The West Virginian. [volume] (Fairmont, W. Va.) 1914-1974, 1920-04-12
Talk Through 90
FEET DE- SOLID ! COAL
Some Extraordinary Re.
suits D in Test Of
War Device.

Amer seriesscf important tests with
he geophone listening device In
vented during the war by the French,
10 detect and locate enemy under
sround Operations, the Bureau Of
Mines Department Of the Interior, an
lounges that this delicate instrument
may be put TO Q numbe. OF remarkable
uses II mining and other industries.
The most extraordinary result OF
these tests Is that the Bureau Of Mines
men have been able, not only to hear
and locate sounds through the earth,
but have actually understood talking
through fifty feet of solid coal ano
have detected the human voice fully
$50 feet away. What this may mean
81 ne near future can. only be cor.
jectured. IAN engineer OF the bureau
was able through 900 feet of coal to
distinguish nine out Of ten different
coal mining tools that were used at
different times, so characteristic are
tho Sounds In one mine where ex-
periments were being made at the face
o. q tunnel, the mine foreman who was
listening heard workmen in another
tunnel preparing to blast and ordered
the engineers to retire until the blast
WAS fired The sounds were so clear
he did not realize that the tunnel head
ings over 800 feet apart.
The greatest value OF the geophone
n mining, so far as known, will be In
connectio with rescue work in mines.
Quite hequently. miners are entombed
IN coal mines following explosions, and
these men may be located quickly and
accurately through the geophone. In
metal mines also where men may be
Imprisoned behind falls or be barri-
caded m some part Of the mine to
which they have retreated in order to
protect themselves from the fumes of
fire these too may be rescued
through prompt location.
When the bureau first began its ex-
periments with the geophone, 1t was
nuestionable whether the geophone
could hear sounds far enough away to
make 1t practicable. The experiments
show that sounds can be detected
through the earth distance of 1900
feet In amined-o out area In coal mine.
through solid coal, 1000 feet, and
through solid rock about half mile.
ri |-4nSfBSoPnOu0 10 dA50 vi 6EedI pdS-
tical value in metal mines where two
tunnels have to be connected. At times
IN spite of as correct surveying as is
possible the two tunnel headings fail
TO come together. Just recently Blu.
reau Of Mines engineers were in a
mine where the two ends Of the tun-
mel failed to meet, and the geophones,
locating the error, showed the miners
the right direction.
Observations with the geophore
have also been made at. mines which
were on fire, where It was found that
the fire made noise enough to be heard
some distance, either because of its
drawing air or the breaking of of bits
oil coal and slate. The geophones by
thus coating the fire gives information
which may enable the mine manage
Ito erect fire stopping in the prop.
er places or to make direct attack
on the fire as for example by drilling
holes for injecting water to the seat
Of the fire. &
It is aisplthe custom In some mining
local Titles drill hole, from the sur
face into mine to carry pipe lines or
cables. Oftentimes these drill holes
do not so to the right places, and it is
with considerable difficulty and ex-
pense that tunnels are diven to meet
the drill hole. With the aid of the geo
phone, the drills can be guided bet
tey especially since drilling can be de-
tecteds Tor nearly a mile.
Very satisfactory results have been
Obtained In attempts made to locate |
leaks In water mains. The water cir
cuiating In the ordinary city main can
be heard with the geophones when
they are placed on the surface, ten to |
twelve feet above the pipe. In the
business district OF Pittsburgh, one
leak was located within a few minutes.
although the water department had
been trying to find it for two weeks.