a
blast furnace when a tuyer leaks. Gases uninflamable at 250
to 300 degrees centigrade quickly fire when a tuyer leaks,
showing higher combustion from the admission of hydrogen
gas. Some critics are disposed to dispute the new theory and
to credit steam only as being a chemical carrier which aids iu
at present unkuown or at least undetermined, reactionary
effects. The scientific and commercial world will await further
developments with more than passing interest.
A DAILY paper telegram credits Dr. S. H. Kmmous, the inventor
of Emmonsite with having solved the problem of reducing
zinc lead sulphide ores. Emmons quantities are annually
thrown aside and commercially valueless. The discovery if
practical will be of immense importance to mining interests.
THE Baldwin Locomotive Works has turned out a Vauclaiu
Compound Locomotive which hauled an express train over portions
of the New York division of the Pennsylvania R. R., at a
speed of from 37 to 40 seconds per mile. It is the handiwork
of S. M. Vauclaiu, General Superintendent, and it is one of the
handsomest engines ever constructed. It weighs 123,800 pounds;
on the drivers, 80,400 pounds ; tank capacity, 3500 gallons
Diameter of driving wheels 78 inches.
AN organization of Naval Architects and Marine Engineers is
in process of formation. The committee of organization consists
of William II. Webb, of New York ; Lewis Nixon, general
manager of Cramps' Ship-building Company of Philadelphia ;
Colonel E. A. Stevens, of Hoboken ; Francis L. Bowles, naval
constructor United States navy, aud Clement A. Griscom, president
of the International Navigation Company. They expect
to incorporate the society in New York and are now sending
invitations to membership, hoping to have the first meeting at
the time of the naval review next spring.
THE Sham Gas Tester has been making an excellent record for
itself in some of Ihe Anthracite mines. Tests at the Pine
Brook Colliery and at the South Wilkes Parre mines were
especially interesting to the congregated mining experts. Mr.
J. R. Wilson conducted the tests or rather experiments. The
superiority of the Tester over the mine camp was proven. In
the Pine Brook Colliery, at the mouth of the up cast f^ of 1 per
ceut of fire damp in an air current of 240,000 feet of air per
minute, was detected. The Davy Lamp used was tested aud
failed to show any gas until 3 per cent, of gas was reached aud
it failed to act after 8 per cent, of gas was reached. The Tester
detected in 20 seconds the presence of one-tenth of one per
cent, of gas, while the Davy is not good for auy gas in less volume
thau 2 per cent. Immense quantities of ignitable gas maybe
present and yet the Davy will fail to record the fact. The
Sham device detects the least trace above the one-tenth of one
per ceut. limit in any part of the mine. The following tests
made at the South Wilkes Barre Colliery will be of interest to
many engineers.
The Davy safety lamp showed a faint cap (blue flame over
the red flame) with 2 per cent, of mine gas in 100. It capped
at full length, that is, showed flame from the wick to the top,
at 8 per cent., and filled and exploded at 8 per cent.
The Richards lamp showed a faint cap at 3 per cent. It
capped at S per cent, and exploded at 10. It extinguished, however,
by the use of the hood at S per cent.
The Thomas lamp (English) capped at 3 per cent., capped
full length at 7 per cent, and extinguished at 8. This lamp is
self-extinguishing.
The Clauuy capped at 4 per cent., capped full length at 7 per
cent, and exploded at 10 per cent.
COMMODORE FOLGER, Chief of the Burea of Ordnance has
given the government some very interesting information in his
annual report, of the 3S1 guns from 4 to 13 inches calibre
required for our war ships; 237 are completed and 116 are afloat.
The breech mechanism of the 10 and 12 inch guns has been
adapted to be worked by hand to avoid the consequences of
electric or hydraulic or other power being destroyed. Wm.
Sellers' nickel steel gun is expected to mark a step of progress.
Rapid fire mechanism has been perfected until five shots can be
fired from the same gun in 19 seconds, and even in 14, which
means that in 6,000 yards the fifth shot will be out of the gun
before the first has arrived at its destination. Mr. Folger is
makiug better smokeless powder than is made in Europe and
has greatly improved the quality of Crown powder. Emmonsite
shells have been fired from rifled guns with 2,000 feet per
second velocity and exploded ou water at 6,000 feet. Shells
with other explosive material have been fired through 6 one
inch iron plates and burst detonatively beyond them. Zinc
classes of guns will be hereafter used on war ships, one of great
length and power using armor piercing projectiles, the other
short guns with large bores firing projectiles with charge of
powerful high explosives to use against unprotected parts.
Smokeless powder, larger bores and breech mechanism demands
more room in the turrets and hence new typical mounts have
been designed, and the hydraulic mechanism has been omitted.
A large supply of automobile torpedoes will soon be delivered to
our government for testing. Naval rams are to be supplied with
submarine guus. Oue ram to be built will carry short bore rifle
mortars, firing projectiles of nickel steel, carrying bursting
charges of 200 pounds of high explosive, also two submarine
guns designed to discharge iu rapid succession projectiles containing
500 pounds of high explosives and with nickel steel
armor carried clean down the sides. The Commodore also recommends
that petroleum be used as fuel iu torpedo boats. All
armor is to be hereafter treated by the Harvey process aud he
thinks that European Governments will alter their decision in
regard to the size, calibre and power of guns and continue to
increase their power. The experiment of a 25 per cent, alloy
of nickel with steel has been satisfactory and it is proposed to
construct the armored tower which shelters the compasses of
one of the new vessels with this material.

December, 1892.] ENGINEERING MECHANICS. 325
THE Crescent Phosphorized Metal Co., of Philadelphia, have
moved from 811 Fairmount Avenue to their new works at 2107
to 2111 Indiana Avenue.
THE Lucas Ship Co., of St. Louis, are starting in to build
steel boats to ruu in the St. Louis-New Orleans trade. They
will draw 7 to 9 feet and carry 1000 to 1500 tons at a speed of 16
knots. This form of boat, it is believed, will meet every requirement.
THE General Electric Company has made its old double reduction
II 30 motor, a single reduction machine and is now rebuilding
a good many old machines for customers. Main-
pieces have been discarded, and the armature bearings are rearranged
to facilitate lubrication. The armature speed is reduced
one-half, and the strength of the tongue of the motor is
doubled. The changes in the new machines make it a most
desirable motor.
THE electric road in the World's l*air grounds will be 3A
miles long, and will have 11 stations. Each train will have one
motor car supplied with four 50 H. P. motors of T. H. make.
The Jackson & Sharp Co., of Wilmington, Del., will build the
car. F*ive engines will be located 10 feet from the ground, aud
non-condensing. A 4000 H. P. battery of Babcock & Wilcox boiler
will be used, burning petroleum for fuel. Green economizers
will be used. A Reynolds-Corliss 2000 H. P., a 1200 H. W. T.
H., a 750 tandem Reynolds-Corliss, a 750 H. P. Hamnioud-
Williams are among the equipments ordered.
THE Mason j\ir Brake and Signal Company of Chicago have
demonstrated the practical value of their signal system for passenger
trains. There are three valves—the conductor's valve,
the signal valve aud the engineer's valve—and a train pipe for
the passage of air, connected with the conductor's valve, is a
small reservoir for measuring the air discharged. The signal is
caused by a reduction of air pressure. This reduction causes a
pulsation which reaches the signal valve ou the engine, which
makes a slight reduction of pressure above a piston. LTnder
this pressure the piston rises and permits the air to pass to the
whistle with which it is connected. The escape ofthe amount
of air which blows the whistle decreases the pressure beneath
the piston, and the valves again assume their normal positiou.
THE Greenfield Steam Engine Works, East Newark, New
Jersey, conducted by W. G. & G. Greenfield, is shipping a large
amount of work to near and far-off customers, among wliich
may be mentioned a 7 x 7 boiler for Charles Wright, of Newark ;
two 9x9 engines for the Morton Iron Works, Brooklyn, N. Y. ;
one 11x12 engine for Ducktown Sulphur, Copper & Iron Co.,
Ducktown, Tenn. ; one 7x7 engine for G. A. Meyers, Paterson,
N. J. ; another, same size, for J. & R. Kingsland ; a 12x12 eu­
gine, making the ninth, for the Equitable Life Ins. Co. ; a large
engine, making the 47th, bought by the Standard Oil Co. ; a
4x6 for the Owl Cigar Co., Quincy, Florida, ordered through
Stratton & Stow ; and a 9 x 9 engine for Pallantine & Sons,
being the fourth ordered by that firm. This record carries its
own endorsement.
THE Thomas coke oven is an improvement on the old Welsh
oven, which was simply a rectangular oven 7x12 feet, and an
arched roof 6 feet high, from which the coke is drawn out of
the movable front by a drag. The Thomas oven is much longer,
36 feet, 7 to 8 feet high inside ; door 4 feet high, front and rear
sides both movable, with swinging doors in two sections made
of fire brick. Both ends are also movable.
Twelve tons of coal are charged and the charge is leveled
from both ends, from whence the charge is also drawn by an
iron rod attached to a drag in the rear. This oven exhibits a
marked economy in production and proves that the bee-hive
is not the best form of oven attainable. The saving of gas now
wasted and the saving of other by-products will soon be at­
tempted at Coalburg, Ala., where the Thomas coke oven has
been tried under the Sloss Iron and Steel Company.
FRASEK & CHALMERS of Chicago are turning out an ore
sampling machiue designed by H. L. Bridgemau of Blue Island,
Ills., which has a capacity of from 15 to 25 tons per hour, and
determines percentage of moisture in ores as well as metallic
and other constituents. The machine gives good results uuder
any ordinary working conditions ; it takes its feed directly
from crusher or rolls, regularly or irregularly, fast or slow, as
the case may be ; it requires uo attention, except for cleaning
out and for the removal of samples, and, iu fact, it transfers
the important function of sampling from the domain of watch­
ful care and discretion to that of mere routine. Being perfectly
impartial, and giving double samples, it removes ground for
disputes, and renders "salting" practically impossible.
It occupies but little space and does its work at a trifling cost
compared to hand sampling. The use of ball-bearings lessens
need of lubrication. Different sized samples can be had according
to material used. This machine will no doubt drive
out the more primitive, costly and cumbrous methods.
ENGINEERS' CLUB OF PHILADELPHIA.
Mr. John C. Trautwine, Jr., presented notes on the Distribution
of Pressure in Masonry Joints, at a recent meeting of
the Franklin Institute, illustrated with sketches on the black
board, showing that the true significance of the ''middle third "
of the joint, and of the "tension " which is said to occur when
that limit is exceeded, lies in the fact that masonry joints are
practically incapable of resisting tension, so that when in such
a joint the resultant of all the pressures falls outside the middle
third, the portion of the joint which, if capable of tension,
would be called upou to exert it, is simply idle, and the entire
pressure is concentrated upon the remainder of the joint, the
width of whicli is three times the distance from the resultant
to the nearest edge. Owing to this, the maximum unit pressure
in such joints increases very rapidly after the middle third is
exceeded ; whereas, iu a surface capable of resisting tension
(such as a cross section of an iron bar) the maximum unit pressure
increases uniformly, however far from the centre of the
section the resultant may fall.
Mr. Wilfred Lewis gave an account of his "Investigation of
the Strength of Gear Teeth," beginning with a reference to the
elementary character of the problem and the great diversity of
rules adopted by many recognized authorities, and showing that
although the form of a tooth had long been known to be an
important factor iu the determination of its strength, none of
the rules in common use took account of the strength as affected
by the number of teeth in the wheel or pinion.
It was admitted that some diversity of opinion might reasonably
exist in regard to the distribution of pressure across the
teeth aud the number of teeth in action ; but it was argued that
so long as imperfections in spacing and shaping existed, as they
still do to a very appreciable amount in the highest class of
machinery, the only safe assumption was that the whole load
was carried at the end of a single tooth.
Ou this basis a graphical solution of the problem was pre­
sented for each step iu a series of 24 equidistant cutters, and
tables were distributed showing the results obtained by the
graphical method.
These tables indicate the relative strength of wheels and
pinions with reference to their number of teeth, and leave the
working strength of the material to the judgment of the engineer.

326 ENGINEERING MECHANICS. [December, 1892.
A SECTIONAL WATER-TUBE BOILER.
The New York Safety Steam Power Co., 30 Cortlandt Street,
New York, are building a sectional water-tube boiler, which is
economical in space and of liberal proportions in grate area and
heating surface, (herewith illustrated).
The furnace extends under the entire boiler. Any kind of fuel
can be used. The tubes all lap welded are arranged in transversely-inclined
series of several tubes per section and are
straight. Every tube aud connection is expanded aud all tubes
are wholly in the furnace and give active heatiug surface. The
movement of the water is constant and rapid. Its course is as
follows: from the steani and water drum located above the
tubes, into which water is fed, it descends the water legs—four
in number, placed outside the furnace, to the water aud mud
drums, at the base ; thence it passes via the tube connections,
into the lower series of headers ; thence through the tubes, over
the fire, into the upper series of headers ; thence via the tube
connections into the steam and water drum again (from whence
it started). Expansion and contraction due to changing temperatures,
occurs without straining or disturbing the position
of auy part. Tubular expansion is reduced to a small fraction,
as compared to that which is due to the employment of
tubes of 16 to 20 feet long.
Outside the furnace—opposite each end of each tube a hand
hole, of proper size to admit a tube, or a tube-expander, is provided
aud fitted with a cap, held to place with a crossbar and
bolt. This cap is accurately faced aud ground to a perfect
steam and water tight joint. The caps are exposed upou opening
the side doors, below mentioned ; and can be examined or
tightened if necessary. I'pon removal of a cap, the internal
condition of a tube is open to inspection, to cleaning, or in case
of leakage in the expanded joint, to re-expansion. Aud in case
of accident to a tube, or depreciation due to long usage, a new
tube can be substituted with but little trouble and delay. Each
end of each mud drum is provided with a removable cap acces­
sible from outside.
The furnace is lined with fire-brick. The only other brick
work required to erect a stationary boiler, consists of two
foundation walls of proper depth, rising above the floor level
about twelve inches.
The sections, drums, etc., when connected and ready for
pressure are tested as may be required. After test, they are
encased with heavy sheet iron, lined with non-conducting
material (Asbestos and Magnesia).
The casing is well bolted to a wrought iron angle or channel
bar frame. The front is of ornamental design, made partly of
cast iron. The furnace door is of handsome design, and substantial
and durable construction. Hinged doors are provided
on front and rear, aud on both sides opposite upper and lower
headers, affording access to interior of boiler, and to tube ends
as before described. One set of grates will accompany each
boiler, same being best design to suit the fuel to be used, and duty
to be performed. The usual complement of valves, gauges, etc.,
is furnished ; all of the best make and quality.
These boilers are proportioned aud rated for generating
power on the basis of the Centennial standard—namely, the
evaporation of 30 pounds of water, at 70 lbs. pressure, from
temperature of ioo°—to be one horse power. Said duty to be
accomplished with a consumption of anthracite coal of good
quality, at rate of twelve pouuds per hour per square foot of
grate with good natural draft. It is to be understood that the
actual steaming efficiency and also the ultimate capacity, is
largely in excess of the rating ou above basis. This boiler has
a large reserve capacity because of the low horse power rating.
In a water-tube boiler the elements which insure safety are
numerous. Primarily- in the strength of the parts which are
combined ; secondly, in the reduced areas exposed to rupture ;
thirdly, in the distribution ofthe total strain.
It follows that a boiler composed chiefly of boiler tubes,
which, when of standard make and perfection, possess an enormous
resisting power, as against explosion, is far advanced in
the direction of safety in comparison with any type of boiler
in which tubular area is a mere fraction of the total area sub­
jected to explosive force.
In this boiler, the above mentioned factors of safety are all
present. Each section of tubes anil headers is tested under 500
lbs. hydrostatic pressure at our works, and known to be sound
and perfect before being incorporated in a boiler.
The main steam drum is made of open hearth homogeneous
flange steel plate, having a tensile strength of uot less than 60,-
000 lbs. per sq. inch of sectional area, and possessing sufficient

December, 1892.] ENGINEERING MECHANICS. 327
homogeneousuess, toughness and ductility, to show a contraction
of area of not less than fifty per cent.
Tbe plate employed will be of proper thickness to enable the
boiler (under government standard of pressure allowable) to
carry a working pressure of 250 pounds per square inch.
The advantages of positive circulation in a boiler are many
aud important.
1st. Without active circulation—the economic use of fuel is a
futile undertaking. With circulation natural, constant and
rapid, economy is attainable to a high degree.
2d. It prevents the deposit of scale or sediment upon the
heated surfaces, aud incidentally the burning or blistering of
the metal.
3d. By producing a condition of internal cleanliness, the
heating surfaces are maintained in their proper state for utilizing
the heat of combustion.
4th. The temperature throughout the boiler is equalized, and
the ill effects of unequal expansion neutralized.
Iu this boiler, the water circulation is natural aud positive.
It is passed through the tubes and exposed to the action of the
fire, in a steady and continuous flow. The steam generated is
quickly conducted to the drum, and in cousequence of the
ample disengaging surface provided, separates from the water
without turbulence, and is dry steam ready for use.
The system of cross-tubes employed in this boiler, results in
the concentration of heating surface to a degree unattainable
by any other straight-tube system ; yet it does not contract the
area of grate. Hence the capacity of the boiler in horsepower
per cubic foot of space occupied is greater than is
afforded by any other boiler now known to the market—
" pipe " boilers excepted.
When a large amount of power is wanted, and the boiler
room is small, this boiler will supply the want. By reason of
its sectional character, it can be delivered in places wholly inaccessible
to any other desirable boiler. A boiler of 200 horse
power cau be passed through a 4' x 4' doorway, window or
sidewalk opening. A boiler of 100 horse power occupies a floor
space 7A feet square, and is less than 10 feet high. There are
no screwed joints or connections iu this boiler.
SPRING VISE JAWS FOR TENDER WORK.
This little device has been used by us with great satisfaction
for several years. F.veryone has noticed what nuisances
are the every day copper clamps. Whenever the vise is
opened they threaten to fall on the floor, and they often do so.
They become hard by use, and have to be annealed ; aud how
often you see a machinist hunting around the workshop for the
*,y
other copper jaw which has been mislaid or used for another
purpose by a fellow workman.
These jaws are made of vulcauized paper, the best material
for the purpose that we know of, which line pieces of the be.st
malleable iron. These pieces have shoulders to catch on the
vise jaws, and they are bound together by a spring counection.
When you loosen the vise to take out or to shift the work, the
jaws expand following the motion of the vise. Of course they
canuot fall upon the floor. They cannot grow hard, and they
cannot be used for another purpose. They will save their cost
in a week. Price, per pair, $2.00. Sold by The Newark Ma­
chine Tool Works. Newark, N.J.
THE Lodge & Shipley Machine Tool Co. of Cincinnati, Ohio,
are turning out a superior extra heavy engine turret lathe, designed
to handle cast iron work on the same plan that the screw
machine handles iron and steel studs. Engine builders will
appreciate it because it does three things at once. It will make
diameters from 30 inches down, either straight or taper. It has
a 30 iuch swing and is in all respects a first class chuck lathe.
CHARLES H. SMITH made tbe following suggestions which he
thought should be observed in overhead electric construction
for street railroads in a paper read at the Cleveland meeting.
Irou or steel poles 32 feet high, in three sections 7, 6 and 5
inches in diameter, respectively, should be used, set in concrete
6 feet in the ground, not over 125 feet apart—span wire No. 4,
B. W. G silicon bronze, 22 feet above track ; cross arm insulated
by wooden plug.
Sections should not be over two miles, separated by trollev
breakers ; hangers and pull off brackets should be of the lightest
make possible. The trolley wire should be put up in mile
lengths to have few joints. Twisted splice joints aud brass cone
shaped tubes slipped over the wire before splice is made should
be used. Overhead switches or switch pans should be avoided.
The guard wire spans should be properly insulated from the
cross arm by at least No. 6 best galvanized iron wire. Feed in
tops should not be more than five poles apart. The feeder
wires should be run to each section and should be 30 per cent.
larger than occasion demands. A cut box should be located on
the pole at each trolley breaker aud should uot carry a fuse.
The fuses should be at the station. There should be lightning
arresters every thousand feet.

328 ENGINEERING MECHANICS. [December, 1892.
SECTIONAL aud exterior cuts of the Hayden & Derby Manufacturing
Compauy's Metropolitan Double Tube Injector are herewith
presented. They have just brought out this machine, after
experimenting with it for over a year. Their object in introducing
this new injector is that they appreciate the demand for
VIEW.
a high-class injector that is complete in detail and will work
under the most severe conditions found in practice. It is a
well-known fact that an automatic or single tube injector has
not the range that is required for a great many of the conditions
found in modern engineering, and in order to get an injector
that has a sufficient range it is necessary to employ injectors of
the double tube type.
The double tube injector is not new, but the method they
employ for operating the steam and overflow valves is decidedly
novel and oue that will be appreciated by the user.
Referring to the sectional cut, notice that the two steam
valves are iu line and the stem operating tbe
steam valves is attached rigidly to the stem
operating the overflow valve, this stem passing
through the cored passage through the
centre of the injector, thereby doing away
with all the exterior attachments that are
employed in other double tube injectors,
aud which, as the user well knows, are very
liable to break and wear. The overflow
valves employed are very unique and simple.
The overflow valve to the lifting apparatus,
which is shown in cut as part 15, is an automatic
valve, which allows the discharge from
the lifting apparatus to pass freely iuto the
discharge of the forcing apparatus, then out
through the main overflow valve into the
atmosphere. By using this automatic valve
they are able to employ the simplest kiml
of a valve for the forcing apparatus. In
other double tube injectors tbe overflow
valves, for both lifting and forcing apparatus,
are complicated and reconnected, and in all
of them the piston form of valve must be
employed that will turn the water from the
lifting apparatus into the forcing apparatus before the final
overflow valve is closed. The operation of this double tube injector
is very simple. By pulling the lever back slightly the
steam valve to the lifting apparatus is slightly opeued, which
allows steam to pass through the lifting apparatus, raising the
overflow valve 15, thence out through the final overflow iuto
the atmosphere, thereby lifting the water. As soon as the water
appears at the overflow the lever is drawn back slowly, which
admits steam to the forcing apparatus, creating thereby a pressure
111 the discharge of the forcing apparatus, this pressure
being much greater than the pressure in the
discharge of the lifting apparatus, which
seats valve 15 and holds it securely to its
seat. Upon further drawing out the lever
the overflow to the forcing apparatus is
closed, which turns the current of water into
the boiler instead of passing out the overflow.
In operating the machine, after the water is
once lifted the lever is pulled back with one
steady motion.
The injector is well made aud all valves
and valve seats being independent of the
body casting they can be removed and ground
by any one and there is uo need of putting
the casting in a lathe to turu up the seats
should they become damaged or worn.
This injector has an extraordinary range.
It will start with 15 to 18 lbs. steam pressure
and without any regulator whatever work at
all steani pressures up to 225 or 250 lbs. It is
a hot water machine. With ioo lbs. of steani
pressure the injector will take feed water at
a temperature of 145 to 150° Fahrenheit.
Everybody knows that the greatest trouble
they have experienced with injectors is that
the machine will uot handle hot water, and in bringing out this
injector they have perfected one that will do away with this
difficulty in other machines.
These injectors have beeu in use for some time, under the
most severe conditions. They have been adopted by the largest
ship building companies in this country, amongst which we
might mention the Newport News Ship Building and Dry Dock
Co., F. W. Wheeler & Co., Bay City, Mich., the Detroit Dry
Dock Co . and the Americau Steel Barge Co.
INTERIOR VIEW.
ZT3
WANTED : Mechauical Draughtsman, a graduate with some
experience preferred, must be industrious, correct aud quick,
to such a permanent position is assured. State experience and
wages expected THE WESTERN GAS CONSTRUCTION CO., Ft.
Wayne, Ind.

December, 1892.] ENGINEERING MECHANICS. 329
THE cut shown herewith shows an eutirely new saw-mill design
just completed by Chandler & Taylor Co., of Indianapolis,
Indiana. This company has long been identified with the manufacture
of saw-mill machinery, and their mills are already
familar to our readers, but within the present year they have
entirely remodeled their line, adding strength and durability to
many parts, besides the adoption of all the improvements
known in the new milling industry.
The leading features given to this, their latest design of mill,
are : A large mandrel with self-adjusting, self-oiling boxes ; an
extension shaft with clutch coupling aud lever and independent
boxes which relieves the mandrel of the pull of the main belt,
giving increased space for off bearing and furnishing a means
of driving edges, cut offs, aud log hauls, etc., without the intervention
of a line shaft.
The Heacock patent belt feed works is provided with all mills
of this design, which aside from the independent steam feed is
the simplest and most powerful feed devised. With this arrange­
ment the feed can instantly be changed by means of a single
lever shown at the sawyer's position in the cut to give a feed
from no feed to four and one-half inch feed on the medium
mill, and to from nothing to seven and one-half inch feed on
the heavy mill.
The patent right for this valuable feature is owned by this
company, and from practical tests made it has been demonstrated
that'the addition of this feed to mills already in use
has increased their daily capacity from one to two thousand
feet.
A choice of carriage propulsion is given and can be either
made by track and pinion or wire cable, the latter being usually
preferred where long timbers are to be sawed. The carriage is
sustained by large track wheels with axles extending from side
to side of carriage, and these wheels in turn rest upon a track
of steel made of the same shape as is used in railways.
The admirable arrangement for sustaining the top saw man­
drel is also to be noted : The top saw mandrel beiug provided
with adjustable self-oiling boxes and devices whereby the teeth
of the upper saw are made to cut under the bark aud carry the
saw dust out of instead of into the kerf.
The above, together with the general details and arrangements
of the parts of the whole outfit, makes a thoroughly complete
and substantial mill in every particular.
Four sizes of these mills are built, all made after the general
design shown in the cut aud covering the range iu capacity from
the smallest to the largest.
THE Ball N: Wood Company, of New York, are kept very
busy in filling orders for their Compound Engines. In the
past twelve months nearly one-half of their entire business
has been for engines of this type. Five years ago twenty simple
engines were built to one compound, and it is interesting
to note these changes in trade requirements as steam users
find it necessary to give more attention to economy in fuel.
Mr. Ball, Vice-President aud General Manager of this company,
has recently invented and taken out patents for a new
valve for use in Compouud Engines, which has added a distinctive
feature to the Ball & Wood Engine, and made it peculiarly
desirable in sections where fuel is expensive. This com­
pany is now filling contracts for a large number of their 300
H. P. Compound Engines, and is about to issue a new catalogue
illustrating their more recent improvements in steam engine
construction.
THE co-partnership heretofore existing between John A. Mil-
liken and Edward D'Amour, under the firm name of Milliken
& D'Amour, has been dissolved aud the business will be
continued by John A. Milliken at 2 Dutch Street, New York
City.

THE DEAN STEAM PUMP.
The accompanying cut shows a new design of pump by the
Dean Bros., of Indianapolis, Iud. The pump is intended for use
in mines, shafts, wells, quarries, pits or reclaiming flooded mines
or in any place where a portable pump is required. It is a
single cylinder, direct acting pump, occupying but little space.
Being double acting it throws a continuous streaui ot water,
and can be operated suspended by a hoist or attached to side ol
shaft. In either case it works equally well.
It has our new noiseless valve gear with adjustable stroke,
which has proven to be the best device yet invented for operat
ing the valves of steam pumps. They are made with a view to
withstanding the rough usage to which they are subjected and
are suitable for permanent use in mines. When requested the
water cylinder is made of guu metal or bronze to resist the
action of bad mine water. The pumps are made in a variety of
sizes and combinations.
All pumps are made under consecutive numbers aud are
thoroughly tested and inspected before leaving our shops.
The pump shown in illustration has steam cylinder, 14 inches
diameter; pump cyliuder, 8 iuches diameter ; stroke, 12 inches;
suction, 6 inches; discharge, 5 inches.
THE Wagner Electric Manufacturing Company of St. Louis,
Mo., have put a motor on the market iu which the armature and
field coils can be removed without disturbing the pillow blocks
The field coils are wound on spools. The armature wire is completely
imbedded in iron core. All the bearings are self-oiling,
aud all the bearings aremouuted on uuiversal ball sockets. The
self-feeding brushes need adjustment only three times a year
and can be changed while the motor is running.
ENGINEERING MECHANICS. [December, 1892.
THE Lukens Iron aud Steel Co., of Coatesville, Pa., has produced
the largest steel plate ever rolled in this country ; dimensions
', inch thick, 113 inches wide aud 400 iuches long.
THE O-lobe Steam Heater Co., of North Wales, Pa., are
making boilers for the Hoboken, N. J., post office, Louis Reh
man, of Newark, N. J., contractor, the stack to which wdll be
built to ascend through a ventilating flue, and the heat radiat­
ing from the stack will be takeu from the flue and used to heat
part of the building.
REAGAN CC CO., 1028 Filbert St., Philadelphia, are putting in
auother of their Water Circulating Grates in The Times building,
wdiere they already have two others.
They have also equipped McCallum & McCallum's Carpet
Mills at Wayne Junction and the Ripka Mills at Manayunk with
the Reagan Water Circulating Grate.
THE Barr Pumping Engine Co., Germantown Junction, Philadelphia,
has recently closed a contract for a 2,000,000 gallon
pumpiug engine of the duplex compound condensing type, for
the city of Bridgeton, N. J., and has just completed a 4,000,000
gallon pumping station at Powellou Avenue station, Philadelphia,
for the Pennsylvania Railroad.
THE A. B. See Manufacturing Company of Brooklyn have a
new form of electric elevator in which the switch is controlled
automatically and the motion of the elevator is controlled by
the ordinary hand rope. The attendant pulls down ou the elevator
rope to ascend, which rotates the wheel, and transmits
motion to the switch, thence to the contact arm of the rheostat
which slowly cuts out resistance. The motion starts gradually
but quickly gathers speed. The Perot motor is used. The
mechanism occupies very little space.
THE Deane Steam Pump Co., oi Holyoke, Mass, is about to
start a Compound Duplex Pumping Engine iu the elevator service
of Messrs. Stern Bros, dry gcod store on 23d St., New York,
to run 23 elevators.
It is the largest pump doing that kiud of service in New
York.
The new five million gallon compound condensing pumping
engine which they are building for the town of Graveseud, L. I.
will be ready to start in about two weeks.
THE tool-works of Fayette R. Plumb, at Frankford, were
damaged to the extent of about 170,000, by a fire which broke
out in the stock-room on the night of Saturday, Nov. 5th.
The entire stock of finished goods was damaged so as to require
refhiisbing, among the lot beiug about |i6,ooo worth
which were all packed ready for shipment.
The loss which was fully covered by insurance, has been
adjusted, and with his characteristic energy Mr. Plumb has
fitted up a temporary stock-room in the basement, which will
be used while the burned one is being repaired, and is getting
out a stock of new goods as rapidly as possible to fill orders.
MARIS & BERKLEY, 2343 and 2345 Callowhill St., Philadelphia,
have just completed two 8-tou jib cranes for the Alan Wood
Co., Conshohocken, being the third order from that Company,
and have shipped oue 15 ton rope drive crane to New Orleans.
They have orders on hand for eight traveling cranes and two
jib cranes for different sections, some as far west as Michigan,
aud for over 4,000 feet of overhead track with trolleys, hoists
aud turntables for The Boston and Montana Copper and Silver
Mining Company at Great Falls, Montana.
They have added quite a number of new tools to their plant
aud having entirely outgrown their present quarters expect to
move to a larger building some time during the coming spring.

December, 1S92.] ENGINEERING MECHANICS. 33 1
SELF-CLOSING WATER GAUGE
The accompanying illustration shows a new water gauge
wliich acts automatically, clearing itself of deposits, and which
closes if tbe class is broken. Behind each valve is a small
chamber in which is a disk with spiral flutes on the outer sur­
face. Wheu the valves are closed these disks are forced by the
extension of the steins shown back to the rear of the chambers,
where they remain until an extra current of steam or water,
such as would occur bv the breakage of the glass, causes them
SELF-CLOSING WATER GAUGE.
to be driven forward and seated, thus preventing tbe further
escape of steam or water.
Supposing there is a deposit of lime in the lower valve cham
ber, the upper valve admitting steam is closed, and the pet
cock at tbe bottom opened. Then by partially closing the
water valve tbe disk is allowed to approach its seat, aud as it
does so it is rapidly revolved by the escaping water acting upon
the spiral flutes, and thus the deposit is cut out all the way to
the seat by gradually opening the valve. The gauges are highly
spoken of by engineers who have used them. They are made
in various sizes by the Ashley Engineering Company, 136
Liberty street, New York City, a full stock being carried.
AMONG recent contracts taken by the Buffalo Forge Co. for
the Buffalo " Hot Blast" Heating and Ventilating System, may
be mentioned one for Messrs. Jackson & Sharp Co., Wilmington,
Del for 140" fan and 75 00 &• heater ; also Shaw Stockiug Co,
Lowell -Mass. , 130" fan and 6500 ft. heater, State University
Buildings at Columbus; two (2) 100" fans for forced draft duty
for the Edison Illuminating Co., New York ; "Plot Blast " ap­
paratus for the Minneapolis Market Buildings ; for the Flour
Exchange Office Building, requiring 140" fan and 7500 ft.
heater, same city ; shops of the St. Paul & Minneapolis R. R,
Omaha Neb. ; eight (8) public school buildings in Salt Lake
City, Utah.
They have now on the press a catalogue containing 2SS pages,
to be bound in library form, descriptive of all goods of their
manufacture, which will be forwarded to any address sent.
MR. E.J.WOOD, consulting engineer of 243 Broadway, N. V,
is introducing to power users the appliances shown in Figs. 1
and 2. It is a simple combination of a pulley with a registering
device and intended to be attached to a shaft, or a machine,
indicating the power being used as well as registering it.
Description.—Fastened to the arms of a pulley is a cast ring
which has wrought iron cups to receive the ends of two springs ;
the other ends of the springs are received by cups cast onto the
ends of two arms fast onto the shaft ; on the hub of the arm is
a circular plate with a toothed periphery Fig- 2 which gears
with a clock.
To the face is fastened a diagram card over which moves a
pencil carried by an arm attached to the arm, when the springs
are compressed in proportion to tbe resistance offered by the
FIG. 1.
FIG. 2.
pulley, the peucil is moved a corresponding space towards the
centre of the card, which being revolved by the clock gives the
power diagram as shown iu F'ig. 2. A dash pot prevents an
excessive oscillation of the pencil.
The appliance is made in halves so that it may be applied to
any pulley.
The cut shows tbe cups cast onto the amis of a pulley, so as
to make the description plain.
MR. G. L. PORTEI', Master Mechanic of the Pennsylvania
Companv at Fort Wayne, increases the efficiency of elliptic
springs under tender trucks by a device which reduces the
length ofthe supporting portion of the spring from 20'+ inches
to 17'4 inches, thereby increasing its stiffness when loaded.
The point of sujjport is transferred from the outer to the inner
end of the section of the casting which is located between the
springs, and which at the outer end is 1 G in long and 1 iu.
thick, and at the inner end, 1 G 111. thick. When the spring is
compressed, and before the inner leaves are straight and parallel,
the poiut of support is transferred from the outer to the
inner end of the casting, reducing length of spring 3 inches,
and thereby stiffening it.

332 ENGINEERING MECHANICS. [December, 1S92.
NELSON'S FEED WATER HEATER FOR MARINE BOILERS.
The need of some reliable and independent apparatus of a
simple character for heating feed water for marine boilers has
long been felt, and the illustration herewith shows such an apparatus,
the invention of Elihu Nelson, Mortimer Building, II
Wall Street, New York. The inventor takes a portion of the
main exhaust on its way to the condenser, and circulates it
through the system of pipes as shown, the reheated water being
taken from the coils by the pump shown on the right and
forced into the boiler. The water to be heated is takeu from
the condenser by the air pump as usual, and raised into the
separating tank showu in section, where any oil orgrease which
is in it floats aud may be removed, the purified water only going
into the second receiver, or tank, before being sent through the
heating coils. Provision is made for cutting off the heater entirely
by valves, as can be easily seen upon inspection of the engraving.
The upper course of the heating coils is shown in section,
giving a clear idea of the course of the steam and water ; it
should be mentioned that the end of the steani pipe where it
enters the " goose neck," so called, is a steam tight screwed
joint, so that no dead water or absolute contact of steam and
water occurs. It is asserted that this heater will raise the
temperature of the feed water to within one or two degrees of
the heat of exhaust; supposing this to be as low as 15 lbs.
above the atmosphere, or 31 pounds absolute, the heat of the
feed water would be 214 0 . Address the inventor as above.
"FACTS ARE STUBBORN THINGS.'
In June, 1874, in Dunkirk, N. Y., two young mechanics, oue
a tool maker in the shops of the Brooks Locomotive works—
the other experienced in Marine, .Stationary Engine, and Rolling
Mill work, commenced tlie manufacture of Twist Drills
and Reamers. They were Americans, and believing that Americans
could make as good steel as any in the world, they adopted
a brand of American Steel for their tools and have used the
same brand ever since. They had oue lathe, one milling
machine, and hired one man. In September, 1876, they moved
to Cleveland, Ohio, rented the lower floor of a new building,
No. 23 Columbus Street, built several milling machines, bought
new tools, hired more men, and hustled themselves. They
worked ten hours a day in the shop and wrote up their books in
W&a
the evenings. They did their own tempering—designed and
built their own machinery, and turned out tools that mechanics
'wanted. Their business grew rapidly, and they soon filled
their shop with machinery and men. In June, 1879, they moved
into a three-story brick building, built for them, Nos. 24 and 26
West Street, occupying the whole building. Having more room
they systematized their work, and studied how to make the
best goods at the lowest possible cost. As they reduced the
cost of manufacturing, they reduced the price of their tools.
By fair aud liberal dealings they made friends of their customers.
Their business grew so fast, that in 18S8, they were
forced to look for more commodious quarters, and rented a new
brick block, three stories high, 100x45 feet, built expressly for
them, aud designed to accommodate their special line of work.
As their business increased, and they manufactured in larger
and larger quantities, they invented and introduced many
labor-saving devices and machines, which still further reduced
the cost of their tools to their customers.
In 18S6 the bottom price to the largest jobbing houses was
25 per cent, off the list. Now it is—well you know what you
are paying for them. Believing firmly in the old proverb that
" you had better go slow and learn to peddle," they had not up
to this time invested any money in laud aud buildings, but in
1890, as they needed more room, they bought the lot 100x333
feet on which their building stood, and in the spring of 1891,
built an addition, three stories high, 45 feet wide by 150 feet
long, more than doubling their floor space.
They rearranged their whole plant, put in a new lot of
machinery of their own invention, built new tempering and
annealing furnaces, aud now have the best equipped factory for
their line of goods in the world. All the old machinery has
been sold or broken up, and they have uot a single machine in
use now that they had ten years ago.
This, in a few words, is the history of the Cleveland Twdst
Drill Co. The management has never changed from the start.
We are practical men and thoroughly understand our business.
We know what you want, and how to make it. You can buy
cheaper tools than ours, but you can't buy better ones. We
carry an immense stock and can fill your orders promptly.
There is but one Cleveland Twist Drill Co, and it will pay you
to write to them. Their office and factory is on the corner of
Lake and Kirtland Streets, Cleveland, O.

December, 1S92.] ENGINEERING MECHANICS. 333
THE Field Electric Co, of Buffalo, New Vork, after con­
siderable investigation, are wiliiug to undertake to construct
trolley boats for the Erie Canal and to guarantee a speed of 12
miles per hour. The Waddell-Entz system of Storage Battery-
cars will be used ou the Second Avenue Line, New York.
THE Peerless Rubber Mfg. Co, 15 Warren St.. N, V. have
doubled the capacity of their w-orks, located at New Durham,
N. Y. The business of this Company has expanded verv
rapidly under the management of President E. L- Perry and
Chas. H. Dale, general sales agent. Their goods arc meeting
with favor.
THE Stirling Water Tube Boiler Co, of Allentown, Pa, have
taken the following orders at Philadelphia, Pa, tlirough their
ageut, Mr. Merllv Linn, Nov. I, 1500 H. P. boiler for the
McCahan cc Co.'s Sugar Refinery ; 300 II. I" boiler for Coxe
Bros. & Co, at Drifton, Pa.; 500 H. P. boiler for Ionia Barb Wire
Co. at Allentown, Pa. The Company has a good deal of new
work in sight.
MR. CHAS. A. DIXON, formerly manager of The Whitehill
Eugine and Picket Ice Machine Works, Newburg, N. V, has
taken the old shops of Wm. Wright and is tearing things out
remodelling and putting in new tools for making Corliss I'ngines
and general machinery.
He expects to be in shape to do a large business about Jan.
15th, 1893.
FREDERICK SARGENT.
MCCHANICAL »ND ELEOTRICAL
ENGINEER.
THE LAND OF SUNSHINE.
A UNIQUE COUNTRV WHERE THE SKIES ARE ALMOST NEVER
CLOUDED, WHILE THE AIR IS COOL AND IIRAC-
ING, LIKE PERPETUAL SPRING.
As an anomalous southern resort, by reason of the fact that
there oue may escape summer heat no less than winter cold,
New Mexico is rapidly becoming famous. Averaging through­
out the entire territory 5,600 feet in altitude above sea level,
and characterized by dry air, which, unlike a humid atmosphere,
is incapable of communicating heat, the temperature in mid­
summer remains at a delighfully comfortable degree through
the day, and at night becomes invariably brisk and bracing.
The sunshine is almost constant, yet the most violent out-of-
door exercise may be undertaken without fear of disstressful
consequences. Sunstroke or prostration are absolutely unknown
there.
It is an ideal land for a summer outing. Its climate is
prescribed by reputable physicians as as a specific for pulmon­
ary complaints, and the medicinal Hot Springs at Las Vegas
are noted for their curative virtues. The most sumptuous
hotel iu the west, the Montezuma, is located at these
springs.
Write to Juo. J. Byrne, 723 Monadnock Block, Chicago, for
"The Laud of Sunshine," an entertaining and profusely illus­
trated book descriptive of this region, the most picturesque
and romantic in the United States.
OFFICE OF
D. H. BURNHAM, CHIEF OF CONSTRUCTION,
WORLD'S COLUMBIAN EXPOSITION,
JACKSON PARK,
CHICAGO.
Nov. 2, 1892.
Ball & Wood Company-,
15 Cortlandt St** N.Y.
Gentlemen:
I have the honor to stats that your engines furnished the entire
lighting to Manufactures & Liberal Arts Building during the dedication
oeremonies of the Worlds Columbian Exposition. The service
rendered was very satisfaotoryi and considering that the engines were
taken directly off the cars and inmediately started on the work,
the results obtained speak well for the perfect condition in which
you turn machinery out of your shops,
We feel indebted to you for the very valuable contribution you
have made to the acknowledged success of the dedication ceremonies.
You understand, of course, that the building above referred to is the
one in which the ceremonies took place;
Very truly yourar,
> y^-*3yAis

Ill ENGINEERING MECHANICS. [December, 1892.
KEYSTONE LUBRICATING GREASE
ECONOMICAL, PURE,
CLEAN, SAFE.
One pound guaranteed to go
further, and do better, than three
gallons of any other lubricating
oil. It is used by thousands of
the largest firms in this country.
BRASS AND IRON CUPS FUR­
NISHED FREE OF CHARGE.
Keystone Lubricant
CAN BE OBTAINED
ONLY FROM THE MANUFACTURERS,
THE KEYSTONE LUBRICANT CO., 209 N. Third St., Philadelphia.
THE NATIONAL FEED WATER HEATER.
A BRASS COIL HEATER delivering Water to the
Boilers at 212° Fahrenheit.
400,000 HORSE POWER NOW IN USE
PRICES LOW. SATISFACTION UNIVERSAL.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE.
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
SEPARATORS
FOR REMOVING WATER, OIL, GREASE AND IMPURITIES FROM
STEAM.
THE COCHR AN ESEPARATORS,HORIZONTALOR VERTICAL
ARE BEING INTRODUCED ON THEIR MERITS, VIZ.: EFFICIENCY AND PRICE.
MANUFACTURED B/ SOLD ON 30 DAYS TRIAL.
HARRISON SAFETY BOILER WORKS,
GERMANTOWN JUNCTION, . . . . PHILADELPHIA, PA.
THE BALL & WOOD ENGINE,
SIMPLE, COMPOUND AND TRIPLE, HORIZONTAL AND VERTICAL,
AS BUILT BY-
THE BALL & WOOD CO.,
Office, 15 Cortlandt St., New York,
Is superior in DESIGN. FINISH and WORKMANSHIP In REGULA­
TION and ECONOMY it has no equal. Built with new tools, from
new patterns, and after long experience, it should and
DOES mark the latest step in steam engineering.
REPRESENTATIVES :
W. B. PEARSON & CO., Home Ins. Building CHICAGO, ILLS.
W. A. DAY, No. 128 Oliver Street, BOSTON, MASS.
HYDE BROS. & CO., Lewis Block, PITTSBURGH, PA.
W. M. PORTER, Hodges Building DETROIT, MICH.
T. W. ANDERSON HOUSTON, TEXAS.
F. H. WHITING DENVER, COL.

INDEX FOR
"ENGINEERING MECHANICS"
Aluminum, its manufacture and uses
PAGE
128, 166
Proceedings American Society of
Media 11 ical Engineers.
Notes on water power—Fibre graphite bearings—Moulding
machine—Novel fly
wheel 171
Experiment with aluminum—Compounding
centrifugal and load governing . . . 172
Refrigerating machine—Steam distribution
—Electric railway and steam roads . 173
Experimental locomotive—Steam engine
efficiency—Tests of a portable boiler . 174
Treatment of structural steel—Measurement
of power—Utilization of power of
waves—Two, and multi: cylinder engine
.'.... 175
New process of cutting cams 315
Strains in rims of fly wheels 317
Test of pump receiving water under pressure—Variable
speed power transmission
321
Analysis of a shaft governor 322
Book and Catalogue Notices.
Life of Robert Fulton 23
Tests of Manganese Bronze, Cramp .S: Sons 112
Fine Tools, Starrett's Catalogue 114
Rue Injector Catalogue—Buffalo Forge Co.
Catalogue 144
Brush Electric Company Catalogue . . . 158
Daniel Kelly Catalogue—Palliser's Specifications
176
Jos. Dixon Crucible Company Catalogue . 177
Engineering Mechanics, copies wanted—S.
D. Button Catalogue—Hand Book of
Electro-Chemical Analysis, Edgar F.
Smith—Electricity Simplified, Sloane—
Stadia and Earthwork Tables, Prof. J.
B. Johnson 198
Clayton Air Compressor Works Catalogue . 270
Text Book of Experimental Engineering,
Carpenter 274
Pamphlet on Platinum, Baker & Co . . . 296
Buffalo Forge Co. Catalogue 331
The Constructor.
Conical gears 12
Hyperboloidal gears 13
Spiral gears 15, 3°
Spiral bevel gears 31
Globoid spiral gears 32
Pitch and face of gears 34
Dimensions of gears 37
Ratchet gearing 58
Friction ratchets 66, 88
Releasing ratchets 90
Checking ratchets 91
Continuous running ratchets 92
Escapements 95. I2 °
Tension Organs 122
Cord friction 148
Wire rope 15°
Chains 153
Chain drums and sheaves 156
Belting and pulleys 180, 202
Rope transmission 203, 224, 246
Chain transmission 249
Strap brakes 252
Pressure organs 276, 305
FOR 1892.
PAGE
Hydraulic tools 308
Pumping machinery 309
Fluid transmission at long distance—Rotative
pressure engines 313
Diagrams, formulas and tables for engineers
and architects 2
Editorial Paragraphs.
Change of name—Higher initial power of
modern powders—Compound locomotive
Great Britain—Railroad activity in
foreign countries 2
Chicago building increase—Baldwin Locomotive
Works Tests—Gov't civil engineers
and politics—Next session of
M. E. Engineers—English ship builders
and whale-backs—English engineers
and high speed locomotives—The
French navy—Foreign steam pipe improvements—Nickel
steel in Great
Britain 29
Rapid transit in the U. S.—The parabolic
roof truss—Naval tactics and quick
firing guns ............ 57
Siege preparations in Paris—Triple expansion
engines—Salt in the electrolitic
process—Tool grinding—Marine Engineering
Dept., Cornell—New wire
rope—Harvey steel in the navy ... 87
Electric stamping machines —F'rench railway
fares—Harveyizing steel rails—A
Siberian R.R.—Brittle Condenser tubes
—Speed of air entering a vacuum—
African civilization—British colonies
and protection—Ventilation in Baltimore
tunnel—Indian water power and
aluminum—The 10th U. S. census and
labor statistics 117
Carbon in Steel—Philadelphia and the Trolley—Diamond
teeth in stone saws—
600 H. P. refrigerating machine —
Triple expansion locomotive—The
Transandine Railway—Locomotive for
mountain service IiS
Electric motors in factories—-Cold galvanizing—Boilers
of English naval ships—
Elevators in Chicago Masonic Temple
—Nickel-carbonyl High potential
transmission The Peyton - Jordan
pavement—East River bridge—Oroya
R.R. extension—Electric supply for
large cities IiS
Candle power of electric lights—Increase of
lighting power of arc lamps—The
storage battery in car propulsion—B.
cc O. R.R. service 147
Heilman electric locomotive system—Sand
filled hollow rails—Electric car lighting—High
voltage currents—Chronographs
Breech mechanism High
grade iron—Arc lights—Fansa Dam,
Bombay Fire protection, electric
launch and signal system at the Columbian
Ex.—Irrigation in the West—
Optical pyrometer 177
Notes from Great Britain—Peculiar electric
lighting in Batignolles tunnel, Paris—
European R.R. Congress — Steam ship
speed and shallow water—A wonderful
English engineer—Telephone exchange
improvement—Solar heat—
Nicaragua canal—Leaking boiler tubes
—Metallurgy of steel 178
Underground cable and electric roads—Gold
plating platinum stills—Gas buoys in
the Clyde—Hydraulic cement . . .
A corrugated diaphragm—A great aqueduct
Electric underground R.R., Berlin—Cement
microbe—Reinforced cement floors—
Politics and engineering Thermic
value of fuel—R.R. road-bed improve­
ment—Closed conduit for electric lines
—Speed of vessels and shoal water .
Breath figures—New beam formula . . .
The Mersey River tunnel—Poor's Manual—
Measurement of internal electric jesistance—Record
of naval construction .
The Puritan and Terror smoke stacks—
Mining Engineers' meeting—Rock cutting
dredge—Baldwin engines at the
Cape of Good Hope—Cheap labor —
Portable coke oven—Papers of Liverpool
Iron and Steel Institute—R. R.
building in Great Britain—Harveyized
plates in England—Educational needs
—Engineering exhibit at the World's
Fair
Chinese Immigration—Crude naval engineering—Micro-copical
chemical examinations
— The Campania — Compressed
Timber
London watei supply—Engineering cripples
Sedan and the new military era—The
Zone passenger fare system—Bethlehem
Steel Works armor plates—Trade
Unionism in England—Laboratory of
physical research—Sprague and electric
propulsion—Acceptingbids—The Paris
199
200
221
222
223
'43
243
Inland Water Congress 244
Hydraulic Elevators—Saw sharpening—
The clinograph—Corliss engine speed
—Steam engine efficiency—The Great
Eastern and modern vessels—Disposal
of refuse—Emigration from Europe . 245
Search lights at the World's F*air—Enameling
metals—Guns for the new battle
ships—Over tight belts—Alloys by
compresston — Shrinkage stresses in
steel castings — English iron trade—
Braine electric tramway system—Crystallization—Rules
for lake vessel build­
ing—Coal cutting machinery ....
Notes from England—Canal extension—
Breaking of rolls—Alloy for tools —
Text book of experimental engineering,
Carpenter—McKinleyism in England
—Locomotive construction
Sewage disposition — Electric pyrometer .
273
274
275
Duluth ship canal tunnel—Eleclric belt line
for Buffalo, Pittsburgh and Cleveland—
Columbia River ship canal—Hydraulic
mining—Earning power of electric
roads—Paris electric conduits—Tele
phone wires in Cincinnati, 0.—Colorado
River Irrigation—Furnace steam
drill—European armor trials—Fuel gas
measurements—Large steamer for the
Sound service—New engine governor
—Ventilation of Baltimore tunnel —
Furnace by-] .roducts in Germany—New
York and Chicago telephone—Vertical
shaft power transmission 303
Uniformity in street rails—Indiana natural
gas—Screw-propeller—Compound locomotive,
John Player's—Municipal ownership
of street railways 304

Electrotechnics,
Calibration of Ammeters 5
Universal Galvanometer ... 6
Voltmeters 7
Resistance—Wheatstone's Bridge 43
Measurement of Resistances 79, 103. 159
Construction of Resistance Boxes 160
Condensers 190, 210
Electric Meters 211
Self Induction 238
Eiectro Magnets 260, 293
Eminent Engineers.
Corthell, Simon Lawrence io3
Whittemore, D. J 137
Chanute. Octave 157
Grogan, Frank \V 207
Strobel. Chas. Louis 240
Hunt, R. W 262
Burr, Prof. Wm. H 270
Graphical Statics.
Funicular Polygon 17
Conditions of Equilibrium 19. 46, 77
Decomposition of Forces 100
Arch Thrust . 102, 130
Elastic Forces 130, 161
Polygon of Pressures 187, 208
Arch Hinged 234, 25(1
Suspended Arch 288
Tlie Marine Engine.
Laws of gases 9
Law of mechanical theory of heat 10
Different conditions of steani 11, 40
Volume .md pressure of mixed steam and water .41, 68
Determination of moisture in steani 98, 134
Paragraphs and Uncontinued
Articles.
Liquid oxygen—Furm of vessel hulls — Penna. R.R.
lines 21
Engine H P. of tlie world—The Portelectric Co.
Railway —Electricity direct from heat —Labor in
England — Parabolic roof truss, correction of
formula—An Austrian puddling furnace — World's
Exposition Tower 22
Ltad coated iron and steel plates—Aluminum launch
—The Swiss rifle—Stone bridges—Khojak tunnel,
India 23
British Institute of civil engineers, list of subjects for
discussion—Test of pipe coverings — Electrical
engineers' dinner 29
A California palace—Atch ison, Topeka & Santa Fc
R. R. System , 45
C. B. & Q R. R. system—Baltimore & Ohio earnings—Canal
projects 46
New journal box—Montana Society Civil Engineers
—Bridge stresses of French Gov't—Testing gas
in mines 49
Riveted joints and diagrams—Technical Soc. of the
Pacific Coast Compound locomotive, the largest 50
English cruiser Edgar—Detecting flaws in metal . . 52
Alternate current motors 54
Engineers' Club, Phila., list of officers 5b
Berlin electric railways—Mersey River tunnel ... 57
Criticism ot parabolic roof truss 71
Steam condensation 72
Beriin electric railways 73
Engineering programme for the Columbian Exp'sition 81
Sewer pipe, strength uf vitrified 83
Petroleum bulk steamers 85
French torpedo boat, trial of 86
Niagara Falls, utilization of ioq
Dynamo machines H3
Phila. Engineers' Club—Technical Soc. of the Pacific
Coast -New York and Chicago 'Phone .... 114
Parabolic roof truss—Trial of Sims-Edison torpedo . 1 is
Bethlehem nickel steel platen—Aluminum coins . . 116
Parabolic roof truss—Belting tests—Large belts . . 127
Attending church by 'phone 120
Specific hear of steam—Next! Water-proofing
masonry 136
Cheap aluminum j ,7
Military balloons—Steam engine improvements —
Measuring distance by sound—Engineer Melville's
report 138
Steam turbine —Flexible metal tube—Large band
saw —Balloon, Prof. Wise-White light Semaphore—Compensation
for labor unit—Increase
ofthe Britishnavy 130
Iron and coal in Colorado - Propeller bosses — Novel
motor 143
Tobin bronze—London and Paris phone 144
Storage batteries— Soo H. P. belt—World's Fair
lights—Electric welding—Car propelling, alternating
145
IXDEX FOR ENGINEERING FOR 1892.
PAGE
PAGE
PAGE
Hydraulic machinery for swing bridges—Locomotive
valves—Numbering hours from 1 to 24—Fast
train on the N. V. Central—Paris underground
railway, electric—Power brakes on freight cars—
Electric fog signal 146
Graphite for pipe joints 158
Cylinder condensation . . 170
Submarine mine, 111 176
Nicaragua canal—Steatite—Alternating currents-
Search lights—Electric lights for omnibuses—
Maxim Hying machine — Punching steel—Petroleum
launches —Haswell electro-browning pro­
Gaskill compound pumping engine 213, 236
Elementary forms of pumps 258
Belt driven forms of pumps 290
Trade Notices.
Sphinx adjustable drawing table—Equitable Building,
Atlanta, Ga
23
Westinghouse engine governor
24_
Spreckel'tJ sugar refineries —Edison Co., Paterson,
25
N- J
33i
Buffalo Forge Co, blowers 28, 143, 328
cess—Electric railway in London—Solidified
petroleum fuel—Oerhken storage battery—European
notes—Screw propellers—Acid in storage
batteries—Wood pavement in Paris 193
Ball & Wood Engine Co. ..... 28, 176, 199, 221, 270
303
Laidlaw, Dunn & Co 23, 54, 85, 115,
143
B. & O. Railroad Co 28, 112, 197, 242, 28
James W. Queen & Co 28, 140, 144
Transmission ol power in warships—Canalization in Shultz Belting Co
269
Europe New colliery fan—Sulphur in pig iron— Wilmot & Hobbs Mfg Co 28, 33°
W haleback steamers 104 Wm. Cramp & Sons—Manganese bronze . 111, 221, 270
Vibration of steam vessels —Revival of American
shipbuilding 195
Temperature in locomotive smoke boxes 197
Monier iron and cement construction 199
Reagan water and Shaking grates 127, 175,
5
Rue Injector Co 143,
Baldwin Locomotive Works, large engine, 50 power
system
A great aqueduct
Luxury ot modern railway travel
200
2t9
207
Ball & Wood engine diagrams
Mt Morris Electric Light Co., N. Y
Prince Edward Island tunnel
Hydraulic experiments
Compressed air as a mechanical motor
209 220
215 240
Jos. Dixon Crucible Co
Sawyer Man Electric Co., engine room
Babcock & Wilcox Boilers
85,
115,
'I esting gases in mines—Tobin bronze -Gelatin Dy Morris Machine Works, Westinghouse Engine and
namite—Electric sparks and petroleum vapor .
Centrifugal Pump
A Belgian electric railway
Question on shafting
Bartlett, Hayward & Co. gas holder for World's Fair
Southwark Foundry Co. and Spring Garden Water
Graphite, uses for 242
Electric locomotives—Test of Hydraulic ram—Large
aluminum works 243
Works
Edison Triple Expansion
Generators
Engine and Multipolar
Foundations, improved method of laying—Electric
riveting machine 254
Steam-blast in combustion—Institute of Mining Engineers,
Great Britain 2:5
Boiler corrosion—Loss of heat fiom uncovered pipes 263
England and protection—English electric units—
Compound locomotive in France 266
Pittsburgh Reduction Co. (removal)
Priestman Oil Engine—Curtis & Wheeler Woodbury
Steam Enguie
Electro Dynamic Co., Phila., Electric Drills ....
Walker & Kepler. Electrical Contractors, Steamboat
Plants
Montreal to Lake Erie by water—Proposed monster
telescope—British Institute of Civil Engineers,
subjects for discussion 267
Canals in Europe—Portland cement—Cutting-angles
for lathe tools—Paris prize papers on electricity
—Canals and railroads on the Isthmus .... 268
Railways of the globe—Electric power distribution
•86
on war vessels .... 26Q
Herculite—[Magnetic vibrations , • . . 271
Electric locomotives—Aluminum and glass building 287
—Curve experiments 273
Wire rope transportation—Austrian mine inspection 285
Vessel smoke stacks 100 feet high—Artesian wells in
the West—High speed compound locomotive,
Penna. R.R
The Zone tariff—Aluminum vessels for domestic use *95
—Asphalt pavement—Some famous ships—New
French cruiser
Aluminum in the foundry—Am. Institute of Mining 296
Engineers—Smaller naval vessels—Water and = 97
light supply, Madrid, Spain—Electric conservatory
heating—North Atlantic currents—Spontaneous
changes in steel—Steel casting—Galloway
boilers—The Vesuvius
Engines and boilers In the navy
Colors from mine refuse—Belgian deep mines—Liver­ 299
pool elevated electric road—Removal of culm by
air blast—Mine explosions—Removal of sulphur
from iron
Lake transportation progress —Chicago foundations
Canals and the railroads—Cast iron car wheels,
cracking of
301
C
57
5&
140
86
265
116
*39
141
142
14.3
M5
146
Ft. Wayne Electric Light Co—Kelly Bros. New
Grate Bar—Union Ry. Co.—Manapenny &•
Weaver, Anti induction Metal—Starrett's Best
Rule 146
H. Gr. Brooks (removal) 170
F. Schmemann, Pipe Dome 175
Magnolia Metal 176, 271
Daniel Kelly, Machine Tools—Van Duzen & Lift
Co., Loose Pulley Oiler —National Pipe Bending
Co . Heater 176
Atchison, Topeka & Santa Fe R.R. Co 158, 195
Cochrane Feed Water Heater 196
Burlington Route . . . .' 197, 242
Westinghouse Air Brake—Mo. Pac. R.R. Co. . . . 197
Browne & Sharpe Milling Machine — Ohio Machine
Tool Works 198
Thompson-Houston Elect Co.—Hotel del Coronado 199
Watertown Steam Engine Co, 209
Cameron Steam Pump 219
Barnes Water Emery Grinder 220
National Feed Water Heater—J. K Griffith's Stopper
for Steel Ladles
Builders' Iron Foundry—Riehle
221
Bros., Testing
Machine -Johnson SE Flad 221
Engineering Mechanics Binder 241, 300
Brush Incandescent Machine—Atlantic & Pacific
R.R. and Grand Canyon 242
J. C. Saxton, Nut Lock —Hartford Steam Boiler Insp.
Co. Report—Simonds Rolled Forgings—Yale &
Towne Co 269
Lodge & Shipley Machine Tool Co 271, 326
Schneider & Co., Creusot, Armor Plates 271
Schuylkill Foundry and Machine Works, Water
Tube Boiler 272
Mortar Carriages, Builders' Iron Foundry 294
Stone Flexible Shaft 297
Allhouse Automatic Coupler 300
Bolte Automatic Time Keeper—Phila, Blue Print Co. 302
II. W. Johns & Co., Fire Felt Covering 303
Crescent Phosphorized Metal Co. (removal) —Lucas
Ship Co.—Gen. Electric Co., New Motor—Mason
Air Brake & Signal Co—Greenfield Steam En­
329
gine Co.—The Thomas Coke Oven—Fraser &
Chalmers, Ore Sampling Machine 325
N Y Safety Steam Power Co., Sectional Boiler. . 326
Newark Machine Tool Works, Vise 327
Hayden & Derby Mfg. Co., Injector 328 330
331
Chandler & Taylor, Saw Mill— Milliken & D'Amour,
dissolution
Dean Bros., Steam Pump—Wagner
332
Electric Co.,
Motor—Lukens I. & S. Co.—Globe Steani Heater
Co.—Barr Pumping Engine Co.—A. B. SEE
Mfg. Co., Electric Elevator—Fayette R. Plumb,
Tool Works—Maris & Buckley, Cranes .
Ashley Engineering Co., Water Gauge . . .
Nelson Feed Water Heater-Cleveland Twist I>rill
Co
Field Electric Co., Trolley Canal Boats—Peerless
Rubber Co.—Stirling Water Tube Boiler Co.—
Chas. A. Dixon, Engines, etc.—Montezuma
H t t l
° 333
Strains in continuous bridges—Displacement of horses
by electricity—W. U. Telegraph, capital increase
— European war—Railways in Palestine—The
Short gearless motor—Thermo-dynamics—Hypnotizing
experiments
Gold in Nicaragua — Popocatapetl electric railway
Gold in Colombia—Bethlehem armor plates—
Coal deposits — Farmers and canals—Sterilization
in Russia from forest destruction—Tools of the
pyramid builders —Railroads in Palestine—Influence
of light on trees ...
Pile driving—Sanitary effect ofthe cholera scare .
Boiler corrosion — Improved casting o{ bronzes, etc.
Fast time on tbe B. & 0 303
Smoke preventing devices—Reduction of Zinc-lead
sulphide ores —Naval architects and marine engineers—Testing
for gases in mines—Com. Folger
and our naval guns—Electric road at the
World's Fair —Phila. Engin'rs' Club proceedings 324
Trolley line consti uction 327
Power Register for pulleys—Tender springs .... 331
Pumps and Pumping Machinery,
WM. KENT.
Duplex Worthington pump 73, 105, 132 163
Duplex Hall [jump Iu;-
Notes on designs and proportions of parts . . . 191, 212

January, 1893.] ENGINEERING
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering.
Published monthly by JOHN M. DAVIS, at 430 Walnut St., Philadelphia
London Office, 270 Strand, D. NUTT, Agent.
SUBSCRIPTION RATES.
Subscription, per year $2 oo
Subscription, pei; year, foreign countries 2 50
PHILADELPHIA, JANUARY, 1893.
A LITTLE common soda, mixed with Portland cement, is a good
covering for steam joints, but is troublesome to mix and apply.
C W. WEISS, of New York, says he has used lava for gas
engine igniting tubes for eight months, and that it is practically
indestructible.
OWING to unforeseen delays Mr. Suplee is unable to furnish
more than three pages of " Constructor " matter for this issue.
The full complement will appear in February issue.
MR. A. E- HUNT, ofthe Pittsburgh Reduction Co., will not become
desperate over the report that a Dr. Meyer, of Berlin, has
discovered a process by which aluminum can be produced at
four cents per pound.
DREDGING machinery has been brought to a high state of
perfection when a vessel can transfer ten tons of earth per minute
from a depth of forty feet below the surface, yet such specimens
of workmanship are becoming quite frequent.
COP dyeing is another improving branch. This saves reeling
into hanks and re-winding, ten to fourteen per ceut. saving.
Special machines are being made by which the dye can fully
penetrate the yarn while ou the cop. This is a mechanical
rather than a chemical improvement.
THE electrolytic production of alkali and bleach is likely to
be very soon reduced to a commercial basis on both sides of the
Atlantic. The chief difficulty at present is that the cathode and
the diaphragm used have to be renewed too often for economical
results. The commercial inducements are tempting and the
electricians will surmount the difficulties.
A GERMAN inventor has made a gauge-glass which combines
the qualities of glass having two coefficients of expansion,
which greatly reduces the initial straius. This glass heated to
400 0 Fahr., will stand cold water without fracture, and when
heated in oil to 420° stood a plunge in cold water. These glasses
have been tried in locomotives successfully.
PROFESSOR KENNEDY might profitably try and renew the ex­
periments which led him to declare that, without exception, the
total engine friction is sensibly constant for varying loads, and
that if the brake horse-power and the indicated horse-power
were plotted, as functions of the load for a given speed, the two
lines would run approximately parallel with each other. Increasing
load means increasing friction as the power exerted
becomes greater, but this apparently reasonable axiom is not
sustained according to some experiments. There is need of
some inquiry in this matter.
ROBERT MCGLASSON, who writes much on the subject
of propeller screws, says: "The screws of the future must be
made capable of suiting variations of tide, current, wind and
weather, load and trim, the "human factor," and the depth
of water, etc. This can only be done on the vessel, and whilst
working. Effect it, and the saving will be great in every way."
MECHANICS. 1
IT is interesting to observe the activity in Southern European
cities, especially iu the direction of electric lighting, and of
power for tramways, in which convenient water power is being
generously utilized. The Edison Company is in the van,
suggesting and pointing out what can be done. In Milan,
that company has the option of using either overhead or under­
All Subscriptions for Great Britain should be sent to London. Price, 12s. yearly.
ground conductors, and, after one year's satisfactory trial, the
Entered at the Post-office in Philadelphia as Second-Class Mail Matter. entire street car service is to be operated electrically. At Geneva
aud other Italian cities, installations are taking place where
water power is abundant and reliable.
IT is remarkable how much "rule of thumb" work there is
iu matters pertaining to naval engineering, especially in the
devices adopted to overcome excessive vibration, which is the
bete noir of eugineers. The Portsmouth (England) naval experts
have coaxed, and threatened, and scolded the war ship to
indulge in less vibration. They put in a new set of triple expansion
engines and then made a better record for speed, but
the excessive vibrations continued even after the diameter of
the propeller was slightly reduced. An entirely new propeller
is now to be experimented with.
EVER since the construction of that engineering wonder, the
Forth Bridge, the conviction has become settled iu the minds
of advanced English engineers that the channel between England
and France would be bridged or tunneled. There are three
plans or schemes now before the engineering, capitalistic and
parliamentary worlds for consideration: the Tunnel scheme,
the Tubular scheme, which proposes the laying of a tube on
the chalk bed, covered with concrete, and, lastly, the Channel
Bridge scheme, the practicability of which is attested by high
English and Continental engineering authority. A new route
or bed has been selected, some three miles shorter than previous
surveys, methods of construction have been considerably modified
and important improvements founded on recently acquired
experience, have been determined upon. The longest proposed
span is 1640 feet. The estimated cost is $165,000,000. With a
toll of #3.00 per passenger, it is calculated the scheme will be
commercially successful.
SHIP-BUILDING will be one ofthe chief features ofthe British
collection at the forthcoming Chicago World's Fair, and the
Clyde will be specially well represented. The Fairfield Company
will make a fine display of models and plans of their crack productions,
including the new Cunarders. Not the least interesting
part of their collection will bean immense drawing showing
the longitudinal section of these new vessels. Messrs. Thomson,
of Clydebank, will have a collection, and it will probably be the
most varied of any, for their high-speed battleships, cruisers,
scouts, torpedo boats, torpedo destroyers, and merchantmen
will be represented. Messrs. Denny, of Dumbarton, too, will
have representations of their recent success, while dredger
models will be sent by several Clyde firms. Lord Armstrong's
firm, Laird of Birkenhead, the Thames Company, and Messrs.
Harland and Wolff will have interesting exhibits. The principal
Transatlantic companies are sending models of vessels of
world-wide fame. The White Star Company are to have a kiosk
representing the arrangements of their ships' berths. The Union
Company, the Currie Line, and the Pacific Company will also
send exhibits.
RABUT, in a paper to the Paris Academy of Science, shows
that there is still something to be learned iu bridge building.
Under preseut methods of construction too much strain is
thrown on the riveting, which, therefore, should be stronger.
His observations were made on eight bridges, with spans rang­
ing from 13 to 204 feet, and static and dynamic deflections were
studied. This iniportaut fact was shown, that under a moving
load at all speeds, both high aud low, the period of vibration of

the bridge was found to be entirely independent of the speed,
and peculiar to the structure. The velocity of the train scarcely
affects the mean deflection, but amplifies the vibrations considerably,
but for large spans these vibrations are still only a
fraction of the static deflection under the same load. There
has been au erroneous assumption regarding the dynamic action
of a live load. The supposed dynamic action does not appreciably
increase the stress in long bridges, the maximum deflection
being practically the same as under a similar static load.
The main girders do not suddenly receive the oncoming load,
but the cross girders do as well as the longitudinals, especially
near the abutments. Rabut found that the dynamic deflection
varied with the degree of freedom of the member strained, and
inversely as its mass, which adds further weight to the present
practice of using plate girders for short spans. The static deflection
ofthe main girders was found to be different from what
the usual formula allowed. The latter members were found
doing more thau their fair share of work. The stresses in both
diagonals and verticals varied from the calculated amounts.
The members were bent at the reaction couples and stiffened
the girder, but produced strains in the bracing. These stresses
were greatest at the center of the span. This might be iu part
obviated if the section of the web members were increased.
The observations of this investigation have unsettled several
theories and may require the re-writing of a few formulae. Under
circumstances where deflection ought to diminish it was fouud
to be increased, especially where cross girders and longitudinals
were connected with each other and with the main girders of
the bridge. Another important observation was that in skew
bridges the elastic line of the main girders is not convex, as
theoretically required, throughout its length, but has two points
of inflection showing partial encastrement of the ends. Torsion
of members is also greater than theory prescribes. Flexible
joints near the abutments, where the floor members conuect
with the main girders would remedy the evil somewhat.
THE value of the steam jacket is a subject which has occupied
much atteution and led to much research among mechanical
engineers. The following is a summary of results of all the experiments
which have been made by a committee of the Institution
of Mechanical Engineers. From these experiments it
appears that the expenditure of a quantity of steani in au efficient
jacket produces a saving of a greater quantity in the cylinder.
The ratio between these two quantities is an important
factor in this investigation. Unfortunately the jacket-water has
not been recorded in many of the experiments of which results
have been collected; but in all the experiments made by members
of the committee it has been carefully measured and recorded.
In the summary, column q gives the percentage saving
in feed-water—that is, the percentage less feed-water resulting
from the use of the jackets; column/, gives the actual saving
iu lbs. per indicated horse power per hour ; aud column r gives
the water condensed in the jackets in lbs. per indicated horse
power per hour. By an expenditure of r in the jackets there is
p -\- r less water passed through the cylinder, p being the credit
balance ofthe account. The examples given in the next column
are taken from tables of actual experiments, of which two of
seven are given :
a
No.
41 .
42 .
43 •
44 •
1 P+r r Ratio.
Per Cent. Lb. Lb. p -f- r to r
. . 17.4 . . 6.15 • . • 3-29 • . . 1.9 to 1
. . 8.6. . 2.76 . . . 1.20 . . . 2.3 to I
. . 10.3 . . • 3-5° • • L72 . . 2.0 to I
. . 19.0 . . . 5-82 . . • 1.13 • . . 5.2 to I
No. 44 shows that for every 1.13 lb. of steam expended in the
jackets, there is 5.82 lb. less feed-water passed through the cylinder,
the net saving being thus 4.69 lb.
It will be seen from the experiments that, generally, the
smaller the cylinder the greater is the percentage of gain from
ENGINEERING MECHANICS. [January, 1893.
the use of the jacket, arising, doubtless, from the fact that a
small cylinder gives a larger jacket surface for the given weight
of steam passing through it than a larger cylinder does. Iu some
experiments it was found possible to measure the consumption
of coal as well as of feed-water, and, as these figures have considerable
practical value and interest, they are in every case
added to the results.
SUMMARIES OF SEVEN SETS OF EXPERIMENTS ON THE VALUE
OF THE STEAM JACKET ON SINGLE-CYLINDER
CONDENSING ENGINES.
No. 35.—Record of two experiments on same engine with highpressure
and with low-pressure steam in the jackets:
Single Cylinder Condensing Horizontal Engine.—Cylinder
15 in. diameter, 30 in. stroke; the body and both ends ofthe
cylinder were jacketed. Experiments made at Messrs. Rivolta's
Electric Works, Milan, in February, 1886, by Signor P. Guzzi.
(College of Eugineers and Architects in Milan, 1887.)
No experiment was made without steam in the jackets, but iu
the one case ordinary boiler steam at a pressure of 48 lb. per
square inch above the atmosphere circulated through the jackets,
while in the other steam was supplied to the jackets from a
small Perkins boiler at a pressure of 187 lb. per square inch
above the atmosphere.
Pressure in jackets, lbs. per square inch above
atmosphere 481b. 1871b.
Duration of experiment 7.2 6.3
Boiler pressure, lbs. per square inch above atmosphere
lbs. 56.2 56.6
Revolutions per minute revs. 79.0 77.4
Piston speed, feet per minute feet 395. 387
Results: Indicated horse-power . . . . i.h.p. 25.3 25.5
Feed-water, lbs.per i.h.p. perhour, total lbs. 28.85 '9-85
Feed-water, percentage less with higher
pressure steam in jackets . . . per cent. — 168
No. 36.—Record of two experiments on same engine with and
without sleam in the jackets.
Single-Cylinder Condensing Horizontal Corliss Engine.—
Cylinder 21.81 iu. diameter, 49-21 in. stroke ; the body only was
jacketed. Experiments made at Prague, in February, 1888, by
Professor Doerfel. (Zeitschrift des Vereines Deutscher Ingenieure,
18S9.) Many other experiments are given in the same
paper, showing the economy of the jacket to vary between 7
aud I2j

January, 1893.] ENGINEERING MECHANICS. 3
be used is only two per cent, of the cost of the power delivered
in London or other large cities. The scientific world has sud-
Sc*u » Sre.Lirt
uia Of inii*3»iisio'* SMIKH JMI/S
T0UHH linta
(4T.4C4 ,„•
Coat }'tetd amz shewn HULL
CentraU Tcujaforiner
&O/JU»L« shewn thus.
denly awakened to the practicability of the transference of
power from coal and its transmission long distances by electri­
city.
A SYNDICATE of Canadian aud British capitalists have applied
to the Dominion government for a charter through Alexander
Ferguson, Q. C, of Ottawa, to construct a canal to connect
Lake Erie, Montreal and New York City by twenty-two feet
navigation, with locks 22 feet draught, 50 feet wide and 450 feet
long. The route will follow the St. Lawrence, reaching Lake
St. Francis with oue lock 48 feet lift at Cornwall. From Lake
St. Francis one arm of the route will descend to Montreal with
one lock of 82 feet at Lake St. Louis, and one of 45 feet at
Montreal Harbor. The other arm will strike Lake Champlain,
descending into it with one lock of about 50 feet, descend
Champlain and pass out through to the Hudson, descending to
tide level with one lock of about 35 feet lift.
Between Lake Erie and Montreal will be seven locks and 363
miles of navigation, of which 45 miles will be canal. Between
Lake Erie and New York will be seven locks and 706 miles of
navigation, of which 131 miles will be canal. Between Montreal
and New York will be four locks and 403 miles of navigation,
of which 115 miles will be canal.
The time from Lake Erie to Montreal will be 32 hours. From
Lake Erie to New York the time will be 60 hours. Between
Montreal and New York the time will be 38 hours.
The striking feature of the scheme is the great lift of the
locks, the greatest being three and a half times as high as any
ever built. Such high lifts are rendered possible by the use of
compressed air operating in locks built eutirely of steel and
working with the greatest speed consistent with safety.
The objections are its immense cost, and the damage to Montreal
as an exporting point, which objections it is safe to say
will not weigh much if there are none more serious.
THREE of our ablest war ship captains are to give the "Vesu­
vius" a rigid test in Port Royal Sound, as to range and accuracy
of firing under various conditions, stationary and moving.
THE subject of leaky tubes in marine boilers is one that gives
rise to more discussion thau remedy. One late correspondent
says : My opinion is that the difficulty may be obviated by im­
parting a certain initial curvature to the tubes. If the tubes are
somewhat curved from the beginning the different expansions
ofthe several tubes will compensate one another by an increase
or decrease in this curvature, and the joints at the ends will not
be exposed to any excessive strains.
As the tubes have to also act as stays, they must be rigid, and
therefore not admit of the suggested curvature.
Another one says : No doubt the overheating of tube-ends has
been due to the disturbance of the water alongside the tubeplate,
this being caused not by the generation of steam from
that point, but by the steam bubbles rising from the most effective
heating surface ofthe furnace, that is, iu the vicinity ofthe
bridge.
Lead those steam bubbles from that part of the furuace
slightly in another direction, and we shall have good circulation
alongside of tubeplate, aud its temperature will be much re­
duced.
And still another: Until the expansion of the tubeplate is
provided for, and the tubes are securely fixed in the plate so as
to exclude the possibility of dirt or deposit of any sort getting
between the joints, and preventing the free conduction of heat
from the one to the other, we shall always be troubled with
leaky tubes.
One, a chief engineer, says it is the admission of cold air to
the combustion chamber that causes the tubes to leak. The
great majority of the cases where tube leakage occurs is where
the ratio of grate area to firebox surface is high, as is the case
iu all boilers in the service which have a single-combustion
chamber, fired from both ends, this being the type of boiler
which has failed most signally. This class of boiler, too, is
further hampered by the want of water spaces, an objection
which does not obtain where the firebox is divided up.
The next one says the difficulty is easily solved by a firebrick
wall 30 in. high ; but we all know this, while mitigating, does
not cure, and is an enormous encumbrance.
W. B. Dixon says : In my opinion it is quite clear the leakage
ofthe tube ends is from either or both—the non-coutemporaueous
expansion of the hole in the tubeplate, or the contraction
of the tube, nor do I believe that at the pressures in use now
any shoulder, such as could be allowed on the water side, or
shoulder or bead ou the tube on the fire side, will prevent leaky
tubes.
WITH the present issue we begin the publication of a series
of articles under the heading "Notes on the Steam Injector,"
prepared by Strickland L. Kneass, M. E-, C. E. During the thirty
odd years that have elapsed since the introduction ofthe original
invention, it has in its improved forms supplanted every other
system of locomotive boiler-feeding and been applied very generally
to stationary marine service ; yet uo full accouut of the
origin and development has ever appeared, and few engineers
can realize the difficulties which had to be overcome in order to
introduce the original invention, or are aware of the full amount
of credit that Giffard deserves. The writer of these articles has
had special opportunity for familiarity with the practical working
and improvement of the injector, and is thus enabled to
furnish the results of the most recent experiment with this
useful and now indispensable invention ; to this will be added
the theory supplemented with general iuformation upou the
subject aud general description ofthe forms most in use, which
we trust will prove of permanent interest to the readers of this
magazine.
THE favorable reports of two military men on the bicycle for
military use will direct further and more critical attention to the
uses which can be made of the bicycle.

4 THK CONSTRUCTOR
Translated by Henry Harrison Suplee.
The intersection of radii from I, with these circles, give the
distauce of the valve from its middle position for various crank
positions. For the position I V2, for instance, the admission
for the left stroke begins, at I £., the expansion, at I / the exhaust,
etc.*
The Zeuner diagram gives the valve position by means of
polar co-ordinates, while the writer's diagram is based on parallel
co-ordinates. To be strictly correct, the valve circles i . 2
and 1 . 2' of tbe Zeuner diagram should fall upon each other.
The arrangement shown has been adopted by Zeuner as more
convenient in practice.
It will be seen from the preceding that the rate of expansion
can be varied by altering the eccentricity and the angle of advance.
This may be carried so far that the direction of rotation
is changed, giving what is termed a reversing motion. A variety
of reversing motions have been devised, which accomplish the
desired relation of parts by shifting a reversing lever. Of these
the most practical are the so-called link motions, of which a
number will here be briefly shown.f
FIG. 1026.
Fig. 1026 a, is an outline diagram of Stephenson's link
motion. The link 3' 3", of convex curvature towards the valve,
is given an oscillating motion by means of the two equal eccentrics
1 : 2', 1 . 2", and is suspended from its middle point 7,
from the bell crank lever S 7'. The motion ofthe link is transmitted
to the valve by means of the sliding block 5, and rod 6.
Fig. 1026 b, is Gooch's link motion. Tbe link 4 is driven by
two eccentrics as before, but is curved in the opposite direction
with a radius 5 . 6, and is suspended from its middle point 8 to
a fixed pivot 8', while the rod 5 . 6 is shifted by means of the
lever connection S 10 . io'.
FIG. 1027.
Fig. 1027 a, is the link motion of Pius Fink. In this form
the link is operated by a single eccentric instead of 'two, as in
the previous forms. This simple mechanism is not as widely
used as its merits deserve.
Fig. 1027 b, is the link motion of Allan, or Trick. In this
design the link 4, is straight, aud both the link and the radius
rod are suspended and shifted by the lever connections 8** . 8,
and t)' . 9.J
move. The eccentric
[January, 1893.
Translation Copyright, 1S90.
2, moves the valve connection 6. 7, by
means of the lever 2.3.6, which vibrates about the point 3, on
the end of the radius rod, the other end of the rod being held
by the link block 5. Instead of the link 4, a radius arm 4o 5, is
often used, the centre 4o corresponding to the centre of curvature
ofthe link, the action being the same iu both cases.*i
FIG. 1029.
Fig. 1029 a, is Brown's valve gear, which differs from the preceding
by the substitution of a straight link of adjustable angle,
for the curved guide link.
Fig. 1029 b, is Angstrom's valve gear. The point 3 ofthe preceding
gear is guided by a parallel motion, and the point 6 is
between 2 aud 3, instead of beyond.
The eight preceding valve gears operate the valve approximately
in the same manner as if a single eccentric of variable
eccentricity aud angular advance were used, the eccentric rod
being assumed of infinite length as compared with r. The path
ofthe successive positions ofthe middle pomt of this imaginary
eccentric is called the central curve of the valve gear.
FIG. 1030.
Fig. 1030 shows the form of this curve for link motions in
general. Form a, is that for cases 1, 4 and 5 ; form b, for case
1, when the eccentric rods are crossed, and form c, in which
the curve becomes a straight hue, is for cases 2, 3, and 6 to
8. In the latter instance, the lead, or opening for admission of
steam at the beginning of the stroke is constant] a point considered
by many to be of much importance.
It is possible to arrange the mechanism in such a manner that
the centre ofthe valve motion may move directly in the desired
central curve, as is shown in Fig. 1031.
FIG. 1031.
This construction involves the rotation of the link about the
FIG. 1028.
crank axis. The only point to be accomplished is to guide the
centre 2' in the path 2' . 2 . 2". Fig. 1031 c, is a direct guide
Fig. 1028 a, is Heusinger's link motion. The link 4, vibrates
for the eccentric with wedge adjustments; b, is Sweet's valve
upon a fixed centre 9, and is operated by an eccentric 1 . 2. The
gear, in wliich the position of the eccentric is determined by a
valve rod is moved from the maiu cross head by tbe connections
centrifugal governor.|| This only uses the central curve from
10 . 11 . 6 . 7, and also by tbe radius rod 5 . 6, which latter is
suspended from the bell crank S. 12'.
% For a further account of this gear, see : Berliner Verhandl, 1877, p. 345
Fig. 102S b, is Klug's valve gear, known in England as Mar­ 18S2, p. 52. Engineering, Aug. 13, Oct 1, Dec. 3, 1880 ; Nov. 4, 1881 ; June 23'
shall's. The curved link 4, is rigidly secured and does not 1882; Feb. 6 and 27, 1885; Jan. 12, 1886 ; Sept. 9, 1887. Engineer. May 26, 1887'
* It is usual to make the valve symmetrical, i. e , e3 = c, which necessarily
Feb. 23, Mar 30, April 27, June 29, 18S3; June 5, 1885. Marine Engineer'
causes the cut-off to take place at'different points for the back and forward 1885, i>o. 1., Civ. Ing. Heft, 7 and 8, 1882 ; Zeitschr, D. Ing., 1885, p. 289, ,886'
strokes.
PP 509-625 ; Revue universelle, 1S82, p. 421; Busley, Scliiffsmaschine,'l p'
tSee also Zeuner, as above; Gustav Schmidt, Die Kulissensteurungen 454; Hartmann, Schiffsmaschineudienst, Hamburg, 1884, p. 53- Bla'ha
Zeitschr. d. osten. Ing. u. Arch.-Vereins, 1S66, Heft. II.; also Fliegner Ueber Steuerungen der Dampfmasch, Berlin, 1885. p. 65.
eine gelr. Lokoniotiv-steuerungen, Schweiz. Bauzeitung, March, 1883', p 75. | See Rose, Mech. Drawing Self-taught, Philad. Baird ; for similar gears
I See Reuleaux, Die Allanische Kulissen steuerung, (Jiv. Ing., 1857, p. 92. see Am. Machinist, Grist, Oct. 5, 1883; Ball, ditto Aug. 18, 1S83 ; Harmon'
Gibbs & Co., ditto Nov. 24, 1883. Also Sturtevant, The Engineer, New York'
Jan. 1888.

January, 1893.J ENGINEERING MECHANICS. 5
2' to 20, and the path is a curve produced by a radial arm as in
Klug's valve gear. The valve is balanced, iu order to reduce
frictiou to a minimum.
The last described valve gear possesses the advantage of great
simplicity but retains the disadvantage of all single valve gears
when used for a high expansion ratio, i.

6 ENGINEERING MECHANICS. [January, 1893.
Their action consists of the two following operations : I. By
the adjustment of one part the release of another part to the
action of an impelling force is accomplished ; 2. By the attaining
of motion of the checked member, the checking is again
produced either directly or indirectly.
These principles also obtain for escapements for pressure
organs, and include a great number of important applications.
FIG. 1035.
The general scheme of such an adjustable gear for a steam
pump cylinder is shown iu Fig. 1035 a. The valve chest dt is
made separate from the cylinder d, and is capable of movement
parallel to it, the connections

January, 1893.] ENGINEERING MECHANICS. 7
A GRAND TRIP FOR THE ENGINEERS.
The three or four thousand foreign engineers who are to visit
this country next summer, will travel extensively over the west
to familiarize themselves with its vast extent, resources aud
characteristics. The Northern Pacific Railroad Company will
come in for a large share of this patronage. The region through
which this road passes between Minneapolis on the east, and
Tacoma, on Puget Sound, uear the Pacific coast, a distauce of
2025 miles, near the northern boundary of the United States,
is perhaps the most picturesque, interesting and prosperous belt
of country on the face ofthe globe. The scenery is varied and
striking, the road is lined with rising towns and cities. Duluth,
one of its eastern termini, is a young giant, a great wheat shipping
centre, full of towering elevators. This road cuts through
the world's greatest wheat belt, 500 miles long by 300 miles
wide. In Montana, it carries the tourist over the grandest
grazing stretches on the continent, from which 100,000 head of
cattle are annually shipped east. The mineral treasures of this
mighty youug commonwealth reach thirty million dollars a
year, and the richness of its mines rivals the riches ofthe most
famous mines of the world, ancient or modern. The engineers
who take time to look, will find immense deposits of iron and
coal along the line of this road iu North Dakota. The lumber
resources of these western sections are inexhaustible. Immense
forests cover the Cascade and Olympic Mountains. It is by
this Road that the great wonderland of America, the Yellowstone
Park, is reached. This park is 55 by 65 miles, a volcanic
plateau, high up among the Rockies, hemmed in by mountain
peaks—where geysers of startling character and magnitude
appal the beholder, and where the cataracts abound on every
hand. Our visiting eugineers will have but one opportunity of
seeing some ofthe grandest sights of America aloug the Northern
Pacific. For all of its 2000 miles there is an ever changing
panorama. Starting from the region of the Great Lakes, and
their inexhaustible miueral deposits and lumber resources, the
visitor passes through the choicest agricultural lauds and grazing
lauds, then through rich mineral regions, and over two
mountain ranges where every variety of scenery presents itself
to the eye, and where some ofthe greatest feats of engineering
are seen in railroad work
From Chicago, the engineers will have a short aud easy ride
to Minneapolis, the eastern terminus, which in itself is a city
worth a visit. The summer heat will not be oppressive in this
high latitude. A better idea of the United States and its unlimited
and vastly diversified resources can be obtained, than perhaps
in any other section of this great country. The passenger
service of this Company is excellent and its trains splendidly
equipped. Our visiting engineers will find this region a charming
one to visit. The western terminus, Tacoma, is a commercial
centre that may yet become the metropolis of the Pacific coast.
From that point visitors can easily reach Alaska, or ride southward,
over well built roads through California, the flower garden
of the world, where the climate surpasses that of Italy for
evenness, to San Francisco the present metropolis ofthe coast,
and from there if they so desire through the orange groves and
vineyards of central and southern California, to San Diego, the
extreme southwestern section of the United States. No grander
trip could be taken, and when the engineers learn of its attractiveness
they will not be slow in selecting it as the one to
make.
A GUN weighing 90 pounds, to be mounted on a tripod weigh­
ing 65 pounds, and which can be operated by three men was
recently tested near Philadelphia before capitalists who contemplate
buying the patent for the gun. Its rapid firing capa­
city is claimed to be 1000 shells per minute.
The gun consists of two ordinary steel rifle barrels encased
in a gun metal shell, the barrels being surrounded by water
. cases to keep them, while in use, from becoming heated. The
machinery sets back from the barrels, being entirely discon­
nected and free from heat.
The feeding mechanism consists of a pair of wheels, having
pocket peripheries mounted upon shafts on each side of the
shell barrels, the shafts being connected with and alternately
rotated by the driving shaft, with guides adjacent to the feed
wheels, adapted to receive the heads of the cartridges as they
pass from the wheels, and combs attached to the shell adjacent
to the wheels for stripping the cartridges from the belts. The
gun is fed ou either side by ammunition belts containing fifty-
five cartridges of 40-calibre, with cups for firmly grasping the
cartridges, open on oue side, so that the cartridges may be removed
therefrom laterally and provided with projecting wings on
the edges, to afford a bearing for the cartridge-removing device.
The guu is so arranged that one or both barrels may be used,
and, in event of one barrel becoming defective, it will not interfere
with the action of the other. By a lever in tne rear, it can
instantly be moved into any positiou by the operator without
stopping the firing. The firing lever is located at the extreme
end of the gun on the right side.
The first test of the gun was with 300 cartridges, which were
exploded in 23 seconds, and this was. followed by a test of 600
shells in 38 seconds. It is claimed that the piece can be used
effectively at a distauce of oue aud a half miles.
THE Standard Steel Casting Company, Thurlow, Pa , have
recently done some delicate and important government work,
which when tested under the supervision of Lieut. C. W. Rnschenberger,
Inspector of Ordnance, U. S. N., showed the fol­
lowing results:
yinch Pivot-stand.
Elastic limit 35,°°o
Tensile strength . . . 74,000
Elongation 3'-25
Reduction of area . . 34.74
yinch Fop-carriage.
Elastic limit 31,000
Tensile strength . . . 72,000
Elongation 30.25
Reduction of area . . 40.90
Box-slide 10" Carriage.
Elastic limit 33,000
Tensile strength . . . 75,000
Elongation 2S.00
Reduction of area . . 36.75
6-inch Front-clip.
Elastic limit 30,000
Tensile strength . . . 71,000
Elongation 30.00
Reduction of area . . 40.71
HIRAM S- MAXIM says of leaky tubes: In experiments which
I have been conducting during the last two years, I find that
where the fire is very hot and the heating surface very great in
proportion to the water, a forced circulation is a sine qua non,
and this is very easily accomplished without the aid of any
other machinery than that already employed on shipboard.
Suppose that the boiler pressure should be 150 lbs. to the square
inch ; I should then have the pressure of my feed water 200 lbs.
to the square iuch, and should have it escape from the feedpipe
iuto the boiler through a small orifice, which may be automatic,
aud which will maintain a constant difference of pressure
of 50 lbs. to the square inch between the water in the feedpipe
aud in the boiler. This will give a solid stream of dense
water escaping through an orifice with a force of 50 lbs. to the
square iuch, and this can be made to operate ou ten times its
volume of the surrouuding water in the boiler after the manner
of an injector.
Editor ENGINEERING MECHANICS : Can you answer these
questions ? There is a very large deposit of pure carbonate of
lime (decomposed shell marl) situated in the bottom of a lake.
The material is extremely fine and will remain in solution for a
long time (48 hours on an average). At present it is dredged
from the bottom ofthe lake with one of Edwards' Centrifugal
Pumps raised into elevated tanks, where it is allowed to subside,
the top water is than drained off, leaving the material too
wet for economical handliug. After beiug drained it contains
about 65 per cent, water.
The problem is how to reduce the moisture, to say, 40 per
cent, water. It must be a cheap process. The lime is used in
the manufacture of Portland cement. Filters of gravel and
sand have beeu tried, but in a short time, a couple of hours,
clogged up. Any hiuts towards a solution would be thankfully
received.

S ENGINEERING MECHANICS. [January, 1893.
DR. WERNER VON SIEMENS was born at Lenthe, Hanover,
1S16, and died at Berlin, Germany. He began his career as a
scientific investigator in 1839 and patented a process for electric
gilding aud later for the electric automatic and iecording telegraph.
He laid the foundation for several important industries.
Dr. Siemens' personal achievements are to be found in the fields
of science as well as in those of technical industry. His scientific
merits induced the University of Berlin to confer on him
the degree of Ph D. in 1S74; they opened likewise for him the
DR. WERNER VON SIEMENS.
doors of the Academy of Sciences in Berlin in 1874, and subsequently
of man)' other academies and societies. Amongst his
many and various achievements in matters relating to science
and technical arts must be mentioned the development of
methods for testing underground and submarine cables, aud determining
the position of faults iu them ; of the Siemens dynamo,
and the Siemens alcoholometer for registering the quantity of
absolute alcohol contained in any alcoholic liquid. Dr. Siemeus
was also the inventor of the pneumatic tube system.
AND now comes Chili with its vast metalliferous deposits to
welcome capital and enterprise in their development. In a
paper recently read before the French Society of Civil Eugineers
it was stated by Mr. Charles Vather that immense deposits of
exceptionally pure and rich ores of iron and of manganese are
to be found through the northern and central regions of Chili.
These deposits are in many cases situated near the coast, and in
localities where transport is easy. As regards fuel, there are
large deposits of lignites from which suitable coke may possibly
be produced, but in any case a practically inexhaustible supply
of wood fuel is afforded by the primeval forests which stretch
along the borders of the rivers and estuaries of these regions.
It would be easy to load vessels with ores of iron containing 50
to 60 per cent, of the metal, or with 45 to 50 per cent, ores of
manganese, at the northern ports, and convey them to Southeru
Chili, where wood and lignites are plentiful, for reduction. Mr.
Vather has examiued these deposits on behalf of the Chilian
Society for the Promotion of Iudustrial Progress, and suggests
that a syndicate should be formed in France to open up these
and the other enormous metalliferous deposits of Chili. He believes
that such a syndicate would be welcomed by the Government,
and that on proving its bona fides it could rely on some
measure of protection for the infant industry being passed by
the Chilian Government. He advises his compatriots to hasten
to develop this lucrative iudustry before they are forestalled by
the capitalists of some other nation.
JOHN S. LENG'S SON & Co., No. 4 Fletcher Street, New York,
are importers of a number of specialties in iron and steel which
engineers and constructors of machinery find it advisable to
preferably use.
Chief among these products are their Patent Weldless Cold
Drawn Steel Tubes for locomotive, marine and other boilers,
hydraulic presses and pipes, boring and mining tools, coils,
hollow spindles, rollers, shafting, connecting aud lifting rods,
axles and axle boxes, bicycles, bushings for link motion of
locomotives, etc , collars, couplings, linings, punches, ferrules,
spinning caps, and all purposes requiring lightness, strength,
uniformity and durability.
These tubes are made from solid blocks of specially prepared
and tested steel, aud are drawn cold, without weld or seam.
They are smooth inside and outside, capable of beiug bent to
auy radius, and make a perfect joint in boilers without copper
or other packiug.
Besides these tubes they handle Leng's improved gate valves,
Lausdell's patent steam syphon pumps and a portable railway
syphon of great value. Circular furnished.
THE CLEVELAND TWIST DRILL Co. have issued a catalogue
showing several lists of tools in their line never before published.
They have also listed more sizes of the ordinary drills
than auy other manufacturers iu their line have done. All the
tools listed in this catalogue they keep in stock. The Millimeter
list is published for the convenience of manufacturers
who would like to buy from stock, Twist Drills, either smaller
or larger than the ordinary sixty-fourths sizes. They have also
given in the Millimeter lists the decimal equivalent, so that any
one cau tell exactly which oue of the Millimeter sizes would
best suit his needs. These catalogues will be cheerfully seut to
any one free of cost on application.
QUESTION.—Can you name a reliable publication giving
tables relative to power transmitted by belting, leather and
otherwise, that will save wading through formulas?—A. McC.
Answer.—This subject is fully treated in Fhe Constructor.
The ouly other work worth anything is Cooper's "Use of Belting."
A safe and approximately correct rule is : Take 60 square
feet of belt passing a giveu point per minute as transmitting
oue horse-power for single belts, or 40 square feet for double
belts. This is a practical rule fully verified by experience.
VAN BROCK writes: "Another ' errorist' has had a liberal
audience iu ENGINEERING MECHANICS ; one Carl Busby,
on the "Marine Engine." What is the difference between
aland engiue aud marine engine? Solely the weight. One
is fixed to the earth aud may be quite light in construction,
the other is bolted to the ever restless sea, and has
got to be very much heavier and stiffer, or it will come to
grief in the first gale, as has beeu the fate of many a marine
engine, though designed by supposed great experts, who nevertheless
did uot know that laud dimensions were worth nothing in
a marine engine. I have seen land engines four times the theoretical
dimensions, run 24 hours a day for 300 days (aud 10
years of that) without trouble, and have seen sea going engines
twelve times the strength assigned by breaking stresses—yet
they gave way—and the vessels and hundreds of lives were lost
for want of sufficient strength iu the parts that had to receive
the greatest strain.
" Have seen ribbed framings bend in a storm—8-inch stay rods
try to buckle—a dozen \% bolts break like file firing—steam
pipes acting like a dying snake—all for want of knowledge of
the eternal value of WEIGHT in sea going machinery."

January, 1893.] NOTES ON THE STEAM INJECTOR.
By Strickland L Kneass, C.E.
Copyright, 1893.
EARLY HISTORY.
and also the mechanical theory, substantially as advanced
by him in 1850, eight years before the construction of his ex­
To Henri Jacques Giffard, an eminent French mathemaperimental Injector.
tician and engineer belongs the honor of inventing, -in the And yet, in common with all new inventions and radical
year 1S5S, the simplest boiler feeding apparatus that has improvements, great difficulty was at first experienced in ob­
ever been devised, in which he applied in a novel and intaining a fair trial of its merits, and in many cases the exgenious
manner the latent power of a discharging steam jet. aggerated claims of its friends interfered as much with its
The arrangements for feeding stationary boilers then early adoption as the openly expressed criticism of its
usually employed were the ordinary steam or power pump, enemies. The great advantages of the new method were
or the equilibrium apparatus, a closed iron tank feeding in­ appreciated, however, by the Academic des Sciences of
termittently by gfavity somewhat in a manner of a return France, who awarded Giffard the Grand Mechanical Prize
trap. But there was an active demand, in locomotive ser­ for 1859. This was all the more complimentary as it was
vice especially, for a compact and serviceable substitute for entirely unsolicited. Prominent engineers presented before
the unsatisfactory plunger pump.
the principal scientific societies analytical demonstrations of
Many years previously Giffard had directed his attention the theory of the injector and allayed to a great extent the
to the improvement of boiler feeders and had patented an suspicion in the popular mind that the inventor was en­
apparatus of entirely different character from the one that croaching dangerously near the claim for perpetual motion.
has made his name so well-known ; but the use of a jet of Combes, Bougere, Reech, Villiers, Zuber and Pochet are
steam for forcing a continuous stream of water into a boiler, among the most prominent scientists who made a special
appeared to him on purely theoretical grounds, to be entirely study of the subject, and the demonstration of Poehet is
feasible, and if the practical difficulties could be overcome still frequently used in modern text books.
would possess man}* advantages over the intermittent sys­ It must not be supposed that Giffard was alone in his
tems. The difficulty seemed to lie in fulfilling the peculiar efforts to supply a continuous feed to the boiler. For ex­
conditions required for the condensation of the steam and hausting and pumping purposes we have record that steani
the subsequent reduction of the velocity of the moving mass. jets had been used as early as 1570 by Vitrio and Philebert
Giffard carefully considered the various phases of the ques­ de Lorme, and other inventors had endeavored unsuccesstion
and made a working drawing embodying his ideas. A fully to force the jet to enter the boiler ; but for reasons that
model was made by M. Flaud & Cie., of Paris, who found, will be given later, it is easy to understand why they failed,
however, considerable difficulty in forming the tubes in the as they omitted to apply the scientific principles that made
peculiar shapes required. But in the shape and proportions Giffard's first experiment a success.
of the nozzles lay the element of success, and the first in­ In 1859, the Injector was introduced in England by Sharpe,
strument constructed entirely fulfilled the expectation of the Stewart & Co., of Manchester, but did not at first become
designer.
popular ; possibly on account of the mystery that seemed to
There have been few other inventions in which the under­ surround its working, and the general skepticism as to its
lying principles have been so thoroughly worked out by the practical wearing powers. Some of the contributions and
original inventor. Giffard seems to have made a very com­ queries published in the engineering papers of the day, are
plete survey of its possibilities prior to placing it before the very amusing, aud a certain writer in one of the most
public, and in his patent specification, describes a number of prominent Weeklies proves most conclusively to his own
improvements that have since been made. In 1S60 he pub­ and probably to some of his readers' satisfaction, that the
lished a small brochure entitled "A Theoretical and Practi­ new method of feeding boilers was an absolute impossibility.
cal Paper on the Self-acting Injector," in which he says: The injector was, however, adopted in many places and'
" Of all the necessary accessories of a Steam Engine, per­ continued to give satisfaction. In the first trip of the
haps the most important is the one used for feeding water to "Great Eastern" Injectors were used in place of pumps,
the boiler; upon its proper working depends not only the but for some reason not explained, they were subsequently
regular running of the engine, but the safety, the very exis­ removed ; this may have been owing to the temperature of
tence of those who approach the boiler ; . . . . nevertheless, the feed water being too warm for efficient service, as this
by a kind of fatality, the apparatus employed up to the pre­ was the weak point of the first injectors constructed.
sent time for feeding is, of all others, that which leaves most The English railroads opened a wide field for the Injector ;
to be desired." After reviewing the disadvantages of the upon most of the locomotives, the earliest feeding pumps
various methods in use, he continues, "It is important, were worked by hand, but afterwards coupled to a special
therefore, to create a new method, free from the imperfection eccentric or to the crosshead. Stretton, in his recent work
and inconvenience pointed out," and modestly adds, " Such on the Locomotive, says that it was a common occurrence for
is, it appears to me, the result obtained by the apparatus to engines with a single pair of driving wheels, to stand on
which I have given the name oi Injector, because it produces well greased rails with tender brakes fast locked and drivers
a veritable continuous injection. Its mode of action, extra­ revolving, in order to fill the boiler full of water. But even
ordinary in appearance, contrary to that which we are in the though the old methods were very crude, engineers in Eng­
habit of seeing or supposing, is explained by the simplest land laughed at Giffard when he attempted to introduce his
laws of mechanics and has been foreseen and calculated in Injector, and it was only after a year of persistent effort that
advance." He describes his invention in detail and ex­ he succeeded in obtaining a trial upon a locomotive, and the
plains very fully the best proportions for its various parts, concession was granted to prove the folly of the inventor

and obtain a respite from his numerous letters and appeals.
In i860 Wm. Sellers & Co., commenced the manufacture
of the Injector at their works in Philadelphia, and the first
Injector was applied to a locomotive in the United States, on
the Detroit & Milwaukee R. R. in October i860. The Pennsylvania
R. R. and Philadelphia & Reading Railroad, followed
in the latter part of the same year. Of locomotive
builders Matthias Baldwin was the first to use the new instrument,
applying in September, i860, a No. 8 Injector to
an engine designed for the Clarksville and Louisville R. R.
To Jos. R. Anderson & Co , Richmond, Va., a No. 4 Injector
bearing progressive number 1, was shipped in October
i860. As indicative of the wearing qualities of these early
instruments it may be stated that there was returned to
Messrs. Wm. Sellers & Co., in 1887, a No. 4 Injector, progressive
No 7, after a nearly continuous service of 27 years,
and having required but few repairs ; it further is interesting
to note, that, owing to improvements recently introduced,
American Injectors are now extensively used in France,
and have been adopted as a standard type by several of the
government railroads in the country of its inventor.
It need hardly be said that the Injector is the most popular
boiler feeder now in use. There have been more than 500,-
000 manufactured in this country for the various kinds of
service, and there is scarcely a locomotive in the world that
is not equipped with oue or two Injectors. Compact, reliable
and economical, it still deserves the high encomium bestowed
upon it by M. Ch. Combes, Inspector General and Director
L' Ecole des Mines,—" It is without doubt better than all
devices hitherto used for feeding boilers, and the best that
can be employed, as it is most ingenious and simple."
DEVELOPMENT.
Having established beyond a doubt the power of a discharging
jet of steam to lift a mass of feed water main' times
its own weight and force it against the initial pressure, it
became necessary to intrust to the hands of a practical
mechanical engineer the constructive details of the new
boiler feeder. The arrangement decided upon, could not in
the light of subsequent events be considered as an entire success,
as it contained inherent defects that caused frequent
failures and prevented the placing of as much confidence in
the new boiler feeder, as the merits of the invention deserved ;
many locomotives that during the first burst of enthusiasm
were equipped with two injectors, were afterward altered so
to have a pump upon the left hand side to be used in case
the injector should refuse to work, and it was not until 1875
or 1876 that more recent improvement in constructs >n restored
the confidence that the original defects had forfeited,
and the pump was driven from service upon locomotives in
the United States ; even yet upon some of the English Railways,
a pump is used on one side of the engine, arranged
somewhat in the manner of the pressure or vacuum pump
for the air brakes.
The curves of the tubes and nozzles as laid down by
Giffard were beyond criticism, and are still used where this
type of injector is manufactured ; his thorough knowledge
of the laws governing the action of the jet and the accelerating
velocity of the moving mass, enabled him, so to con­
ENGINEERING MECHANICS. [January, 1893.
struct the curves of approach and recession, that they have
been used as a prototype for all subsequent forms of injectors
; except for one change advanced by our increased information
regarding the action of steam during expansion,
and a few minor modifications for economy of manufacture,
or for adapting the injector to special purposes, no change
in the contour ofthe tubes has beeu made.
But that there has been development, cannot be denied ;
it mav be considered as following three lines:
First. Constructive changes.
Second. Carrying out the ideas suggested by Giffard in
his pamphlets or patent specifications.
Third. The discoveries of new properties of the jet, or
the application of new principles.
Almost all important inventions follow in this natural
sequence during their development, and the injector was no
exception to the rule. Genuine mechanical ability is seldom
combined with inventive genius, and it almost always follows
that the fullest development is obtained in other hands than
those of the original inventor. The first improvements were
therefore in the line of correcting the defects that became
apparent after the injector had been subjected to the test of
actual service ; changes required to facilitate repairs, or the
adjustment of the positions of the tubes. In the second division
lies the basis of many subsequent improvements that
have since proved very valuable, and Giffard has never been
given sufficient credit for his wonderfully wide grasp of the
possibilities or future development of the injector. Of the
third there will be less to relate, as the only real advance has
been with the discovery in 1865, of the peculiar property of
the moving jet by which the instrument was made self-regulating,
and with the novel arrangement of tubes by which
the re-starting feature was added.
Injectors now placed upon the market by our most reliable
makers combine most of these improvements and leave
little to be desired, and it is difficult to anticipate the direction
in which material improvement can be made.
The general appearance of the injector as now constructed
is entirely different from the original form, aud it would be
exceedingly difficult for any one not specially familiar with
the subject to recognize one made in 185S ; the arrangement
of the adjusting handles, peeuliarh* shaped body, aud queer
little peep holes present to the modern eye a ven* odd appearance,
while the heavy flanged pipe connections and steam
cock do not contrast at all favorably with the neater form
then adopted for use on American boilers ; but the absence
of all moving parts, and the economy due to the return of
the actuating steam to the boiler, at last made such an impression,
that the inertia of the popular mind against innovation
was gradually overcome and the defects of construction
overlooked ; improvements have since been introduced as the
necessity was felt, and the opportunity ripe.
Figure 1* shows a sectional view of the earliest form of injector
manufactured for public sale, and was intended for
use on either stationary or locomotive boilers ; it was made
entirely of brass, with the body composed of three pieces,
screwed and bolted together, and the steam, feed, and boiler
connections terminating in flanges, as is still the general
* See February number.
( To be eon fill lied.)

January, 1893.] ENGINEERING MECHANICS. «
GRAPHICAL STATICS and its APPLICATION TO CONSTRUCTION.
BY MAURICE LEVY.
CHAPTER VII.
CONTINUATION OF THE RESEARCH OF THE ELASTIC FORCES,
THE RECIPROCAL FIGURES AND THE METHOD
OF CULMANN.
§87.
DEFINITION OF THE GEOMETRICAL FIGURES FORMED BY
THE ARTICULATED SYSTEMS CONSIDERED IN THIS CHAPTER.—
Let us consider a figure formed of right lines uniting points
distributed in any manner in a plane. These points are what
we shall call the apexes of the figure. Every portion of the
right line comprised between two apexes will be called a line or
side of the figure. Finally, we shall designate by the word tie
the union of the sides starting from the same apex.
We shall consider only figures whose sides pass at least
through two apexes, and we can admit that each side passes
through two apexes onl}'. It will be sufficient for that if i
apexes are placed on one and the same right line, to regard the
i — 1 segments which the}- determine on this right line as so
man)- distinct sides of the figure.
I 88.
FIGURES CAPABLE OF DEFORMATION, STRICTLY INCAPA­
BLE OF DEFORMATION AND WITH SUPERFLUOUS LINES.—
We shall divide the geometric figures just mentioned, at first
into two classes : figures capable ofi deformation or whose
angles can vary without the lengths of the sides varying, and
figures incapable ofi deformation whose angles are determined
when the lengths of the sides are given.
The figures incapable of deformation themselves comprise
two categories which it is important to distinguish : those which
are such that they cease to be incapable of deformation when a
single one of their sides is suppressed will be called strictly
incapable ofi deformation or strictly defined inform ; those, on
the contrary, which do not lose the quality of being incapable
of deformation when oue or several of their sides are suppressed
will be called with superfluous lines, because they contain more
lines than are strictly necessary to define them in form.
A triangle is a figure strictly incapable of deformation ; an
articulated quadrilateral is capable of deformation ; a figure
formed by a quadrilateral and one of its diagonals is strictly
COMPLETE POLYGON WITH n APEXES, NUMBER OF CONDI­
TIONS NECESSARY TO DEFINE IT.—The figure formed by the
* See, for further developments, the note on funicular curves.
union of the lines joining 11 points of a plaue two by two
might be called a complete polygon with n apexes. Such a
Hence, the thrust which a parabola arch suspended or sup­ figure includes 11 —- —- sides. But there evideutly exists
ported whose bearing is 2 a, -.chose" versed sine fi, whose weight
2
per metre according to its chordp, exercises on its abutments is among their lengths a certain number of relations.
pal
-'/'
To find them all, let us look at two of the n apexes chosen
arbitrarily sl and B (Fig. 20). The remaining apexes are in
number 11 — 2 ; the lines which join them two by two, in nuui-
We sometimes employ this formula under the name of first (n — 2)(n — 3)
approximation, in order to calculate the thrust of au arch dif­ ber -.
fering little from the parabola (as a circular arch very surbased)
when its weight is vertical and uniform accordiug to the chord-
For a very elliptical arc, it is moreover confounded with the
approximate value found in (j 8I> for the thrust of a circular arc
-bearing a uniform normal weight.*
2
I said that all these lines, none of wliich ends in the points
A aud B, can be expressed by the function of those which end
iu these two points.
Fig. 20.
Therefore, let CD be any line comprised between two apexes
C aud IJ. Among the six lines which join the four points
A, B, C, D, there exists a relation which admits of expressing
the line CD in the function of the five others.
n (11 — 1) . ...
Hence, amoug the lines joining the 11 points, there
exists relations. These are, moreover, the only
distinct ones which cau exist; for all the lines, such as CA and
C B, joining one apex C to the two points A and B, can be
taken arbitrarily, as well as the line A B.
Through each apex C, pass two lines ending at A and B. Let
C stand for the n — 2 apexes, for 2 11 — 4 lines more the one
A B, in all 2 n — 3 which are arbitrary. If they are given, all
the others, in number are deduced from them ;
2
they are therefore superfluous. The 2 n — 3 arbitrary lines aud
the which are determiued when the first are
2
given, form besides the whole of the lines of the figure ; for we
have identically
(** —2) (*/ — 3) n (n — x)
2 n — 3-\ = .
2 2
(11 — 2) (11 —3) . . .
If, 111 the equations existingamougthe lengths
of all the sides ofthe figure ; in place of regarding as known all
the lines, to the number of 2 11 — 3, which end in the two particular
points A aud B and as unknown the others, we suppose
any given sides 2 11 — 3, we shall be able to deduce from them
the remaining sides.
It is self-evident that it is necessary for that, that the sides
which are given be independent of each other, i. e., that among
them are not found auy which are so chosen that among their
lengths there exists a relation by virtue of the equations them­
incapable of deformation ; a complete quadrilateral, i. e., the selves which the question is to solve. Such would be six lines
figure formed by the six lines joining four points of a plane, joining four points of the figure ; the length of six like lines
includes oue superfluous line. Five of these six lines define could not be given arbitrarily without the given ones being iu
entirely the form of the figure, so that the sixth can be found contradiction to the equations to be solved, and the problem
either analytically or graphically by the aid of the other five. would be impossible ; if they are given in such manner that the
Hence, among the lengths of the six lines which join four relation which exists among them be satisfied of itself, that
points of a plane, there exists always a relation which admits of would be equivalent to giving only five distinct ones, and the
finding oue of them by the function of the other five.
problem would be indetermined.
?89.
But, if the 2 n — 3 given sides are independent, the equations
will furnish the magnitudes of all the other sides of the figure
in the function of those.
The expressions which we shall find will indicate, in each
case, whether the problem is possible or not. Thus, three sides

12 ENGINEERING MECHANICS. [January, 1893.
of a triangle define it; but in order to be able to construct it, it
is necessary that the longest side be less than the sum of the
other two. Iu ever)' figure, the sides given will so have to
satisfy certain inequalities that Analysis or Geometry will
determine for each figure.
But, if a figure is constructed and consequently possible, the
knowledge of 2 n — 3 of its sides (supposed distinct) will define
the others. Hence :
n (11 — /)
l.et us conceive that a new figure be constructed infinitely little different
THEOREM.—In order thai the - m 11 tual distances ofi
from the first with sides having the lengths ax + & ax, ti,2 -f 5 04,, a3 + 8 a3, . . ,
Among the lengths of its sides we shall have the relation
n points ofi a plane be determined, it is necessary and sufficient
that 2 n — 3 of them be known.
f[a\ + 8 alt a2 + 5 a2, a$ + 5 a3, . . . , am -+- 6 am) ~ o,
Now, when all the mutual distances of various points are
and, by eliminating the two equations member by member,
known, the angles also which these lines make betweeu them
are known, since any one of these angles forms a part of a triangle
whose three sides are known. We have, therefore, all the
elements which constitute the form of the figure. Hence :
8/
S,H +
Sf
a2 + j $ a3
0 a-. + •
a figure having n apexes is determined in form by the knowl­
'/A
6 ax ' "' ' 5
- o O-rtx = 0.
o um
which indicate. 1 ? fully that in general the tn sides cannot receive independent
lengthenings. But let us suppose that the m lengths a\f a*, a-j, ... am be
chosen in a way to satisfy the m equations
edge ofi 2 n — j- ofi its sides.
I 9°-
NUMBER OF SIDES OF A FIGURE CAPABLE OF DEFORMATION,
STRICTLY INCAPABLE OF DEFORMATION, WITH SUPERFLUOUS
LINES—According to that, let m be the number of the sides
fluenced by it. This requires that each side can be separately
lengthened or shortened within ceitain limits, all the other
sides preserving invariably their lengths. In particular, the
length of each side should be able to be increased or diminished
in an infinitely small quantity, all the other sides preserving
their lengths, either invariably, or in infinitely small degrees
near the greater positive or negative lengthening of the first
side.
It is evident that, in order that a figure be freely dilatable, it
is in general necessary and sufficient that it contain no superflu­
ous line ; in other terms, that it be capable of deformatiou or
strictly incapable of deformation.
The conditiou is in general necessary. In fact, let us take a
figure including a superfluous line, for example the six lines
joining four points. As the length of five of these lines deter­
mine the length of the sixth, the five cannot remain invariable
without the length of the sixth remaining invariable; inversely,
if the length of one of them changes in a definite or infinitely
small quantity, the length of the five others wiil change, in
general, in quantities of the same order. The same reasoning
is applied, much more, if the figure contains more than oue
superfluous line.*
* This reasoning may always be at fault.
Let us consider, for example, a figure including one superfluous line, in
such manner that among the lengths a,, a... a3 am ofthe in sides which
compose it, there exists a geometric relation able to be expressed by a certain
equation
/("l. "I.a-i, . . ., a,„) =- o.
The condition is also, in general, sufficient.
Iu fact, to say that a figure contains no superfluous line, is to
say that all its sides are independent of one another, that they
may be chosen arbitrarily* consequently we can increase or
diminish the length of any one of them, the lengths of the
others remaining invariable, without the figure ceasing to be
possible f
•5 ax
- o,
8 am
Then the relation among the lengthenings 5 a\, h a-2, • • . , -5 am is satisfied,
whatever be these lengthenings. In this case, although the figure contain
a superfluous line, its various sides can receive dilatations infinitely small,
entirely arbitrary.
really existing in a given figure with 11 apexes ; m will be at
n (11 — 1)
most equal to .
Let us put
m = 2 n — 3 + k,
k being a whole number.
1° If k

January, 1S93.] ENGINEERING MECHANICS. [3
PUMPS AND PUMPING MACHINERY.
BY WILLIAM KENT, M.E.
(Continued from page 292.)
The regular sizes of the Van Duseu & Tift Jet Pump are the
following:
No. of
Pump.
1
2
3
4
5
6
7
8
9
IO
Discharge
Pipe.
A in.
;V "
1
1%"
2 "
2 A "
3 "
4
5 . "
Suction
Pipe.
A in-
1 "
1 a"
2 "
2 ^ "
3 "
4 "
5 "
6 "
Steam
Pipe.
-'s in.
A "
A "
A "
tf "
H "
1 "
1 "
i'X ••
i)4"
Steam-Jet
Diameter.
rVs «.
1 -. ..
1 .j
1.. ..
2
(Hi
5 *<
JJJiT
isn
4 d .<
Ton
_i>0 n
1 60 OU "
Tdo" 8 0

M
The Arclnmedean Screw.—This consistsof a screw blade turned
around a solid axis, similar to a winding staircase, and inclosed
in a hollow cyliuder (Fig. 7S a). When placed in an inclined po-
ENGINEERING MECHANICS. [January, 1893.
one may raise 40 gallons of water 10 feet high in a minute—a
larger amount of work than can generally be done with hand
pumps, owing to friction in the latter. This pump is said to
have been invented by Archimedes, and it is in use to a limited
extent in Egypt.
Pohle's Air-Lift Pump.— A paper read before the Technical
Society of the Pacific Coast in 1890, by Ross E. Browne and
Hans C. Behr describes some tests made by them of the socalled
air lift pump devised by Dr. J. G. Pohle, of San Francisco
shown in the accompanying drawings (Fig. 79). The
pump column is an opeu pipe partly submerged in the water to
be pumped. A small pipe leading from an air receiver to the
foot of and a short distance into the pump column delivers
compressed air, which forms in piston-like layers, and rising
rapidly in the column does the work of pumping. The water
is discharged in alternate layers with the air. The apparatus
tested was erected without due regard to best dimensions, and
it is stated that the efficiencies found could have been increased
by a few simple alterations. Pipes of different diameters were
FiG. 78 a.
not provided, and the experimenters were able to change only
sition with the lower end in the water, the latter is caught the belength
of the pump column, the amounts of submersion and
tweeu the screw blades, and, the cylinder being turned in the
lift and the pressure in the receiver ; hence the quantity of air
PohWs Air Lift Pump.
FIG. 79.
proper direction, the water will be raised and discharged at the supplied. The diameter of the pump column was 3 inches, of
upper end. This apparatus may be usefully employed in rais- the air pipe 0.9 inch, and of the air discharge nozzle }i inch.
ing water to a limited height (10 to 15 feet or less). By its aid (To be continued.)

January, 1893.] ENGINEERING MECHANICS. *5
PROCEEDINGS
OF THE
AMERICAN SOCIETY OF MECHANICAL ENGINEERS
New York Meeting, Nov. 29th to Dec. 2d, 1892.
(Continued.)
It is desirable here to find relatively exact terms to represent the forces
of tangential and angular [nertia.
Referring to Fig. lS again, let x = the radius of gyration of the
weight about its center of gravity, y = the distance of the center of
gravity from the center of the shaft, and z = a — y = the distance of
the center of gravity from the center of the supporting pin.
The demonstration may be found in any advanced treatise on
mechanics that
Mr 2 = Mf -f Mx"- .-.
Mr 2 = MA -f Mx- .-.
— AL — Z1+ A y y
y + x-
= A + x 2
AfiAs
Mif'r2
ay -
=y^AA - y
A + x i+
yAfyy y)- -*«
2
z 4- X
2 — -X* |
y
yz — x'
Z l -f X*
Myz — Mx*
AiA~-\Ayy
From this it appears that Myz is the tangential inertia My reduced to
a moment about the supporting pin, and Mx 2 is the angular inertia,
which in this case is a negative moment about the same point. Again
removing the factor M for purposes of convenience, and differentiating
successively with respect to x,y, and z, and equating each result to o,
then solving for the variable quantities as follows:
d yz 2x (z 2 -(- x 2 ) — 2x (yz — x 2 )
dx z 2 + X*
(A + x 2 ) 2
d yz — x 1
dz z 2 + X*
y
— 2x (A 4- y*) = °
X — 0
y{A 4. y - 2, (yz --x-)
A + y
— yz"- = o
d yz — x d y (a—y)
dy z- -J- x' 1 dy 8 s -J- x'.
a 3 — 2n-y -\- ay 2 — 2a'y 4- \ay* — 2y s -)- 2a 2 y — 2ay 2 -\- 2}p
tAyAf
y 2 — 2ay -j- a 2 = o
y = a
A second testing differentiation of each of these primary results shows
that the quantity
yz — .
Mrfr, A -f- x 2
is a maximum when x and 2 are o and y = a.
The investigation might easily be checked at the point of the ditterential
with respect to x, for if x = o
n — *'2 —y and r a = r x = z then
.
and
Mrjr,
Mrfr.,
while the efficiency of such an arrangement of centers with a concentration
of the mass increases as the mechanical centers approach the
weight pin.
In the same manner the formula
Mr 2 r2
Mr 2 r 2
yz — x 2
z 2 4- .r' 2 becomes
Mrfr3
"Mr,'r2
yz 4- x*
A + x 2 '
y 2 — ay -\- x"z
2 4- X 2
+
and
Mr 2
Mr, 2
r
n
r
t
yz + x 2
•• 4- x 2
y 2
+
s' 2
ay
+ 4-
X 2
in the other two possible modifications where the center of gravity falls
without the space between the centers of support and revolution.
The efficiency increases in both these cases as x grows greater and z
grows less, but in the former as y = a, and the latter as y = — a, so
that a maximum efficiency of a last arrangement of centers is impossible
until y has passed through infinity and the whole plan has reverted
to the preceding one. The investigation is, therefore, confined to a consideration
of but two designs, and these merge into each other.
It may be urged in criticism that no account whatever has been taken
of the influence of centrifugal force in effecting adjustment, and that it
has been restricted to the office of determining the degree of regulation.
The slight is intentional, and additional advantage is taken of this opportunity
to insist that in the perfect governor centrifugal force should be
reduced to a minimum while that of inertia assumes the position of
approximately the sole adjusting force for changes of load and steam
pressure.
It will be necessary to allude still further to the comparative action of
all these forces as influenced by the relative location of their centers of
support and application of force; but, as a preliminary to the further investigation
ofthe properties of governors, it will be necessary to understand
the relations between Speed of Engine, Permissible Variation of
Angular Velocity, Weight of mFly Wheel, Time of Governor Adjustment.
A familiar form of fly wheel ' formula = AAc is
where
. HP.
Wt is the weight of rim,
C is a constant,
A* is revolutions per minute,
D is diameter of rim in feet.
It is, however, only approximately correct, and wholly misleading as to
the relative values of the variable quantities.
Another is
C . AP
Wt =
where A P represents cylinder capacity, and /"is a secondary constant.
This is fundamentally proper, but is insufficient because of the form
in which the variable quantities appear; so that it is advisable to evolve
a wholly new formula which will be accurate and available.
The excess of power in the fraction of a revolution must be equal to
the energy due to increase of velocity of the fly wheel in that time;
hence, as
33000 //. P.
is the foot pounds of work in one revolution, and
33000 H. P.
R.
is the excess of energy during a portion of the stroke, which tends to
increase the velocity of the fly wheel, but which is unnecessary in positive
value for this purpose ; and as
M ( " )
is the energy of increase of velocity of fly wheel corresponding to the
excess of power; or, in other words, is the result of the sum of the
tangential forces in excess of the opposing ones, and is the work absorbed
by the fly wheel for service as kinetic energy during subsequent
retardation; therefore,
33000 H. P.
~At. (-7-) (')
I ,et = b = per cent, variation of speed c = v (b-\- 1) . . . (2)
33000 H.P. Wt.
64.4 A U> + J]2 - ^
X
Wl. v 2
64.4
(

16 ENGINEERING MECHANICS. [January, 1893.
where C is the combination of all the numerical quantities, and varies
from 10,000,000,000 to 20,000,000,000.
Substituting for //'/. in equation (3), and giving x same value
[x = |), we have
33000 11.p. _ (3.14) 2 c {i> 2 + 2b) R I ns
R ' 64.4 x 3600 x IV'P^ '
From the equation
Mv 2 __ ?r/. 3.X4' 2 /)*-* A' 2
_ CUP {2.14)- J) 1 A'-'
_ 850000 II P.
P + 2/> = .OO48
b — .OO23 (5)
2 64.4 3600
A 2 Z> 2 X 64.4 x 3600
~R~
Fly wheel energy per H.P. = -A. _ (6)
Properly interpreted, these formulae are full of interesting information
Jt will appear from (4) that the weight of the fly wheel should vary
inversely with the cube of the revolutions and the square of the diameter,
which is the true relation between these quantities.
Referring to (5), the limit of variation of speed with such a weight
of wheel from excess of power per fraction of revolution is less than
.0023.
Equation (6) gives the rate of reduction of total energy in the wheel,
due to velocity, as the speed increases, and incidentally shows the advantage
of high speed in the ability to stop and start quickly, and the proportional
inability to do damage in case of accident.
If in (3) is substituted for b the value .02, which is generally acknowledged
as acceptable service for degree of regulation of a governor, and
the equation solved for x thus :
33000 HP. (3.14V P> 2 R 2 CH. P.
AA X = - VJ -L .O4O4.
R R- D' 1 X 64.4 X 3600
Then x = 1.04 is the number of revolutions necessary to increase the
speed of the fly wheel two (2) per cent, with no resistance to the full
power of the engine during that time, except that of the fly wheel.
If the steam distribution were perfectly controlled over the time of
this change of speed, so as to correspond to each increment, then the
average effective power will be one-half the full amount, and the time
required to make the change of .02 will be increased to double, or the
time required to make 2.0S revolutions of the engine ; and the real problem
of governor design is to effect a rapidity of adjustment over the
whole range of the governor, during the time required to accomplish
2.0S revoluiions of the fly wheel.
A lighter fly wheel than that indicated will allow less time for adjustment,
but except for this single possible correction the figures are positive;
and a governor is proportionally far from perfection that requires over
2.08 revolutions to adjust through extreme positions under an instantaneous
change of its entire rated load.
However, as the force of inertia is a variable amount, and dependent
on the angular acceleration of the fly wheel in the perfect governor, the
actual speed of adjustment will vary with the weight of the rim.
The constant appearance in these formula? of an isolated R may be
explained by the fact that the disturbing element cf excess of power per
revolution becomes proportionally less as the speed increases, and its
presence further indicates that even with a purely centrifugal governor
the time of regulation will decrease inversely with the speed, although
not proportionally, but will, however, be more liable to surge in the
higher speeds without the co-operation of the inertia forces.
In the following figures only the elementary single weight is shown,
and for the purpose of convenience in the analysis of the adjusting forces,
is supposed to be balanced for gravity. The eccentric is not shown at
all, and may be assumed to be properly operated upon by the movement
of the weight through a convenient connection.
Fig. 19 illustrates probably the most common form of distribution of
centers of support and movement where the evident intention is to use
the greatest leverage of the centrifugal force. As a matter of fact, centrifugal
force is the only element that is utilized for adjustment, since the
tangential inertia is directly resisted by the supporting pin and is thereby
rendered inoperative. In Fig. 19 the area is so small compared to its
thickness that the centers of gravity, gyration and oscillation arc practically
identical and r% is substantially equal to zero by the arrangement,
and the expression
1 L •= o,
mr£r2
so that this is a form more or less nearly approaching the type of the
pure centrifugal governor.
This is true whether the figure illustrate right or left hand rotation.
Fig. 20 illustrates a method of improving the action of this governor
without changing the center of gravity of the weight or the resulting
moment of centrifugal force. The elements of composition are so far
removed from the center of gravity that their angular acceleration about
the pin [P) becomes prominent; but, to be effective, it is possible to run
FIG. 19. FIG. 20.
the engine in left hand rotation only—otherwise, the new force becomes
negative in effecting adjustment. rs is made positive, and all the radii
except that of center of gravity*are increased.
In Fig. 21 still another form is shown, and here the moment of the
inertia of the weight becomes a prominent force, uniting with that of
centrifugal with the engine in right-hand rotation, but opposing it in lefthand
rotation.
In Fig. 22, with the same distributicn of material in Fig, 20 as in Fig.
19, there is still greater complication, for in this case both tangential
FIG. 21. FIG. 22.
inertia and angular ihrrtia work in harmony in either condition to oppose
or assist centrifugal force according to the direction of rotation.
Fig. 23 is still another possible modification, reversing the action of
inertia, rendering it necessary that the governor be operated through
left-hand rotation in order that the two forces unite in their action.
In Fig. 24, showing a redisposition of the particles about the center
of gravity as shown in Fig. 23, to correspond with Figs. 20 and 22, the
influence of the three lorces becomes still more intricate, since, under a
left-hand rotation, centrifugal force and that of tangential inertia unite
in opposition to angular inertia, while with a right-hand rotation centrifugal
force and angular inertia join against tangential inertia. In this
figure, the angular inertia has been purposely arranged to illustrate a
perfect balance between it and the tangential inertia, leaving centrifugal
force alone operative.
Fig. 25 is a fair example of an intelligent distribution of centers to
utilize in a measure all three forces, but the governor must be run in
left-hand rotation or be subject to the disturbance of a conflict between
them.
It might still further be slightly improved by increasing the effect of
angular inertia.
In general, it may be stated that with a maintained constancy of
moments of inertia of the weight about the two centers of support and
revolution, the angular movement of the weight about its own center is
proportional to the ratio —, and the actual angular movement is —
'a

January, 1893.J ENGINEERING MECHANICS. 17
multiplied by the angular increment of advance of the By wheel, and
corrected for the assumed constant relation between the two moments of
inertia of the weight.
In fig. 19, >-, is o, and the force of inertia is ineffective, as we have
already determined.
In Figs. 21 and 22, ;-. is much greater than is the case in Figs. 2 and
7, so that inertia is proportionally less useful, and the shape of the weight
in F'ig. 22 is advisable as permitting a more active adjusting force. On
the contrary, in the form Fig. 23, ,:, may be made as large as desired,
thus increasing the action of the force of tangential inertia, while the
mass itself may be so concentrated that its angular inertia in opposition
may be insignificant.
From the foregoing it will be understood that in general the necessary
time of regulation glows less in proportion:
•^~\
A A
^ .
>M
FIG. 25. FIG. 26.
(I) As the lever arm of the weight grows shorter;
(2) As both weight and pin are located further from the shaft;
(3) As the speed of the engine increases;
(4) As the fiy wheel is made lighter;
and that the perfect governor approaches the form in Fig. 26 (which,
however, is extremely difficult of application) where centrifugal force
becomes reduced to a minimum, while both the tangential and angular
inertia of the weight reach a maximum and are co-operative with the
centrifugal force, and where rl and ;'., become identical with r2 and r
respectively, so that — 2 - and • both become a maximum.
To meet a possible doubt as to the efficiency of regulation attainable
in the several forms that have been shown, the following demonstration
is given :
In Fig. 27 let e9 represent the engine shaft about which the governor
revolves, P the weight pin or center of motion of the weight, IV, as it
moves from the shaft under centrifugal force.
The axes of x and y intersect at P, and x and y are the ordinates of
any particular position of the weight IV.
The centrifugal force of the weight in any position is proportional to
its distance from the shaft, and the rotative effect is proportional to the
product of this distance by the lever arm ; therefore,
From the equation to the circle,
y 2 -j- x 2 — cd
s*
From the figure,
1 = (" 4- A + A
= (a 4 x? -j- a-
= 2tl 2 -\- 2tix
A
a 1 -4- ax
= «»(*•» — .*»).
Thus the rotative effort of the centrifugal force is variable, according to
the formula:
z 2 -f flV = «*,
which, being of the second degree and symmetrical about both axes,
brands it as representative of an elliptical form of curve.
Following the investigation still further, and selecting a general
arrangement of the parts (Fig. 28), where the weight does not start from
the center of the engine shaft, but at a distance, b, to one side of it.
Then, as before,
z — vw
-.2 __ j/2^2
V 2 -\- x' 2 = a 1
j' 2 •= a 2 — x 2
v 2 =• (c 4- .r) 2 4- r 2
= A 4- 2CX fi-

iS ENGINEERING MECHANICS. [January, 1893.
differing only by a constant factor; so that if in Fig. lS, the ma-s of
the weight should be varied proportionally with

January, 1893.] ENGINEERING MECHANICS. "J
In a vertical engine the balance, as applied at each half of the stroke
may be unequal, so that the mean effective effort over the whole stroke
shall equal and neutralize gravity upon the reciprocating masses; still,
however, maintaining the proper inclination to balance as well the inertia
eflect, as per Fig. 32.
The vertical distance between the curves represents ihe neutralizing
effect on gravity.
v\ ith a properly varying angular movement of C( repression, it is also
perfectly possible to lit a spring tension that shall exactly balance the
forces represented by the inertia curve, together with that of gravity.
Under the same speed of revolution of the engine, and with the
necessarily varying valve strokes incident to the varying cut-offs, the inclination
of the curve of inertia scarcely changes, and may be considered
practically uniform, so that the curve corresponding to a longer or
shorter stroke may be found by proportionally increasing or decreasing
its length on the line of the indicated inclination. Thus Fig. 33.
The crowning excellence of this balancing device is found in its
ability to automatically adjust for the new conditions of strain, because
ship canal; the second for supplying the Yorkshire centres of
industry; and the third for supplying the centres of industry in
the Midlands and the metropolis. The arguments that might
be pertinently advanced in favor of central power generating
stations, such as he suggested, were almost identical with those
associated with the centralization of a gas and water supply or
a sewage treatment station ; but the arguments were more ade­
quate tban in either of these examples. After pointing out the
numerous obvious advantages of such central power generating
stations, the writer went into detail as to the method ou which
he proposed to carry out his project; and with regard to the
engine power which would be required, stated that this would
be obtained by means of a gas motor plant. The ultimate pos­
sible results of fuel gas aud gas motor plants on a large scale
were, that with such a plant the dynamic power enclosed in the
indicated card of pressure of a cylinder, equivalent to the raising
or elevation of 33,000 lb. 1 ft. high in one minute, might be
obtained with an exrjeuditure of from A 'b- to 1 lb. of solid
fuel. It must be obvious to any one that direct and perfect
combustion actually inside the wall of a motor cylinder must be
more economical than the combustion, more or less imperfect,
in the flues of a steam boiler, even if effected under the most
favorable conditions.
For generating power for driving electric generating machines
they would require high efficiencies with small powers, and a
motor of 500 horse-power was the largest that should be used
for this character of work. The efficiency of dynamos or elec­
FIG. 33.
tric generating machines was so nearly perfect that there was
only questionable advantage in building excessively large types,
but the motive power and elements should be such that if one
or two parts went wrong, it would not involve the stoppage of
the entire motive power plant; besides, it should be possible to
reduce or increase the power of dynamic energy production iu
proportion to the demand, and with large steam engines of
iooo horse-power aud upwards this would uot be practicable.
the same character of movement that varies the strain likewise and
similarly changes the resisting force. The only office of the eccentric There was another and important advantage in relatively smaller
becomes then a means of impulse by which a vibration is maintained, gas engines. The pulsations of piston effort could be so ar­
since it is no longer called upon for strength of resistance, and may be
made comparatively insignificant in size.
From experiment it appears that the varying inertia strain is accountable
for the possibility of perfect isochronism without obstructing
ranged that their effect on the supply would be inappreciable.
In the arrangements of the plant for the projected coal-field
generation stations, gas motors of 300 brake horse-power were
mechanisms, and that the application of the inertia balance serves to intended to be used, a pair of these engines being allotted to
permit a far higher degree of regulation without interfering in the least
wilh rapidity of regulation.
At a recent test of the device in an electric light station, on an engine
of 500 H.P., running at a speed of 220 revolutions per minute, where
each alternating current machine, coupled direct, one driving
the armature iu one directiou, aud the other the field magnets
in a contrary direction.
the balance found it necessary to resist reciprocating pressures of 2 '/2 In the project for transmitting power from the South York­
tons at each extreme of the stroke, there was not even one revolution
difference between the corresponding speed of no load and full load.
shire Coal-field to the metropolis, a plan of trunk lines had been
drawn up which could be utilized for serving the large towns
en route, including Derby, Nottingham, Leicester, Northamp­
A GREAT PROJECT.
ton, aud Bedford, but it was suggested that an auxiliary gener­
No more important undertaking has ever been proposed than ating station should be put down iu South Staffordshire, a trunk
that involved in the proposed generation of electric power in line from wliich would serve Wolverhampton, Birmingham,
the English coal-fields and its utilization elsewhere. The sub­ and the industrial areas in the line of its route, across to the
ject was handled in a paper by Mr B. H. Thwaite, C. E , ou the poiut where it joined the maiu trunk line serving the metropolis.
"Economic Possibilities ofthe Generation of Electro-motive The other two projects for supplying electro-motive force to the
Force in the Coal-fields of this Country, and its application to principal industrial centres of Lancashire and Yorkshire would
Industrial Centres." The carbonaceous fuel power resources of be located, one uear Barnsley, the other near Wigan. From
this country had, he said, been one, if not the main source of the Barnsley station the main trunk line would serve the indus­
England's industrial greatness, but with the entrance of the trial areas betweeu Chesterfield aud Sheffield in the south, and
new electric agency into the domains of practical engineering, Leeds in the north, serving the Batley aud Dewsbury district
the advantages we owed to our contiguity to the coal-fields, and en route, whilst a branch trunk line would serve Huddersfield,
to the possession of these fuel-supplying areas, was beiug grad­ Halifax, and Bradford, aud their adjoining industrial areas.
ually undermined, and unless we utilized these new resources, The loss of efficiency in the different trunk lines had, Mr.
so as to obtain the maximum practicable efficiency from them, Thwaite observed, been proved to be a negligible quantity, and
by the aid and assistance of the electric agent, our industrial the interest on cost of mains would almost be covered by the
career would in all probability pass through another and serious mere cartage to the station in many instances, beside the other
retrogression. With the object of utilizing with the greatest great advantages he had already set forth. From the Lancashire
efficiency the resources we had at our command, Mr. Thwaite generating station, near Wigan, one trunk line would serve
brought before the meeting three projects of electrical transmis­ Bolton, Bury, Heywood, and Rochdale, and a loop line would
sion of energy generated in the coal-fields The first for supply­ serve Oldham, Stockport, Macclesfield, aud Manchester, another
ing the Lancashire centres of industry, and the area adjoining the trunk line would serve Blackburn, Preston, aud Clitheroe, and
a loop line branch would serve Accrington, Burnley, and the
Rossendale and Accrington valleys, whilst a trunk line passing
south from the station would supply St. Heleus, Warrington,
Runcorn, and Widnes, and a loop line would continue along
the ship canal to serve the future industrial areas of progressive
Lancashire.
Another advantage of the scheme would be that as the great
power stations were all proposed to be located in the centre of
the coal-fields, this would enable the different colliery owners to
obtain on satisfactory terms the unquestionable advantage of
electro-dyuamic energy for traction, pumping, winding, lighting,
coal getting, ventilation, and drilling purposes. Mr. Thwaite

said that ten years ago he had forecasted that when once the
Manchester Ship Canal was made, its banks would become the
future area of new industrial developments, and with a line of
power supply, a perfect railway connection, aud a means of
over-sea transmission, it could be stated that uo other area in
the world would offer such facilities for cheap industrial production
as this area would be with the supply of cheap electricity,
aud unlimited energy proposed. To realize the marvellous industrial
fecundity of Lancashire and Yorkshire, they had only
to glance at the lines of the telephonic system already established,
and the proposed lines of electric power transmission.
There they had the very acme of economy in transmitting
thoughts; let them go a step further, and imitate nature by
laying down a nervous industrial system to distribute power,
and the picture, with the ship canal complete, was perfect, and
would be worthy of the enterprise of the counties of the Red
and the White Rose.
THE MYSTERY OF STEAM.
Can steam flow from a region of higher pressure into a region
of lower pressure without undergoing liquefaction ? There is
no direct intimation giveu to the contrary in any text-book of
thermo-dynamics. Rankine, indeed, states the conditions under
which such a flow may take place, with the result that the
steani will be slightly superheated ; and he was no doubt right,
but ouly withiu limits, the significance of which is usually
overlooked. The practical importance of the question which
we have asked will be understood when it is borue in mind that
in steam engines the steam always flows from the region of
higher pressure, the boiler, to the region of lower pressure, the
cylinder. If it can be shown that under such conditions liquefaction
must take place, it follows that nothing that can be done
in the way of using a cylinder of non-conducting materials can
totally stop what is known as initial condensation ; and that
being the case, we shall have to seek the attainment of maximum
economy not in jackettiug, but in converting steam by
superheating into the condition of a gas, which certainly does
not undergo liquefaction in flowing from a region of higher to
one of lower pressure.
Before any answer can be given to our question, it is necessary
to consider what the nature of steam is, and in what way
it differs from the so-called permanent gases. The main difference
lies in the relation which the sensible and latent heats
bear to each other in the gases. The latent heat, as a rule, that
is to say the heat converted into work iu converting the gas
from a liquid to a fluid, is probably very small as compared with
the sensible heat. In other words, all the gases are enormously
superheated at ordinary temperatures. Iu ordinary non-superheating
steam the proportion is much larger. Taking water at
32 deg. Fall., and converting it into steam at 212 deg. Fah.,
Isherwood thus divides tbe work : Representing the total as 100,
we have expended in raising the temperature of the water from
32 deg. to 212 deg. 15.776 per cent.; in increasing the volume of
the water between 32 deg. and 212 deg., .0002 per cent. ; destroying
the cohesion of the water, that is, converting it into steani,
77.940 per ceut. ; and iu increasing the volume of water from
that which it had at 212 deg. to that which it has in steam,
6.282 per cent. The whole of the heat is thus accounted for,
and in a certain restricted sense it may be said that steam possesses
no intrinsic energy. All that the water has received in
the form of heat has been expended in producing and maintaining
a change of state. That is to say, it can perform no external
work of any kind without undergoing a change of condition.
It contains just heat enough aud uo more to maintain it
as steam. The total amount of work done upon it is accounted
for by its change of state from water to steam, and the moment
it is compelled to do work it gives up some of the heat necessary
to its permanence of state, aud undergoes liquefaction.
In other words, ordinary boiler steam is in the condition known
to chemists as the critical state , and the least augmentation of
ENGINEERING MECHANICS. [January, 1893.
heat will, on the one hand, superheat it, while, on the other,
the least withdrawal of heat will cause partial liquefaction, and
the heat may be withdrawn in either of two ways, namely, by
the performance of work, or by the subtraction of heat.
Let us, to simplify matters, suppose that we have a triple expansion
engine, the cylinders, pistons, &c, of which, instead of
being made of iron, shall be composed of a material which is
absolutely neutral, which will neither absorb nor emit heat,
which can neither conduct it nor radiate it. Let the steam be
quite clean and free from suspended water. Will or will not
liquefaction take place in the first cylinder, with which alone
we shall concern ourselves? Beyond all question, liquefaction
will take place due to the performance of work, and amounting
in round numbers to about 2.5 lb. per horse-power per hour, and
this power will be very much in excess of the indicated power
developed iu that cylinder, because of the work done in overcoming
the high back-pressure. But is it reasonable to expect
that liquefaction takes place from any other cause? We think
it is, and practice and experiment both go to show that it does
take place, although it is uot easy to give the precise reason
why. Mr. Donkin has, with that energy and perseverance for
which he is remarkable, gone on adding to and modifying the
glass experimental apparatus to which we have often referred.
By putting a second glass cylinder outside the first, with an air
space between, changes have been produced in the phenomena.
It will be remembered that the apparatus is so coupled to a
beam engine that the steani enters it and exhausts from it just
as though it were a real steam cylinder. The presence of the
hot air space appears to prevent the formation of drops on the
glass inside, but the water coats the surface at each stroke, and
runs down in an even layer. The surface is uniformly wetted,
iu fact. It is easy enough to see through this what goes on.
The supply of steam enters through a pipe in the centre of the
upper cover of the cylinder. Now, the moment the valve opens,
steam rushes in, not transparent but in a cloud, which clears up
instantaneously, and then mist forms again, and remains until
the exhaust port opens, when rapid reevaporation takes place,
and the inside of the cyliuder becomes quite clear. The opening
of the steam valve is again followed by the entry of, as it
were, a puff of smoke, which clears up as before described, and
so 011. This is, we think, a most suggestive experiment. We
have here an entry of wet steam followed by dry steam at each
stroke, and it must be remembered that all the steani pipes, &c,
are carefully clothed. Thus, then, it appears, that steam flowing
from a region of high-pressure, the steam pipe, to one of
low-pressure, tbe cylinder, is instantly liquefied. Why ? No
contact has taken place between the steam and the metal or
glass ofthe cylinder. The cylinder no doubt contains steani of
a temperature and pressure proper to the condenser, and iu
mingling with this some liquefaction must be caused in the
entering steam ; but it is easy to see that the quantity of lowpressure
vapor present weighs far too little to produce an appreciable
effect. We must, then, seek for some other cause, and if
possible find one which will not only explain the results obtained
by Mr. Donkin, but which will cjver a very much wider
range. And here, it may be said without hesitation, that if we
could do this, we should at once be in a position to formulate
a far more satisfactory theory of the steam engine thau any
whicli has yet been promulgated.
Let us consider first what are the phenomena of liquefaction.
If we refer to the text-books, we shall gather from them that
steam contains heat iu two forms. Oue is known as " sensible"
and the other as "latent," and we are told that the sum of
latent and sensible heats is very nearly constant, undergoing a
small augmentation as the pressure rises. Thus, for example,
the total heat from 32 deg. Fah. with an absolute pressure of 70
lb. is 1174.28 deg., while at a pressure of 140 lb. the total heat
is 1189.90 deg. But in point of fact the term "latent heat" is
misleading. There is no heat in the steani but that which can
be measured by the thermometer. Thus, with 70 lb. steam the

January, 1893.] ENGINEERING MECHANICS. 21
actual heat present is 3027 deg , while the so-called latent heat
is 900.8 deg. The latter quantity has disappeared. It has been
wholly converted into work. It represents the 77.9 per cent.
mentioned above, and has been expended in destroying the
enormous molecular cohesion of the water, and imparting to
the molecules an energy quite similar in kind to that possessed
by the permanent gases. But the mere driving apart of the
molecules is not sufficient. They continually tend to run toge­
ther again uuder the influence of external pressure, and this is
ouly prevented by the presence of true heat. If, then, there is
any loss of heat, there will be liquefaction, and the molecules
in coming together give back the whole of the work that was
expended in separating them, and this reappears as heat, and
thi; heat, unless withdrawn in its turn, prevents further liquefaction
from taking place.
We have now to consider whether it is or is not possible for
steam to liquefy without losing sensible heat. It is extremely
difficult to give an answer to this question, because it appears
to constitute a problem insoluble by direct experiment, except
to a very limited extent. The liquefaction which takes place
in a steam cylinder is far too complex a process to help us
much. There is, however, some reason to think that under certain
conditions steam will expand and do work, and yet not
lose sensible heat. It is of course impossible to deal with this
supposition on any positive basis. But oue experiment may be
named as bearing ou it. Let us suppose that the classical experiment
of Joule with compressed air is repeated with steam.
It is about as certain as anything can be that liquefaction would
take place in the first bottle, and superheating in the second ;
aud yet there would be no loss of heat as a whole, aud no external
work would be done. Theoretically, on suffering the contents
ofthe bottles to mix again, the water of liquefactiou ought
to re-evaporate. Let us now apply this experiment to a steam
engine. We have a steam pipe which is full of steani—that is
the charged Joule bottle. We have the cyliuder, into which the
steam rushes, the moment the valve opens the steam-port—that
is the second Joule bottle. Under these circumstances it seems
to be fair to conclude that liquefactiou.will take place in the
steam pipe, and the water so produced will instantly afterwards
be blown straight into the cylinder; but we know that under
these conditions the water will be " knocked out of the steam,"
and will never be re-evaporated until the pressure falls during
expansion. Again, when the steam is passing during exhaust
into the intermediate receiver, it is by no means impossible that
liquefaction may take place in the high-pressure cylinder in
precisely the same way. All the time, although liquefaction is
taking pla^e, there is no direct withdrawal of heat, but there is,
so to speak, a change in its location from one place inside the
engine to another
There is another aspect of the question which deserves care­
ful consideration : Cau steani lose latent heat—we use the words
simply for convenience—without losing sensible heat, and in
that case what would happen ? In other words, cau steam
undergo liquefaction without cooling? We do not think too
much weight should be attached to the conversion of heat into
work on the piston of a steani engine, because no one knows
whether the molecular energy of the steam first reappears as
heat, and is then converted into mechanical work, or whether
the change takes place direct. We are as ignorant on this point
as we are as to how a bearing heats. But the importance of the
question may be gathered if we keep in mind that but one
cause of liquefaction is ever considered by those who attempt
to improve the steam engine. They assume, one aud all, that
the only cause of liquefaction is the abstraction of sensible heat.
"Keep the cylinder and all connected with it hot, reduce the
range of temperature in the cylinders by multiplying the num­
ber, and the best results will ensue." If, however, it cau once
be shown that the energy of the molecules—otherwise, the
latent heat—can disappear without ever reassuming the form of
sensible heat, we have at once a different picture of the action
iu a steam engine, and we begin to perceive that it may not be
enough to keep the cylinder hot, but that something else must
be done.
It is, we think, desirable that before we conclude we should
explain that we have been as careful as possible to avoid dogmatizing.
Our object has simply been to suggest. It may, per­
haps, be contended that we have said things which are quite
inconsistent with the learned views of the authors of various
treatises ou thermo-dynamics. We do not think that this is
really the case. But if it be, then let us consider next whether
any writer has been able to give a satisfactory explanation,
based on text-book thermodynamics, of what really goes on in
a steam eugine. The answer must be in the negative. The
extraordinary anomalies which in practice we continually
encounter cannot be all explained on any existing theory. It
is quite impossible, however, to make any progress to the true
solution of the difficulties and perplexities we meet with daily,
unless possible, if not probable, solutions are suggested, examined,
aud appraised ut their proper value. That steam is not a
gas, and does uot behave like a gas, is certaiu. The assumption
that liquefaction can only be caused by the direct abstraction of
heat, or the performance of work iu impelling a piston, appears
to be untenable. The shape of an engine, and the arrangements
of its parts, appear to exert a most powerful influence on the
consumption of steam. The amount of liquefaction appears to
be absolutely independent of the range of temperature in a
cylinder. There appears to be no certain relation between tbe
expenditure of steam and the use or disuse of a jacket. It is
time, we think, that physicists opened their eyes to these things,
and devoted their attention to the investigation of the real
properties aud peculiarities of steam. The altogether too-prevalent
notion that Regnault, Fairbairn, and Rankine have left
nothing to be learned should be dismissed for ever. Mr. Donkin
has already proved its futility. It will be time enough to
close the whole inquiry when it has been definitely ascertained
how the heat generated in a furnace becomes converted into
indicated horse-power, and not till then. — The Engineer.
THE Shone Hydro-Pneumatic System of Sewage is a system
in which the motive power is compressed air automatically acting
direct on the sewage, and which uses a minimum of water
without strainers. Sewage districts can be more conveniently
laid out under this system, and under it sewers are self-cleansing.
It is in use at the Columbian Exposition, where 26 ejector stations
are established, with a united capacity of 17,000,000 gals.
in 24 hours, connected with 5 miles of cast iron pipe, 2 to 10
inches in diameter, laid at a depth of 4 A feet, besides 4j 3 0- miles
of cast iron sewage discharge pipe from 6 to 30 inches in diameter.
The maximum lift of the sewage is 67 5 § ft., and the
maximum total head pumped against is 107^ ft. The air pipe
line was tested to 90 lbs. after laying without appreciable loss,
and the pressure maintained will be 47 lbs. to the square inch.
There are four wrought iron receiving tanks 32 ft. in diameter
and 55 ft. high, in which the solid matters will be precipitated
by chemicals, and afterward pressed into cakes and burnt. The
effluent will be ruu into the lake.
THE use of petroleum as fuel on torpedo boats has been
decided against by the special commission of the French Gov­
ernment, because out of ten cans of petroleum experimented
with under the conditions in which they would be placed on
board torpedo boats, eight became ignited from concussion
after twelve shots had beeu fired upou the armor plate protecting
them.
THE Joseph Dixon Crucible Company are adding a 175x75
foot floor, the fifth, to their present factory. The company will
also establish a rubber and brass plant for the manufacture of
pencil accessories.

^J ENGINEERING MECHANICS. [January, 1893.
A GRAPHIC REPRESENTATION OF THE DISTRIBUTION OF
HEAT IN STEAM ENGINES.
The accompanying diagram represents the heat supplied to
and discharged from a steani engine iu the form of debit and
credit sides of an account. The left-hand half of each diagram
represents the heat supplied to, and the right-hand half the heat
discharged from, the engine, the length of each rectangle indicating
on a uniform scale the number of thermal units. It is
obvious that, even after the general arrangement of the diagram
has been decided upon, much of its value depends on the
choice of a suitable unit to form a standard of comparison for
trials made under different conditions. A little consideration
will show tbat a fixed weight, say I lb., of what ma) - Let Wc = pouuds of water for coudeusiug per minute.
" II = total heat of evaporation at boiler temperature.
" L = latent heat of evaporation at boiler temperature.
" T = temperature of boiler.
" tf = " " feed water.
" tc— " condenser.
" tr = mean rise of temperature of coudeusing water.
The heat supplied per minute by steani passing through the
cylinders
= W F (H — t, + 32 deg.) (')
The heat supplied per minute by steam condensed in the jackets
= Wj L (2)
The " equivalent boiler feed " is the weight of steam passing
be called
through the cylinders per minute which can supply to the
the "equivalent boiler feed" is the most convenient unit to
engines a quantity of heat equal to that received frem the
adopt, as it admits of a fair comparison being drawn betweeu
above two sources, aud is giveu by the expression :
jacketed aud unjacketed as well as high and low speed engines.
Iu order to render the subsequent calculations more intelligible, [ ZAAAlAA "iLX .-Lr = \yp _|_
_Wj L
(3)
a brief description of the engines will be given. They are H — t, + 32 deg. "" ' H- -tf 4-32 deg.
triple-expansion engines of the vertical inverted marine type The heat converted into work per minute
with large intermediate receivers and a surface condenser. All
the cylinders and receivers are steam jacketed, and the water
= I.H.P x 33.°°° I.H.P. 4- 42.75
772
of condensation from the jackets returns by gravity to the The heat discharged into the condenser per minute
(4)
boiler, so that only the latent heat of evaporation of the steam
Wc t, 4- WF (fi — tf) (5)
TRIFLE CYLIUDER EXPANSION.
Jackets
DOUBLE CYLINDER EXPANSION.
Jackets
DIAGRAM OF HEAT DISTRIBUTION PER POUND OF EQUIVALENT
condensed in them has to be supplied by the boiler. The cylinder
ratios are: High-pressure to intermediate, 2.56; intermediate
to low-pressure, 3.37 ; but in all the trials represented, each
engine ran indep ndently, having a separate brake, so that the
actual cylinder ratios varied according to the relative speeds of
the engines in the different trials. Trials marked "jackets on"
had steam in both cylinder aud receiver jackets, whi'e those
marked "jackets off" had steani in the receiver jackets only,
the cylinder jacket connections being then open to the atmosphere
The pressure of steani in the jackets WES that of the
boiler throughout. The heat supplied to the engines is derived
from two sources, the steani actually passing through the cylinders,
and the steam condensed in the jackets. The heat
accounted for by the engines consists of the heat converted
into work and the heat discharged into the condenser, the heat
required to balance both sides of the account being that lost by
radiation.
Let W F = pounds of steam passed through cylinders per
minute.
" Wj = pounds of steani condensed in the jacket per minute.
SINGLE CYLINDER EXPANSION.
Jackets
BOILER FEED
The heat lost by radiation will be the difference between the
heat supplied to, and the beat accounted for by, the engines,
and is represented by the rectangle required to make both sides
of t*..e diagram of equal length. It may here be noted that the
net result of all errors of measurement will be included in this
quantity. If equations (1), (2), (4), and (5) be each divided by
equation (3) the results are the numbers of the thermal units
required for constructing the several component parts of each
diagram, which can then be drawu to any convenient scale. As
there was considerable variation in the temperatures ofthe feed
water iu the different trials represented, the bases of the diagrams
have been fixed relatively to a line of uniform feed temperature
iu order to facilitate comparisons. The distances of the upper
series of points, connected by a full line, from the line marked
o deg. Fah., represent the temperatures of the boiler, while
those of the lower series represent the temperatures of the
steam at the end of expansion in the low-pressure cylinder.
As the radiation per pouud of steam not only depends on the
temperature of the steani and the surface exposed, but also on
the rate at which it is passed tlirough the engines, the hot-well
discharge has beeu marked on each diagram, and is represented

January, 1893.] ENGINEERING
by the series of poiuts connected by a broken line. In the
triple cylinder expansion series it will be noticed that although
the jackets are ou in trial (4), the efficiency is only about equal
jackets off. In order to explain this, it may be mentioned that
in trial (4) the cut-off in each cyliuder was about 90 per cent, of
the stroke, in trials (5) and (6) about 50 per cent., and in trial
(7) about 75 per ceut. These results appear to indicate that not
only is there no material gain by jacketing au engine with so
late a cut-off as 90 per ceut. of tbe stroke ; but, further, that au
unjacketed engine with a cut-off at 50 per cent, of the stroke
will give a higher efficiency than it. In trial (8) the cut-off in
each cyliuder was about 35 per cent, of the stroke, so that the
low efficiency, in this case, appears to be due to excessive condensation
caused by a too early cut-off for an unjacketed engine
combined with a very low speed, as shown in the hot-well discharge.
In trial (9) the cut-off was about So per cent, of the
stroke, and there was no steani in the jackets of the receiver
betweeu the high and intermediate cvlinders. There was
nothing in the conditions under wliich those of the doublecylinder
expansions series were made which necessitates further
explanation than is giveu by the diagram. For the singlecylinder
expansion series the steani from the boiler was first
passed into the receiver between the intermediate and lowpressure
cylinders, aud in trials (20), (21), and (22) the pressures,
in passing into the receiver, were reduced to about 10 lb. from
boiler pressures of 25 lb., 41 lb., and 61 lb. respectively.
Although the steam in the jackets was at boiler pressure in
each case, thus securing a greater fall of temperature between
the steam in the jackets and that in the cylinder, and consequently
a more rapid flow of heat, no par,t of the loss due to
initial throttling appears to have been made good during the
passage through the cylinder. Trials 21 and 22 were made
under the same conditions with the exception of jacketing, and
a difference iu boiler pressures before throttling. Below is
given approximately a list of the number of times the steam
was expanded in those trials whose numbers are placed opposite.
Number of Number of
Trial. Expansions.
I 26
2 21
3 26
4 11
5 16
6 20
7 10
S 21
9 9
13 10
14 10
16 6
17 8
A NEW soldering metal for aluminium has been prepared by
Mr. Alexius Rader, of Christiania, Norway. It consists in combining
cadmium, zinc, and tin mixed in substantially the following
proportions : Cadmium, 50 per cent. ; zinc, 20 per cent. ;
tin, the remainder. The zinc is first melted in any suitable vessel,
when the cadmium is added, and then the tin in pieces.
The mass must be well heated, stirred, and then poured. This
soldering metal can be used for a variety of different metals,
but is specially adapted to aluminium.
SIXTY-TWO holes were bored at street crossings between South
Ferry and Thirty-third Street, New York, at the instance of the
Rapid Transit Commission, varying in depth from 7 feet to 163
feet, the average being 65 feet. Rock was reached only in a few
cases. A portable pile-driver, with a hammer weighing 150
pounds, fall 6 feet, was used.
MECHANICS. 23
ATLANTIC GREYHOUNDS OF THE FUTURE.
IN the course of a lecture on "Naval Architecture," delivered
before the members of the Dundee Mechanical Society ou the
to that of trial (-j), and lower than in trials (5) and (6) with the
evening ofthe 26th ult., Mr. R. M. Short indulged iu some extremely
advanced aud fanciful prognostications as to what "the
ship of the future" would be like. Referring to tbe complete
way in which irou and steel had superseded wood as the struc­
tural material, he remarked that what might supersede or supplement
steel no one could say. Aluminium had already been
used for small yachts ; but until some means were found of pro­
ducing that remarkable metal cheaply, it was impossible to
foretell of what material the ships of the future would be built.
The change iu material had been no more marked than the
change iu size ; and if dimensions were to increase iu the ratio
of the last few years, they knew not what monsters might be
afloat within the next twenty years. . . . Just as the triple and
quadruple expansion engines promised to save space and coal,
the long-hidden power of electricity bade fair to laugh at their
cumbersome cranks and connecting-rods, their pistons and cylinders
; and at one vast stroke sweep away their machinery and
apply its force direct. As it had been in the past, so would it
be in the future, but only now were they beginning to see the
first movings ofthe mightiest force the world .had yet seen. To
them, a nation of shipbuilders, that new force would revolutionize
their methods of commerce, aud bring in as realities
what they had scarcely dreamt of. The vessels to be built
when that new force was fully harnessed for their use would be
leviathans, to which the present greyhounds of the Atlantic
would be as the canoe of the South Sea savage to an oceanliner
of to-day. No docks would be large enough to hold them,
but they would have attendant fleets to ply between them and
the shore. Their dimensions would preclude forever the possibility
of sea-sickness in the wildest weather ; their decks would
be intersected by great avenues, along whose breadth would ply
the traffic of a city. The prison-like cells, now dignified by the
name of state-rooms, would be replaced by the spacious apartments
of vast hotels, and the Atlantic would become a mere
ferry ; the old world and the new world would be joined by a
floating city of the sea.
IN Great Britain and Ireland 12,000 traction engines are in
use, where they are widely employed for almost all manner of
agricultural work—hauling 011 highways, in metal yards aud
on docks, road-rolling, plowing, hauling timber from forest to
mill, land irrigation aud for electric light purposes. Their use
is being rapidly extended, and their adaptivity to so many
forms of work reduces cost of labor over other methods. The
cost of hauling shows a saving of 50 to 75 per cent. In an ordinary
threshing engine, S'. x 12 in. cylinder, driving a 54
in. machine, the consumption of coal is 67 pouuds per hour;
for an 8 x 10 cylinder, 56 pounds. At recent trials the consumption
of coal was from 1.84 lbs to 2.56 lbs. per brake horse
power. The business has grown rapidly within a few years.
The traction engine has every chance iu England with perfect
roads, cheap or often cheaper coal than here, and traffic and
patronage scattered along the highways everywhere. Here
conditions are different. Roads are not good, population is
scattered, coal is neither cheap nor easily obtained over a large
area. Yet for all there are opportunities for the traction engine
among us, and it will no doubt some day creep iu between
the express wagon and accommodation train, after acquainting
itself with farm work. That farming operations could be
cheapened and simplified by traction engines is evident from
what has been accomplished iu Great Britain. The system is
quite new even there, and almost unknown here, but conditions
are arising among our agricultural classes and in sub­
urban localities that will certainly open a way at least for this
expeditious and economical method of hauling small freight
and applying power to supplant or supplement hard labor.

A ENGINEERING MECHANICS. [January, 1893.
METAI. ties in Belgium do not appear to have met with unqualified
success. The Belgian State railways have for five
years beeu testing the relative values of metal and wooden ties.
Official reports of the tests state that it was very difficult to
keep the track laid with metal ties in good shape, particularly
as the stone ballast under them was gradually pulverized. The
ties themselves were much damaged after five years' wear by
cracks starting from the bolt holes. l"p to the time of making
the reports from which these facts were taken, the track laid
with metal ties had cost for maintenance about nineteen times
as much as the track laid with creosoted oak ties, aud many of
the metal ties were so badly damaged that they would soon
have to be removed. In Austria, however, it seems probable
that metal ties will in due time be used on an extensive scale.
The State Railways Administration, it is reported, has contracted
with the syndicated Austrian rail mills for a large supply of
metal sleepers at a price but slightly inferior to that paid for
steel rails, with the proviso, however, that a lower rate is to be
accepted should the demand exceed 25,000 tons. It also stated
that the Southern Railway is inviting tenders for the supply of
35,000 iron ties.
In a paper read before the Victorian Institute of Engineers,
Professor W. C. Kennot discusses the question ofthe maximum
load per square foot of floor surface due to the weight of a dense
crowd. Considerable variation is apparent in the figures given
by many authorities, as the following table shows:
Weight of
Authoritv. crowd, lbs.
per sq. ft.
French practice, as quoted by Trautwine and Stoney 41
Hatfield ("Transverse Strains," p. So) 70
Mr. Page, engineer to Chelsea Bridge, London,
quoted by Trautwine S4
Maximum load, on American highway bridges according
to Waddell's general specifications . . . 100
Mr. Nash, architect of Buckingham Palace, quoted
by Trautwine, also Tredgold 120
Experiment by Mr. W. N. Kennot at Working
Men's College, Melbourne 126
Experiment by Professor W. C. Kennot at Melbourne
University M3- 1
Experiment by Mr. B. B. Stoney ("On Stresses,"
p. 617) M7-4
The highest results, viz , those of 140 lb. per square inch, were
obtained by crowding a number of persons previously weighed
iuto a small room, the men being tightly packed so as to resemble
such a crowd as frequently occurs on the stairways and
platforms of a theatre or other public, building. We may point
out, however, that in these cases part ofthe weight is undoubtedly
carried direct by the walls of the structure, owing to the
friction of the bodies of those against them, but it would, perhaps,
be unsafe to rely on this.
A RECENT issue of the Paris Genie Civil describes the sinking
of iron piles in Chili with a water jet. Some of the piles
were 14.76 111. iu diameter, with a flat bottom flange or pedestal
41.92 in. in diameter, aud were sunk to a depth of 2S ft. below
the bottom of the river through very coarse, compact sand, in
which screw piles penetrated with great difficulty, and sharp
piles could only be driven from 11.8 to 14.1 ft. A pump delivering
about 12,000 gallons per hour through a 4.92 in. pipe
would sink two piles, each having a 2.05 in. pipe projecting
about 7.S7 in. below its base with a 5.9 iu. opening. The pile
beiug put in position and the water jet started, it sank nearly
three feet by its own weight, after whicli it was worked down
by means of au endless cable leading from the drum of a hoisting
engine around a horizontal pulley bolted on to tbe pile so
as to revolve the latter about its vertical axis. An average of
eighteen hours was required to sink each pile. On one side of
the river a double-action Worthington pump was used, and on
the other a Tangye pump.
THE following are the dimensions of a tank locomotive built
at an English works for mineral traffic and steep grades.
_ ,. , ( 18 in. diameter by 26
Cylinders -
I in. stroke.
Leading, driving and trailing wheels . . 4 ft. 3 in. in diameter.
Radial wheels 3 " 6 "
Wheel base, fixed '4 ft- 5 in-
" total 20 " 8 "
Height from rails to centre of boiler . . 7 "
Boiler, smallest diameter, inside . ... 4 " 4 in.
Length of boiler from smoke-box tube
plate to front plate of firebox .... 10 " 6 "
Number of tubes of 2 in. outside diameter
.... 1S1
Heating surface in tubes 1023 sq. ft.
" " " firebox no "
" total 1133
Grate area 20*4 "
Capacity of tanks 1750 gallons
" coal box 32 cwt.
Weight of engine in working order . . 56^ tons
The engines work entirely on heavy mineral traffic; the load
on the down journey being 500 tons plus the weight of the
engine, and this load is drawn up a grade of 1 iu 400 for a distauce
of 3J-2 miles. The average consumption of coals under
this load is about 36 lb. per mile.
AT a recent meeting of the Paris Academy of Sciences, a
demonstration was giveu of the existence of interference of
electric waves in a closed circuit, by means of the telephone, by
M. R. Colsou. A Rfiumkorff coil was kept vibrating at 130 per
second by a thermopile. To one of its terminals was attached a
copper wire ending in a hook, to which a linen thread soaked in
calcium chloride was attached by one end, the other hanging
free. One of the terminals of a telephone was placed in contact
with the thread, the other terminal being isolated. Under
these conditions, the souud iu the telephone was completely extinguished
at a certain distauce from the copper. When both
the ends of the thread—which was 3 m. long—were connected
up by fine copper wires, two points of extinction were reached,
one from each end. On shortening the thread these points
approached each other, and formed a zone of extinction betweeu
them. This zone of extinction spread over the entire
copper wires, as the thread was shortened to zero. The neutral
zone is due to interference of two waves of the same period aud
of equal potential, meeting in opposite directions.
IN some experiments on the laws of compressibility of
liquids, by M. E. H. Amagat, deformations of the piezometers were
investigated and allowed for, and the pressures carried as far as
3000 atmospheres. The liquids operated upon were ether, alcohol,
carbon bisulphide, acetone, the ethyl halides, and chloride
of phosphorus. In every case the coefficient of compressibility
was found to decrease regularly as the pressure increased. At
3000 atmospheres that of water was reduced by nearly one half
its ordinary value, that of ether by two-thirds. This diminution
is greater the higher the temperature. The ratio of the difference
of the coefficient to the corresponding difference of tem
perature increases rapidly with tbe temperature aud decreases
rapidly as the pressure increases.
To silence the exhaust of a gas engine take the exhaust to
a tube outside the building, which tube is slit by a saw for a
length of about 6 ft. and two semicircular portions opened out
so as to give a V-shaped slot on each side of the tube, through
which tbe gases escape. The gradually increasing opening
thus provided for the exhaust gases is said to completely silence
the troublesome noise and vibration so common with this type
of motor.

January, 1893.] ENGINEERING MECHANICS.
BOARD OF TRADE ELECTRICAL STANDARDS.
The following are the resolutions passed by the London Board
of Trade Committee on Electrical Standards :
1. That it is desirable that new denominations of standards
for the measurement of electricity should be made and approved
by Her Majesty iu Council as Board of Trade standards.
2. That the magnitudes of these standards should be determined
on the electro-magnetic system of measurement with
reference to the centimetre as unit of length, the gramme as
unit of mass, and the second as unit of time, and that by the
terms centimetre and gramme are meant the standards of those
denominations deposited with the Board of Trade.
3. That the standard of electrical resistance should be denominated
the ohm, and should have the value 1,000,000,000 in
terms of the centimetre and second.
4. That the resistance offered to an unvarying electric current
by a column of mercury at the temperature of melting ice 14.-
4521 grammes in mass of a constant cross sectional area, and of
a length of 106.3 centimetres may be adopted as one ohm.
5. That a material standard, constructed in solid metal, should
be adopted as the standard ohm, and should from time to time
be verified by comparison with a column of mercury of known
dimensions.
6. That for the purpose of replacing the standard, if lost, destroyed,
or damaged, and for ordinary use, a limited number of
copies should be constructed, which should be periodically
compared with the standard ohm.
7. That resistances constructed in solid metal should be
adopted as Board of Trade standards for multiples and subniultiples
of the ohm.
8. That the value ofthe standard of resistance constructed by
a committee of the British Association for the Advancement of
Science in the years 1863 and 1864, and known as the British
Association unit, may be taken as .9S66 ofthe ohm.
9. That the standard of electrical current should be denominated
the ampere, and should have the value one-tenth (0.1) in
terms ofthe centimetre, gramme, and second.
10. That an unvarying current which, when passed through
a solution of nitrate of silver in water, in accordance with the
specification attached to this report, deposits silver at the rate
of 0.001118 of a gramme per second, may be taken as a current
of one ampere.
II. That an alternating current of one ampere shall mean a
current such that the square root of the time average of the
square of its strength at each instant in amperes is unity.
12. That instruments constructed on the principle of the balance,
in which, by the proper disposition of the conductors,
forces of attraction and repulsion are produced, which depend
upon the amount of current passing, and are balanced by known
weights, should be adopted as the Board of Trade standards
for the measurement of current whether unvarying or alter­
nating.
13. That the standard of electrical pressure should be denominated
the volt, being the pressure which, if steadily applied to
a conductor whose resistance is 1 ohm, will produce a current
of 1 ampere.
14. That the electrical pressure at a temperature of 15 deg.
Cent, between the poles or electrodes of the voltaic cell known
as Clark's cell, prepared in accordance with the specification
attached to this report, may be taken as not differing from a
pressure of 1.434 volts by more than one part in iooo.
15. That an alternating pressure of one volt shall mean a
pressure such that the square root of the time average of the
square of its value at each instant in volts is unity.
16. That instruments constructed on the principle of Lord
Kelvin's quadrant electrometer used idiostatically, and, for highpressures,
instruments on the principle of the balance, electro­
static forces being balanced against a known weight, should be
adopted as Board of Trade standards for the measurement of
pressure, whether unvarying or alternating.
IT will be remembered that some seven years ago Command­
ant Reuard, director of the central establishment of military
balloons at Chalais-Meudon, France, made a number of experi­
ments with the dirigible balloon La France. Since then he has
not been idle, but engaged in perfecting a propelling mechan­
ism which will be tried at an early date. The new balloon,
General Meusnier, is cigar-shaped, like its predecessor La
France, and measures 70 metres from tip to tip, with a diameter
of 13 metres and a capacity of 3400 cubic metres. The car,
which is constructed of bamboo and steel, contains a cabin for the
machinery and men. The motor employed is worked by means of
gasoline and balloon gas, and develops 45 horse power during
eight to ten hours. It is able to drive the balloon at a speed of
40 kilometers an hour, or n metres a second. The total weight
of the machinery, with the carburetter, the gasoline, and accessories,
will not surpass 1200 to 1400 kilogrammes, or 30 kilogrammes
per horse power. Until now petroleum motors of
large size have weighed 150 to 200 kilogrammes per horse
power ; but M. Reuard has been able to reduce the figure by a
new arrangement, which we are not at liberty to disclose. The
screw propeffer is placed in front of the car, aud the rudder behind.
The balloon has beeu entirely constructed at the Chalais
works by engineering soldiers who are studying the art of ballooning.
It is expected that the trial ascent will be made during
fine weather iu the early part of next year.
A NEW English street car system is thus described: An insulated
cable is laid between the ordinary tram lines, in a hemispherical
tube formed by a groove in the bottom of a contact
rail of cast iron, and a foundation of bituminous concrete. The
contact rail is divided up iuto sections, each of which is completely
insulated from its fellows by being laid in bitumen and
asphalt. Contact boxes are provided at intervals, in which
are electro-magnetic contacts, each of which puts two consecutive
sections of the contact rail into communication with the
main conductor already mentioned. The cost of the system is
$7,000 per mile.
THE Standard Steel Casting Co., of Thurlow, Pa., have recently
done some delicate and important government work
which has been subjected to tests under Lieut. C. W. Ruschenberger,
U. S. N., which showed results above the average of
such material.
For a 1 Pivot Stand, No. 1 Test, 2 in. section, .505 diameter
elastic limit, was 35,000 pounds; tensile strength, 74,000
pounds; elongation, 31.25 ; reduction of area, 34.74.
No. 2. Elastic limit, 30,000 pounds ; tensile strength, 71,000
pounds ; elongation, 30 per cent.; reduction, 40.71.
No. 3. Elastic limit, 31,500 ; tensile strength, 72,000 ; elongation,
28; reduction, 37.58.
Pivot Stand for Gun.—Elastic limit, 34,000 ; tensile strength
71,500; elongation. 27 ; reduction, 35.6S.
Front Chip.—Elastic limit, 30,000; tensile strength, 71,000;
elongation, 30; reduction, 40.71.
THE Schuylkill Foundry & Machine Works, of Conshohocken,
Pa., manufacturers of Wood's Water Tube Boilers
have just shipped to the Berwind-White Coal Mining Co. :
600 H. P. of Boilers, Castiugs, etc. ;
400 H. P. to the Lukens Iron and Steel Co., Coatesville, Pa. •
300 H. P. to John & Jas. Dobsou, Falls of Schuylkill;
150 H. P. to Conshohocken Brewing Co., Conshohocken, Pa.;
200 H. P. to Gulf Brewing Co., West Conshohocken, Pa, ;
iooo H. P to the Mining and Horticultural Department,
World's Exposition ;
1500 H. P. to Electric Railroad, Chicago ; and are now negotiating
for 2500 H. P. for the Johnston Tower Co., World's Expo­
sition and for 12,000 H.P. for Boston parties. They report
business very active.

26 ENGINEERING MECHANICS. [January, 1893.
STARRETT'S CALIPERS.
These cuts represent long-needed tools, viz., simple, light,
low-priced aud reliable calipers of wide scope for both inside
and outside work, that can be instantly adjusted to their full
extent, and as quickly locked firm in the joint, and yet provided
with a sensitive adjustment. They are made to supersede the
the joint is locked) to clear the obstruction, then moving it
back against a stop, where it will show the exact size measured.
LOCK-JOINT CALIPERS.
sensitive adjustment.
No. 43 shows Dividers, with lock-joint attachment and sensitive
adjustment. They are light and stiff, with large capacity,
old-style firm joint, also the lock-joint with split leg adjustment instantly opened, closed and locked. The points are nicely
formerly made. The improvement consists, first in a socket
joint made tapering, and locked or released by a partial turn of
tempered. Factory at Athol, Mass.
the knurled disc drawing it together. A spring washer under CHARLES S. CHURCHILL, C. K., in a paper read before the
the disc maintains an easy friction in the joint when unlocked. Engineers' Club, of Philadelphia, 011 the requirements of a rail­
To further describe, in the under side of short arm is a slot road on which a locomotive engine could make a speed of 100
containing a stiff spring. Riveted into the middle leg and pro­ miles per hour. Grades should be fixed at 20 feet per mile with
jecting through an opening in the arm, is a threaded stud on a possibility of 30 feet. Curves should seldom be sharper than
which is a knurled nut having a beveled hub—this bears against 1 degree, never sharper than 2 degrees. As to road bed, tracks
a cone in the arm—tbe action of the spring holding them to­ should be spaced 12 feet from centre to centre, ditches outside
gether turning the nut, presses them apart and adjusts the leg at least 7 feet from the edge of the rails. Slopes of cuts and
while the joiut is locked. The spring taking up all back lash, fills should be 1 >^ to 1, and all earth cuts thoroughly sodded.
the legs are firm.
Rock cuts should be taken out at a slope of % to I and
thoroughly cleared of loose material. Berm ditches should be
provided at the top of all cuts. The roadbed under passenger
tracks should be tile drained. The edge of the roadbed should
be limited by a line 7 feet from the outer rail of the freight
tracks. Box or arch culverts should be provided, laid in good
cement, and of ample size to care for the water sheds. No
road, highway or street, should be crossed at grade, as it would
be practically impossible to give the necessary warning, or to
check the speed at each crossing. All of the right of way
should be substantially fenced, the posts being not farther
LOCK-JOINT TRANSFER CALIPERS.
simplest device.
The rails must be truly level on tangents, and the outer rails
These instruments (Nos. 36 and 37) not only have all the ex­
on curves of 1° to 2
cellent features of Nos. 38 and 39, as described above, but in
addition to common use may be used inside of chambered cavities,
over flanges, etc., removed and replaced without losing
the size calipered. This is done by loosening the nut, binding
one arm to the auxiliary leaf and swinging it out or in (while
0 should be elevated 5 in. above the inner
rail, by raising the former and depressing the latter each half
this amount. Across through-bridges the tracks should be protected
by inside guard rails 7 in. from the maiu rail. Switches
should be as few as possible, and the best pattern of the point
switch seems to be the most desirable. Spring rail frogs would
N942
HERMAPHRODITE CALIPERS.
N943
DIVIDERS.
No. 42 shows Hermaphrodite Calipers, with lock-joint and
apart than 8 feet.
Draw bridges could not be used and stone arches always if
possible, if not, plate girder bridges with buckle plate floors, up
to a span of 100 feet, riveted trusses up to 120 feet and pin connected
trusses for greater spans. Stone ballast 2 l /2 inches and
less ; 12 inches under tie at centre of track. White oak ties,
face 7 inches wide, SA feet lon S. 28o ° to the mile '< rails ' IO °
pounds to the yard. The Sayre joint to secure smooth riding
should be used. The rail should be supported at the joint from
beneath as well as at the head. The interlocking bolt is the

January, 1893.] ENGINEERING MECHANICS. 27
be best from our present point of view, and should be of
improved pattern, built on a three-quarter inch plate, the wing
rail having the spring near the end, with a lever to hold it in
position, the top being bevelled to prevent a possible forcing
open of the wing rail by badly worn engine tires. Distant signals
should be placed so that even at these high speeds a train
could be stopped before reaching the switch.
Tracks should be constantly patrolled, and an interlocking
system of signals, perhaps preferably an electiic one, will be
found necessary for proper protection. The possible ruuning
of trains at such high speeds depends to a large extent upou
the ability of engineers to provide proper protection.
No existing road, at least in this country, fulfills them to­
day, and speeds of 80 to 100 miles per hour could not now be
used. Comparatively few of our trunk lines, from the nature
of the country traversed, could be brought up to this condition,
and it is improbable that a new 4-track railroad will be built
especially for such high speed service; hence portions of existing
lines, in suitable sections of the country, must be regarded
as the only roads which may in time develop an increase over
present speeds. Such sections having been improved in grade
and alignment, a locomotive capable of hauling a train on a
straight aud level track, at the rate of 100 miles per hour, may
make, on a properly protected line, an average speed of from
70 to 80 miles per hour.
BARNES FRICTION CLUTCH PULLEYS.
The accompanying cuts represent the principles of one ofthe
latest improvements in the line of friction clutch pulleys and
cut-off couplings manufactured by the J. H. & D. Lake Company,
of Hornellsville, N. Y.
Fig. 1 affords a sectional side view ofthe Barnes Screw Lever
Friction Pulley in released position, showing the driving hub
keyed to the shaft.
S//SSMS , /SASAK-SSSS?SSSSSS/.
FIG. 1.
Fig. 2 is a sectional end view describing the friction hub encircled
by friction-ring, the former of which is cast in one solid
piece with the pulleys. Projecting lugs on opposite sides of the
driving hub of the ring drop into lugs, or lug cavities, of the
friction-ring; and when the clutch is on these lugs take all the
driving power. This is an improvement over the old bolt fasten­
ing system, the bolts of which are more liable to be affected by
the twisting strain upon the hub from the friction of the clutch.
At the extreme top and bottom of Fig. 2 is shown a view of a
simple device which evades the use of much complicated machinery
and more than substitutes the coresponding complex
parts of some previous inventions. It is a lever nut on each
side of the friction-ring, one-balf of the nut being cut with a
right thread and the other half with a left thread. Sufficient
space between opposite sections of the ring is given for contraction
or clutch, which is effected by means of right and left
thread screw-bolts entering the lever nut from opposite sides,
secured by set-screws. Duplex levers are attached to these nuts
at their upper section and to the hub at their lower section.
When the shipper sleeve is thrown against the flange by the
operating lever, the duplex lever turns the nut sufficiently to
FIG. 2.
produce a friction that was never known to lose its grip, nor
has a thread of these screw-bolts ever been known to break.
The screw-bolts are adjustable to any desired pressure, however,
in case the clutch should ever become lax. They give the pulley
a positive grip and absolute release from the hub by each opposite
shift of the operating lever, without the use of springs.
The Barnes Screw Lever Friction Clutch Pulleys and cut-off
couplings are adapted to both heavy and light work.
F. WEBER & Co., 1125 Chestnut Street, are handlingSchmenke,
Kuh & Co's., direct black print paper " Progress," which shows
black lines on white grounds.
It is the only direct Positive Process Paper in the world. It
does not require any developer like any other positive process.
It is as simple as the blue process, and requires only a water
bath.
The result which can be obtained from this paper is better
than any other, as up to the present time all positive prints became
brittle, while we guarantee this paper to keep its strength
and feel safe to say, that it is the best Positive Process ever
known here or in Europe.
This process is simple and does away with the developer.
The prints, as soon as they are dry, become stronger and
tougher than the paper was before, and are everlasting. The
lines will come out more distinct, and even the finest mark or
shade will show on the print with a wonderful distinctness.
The paper, when prepared, will keep longer than any other
kind of paper, even when six months old, good results can be
obtained.
The paper is to be treated as the ordinary blue print paper.
It requires only a water bath which must be kept clean, and
the prints should be left in the bath about ten to fifteen
minutes.
It should be exposed from five to ten minutes according to
the strength of the sun.
Expose the paper until it becomes white under the tracing.
If the paper has not been exposed long enough, the ground
will not be clear, and if the paper has been exposed too long
the fine lines will be faded.
Keep the paper dry and in a dark place.
IT is stated that a Spaniard, Sehor Barbozo de Sousa, has in­
vented an appliance for the submarine transmission of letters in
pneumatic tubes of great length, by which a letter deposited in
the tube at Rio de Janeiro would arrive in Europe during the
same day. How the difficulties connected with the air friction
in small tubes for such purposes- are to be overcome is not
stated.

28 ENGINEERING MECHANICS. [January, 1893.
HIGH SPEED LOCOMOTIVES.
S. M. VAUCLAIN, M. E., Superintendent of the Baldwin
Locomotive Works writes to the Engineering News:
You have solved the secret of the problem of attaining high
speeds. It is in the use of the piston valve, which works freely
and equally as well at 200 lbs. as at lower pressures. The old
slide valve is not to be considered at all. You are aware that
the engines of our ocean greyhounds, such as the " City of
Paris," are fitted with valves of this description and could uot
make the revolutions they do had a large slide valve to be
operated.
All our compound engines are fitted up to operate at 200 lbs.
steam pressure, and it is only the natural timidity of the rail­
road men that prevents the adoption of this pressure. We have
several locomotives in service now using 200 lbs. pressure, and
the owners will not think of employing less. The Chicago,
Milwaukee & St. Paul R. R. discovered the inability to operate
slide valve engines at this pressure, whereas the compound
engine, with piston valves, was iu her element at that pressure.
The compound locomotives built for the Pike's Peak (Abt rack
rail system), Rio Grande R. R., and several others are working
and giving no trouble at this pressure. Long port openings,
economy of steam, and frictionless parts are the essentials to
100 miles per hour, and I will soon be there.
The piston valve is taking the place of the slide valves in all
advanced ship and locomotive construction. This, with an in­
crease of steam pressure in the locomotive to 200 lbs., and an
adaptation of air brakes to stop a train making a mile a minute
iu eight or ten seconds, will open the way for 100 mile an hour
engines, the proper roadbed condition: being kept in mind, as
elsewhere refered to.
WITHIN two years a railway will be completed across South
America from Buenos Ayres to Valparaiso, which can be covered
in sixty hours. At present 42 miles of mountain work remain
to be done besides some bridge work. When it came time to
give out a contract for a 246 span British builders said the
shortest time in which it could be built was eight months. An
American firm (The Phrenix Iron Co., Philadelphia) were called
and they answered they could deliver all the material along
side in New York harbor in eight weeks—not only for the one
bridge in question but for four which were required. There
were three American bidders whose offers were as follows :
Name. Price.
$12,575
18,485
I7.4&5
Weight.
tons.
156
156
164
Price Per
Ton.
JC S. d.
16 2 0
16 17 8
*5 3 5
Delivery
weeks.
12
8
8
The Phoenix Company received the order on account of early
delivery. The tensile strength of the steel used was to be
from 26 to 30 English tons to the square inch, with an elonga­
tion of 20 per cent, iu 8 in. before fracture. The builders were
to guarantee that the bridges satisfied the test requirements
when iu position. The main girders were to be 15 ft- 1 iu. be­
tween centres, to carry the single line of metre gauge (3 ft.
3Vi in.).
ELECTRICITY AND MAGNETISM: Being a Series of Advanced
Primers. By Edwin J. Houston, A.M., author of "A Dictionary
of Electrical Words, Terms aud Phrases." New York.
The W. J. Johnston Co., Ltd., 41 Park Row. Cloth. 306
pages, 116 illustrations. Price $1.00.
During the Philadelphia Electrical Exhibition of 1S84, Prof.
Houston issued a set of electrical primers for the benefit of the
visitors to the exhibition, aud the great popularity and wide
general sale they attained showed that the public appreciated
the attempt to furnish them a literature they could easily read
and understand. As these primers have beeu out of print for
some time the author has prepared a new series, but on some­
what different Hues.
During the last eight years the advances in the applications
of electricity have been so great and so widespread that the
public would no longer be satisfied with instruction in regard to
only the most obvious and simple points, and accordingly the
new primers are of a more advanced character as regards mat­
ter and extent; the treatment, however, remains such that they
can be easily understood by any one without a previous knowl­
edge of electricity.
This volume contains eighteen primers in all, tbe last one
being a review, or "Primer of Primers," which sums up the
salient features of the different topics treated. The subjects of
the different primers relate to the various sources and phenom­
ena of static and current electricity, and of magnetism, with
practical deductions and applications. Atmospheric electricity
and the phenomena ofthe earth's magnetism receive a particu­
larly interesting treatment, and the primers on the electro­
magnet, electro-receptive devices, and frictional and influence
machines are very practical in their scope.
A feature ofthe work is the abstracts from standard electrical
authors at the end of each primer, which generally have reference,
and furnish an extension, to some important point in the
primer, and at the same time give the reader au introduction to
electrical literature.
While the work is primarily intended for popular reading
the care of statement and logical development of principles
make it a valuable work for electricians who wish to gain a
knowledge of, or to review the, principles upon which the
science is based.
ORIGINAL PAPERS ON DYNAMO MACHINERY AND ALLIED
SUBJECTS. By John Hopkinsou, M. A. D. Sc, F. R. S. New
York. The W. J. Johnston Co., Ltd. 1892. 249 pages, 98
illustrations. Price $1.00.
This collection includes all written on electro-technical subjects
by the distinguished author, most of which have marked
eras in the advance of electrical science. Perhaps no other
contributions to electrical literature since the days of Faraday
have been of as an important character as those contained in
the present volume, and this is true whether considered from a
theoretical or from a practical standpoint.
In the first paper that invaluable aid to the study and design
of dynamos, the characteristic curve, was first announced and
the following three papers are devoted more or less to developing
its applications.
The fourth aud fifth papers, on the theory and design of con­
tinuous current dynamos, furnished the fundamental principles
upon which the design of such dynamos is now based.
The sixth paper established the important principles in
regard to coupling alternating current machines; the next
three papers are ou the transformer and tbe remaining two on
the Theory of the Alternate Current Dynamo and Electric
Lighthouses respectively.
The majority ofthe papers contain no mathematical formulae
and several others so little as not to prevent their being understood
by a non mathematical reader.
These papers, with the authorization of Dr. Hopkinson, are
for the first time published in a collected form and rendered
accessible to the general public, and they should furnish a
fruitful source of inspiration to those in search of knowledge
at first baud.
A MILITARY balloon is being made in France, 230 feet long
43 feet greatest diameter. Speed 28 miles per hour against
winds. Weight of machinery equal to 66 lb. per horse power.
The screw will be in front and will make 200 turns per minute.
This design is the outcome of a great deal of experimenting
aud theorizing, aud it has received some creditable endorse­
ments, but there is no assurauce of practical success as yet.

January, 1893.] ENGINEERING MECHANICS. 29
A CORRESPONDENT on the subject of "Friction," says :—" I
agree with the remarks in your November issue of ENGINEER­
ING MECHANICS, as to the common mistake of running too
tight belts, involving as high as from 22 to 39 per cent, loss of
power, and consequent waste of fuel of at least three pouuds
per horse power per day. True, and for this reason, to quote
the eminent authority, Chas. H. Haswell,' The frictional capacity
of bare pulleys for transmission of power is very limited in com­
parison with the tensile strength of belting. The resistance of
a belt to slipping depends essentially upon the character of sur­
face of pulley, friction being greater between surfaces of a simi­
lar character thau between those of different character,"—such
as leather aud iron. Thus it is that on a bare pulley the drive
can only be obtained by a dead pull against the shaft or dynamo
by a more or less tight belt, placing an undue friction on the
bearings and machines, aud an unnecessary load and stress on
both shafting and bearings, there being no affinity of substance
between the belt and the irou. The fact is the friction is in the
wrong place, and the only way to avoid such errors and waste
is by facing the pulleys with some material which shall change
this friction from the bearings to the face of the pulley, and thus
secure a rotative motion with a slack belt, instead of a dead pull
with a tight one. The difficulty in my experience hitherto has been
that the various coverings and processes were so unreliable, and
so soon worn out as not to be worth the expense of fixing. I
have, however, found that the covering invented by the Mercury
Pulley Covering Co., of Franklin Street, Philadelphia, is un­
doubtedly durable and reliable, aud has the merit of being of
thin and even texture, and of great wearing quality. I am using
it on ten dynamos and drivers, aud ran it within a few minutes
of fixing, which was done in a very short time, without removing
the pulleys."
THE National Pipe Bending Company, of New Haven, Conn.
manufacturers of the National Feed Water Heater and coils and
bends, report a very large business for the year 1S92, their sales
of Heaters the first nine months aggregating over 40,000 horse
power, and supplying as they do some of the largest mills in
the country. Also many electric stations, including electric
light and electric railways. They have furnished the new
Wamsutta Mills at New Bedford with 1800 horse power beater,
the Pierce Mill with 1400 horse power, the Bristol Mill with
1400 horse power, the Columbia Mill with 800 horse power, the
Allegheny County Light Co., of Pittsburgh, have bought their
second heater this year of iooo horse power, and are now mak-
ing 500 horse power for the Brooklyn City Railway Company,
two of 700 horse power and one of 600 horse power for new
mills, another of 300 horse power for the Brockton Railway,
200 horse power to the Lookout Mountain Railway, iooo horse
power to the Boston Electric Light Co., two of Soo horse power
for cotton Mills in Massachusetts, and various smaller sizes ag­
gregating about 3000 horse power. This firm also make coils of
all styles of iron, brass and copper pipe, of which two samples
are shown above.
THE Cleveland Twist Drill Co., of Cleveland, Ohio, writes :—
It may interest some of your readers to know that we have just
got out for a prominent engine manufacturing company in
Pennsylvania, what we believe to be the largest solid milling
cutter ever made. This cutter is 2i // long, 3" in diameter, fin­
ished size, with a 2" hole for arbor, and a keyway through the
entire length. The steel in the rough state weighed 150 pounds.
The anxiety which we felt when the big tool was ready to
plunge into the hardening bath, can better be imagined than
described. That it was successfully tempered and finished without
crack or blemish, we think speaks well for our facilities for
handling this class of work. If any of your readers know of a
larger spiral milling cutter than this, made from one piece, we
would be glad to hear from them.
C. V. BOUGHTON, of Buffalo, N. Y., according to a floating
telegram in the daily press, has invented au instrument of which
the above reliable authority thus speaks : "It is an instrument
by which vessels at sea can communicate at long distauce, and
was pronounced a success by experts present. The instrument
consists of a key-board by which 106 incandescent lights are
controlled and made to produce the signals of the Morse tele­
graphic alphabet. The connecting wires, over 5,000in number,
occupy a space of only eleven by twelve inches. The dots of
the telegraph characters are represented by two illuminated
lamps, the spaces by twelve unilluminated lamps, the dashes by
twelve illuminated lamps. The inventor claims that thirty-two
candle power lamps can be seen at a distance of ten to fifteen
miles. Mr. Boughton has secured patents in this country and
Europe. A complete instrument will be built and placed at the
disposal of the United States government, to be exhibited on
the model of the warship Chicago at the World's Fair.
STEAM GAUGES AND YANKEE CLOCKS.
DANGERS OF UNCERTAIN RECORD OF STEAM PRESSURE.
Steam gauges to-day are almost as numerous as clocks, and
are made in as great variety with a view to cheapness, until
they reach the same point as cheap clocks, not always to be relied
upon. The steam gauge is the true pulse or iudicator of
the strains put upon the boiler, and since every boiler has its
limit of strength, beyond which point the whole establishment
is imperiled, it is a matter of the highest importance that the
gauge which is the sole indicator of the internal strains, should
be accurate and durable. If a gauge indicates only 20 pounds
pressure under actual pressure of 30 pounds, this ap­
parent slight excess of 10 pounds places au extra load
of over two tons per square foot beyond what the in­
dicator shows and is a false register to that extent. If
owners of steam boilers could as readily test their
gauges as they can test their time pieces, they would
frequently be alarmed at the inaccuracy of their gauges.
This inaccuracy is induced first by crystallization of
the springs, which springs are always light, and are
enabled to resist the heavy boiler pressure through a
system of leverage made in various relative propor­
tions. Where the proportions are, for example, 50 to
100 to auy error caused by friction, or otherwise, it
is multiplied in the same ratio.
Accuracy and durability can be obtained in a gauge that is

3° ENGINEERING MECHANICS. [January, 1893.
free from springs and friction bearings, etc., in the United
States Standard Mercury Gauge, which measures by weight
alone without any springs whatever, and is both correct and
durable, so much so that it is the adopted standard of test by
all authorities who have examined into this important question.
This accurate gauge is like au accurate time-piece. It cannot
be sold at Yankee clock prices, but notwithstanding the fact
that its costs are greater, no steam user should be without at
least one of these gauges on his uest of boilers, and where any
gauges are used in any oue establishment, one of these gauges,
with a suitable test-pump, should always be ready to determine
the accuracy or inaccuracy of all gauges in use.
Shaw's Mercury Test Gauge has beeu supplied to all navy
yards of the United States Government, to all Supervising Inspectors
of Steamboats of the United States Government, to
the University of Pennsylvania, to the State College of Pennsylvania,
the Sibley College, Cornell University, New York,
Stevens Institute, Hoboken, New Jersey, and numerous other
educational institutions.
It is the accepted standard of test for a large number of railroads
throughout the United States. It is the accepted standard
of test in daily use by a great number of the largest
establishments in the United States, such as Baldwin's Locomotive
Works, Phrenix Iron Co., A. C. Frick & Co , Allison &
Sons, Morris, Tasker & Co., aud a thousand others.
It is the standard of test ofthe city of Philadelphia in charge
of the Boiler Inspection Department.
It is the standard of test in cities as far west as the city of
Denver, Colorado, in charge of the Steam Boiler Inspectors.
This gauge is warranted to be accurate aud durable, and no
steam user should be without at least one of these gauges on
his steam plant. The foregoing statements would be incomplete
were no reference made to the gauge which pre-eminently fills
all requirements. The reputation of the Shaw Mercury Gauge
extends wherever gauges are used. Made by the inventor,
Thomas Shaw, M.E., 915 Ridge Ave., Philadelphia, Pa.
BUFFALO STEAM PRESSURE BLOWER ON ADJUSTABLE BED,
COMBINED WITH DOUBLE UPRIGHT ENCLOSED ENGINE.
Herewith we illustrate the latest improved construction form
of Buffalo Steam Pressure Blower on adjustable bed, combined
with double enclosed upright engine. This arrangement gives
positive control over the tension of belts, and insures the greatest
rigidity, ease and adjustment, perfect alignment, and where
desirable, au immediate change in the speed of the blower.
The latter is a very desirable feature, especially in cupola work,
because in hot weather it requires an increased volume of air
to melt the same quantity of air over that of cold weather. It
will readily be seen that the above arrangement possesses
marked advantages over a blower receiving power by belt transmission.
A special description of this engine will be supplied
by the manufacturers, Buffalo Forge Company, Buffalo, N. Y.
A distinguishing feature of Buffalo Steel Pressure Blowers,
common to those of no other manufacture of the same type, is
the solid case, the periphical portion of the shell being cast in
one solid piece, to which the centre plates are accurately fitted,
metal to metal. It will thus be seen that the objectionable and
slovenly " putty joint " is entirely dispensed with. Ready access
to the interior of the blower, without entirely taking it
apart, is also thus afforded. With blowers of every other manufacture
the "putty joint" feature of the shell or casing is an
indispensable adjunct, although it is a construction point which
is, at the best, something to be avoided iu an efficient machine.
The Buffalo Steel Pressure Blowers are designed and constructed
especially for high-pressure duty, such as supplying
blast for cupolas, furnaces, forge fires, and blast machines, for
any work requiring forcing of air long distances, as in connection
with pneumatic tube delivery systems. They are adapted
for all uses where a high pressure or strong blast of air is required.
The journals are long and heavy, in the standard ratio
of length to diameter of 6 to 1, and embody a greater amount
of wearing surface than those upon blowers of any other construction.
Attention is directed to the special cuts and descrip-

January, 1S93.] ENGINEERING MECHANICS. 31
tion of the patented journals and oiling devices employed on
these Blowers, which are unique features.
The bearings are readily adjustable, and any wear can be
taken up. which is an important point attending the durability
of a quiet running of a perfect machine.
Buffalo Steam Pressure Blowers possess the fewest number of
parts of any like machines ; in fact, the blower is practically
one piece, so that under any service the bearings invariably are
in perfect alignment, vertically and laterally, with the rest of
the machine. In the items of durability, smooth running and
economy of power, they are thus rendered far superior to any
blower with so-called universal journal bearing which is commonly
employed.
In every point of construction the greatest pains have been
taken to simplify all parts, and at the same time to give them
the greatest strength. To adjust, repair and keep in order a
Buffalo Blower is a very small matter, and readily understood
by a machinist of average ability.
Hundreds of the machine illustrated by the cut are in use in
the largest manufactories of the world. They are also widely
used by gas construction companies.
CALIFORNIA.
The fame ofthe climate of California draws to that charming
State new friends every year, particularly from sections where
long, severe winters, followed by trying spring seasons, work
such disastrous results among the weak and debilitated.
The great improvements in passenger train service, higher
degrees of comfort in the cars, aud shorter time required on the
trip, combined with the cheapness of the excursion tickets now
being sold to California and back by the Santa Fe Route, make
the journey agreeable and, one cau almost say, economical.
The many delightful resorts now established in California afford
every comfort and luxury desired by the fastidious, and present
unique attractions.
The Hotel del Coronado at San Diego, the Raymond at Pasa­
dena, the Redondo at Redoudo Beach and the hotels at Santa
Barbara, Monterey, Riverside, Los Angeles and many other
points, have grown as famous as any on the Atlantic Coast—
and a fact that should not be forgotten is that they are resorts
all the year around, although the greatest number of people
from the East are in California between the months of November
and May.
The Atchison, Topeka & .Santa Fe Railroad is now preparing
a new illustrated book, descriptive of a trip to California over
its lines, which will be mailed free to any applicant who may
write to John J. Byrne, Asst. Passenger Traffic Manager, 723
Monadnock Block, Chicago, 111., enclosing five cents in postage
stamps, the amount required to carry through the mails.
RECENT PATENTS.
488,064—Magetic Separator, by Harvey S. Chase of Boston,
Mass., assignor by mesne assignment to the International
Ore Separating Co. of New Jersey. Filed Jan. 29, 1892. Serial
No. 419.668.
Brief:—The ore is run upon an endless belt which travels
around parallel pulleys, and the under part of which passes
through water contained in a tank enclosing the device. Above
the lower side of the belt are magnets which attract pure ore to
HARRISON SAFETY BOILERS
-COMBINE IN THE HIGHEST DEGREE:-
ABSOLUTE SAFETY FROM DESTRUCTIVE EXPLOSION.
ECONOMICAL AND RAPID GENERATION OF DRY STEAM.
DURABILITY, LOW COST OF MAINTENANCE, GENERAL EFFICIENCY.
MERITS HPZR.O-V-EJ'IT BY T-WENTY-jTIVE YEABS SERVICE.
First Cost Moderate, owing to Simplicity of Construction and Inexpensive Setting.
New pamphlet, describing latest improvements of setting, together with drawings and specifications of boilers
of any size, from 4 H. P. to 240 H. P., promptly mailed upon application.
HARRISON SAFETY BOILER WORKS.
Germantown Junction, Philadelphia, Penna.
New York, If. Y., 41 Dey Street. Atlanta, Ga., 9 North Pryor Street.
Chicago, III., 187 La Salle Street.
the surface of the belt, dross being dropped from the belt at the
end where the belt turns over the pulley. The ore retained on
the belt falls in another part of the tank. The separated masses
are raised out of the tank by a carrier belt that rises over ends
of the tank.
488,141—Process of Insulating Electric Conductors, by
Charles Cuttriss of New York City, assignor to the Knudson-
Cuttriss Wire Co. Ltd., of same place. Filed Jan. 20, 1892.
Serial No. 418,643.
Claims :—The method of preparing cotton sliver for application
to electrical conductors, which consists in drawing the
sliver in its natural state through a boiling non-viscous insulating
fluid, and as oil and then matting or felting the same and
expressing the surplus oil taken up by it.
488,1*54, 488,155, 488,150, 488,1.57 —Elevated
Rail Road, etc., by Ephraim M. Turner of St. Louis, Mo., assignor
of one-half to R. E. Maddox of Fort Worth, Texas.
Filed Oct. 12, 1891. Serial No. 408,549.
The scope of these patents, relates entirely to a method of
construction of the structure or elevated road way.
487,700—System of Electrical Transmission of Power, by
Nikola Tesla of New York City, assignor to the Tesla Electric
Co. of same place. Filed May 15, io'SS. Serial No. 273,997;.
Claims 2 :—The combination with a source of alternating
currents of differing phase, and comprising a rotating magnetoelectric
machine yielding a given number of current impulses
or alternations for each turn or revolution, of a motor or motors
having independent energizing circuits through which the said
currents are caused to flow, aud poles which in number are less
than the number of current impulses produced in each motor
circuit by one turn or revolution of the magneto-machine.
487,819—Bridge, by Lewis Barnes of Philadelphia, Pa., assignor
to Wm. A. Nichols of Wayne, Pa. Filed March 5, 1S92.
Serial No. 423,924.
Brief:—Combination with a portable bridge of a wing connected
thereto and comprising a base-piece having holes for the
reception of anchors ; a stringer connecting the base-piece to
the bridge and supports connecting the stringer and base.
488,044—Hoisting Apparatus, by John E. Walsh of New
York City. Filed Aug. 24, 1S92. Serial No. 443,977.
THE Lunkenheimer Company of Cincinnati, Ohio, have issued
the following circular to the trade: The increased demand
for the Lunkenheimer brass and iron specialties, and the introduction
of new products, has compelled us to double our capital
to $500,000, and as soon as possible our manufacturing facilities.
This will place us in position to give all orders even more
prompt and satisfactory attention than heretofore. The Company
will after January 1, 1893, transact its business as the
Lunkenheimer Company, with officers as follows: E. H. Lunkenheimer,
President; 1 C. F. Lunkenheimer, Vice-President and
Treasurer ; D. T. Williams, Secretary. A continuance of the
liberal patronage heretofore bestowed is respectfully solicited.
0 IHSUR
AT THE LEAST COST
MODERN METHODS.
.HOME OFFICE. PHILA.PA

iii ENGINEERING MECHANICS. [January, 1893.
KEYSTONE LUBRICATING GREASE.
ECONOMICAL, PURE,
CLEAN, SAFE.
One pound guaranteed to go
further, and do better, than three
gallons of any other lubricating
oil. It is used by thousands of
the largest firms in this country.
BRASS ANO IRON CUPS FUR­
NISHED FREE OF CHARGE.
Keystone Lubricant
CAN BE OBTAINED
ONLY FROM THE MANUFACTURERS.
THE KEYSTONE LUBRICANT CO. MARK.
209 N. Third St. Philadelphia.
THE NATIONAL FEED WATER HEATER.
A BRASS COIL HEATER delivering Water to the •
Boilers at 212° Fahrenheit. ^9
500,000 HORSE POWER NOW IN USE l|
PRICES LOW. SATISFACTION UNIVERSAL. -^^
OR EN HEARTH.
Also COILS and BENDS of IRON, BRASS and COPPER PIPE. «g|
THE NATIONAL PIPE BENDING CO. 72 RIVER ST. NEW HAVEN CONN.
AIR COMPRESSORS.
Norwalk Iron Works Co,
SOUTH NORWALK,
O-OLKTIXr.
STANDARD
. STEEL CASTINGS CO.
THURLOW, PA.
Scientific American
Agency for
CAVEATS,
TRADE MARKS,
DESICN PATENTS,
COPYRICHTS, etc.
For information and free Handbook write to
WUNN ,.* CO.. 301 BIU.ADWAY, NEW YORK.
Oldest bureau for securing patents in America.
Every patent taken out by us is brought before
the public by a notice given free of cbarge in the
SftitntUk JVmman
Largest, circulation of any scientific paper in the
world. Splendidly illustrated. No intelligent
man should be without it. Week'v, S3.00 a
year; fl.ot) six months Address MUNN & CO.,
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F. H. WHITING DENVER, COL.

February, 1S93.] ENGINEERING MECHANICS- 31
ENGINEERING MECHANICS.
Devoted to Electrical, Civil, Mechanical, and Mining Engineering.
Published monthly by JOHN MC. DAVIS, at 430 Walnut St., Philadelphia
London Office, 270 Strand, D. NUTT, Agent.
All Subscriptions for Great Britain should be sent to London. Price, 12s. yearly.
Entered at the Post-office in Philadelfhia as Second- Class Mail Matter.
SUBSCRIPTION RATES.
Subscription, per year $2 00
Subscription, per year, foreign countries 2 50
PHILADELPHIA. FEBRUARY, 1893.
AT the tenth annual meeting of the Civil Engineers' Society
of St. Paul, Geo. L. Wilson was elected President, J. D. Estabrook,
V. P. ; C. L. Annan, Secretary ; A. O. Powell, Treasurer ;
A. Wiinster, Librarian.
THE Corinth Caual, which was first suggested by a man of
the name of Nero, will be completed iu two years. Depth, 27
feet, S inches; width, 2S0 feet. So far S2 million cubic metres
have been excavated, and 3*2 millions remain to be takeu out.
PROFESSOR AYRTON* says that when steel caunot be used for
springs in electrical measuring instruments, for magnetic reasons,
phosphor-bronze has proved a very efficient substitute, beiug
superior to German silver or the alloys of platinum and
iridium.
ANOTHER lathe improvement consists iu a feeding mechanism
in which the speed of rotation of tool is constant and the
extent of its tnotiou or feed is made adjustable. A lever adjusts
one of a pair of friction wheels with the aid of tappets,
cams and drums with grooves.
THE long and interesting discussion on pile driving in which
Crowell, Trautwine, Wellington aud others have taken part
seems finally to have been referred to the foreman of pile driving
work for solution, whom it is agreed must be guided by the
action ofthe piles themselves as they are being driven.
THE English Gas Companies do not suffer much at the hands
of Electric Light Companies. There are 410 companies this
year against 405 a year ago, and 394 in 1889, since which time
capital invested has expanded from 60 million pounds to 63 •_.
million pounds. Gross receipts increased one million pouuds,
and quantity of coal used, one million tons. Dividends de­
clined 2)4 per cent, by reason of increased expenditures.
A NEW method of smoke consumption is to burn the smoke
by driving it through the fire itself. Various cities in England
are preparing to use this method as well as gas and electric
lighting works. The deposit made by burning a giveu quantity
of coal by the new system was : carbon, 7.20 ; hydrogen, 23 ;
mineral matter, 83.15 ; nitrogen and oxygen, 3.42 as against
70.76 carbon in dry soot ; mineral matter, 16.88 ; nitrogen,
6.38. Mr. Lygott the inventor, has convinced some of the
scientific minds of England that he has solved the smoke
problem.
THE Japanese Government owns the fastest cruiser afloat.
Speed, 23 knots; horse power, 15,000. Its armament comprises
every refinement that modern artillery science can produce.
This government possesses four cruisers of great efficiency and
power. Its policy seems to be to keep pace with naval engi­
neering in the rest of the world.
AN iuveutor proposes to improve ou the "Serve'' boiler tube
by using in addition to internal longitudinal ribs, a retarder or
strip of spiral or any convenient shape, placed iu the centre of
the tube betweeu the edges of the ribs, with a diameter about
equal to the space within the edges of the projections or ribs,
by which means the gases are brokeu aud more effectual con­
trol obtained, producing greater evaporation.
WITHIN 6 to 12 miles of Berlin, 18,000 acres divided into four
farms are supplied with from 2500 to 4500 gallons per farm, per
acre, per da}'. Berlin has 12 sewerage districts, from which the
product is carried to suburban pumping stations, from whence
it is forced by pipes to the farms, where sluice valves are fitted
aud side outlet branches, all of which are eight iuches in diameter.
Underground drains facilitate flow to collecting ditches.
The farms show a profit of 1200 to 1400 per ceut. on cost of
working.
IRRIGATING engineers are making excellent records for themselves
in the west. A great number of vast irrigating schemes
are now under consideration by capitalists and enterprising
men, under the tutelage of hydraulic engineers, who clearly
recognize the vast possibilities for development in a comparatively
worthless section of country. F. C. Kendrick of Ph.enix,
Arizona, has charge of a scheme looking to the construction of
canals, reservoirs and ditches, through which to irrigate a large
area of desert laud. The Rio Verde river will furnish the water.
The maiu ditch will be over one huudred miles long, sixty feet
wide aud ten feet deep. The main reservoir will be six miles
across—solid masonry. Hundreds of miles of lateral ditches
will be dug. The soil is suitable for most all semi-tropical fruits,
oranges, lemons, figs, grapes, apricots. Over 200,000 orange
trees were planted last year. The irrigation engineers are
doing a valuable work in redeeming so much comparatively
valueless land in the desert west.
TAKING one hundred representative cities in Great Britain
SINCE the application of electricity to blasting, a wider field
the cost per head of population of municipal taxation is $2.50,
has been opened for improvement aud greater economy. Cost
against ^16.77 in this country. One remedy which is of impos­
per cubic yard of dislodged material has declined to much less
sible application, is to elect and retain officials irrespective of
than when only ordinary explosives were used. Wm. L. Saun­
politics or political changes. Englishmen abhor political
ders, C. E., has contributed some interesting results in Ameri­
changes for mere purposes of party spoil, aud in their country
can methods which seem to be in advance of other methods
it would be impossible for the people who fill most of our
used abroad.
municipal offices to receive the slightest consideration. The
abominable and discreditable municipal management that obtains
in most of our American cities will perhaps iu time be
cured by the righteous iudignatiou of the people, but the time
appears far off. While we are effecting economies in industrial
processes, iu manufacturing, in transportation, iu everything
where ingenuity can effect economies, we are permitting the
continuation of the most wasteful methods in municipal management,
because a class of people are our masters iu municipal
affairs who would not be tolerated in our offices, factories or
counting rooms.
THE vast bodies of low grade refractory ores in the Western
mining regions has kept inventive talent at work, resultiug in
the development of a number of processes of greater or less
merit. The Coplen process is one which embodies a separation
of pulverized ores according to size, for ultimate treatment by
gravity. F. J. Weist has an improved form of smelting wliich
employs a crusher, a pulverizer, a chemical room, four furnaces
aud a drying floor, by which at present worthless material is

made to give up its precious portion. The Meholliu process is
another in wdiich chemical aud electrical action are combined or
used simultaneously, after very fine pulverizing, carbon plates and
copperplates are used, separated by a porous diaphragm. An
electrical current .25 volts acts on the wet pulp on the carbon
side, after which it filters through into auother bath, where the
mineral constituents are precipitated ou the copper plates.
The criticism made is, that this is good in laboratory practice
but not on a commercial basis, a claim which the promoters
dispute and apparently with good reason.
THE struggle of marine engineers to strengthen the structural
parts of the ship's machinery without encroaching ou
space has not been relinquished. Herr Middeudorf suggests
methods of strengthening butt connections of the shell plating.
The longitudinal structural ties above and below have to stand
alternate compression and teusion. The coruer ties are made
safe by a double bottom with its longitudinals ; but the upper
flange is represented by the deck stringers aud sheer strakes,
which are strengthened in various ways. But every device is
attended with difficulties wdiich the above writer thinks he has
devised means of removing, in proper butt connections. The
plan consists in the overeapping of the plates in conjunction
with the fittiug of an inner butt strap which may be termed
the "back strap." By this expedient it is rendered feasible to
give the rivets in the outermost row ou each side a spacing of
from 7 to 9 diameters as in the case of the frames, the second
row having to be closely spaced to admit of sound caulking.
THE Electrical World is publishing a series of articles upou
the practical application of electricity to the various farm operations
and implements, with illustrations of a plant which is
situated in one of the finest agricultural States of the West,
and which shows in detail how the electric motor can be made
to perform most of the work which the horse or the steam
engine is now called upon to do.
There are four classes of farm work to which electricity is
applicable: First, for power purposes ; second, lighting; third,
heating, and fourth, for the operation of telephones, signals,
alarms, etc. Examples under these various heads are numerous.
For instance, hay, grain aud other products cau be
hoisted by electric power, which cau also be applied to ordinary
elevators. An electric motor may run pumping apparatus,
which will furnish water for the drinking troughs, for fire purposes,
or for watering the garden, use in dairy houses, etc.
All such miscellaneous machines as threshers, grinders, shellers,
hay presses, grindstones, etc., can be readily operated by
electric motors. It is very probable that iu time electric railway
lines may exist over the best agricultural regions, furnishing
communication between the different farms, as well as
small tramways on separate farms, connecting the different
buildings, while electric plows and vehicles of all sorts are
among tlie possibilities.
THE English Spectator says: Mr. W. II. Preece, chief engineer
and electrician to the Post Office, has put up a wire a mile
long on the coast near Lavernock, aud a shorter wire 011 Flatholm,
a little island three miles off in the Bristol Channel.
He fitted the latter wire with a •' souuder " to receive messages,
and sent a message through the former from a powerful telephonic
generator. That message on the main land was distinctly
heard ou the island, though nothing connected the two,
or, in other words, the possibility of a telephone between
places unconnected by wire was conclusively established.
There is a possibility here of inter-planetary communication,
a good deal more worthy attention than any scheme for making
gigantic electric flashes. We do not know if we can communicate
by telephone through the ether to New York or Melbourne,
with or without cables; but we do know that, if we
ENGINEERING MECHANICS. [February, 1S93.
cannot, the fault is in out generators and sounders, aud not iu
any prohibitory natural law.
Will our habitual readers bear with us for a moment as we
wander into another and. as many of them will think, a suprasensual
region? The thought in a man's brain which causes
him to advance his foot must move something in doing it, or
how could it be transmitted down that five or six feet of distance
? If it moves a physical something internal to the body,
why should it not move also something external,—a wave, as
we all agree to call it, which, ou another mind prepared to
receive it—fixed with a sounder, in fact—will make an impact
having all the effect in the conveyance of suggestion, or even
of facts, ofthe audibility of words?
Wh)-, in fact, if one wire can talk to another without connection,
save through ether, why should not mind talk to mind
without any "wire" at all? None of us understand accurately,
or even as yet approximately, what the conditions are; but
many of us know for certain that they have occasionally, and
by what we call accident, been present to particular individuals,
and that, when present, the communication is completed
without cables, and mind speaks to mind independently of any
machinery not existing within itself.
Why, in the name of science, is that more of a " miracle,"—
that is, an occurrence prohibited by immutable law,—than the
transmission of Mr. Preece's message from Lavernock to Flatholm
?
THE advantages of a stiff bottom chord in a lattice span, can,
according to an elaborate elucidation of the subject of Thin
Floors for Bridges, in November transactions of the A. S. of C.
E., by Albert F. Robinson, be secured bylines of horizontal
struts extending the full length of both trusses, and by stringers
which act as guards, keeping derailed cars from striking the
rude members. The two lines of struts would perhaps cost not
over $4. per linear foot, weight no lbs per foot. The objective
point sought iu thiu floors, is while keeping the bridge strong
enough to safely carry the loads, to effect economies in
approaches to bridges, abutting damages due to elevated track
and in operating expenses. Many, iu fact all elevated bridges
in cities, with shallow floors do not stand the traffic. The rivets
give way necessitating frequent re-rivettings, and the life of
such bridges is below the average. Mr. Robinson thinks he
has designed a thiu floor especially adapted to pin-connected
spans aud plate girders, which is fully as secure in case of derailment
as a lattice span of the same approximate length and
weight.
Solid or box floors are now generally used abroad, but some
data is wanting coucerning the power of box floors to distribute
loads, yet in no case have they ever failed to give satisfaction.
A 40,000 lb. load distributed over 4 braces covering 4 ft. 2 in.,
showed a bendiug moment frr the total load on four boxes of
1,362,200 inch-pounds, giving the moment of resistance for four
boxes .173 aud " C " the extreme fibre strain, 7.900 net. Counting
the maximum loading as being distributed over only three
boxes, the end reaction will be 9,200 lbs. per box, or sufficient
for three V-in. iron rivets. Where stone ballast is used, 10,000
lbs. is a fair strain for the medium steel used.
The thinner floor costs more. In a 150 foot span the weight
by present method is 287,900 pounds, by proposed method
346,300 pounds, or 456 pounds per linear foot.
The increased cost of the thinner floor is offset by sufficient
advantages to warraut its adoption. In a given 150 foot span,
the weight by present method is 287,900 pounds ; by proposed
method 346,300 pounds ; difference 58,400 or 456 pounds per
linear foot. In another case of a 50 foot span, the difference is
only 183 pounds per linear foot between the two methods of
construction, when side stringers are used and 2S3 pouuds when
they are omitted.
Engineers would like lighter ballast for road beds than stone
aud speak of a concrete in which coke takes the place of stone.

February, 1893] ENGINEERING MECHANICS. 33
A ballast of burned clay has been tried, but it makes dust. The
solid floor bridge meets the conditions of traffic better thau any
other, but there is room for improvement in many details which
engineers are seeking to effect. The bridge of the future will
be radically differeut from the bridge of to-day. Not ouly will
theories of construction change but radical modifications will be
made in material used.
THE proposed American cable from San Francisco to Australia
is giving our English cousins coucerned iu cable enterprises
more or less concern lest we divide the spoils with them.
The cable will be laid; but the resulting competition will not
decrease the revenues ofthe London cable companies.
THE investigations that have been so laboriously and faithfully
conducted by the British Board of Trade have doue more to
stimulate care aud avoid boiler accidents than volumes of books
writteu about the subject. The man who happened to be killed
was always convenientl)- blamed by the coroner's court as the
oue who caused the explosion. The law now requires that
formal inquiries be made, conducted by qualified persons possessing
judicial powers.
THE fact comes out ou investigation that 276,585 families living
in the tenement houses of New York city burn 840,000 tons
of coal between November and April, for which they pay from
$9. to $10.50 per ton, affording the peddlers and grocers a total
profit of $3,iSo,ooo, over fair prices. The Brooklyn dealers sell
345,000 tons in baskets and bags, similarly taking $1,247,000
for their share. The Jersey City tenement house people pay
$226,000 profit above the average retail prices. It is not the
coal producers that profit by this robbery, but the coruer grocer
and peddler, for all of which there is uo remedy, except iu
these municipalities going into the coal business, aud establishing
yards where coal will be sold in competition with the
above classes at ordinary retail prices.
COMPLAINTS are increasing of bad work being done in the
putting in of electrical equipments, steani appliances, boilers,
engines, heating devices, ventilating appliances, et cetera, iu
large public and private buildings, clubs, offices, and so on.
Most of this work is falling to the lot of the " practical " man,
the architect, builder, machiuist, and so on, wdiose definition of
practice is, "whatever he knows," and whose definition of
theory is, " what he don't know." The remedy is to employ an
engineer, electrical or mechanical, to say and see. Much time.
money and annoyance would thereby be saved. Instances of
ridiculous mistakes, ignorances and mismanagements cau be
called up by auy professioual engineer, perpetrated by selfstyled
practical men in the doing of work for which they
imagined themselves fitted.
A NEW method of making weld'ess cold-drawn steel tubes,
suitable for bicycle making and other machine work, where
strength, lightness and accuracy are required, has been invented.
The steel from which the new tubes are made is of special
quality, and is received from the steel works in the form of
sheets. Circular flat disk are then cut out of the sheets ; these
disks are pressed into the form of shallow cups, which are then
pressed successfully through dies of decreasing diameter, thus
reducing the diameter and increasing the length of the cups
until the flat disks of steel have assumed the form of tubes of
the required length, with one end closed, the closed end being
cut off after the final drawing operation has been performed.
FIGURES compiled from three representative anthracite coal
mines show that the average amount of coal won runs from 33
to 40 per cent, of the total quantity of coal in the ground. Thus
are immense quantities of coal sacrificed because it cannot be
mined at a profit. The total shipments of anthracite coal up to
Jan. 1, 1S93, were 820,000,000 tons, of which 160,000.000 tons in
round figures were refuse. Out of 26,000,000 tons of coal mined
in the mines of the Girard Estate, 5,288,243 tons were lost as
culm or were carried away by the streams.
Present mining methods are in need of radical reformation,
not ouly in anthracite coal fields but iu bituminous. The mining
engineers have a most urgent problem before them, iu devisiug
how the percentage of coal won can be increased. This terrible
waste of the richest solid fuel on the continent is a matter of
regret. Trade competition has something to do with it. In the
Maryland fields a bench of four feet of good coal is covered up
by withdrawing the pillars as the work proceeds.
THE Locomotive Exhibit that will be made under the auspices
ofthe Baltimore & Ohio R.R. Co .showing the evolution ofthe
locomotive from its swaddling clothes, clothes and all, to the
present triumph of engineering skill and genius, will be perhaps
the most valuable as well as the most interesting exhibit
to railroad men iu the Railway Department of the World's
Fair. The object of those iu charge of this important work is
not to gratify idle curiosity or attract attention of the mass of
ignorant gazers, but to furnish instruction aud information to
eugineers and mechanics as to the struggles the mechanics of
the past have made. This company's exhibit will be designated
: " The World's Railway ; Its Conception, Inception, and
Perfection ; Its Motive Power, Equipment and Appliances."
This important work is under the immediate supervision of Maj.<b