Evening star., 1915-02-06

II SAFETY IN MINES. III
By Frederic J. Haskin. HI
Coal mining is, and probably must al
ways remain. one of the hazardous oc-
cupations. The public hears only of
the occasional great disasters, in which
a number of men lose their lives, but
more miners are killed in the long run
by rock or coal falling from the roofs
of mines. usually one at time. than
in any other way. Every miner who
goes underground takes decided risk.
and some of the workers are in imme-
diate danger every day. as. for example.
the shot -f1rers," who remain inside
the mines to touch Off charges of pow
der or dynamite after all of the others
have left. In the better equipped mines
the blasting charges are now exploded
by an electrical apparatus operated
from outside the mine; but the shot
firer'' is still employed in some of the
smaller mines, and none but the most
courageous men will accept the posi-
ton.
Generally speaking, however, the op-
orators of mines are doing all in their
power to promote the safety of their
employees, in accordance with the ad-
vice and recommendations of the United
states bureau of mines. Nearly all Of
the larger operators now have rescue
apparatus and corps of trained men,
equipped with helmets and oxygen
tanks similar to those carried by the
70 Of hn h11r nf mi Sn
that they are fully able to cope with
any accident. Smaller operators are
usually not so well equipped, but are
willing to cooperate with the bureau
rescue work and in promoting safety.
State governments are also co-operat-
ing with the bureau of mines, and in
Illinois, especially, valuable studies are
being made, with the assistance of the
Illinois geological survey, Of the oc-
currence of gas in mines
1t rs in the prevention of mine acci-
dents, however, that the most notable
advances have re-
Cause of Most "ently been made,
Mine Explosions. the the prevention of of
explosions. OF ffty-seven accidents
that were investigated by the bureau
of mines within the past year twenty
six were caused by explosions, which
was twice many were caused by
any other one agency, fire coming next
as the cause of thirteen accidents. A
typical coal mine explosion of the
worst sort was that at Dawson. n. NJ,
last October, in which 263 men were
entombed, and perished. A rescue car
ha of fn
the spot from Kansas. and men equip
ped with breathing helmets and oxygen
tanks sent into the mines, but rescue
was for the most part impossible. Two
of the helmet men lost their lives in
the effort to save some of the miners.
Owing to the suddenness and terrific
force of these explosions, and the for
nation of poisonous gases, death for
many miners is inevitable whenever
they occur, and rescue work hazardous
and uncertain. 1t is in the prevention
of explosions that work is needed and
is being done.
The discovery that coal dust, in sus-
pension, is highly explosive sub
stance and the cause of most of the
great explosions in coal mines is the
most important in this line that has
been made in many years. The bureau
of mines has just completed series
of remarkable experiments with the
explosibility of coal dust. the results
of which will soon be published In full.
It has been found that the gas called
fire damp" upon which most of the
explosions have hitherto been blamed,
could not be the cause of any but
purely local explosions, while explo-
sions of coal dust will send a wall of
flame into every open part of the mine.
Coal dust is inevitably formed in the
M
the coal and in load
How Coal Dust ing it upon cars. The
Is Exploded. the aoors roof tim
bers. cars, and all other stationary sur
faces. When charge of blasting pow
der is set off, this dust is thrown into
the air, and. If the flame from the blast
ing charge reaches it, Will explode with
great force and the flame will be car
ried an indefinite distance, as more and
more dust is thrown into the air.
The exact workings of this terrific
experiments conducted by the bureau
! of mines at the government expert
mental mine at Pittsburgh: Artificially
| made coal dust was distributed amour
| the mine. The explosion was started
by small cannon loaded with four
| pounds of black powder tamped with
clay This cannon naturally threw out
| a stream of fame to a distance of from
| ten to fifteen feet. The flame was ex-
tended by the coal dust Immediately In
| front of the cannon to a distance OF
| from as to 1876 feet The shock wave
| from this first dust ignition Travelled
| through all available passages at the
| rate of 1850 feet per second. kicking
! up dust as it went. which was 1nme-
| diately ignited by the following wall OF
! flame. In a word, the explosion ere
| ated a wall of fame, which rushed
throughout the mine, wherever there
| was coal dust. and which. needless to
| say, carried instant death for every
| living thing in its path. The expert
| menters reached the conclusion tina,
| coal dust is the most fnsidious anc
| deadly source of danger in a mine.
| Yet It Is Inauffestfy impossible u
| mine coal without causing q great dea
II Of dust to aocu.
| Mix Rock Dust mulate within th<
,fw,