Untitled - eCommons@Cornell - Cornell University

280 COLLEGE OF CIVIL ENGINEERING.
human agencies ; and from the sifting of the cements, through the
operations of moulding, mixing, condensing, and testing, to even por
tions of the computations, every maneuvre in this laboratory is done
by machinery. The time of setting of cements is obtained by a
machine describing curves characteristic of their nature.
4. A Bridge Laboratory for the study of stresses in many types
of trusses, the determination of the effect of permanent and variable
strains upon the nature and requirements of bridge designs and their
details, etc. This laboratory has under way important investigations,
and has lately been fitted with an original apparatus of great accuracy
for determining the compressibility and modulus of elasticity of stones.
5. The Gravimetric Laboratory where cold and hot pendulums
swing in connection with other instruments of precision. The college
mechanician has now completed a set of half second pendulums for
field work determinations of the force of gravity, and studies on the
form of the earth like the extremely accurate ones devised by Presi
dent Mendenhall for the U. S. Coast Survey, with improvements sug
gested by previous experience with them.
6. A Geodetic Laboratory for the determination of the values
and errors of graduation of circles and levels of high precision, fitted
with level testers, collimators, cathetometers, etc. , etc.
7. A Magnetic Laboratory in which is acquired the skill neces
sary to use the Kew magnetometer and Barrow's circle. The instru
mental constants are derived in an isolated "
copper house "
; but the
magnetic quantities are obtained each year, by the students in civil
engineering, at the astronomical stations of the systematic survey of
the State. This work has been carried on since 1874 under the ausdices
of Cornell University.
8. A Metric Laboratory for the absolute comparison of lengths,
provided with line and end comparators and dividing engines, within-
dependent microscopes mounted on isolated piers. This room is built
with hollow double walls, and provision has been made to maintain it
at a constant temperature. It has been constructed with great care,
and contains a four meter comparator of extraordinary precision. Tel
escopic observations may be made through tubes in the walls, which
avoid the necessity of entering the room, thus disturbing its tempera
ture. In this laboratory are placed many other machines and appara
tus for experimentation in such portions of optics, thermo-dynamics,
etc. , as form special parts of the educational equipment of the engi
neer.
9. A Bacteriological Laboratory in which students may become
acquainted with bacterial forms and such portions of the subject as
bear upon sanitary engineering. The optical apparatus has been ex-