The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1910-06-12

protects their eyes. and a shield out
side the building is so directed that the
vision of the men is directly on line
with the long cylinder stretched along
the ground.
Every eye being glued to this slit
in the observation house wall. but
ton is pressed, the mortar is fred, and
the coal dust. or fredaulp in the gal
lery. explodes with loud report.
There are sixteen portfolios along the
side OF the cylinder. and the miners
are told to note by these how the blaze
of the explosion progresses along the
tube from the mortar to that covered
with the paper drumhead. The eN-
plos'on, of course. blows the paper out
and at the same time sixteen iron doors
to row of openings along the top Of
These doors and the drumheads. of
course. save the entire plant from be-
ing totally wrecked by the explosion.
AS 1t is. smoke pours out of the tube
and there is loud defamation.
This test will give many miners their
first demonstration of the fact that coal
dust Is highly explosive and will teach
them much that they ought to know
about the explosiveness of fredamp At
the same time the apparatus Will de-
monstrate the comparative safety or
different explosives purposely used as
blasts in mine regions, where dust and
damp may be found Various charges
of dynamite, black powder and various
safety explosives will be fired off
from the mortar in the presence of the
coal dust and hredamp. while the min
err watches their comparative effects
and learns the strength of the charge
of each that can be used without dan
ger of an explosion. With these tests
the Bureau of Mines will standardize
mine explosives and recommend as
"permissible" those which act with
safety in the explosives gallery
To demonstrate how a mine may be
blown up by sparks fromdefective cleo
trio wiring in mines, there is second
gallery" thirty feet long by ten in
diameter. The gas and dust pumped
into this tube are fired, not by NOR
tar. but by simple electric spark
flashing between two ends OF Wire
An odd contrivance is rugged up 70
demonstrate that some of the safer ex-
plosives are also the most powerful
This is pair OF mortars placed mouth
to mouth, one mounted upon little
car that runs upon track. and the
| other swung as a pendulum from
great beam with knife-b blade edge
This edge, arranged to reduce friction
rests upon a bar placed across two high
nyramids OF concrete. When the NOR
| tars are fired together the suspended
one flies backward with pendulum
\ swing, whose distance, recorded by
/ scale, measures the power or the eX'
| plosive.
Practice In Smoke-Fillcd Chamber.
How the miners will learn to rescue
their comrades in dread times OF hrs
and explosion Is Illustrated in the &C
companying photograph. that SHOWS
a miner on stretcher another pros
trate upon the floor and three othef'
wearing the oxygen helmets,
There is apparatus for filing thl
room with smoke. through which tn
|helmeted miners are taught to clim
over and crawl through all sorts
distractions arranged in drifts an
headings, To the right OF the pictur
is one OF the distractions, sort Q
bridge which goes over an end of tn
structure in the centre of the space
1t is Enclosed In wire netting and IN
flooring is piled with disordered tim
hers. while in some places steep step
several feet high must be climbed. An
elsewhere in the picture are seen open
inrs through which the men mus
crawl, some of them admitting the'
only on hands and knees. The man ~
ing upon the floor in the foreground 6
starte the oxygen treatment TOR tnos
overcome by mine smoke or gas. Th
n f,gures carrying the stretcher wea
three cans worn upon the rescuer
back. The course to be taught at Z.
new rescue school will include q
II nroner use OF these devices. The eff
n clancy of new inventions for sustain
4 ing life in mines will be continuous
II made in this same smoke chamber.
II Another interesting room is u
Il lamp testing gallery where mine
II VIII be taught that safety lamp"
II too often mere misnomer and tra'
u name, A long, square tube covers g!