1873 - Old Forge Coal Mines

TO
ANNUAL REPORT OF THE
This would supply nearly double the required quantum of air. Although
this result may appear satisfactory, yet it may not be sufficient to
render harmless the quantum of noxious gases, vapor and impurities generated
in the mine. As we see in this case the velocity is only 3^ feet per
second, or 2^ miles per hour, scarcely perceptible.
Unless the mine in this case was tolerably free from noxious impurities,
the ventilation could not be satisfactory ; hence the inspector's duty would
be to direct an increase in the supply of air, as it would insure safety.
Rule.—Biriam, the measurements of the velocity taken as above, i. e.
220 feet the section area, the opening being 42 square feet. Here we
multiply the velocity, 220, by 97=213.40. We reject the two right hand
figures, 40, and we have 213, which we multiply by the square area of the
opening, 42. Then 3213+42=8946 feet, to which we add 40 for the number
which overcomes the inertia of the investment, making the actual number
of cubic feet of air supplied=8986.
Thus
220 velocity.
1540
1980
.97 constant decimal fraction as a multiplier.
21340
42 area of opening as measured.
426
852
Plus
8946
40 number to overcome inertia.
Equal
8986 cubic feet, answer.
The difference in this case being 186 feet, which is of little importance
in this respect. The. Cassela instrument appears to be the one adopted by
the War Department for marine and land service.
Thermometer.—An instrument to measure temperatures, and was invented
by M. Sanctoria in 1590. This instrument is formed of a delicate
glass tube, with a bulb at its bottom which is filled with murcury ; its face
is divided into a scale of equal parts. In Fahrenheit's scale the zero is
fixed at 32 degrees, rising to an unlimited number and falling down to 60°.
With the greatest accuracy it registers the slighest change in the atmosphere,
either up or down, or in fluids by the expansion or contraction of
the murcury in the bulb.
Murcury is possessed of very remarkable properties, and is well adapted
to this purpose. Its ability to accommodate itself to these conditions and
changes of atmospheric temperatures is singularly peculiar and uniform.
For a very low temperature alchohol is preferred, as it is known never to
solidify, under any condition, even with the most intense artificial cold of
the carbonic acid bath.
There are different thermometers is use, but only three of which are in
practice, viz:— Fahrenheit, a Hollande's scale, is adopted in America,
while Centigrade's and Beamur's are used in Europe. There are two fixed
points in each—the boiling, and melting of ice points. But the gradations
on these scales differ in such arbitrary degrees that we deem it but proper
to explain their different readiugs so as to reconcile their variations.