coal trade bulletin - Clpdigital.org

46 THE COAL TRADE BULLETIN.
The Bureau believes that lamps that have passed
the Bureau's tests ancl have been approved as permissible
for use in gaseous mines will satisfy the
requirements of safety.
INTENSITY OF LIGHT.
The reasons for selecting this minimum value
have been previously stated in this paper, ft is
taken to mean the least value of the mean candlepoyver
of light stream that a lamp should produce
at any time.
FLUX OF LIGHT.
The reasons for selecting these minimum values
have been previously stated in this paper. They
are taken to mean the least values of the total
flux of light produced by a lamp at any time.
Provided that in the case of cap lamps having a
solid angle of light stream of more than ISO 0 the
flux of light shall be increased in proportion to
the increase in the cross section of the light
stream.
TIME OF BURNING.
The time of burning as stated here is taken to
mean the time during which the discharge voltage
exceeds the lower limit established by the
manufacturers, and the lamp is producing not
less than the specified flux of light at a mean intensity
of light stream not less than 0.4 candlepower.
DISTRIBUTION OF LIGHT.
Any requirement as to the distribution of light
will of course apply only to lamps that use reflectors
of some kind. No value is given in the table
to this qualification because an intelligible statement
requires considerable space. it is clearly
desirable to have a uniform distribution of light
and yet too uniform a distribution would entail
unwarranted expense. The following is suggested
as a reasonable requirement that will preclude
uneven distribution of an annoying or inefficient
character.
The distribution of light shall be determined
both by observation and by photometric measurement.
The lamp shall be placed three feet ayvay from
a plane surface that is perpendicular to the axis
of the light stream of the lamp. When so placed
the lamp shall illuminate a circular area not less
than seven feet in diameter. All observations
and measurements of distribution shall be referred
to this seven-foot circle, regardless of howlarge
an area the lamp may iluminate.
As observed with the eye there shall be no
"black spots" within the seven-foot circle nor any
sharply contrasting areas of bright and faint
illumination anywhere. As measured photometrically
the distribution of light diametrically
across the circle shall fulfill the following requirements.
The average illumination (in foot candles) on
the best illuminated 1/10 of the diameter shall
not be more than twice the average illumination
throughout the diameter and for at least 50% of
the diameter the illumination shall be not less
than the average.
REFLECTOR ANGLE.
This refers of course to the solid angle of the
stream of light. A reflector whose cone of light
has an angle of 100° will illuminate a circle about
seven feet in diameter if placed three feet ayvay
from the surface so illuminated.
MECHANICAL AND ELECTRICAL CONSTRUCTION.
It is not necessary to suggest to niining men
that anything should be well made if it is to be
used underground. Under this head should be
considered simplicity of design, strength of parts
and fastenings, design of moving and removable
parts, and the design and construction of electrical
circuits and contacts.
The 450 miners employed in the Wheeling Creek
mine of the Lorain Coal & Dock Co., yvho had refused
to work in the mine since the death of Frank
Hora, returned to work Feb. 9. Coroner Myers,
at the inquest, found Hora died from an explosion
resulting from a carbide lamp, and the mine superintendent
refused to permit, the miners to use carbide
lamps, whereas they refused to enter the
mine. They began yvork, however, with oil lamps.
Alleging that John Heron, mine foreman of the
Crystal mines of the United Connellsville Coke
Co. at Outcrop, Pa., had permitted Frank Fordyce
to fire a blast from 'solid" yy hile other employes
were in the immediate vicinity, Mine Inspector
I. G. Roby made information against Heron charging
him with violation of the mining layvs.
John Moore, president of Ohio United Mine
Workers of America, has declared the bills drafted
by the Ohio coal commission, appointed last spring
by Governor Cox, impracticable in mining practice.
According to the report of the auditors the treasury
of District No. 1, (anthracite) on Dec. 31.
1913, held a balance of $69,211.45- The membership
at the same date was given at 60,000.
In posting mine safety notices in Ohio mines in
conformity yvith recent layvs it yvas found necessary
to print them in seven languages.
The Transatlantic Trust Co., of New York, has
served notice that it will resign the trusteeship
of $2,000,000 wortn of bonds of the National Bituminous
Coal & Coke Co. on April 21, 1914.