Bonners Ferry herald. [volume] (Bonners Ferry, Idaho) 1904-current, 1922-09-21
BY JAMES p. HoRNAoAY

BY JAMES p. HoRNADAY
Westinghouse the result Of exper-
ments made by the bureau of mines,
the geophone, novel instrument used
amid the reek and slaughter of the
World war for the detection of earth
and rock sounds made in the con-
struction of military mines and tun-
nels, promises to become an active
factor in the saving of the lives of
miners entOmbed as the result of fires
and explosions. In the course Of tests
conducted In the bureaus expert
mental coal mine near Pittsburgh,
blows with sledge on the coal face
were heard, by means of the geophone,
at distance of $50 feet, with various
rooms ana entries Intervening.
On a suspended pipe line, light
hammering with the knuckles was de-
tected at distance Of 1900 feet. Or
binary talking and singing could be
detected through 100 feet OF solid
coal. BY the use Of two geOphOnes.
one instrument to each ear. ii Is pos
sibie to determine the direction from
which a sound is coming through the
earth, and thus to locate the approx
mate position of an entombed miner.
The bureau gives recommendations
for signal code Of poundngs by
sledges or other means which will es-
tablish communication between the
reseuing party and those entombed
Another promising use of the geo
phone Is In the location of leaks in
water pipes. BY means Of the instru-
ment is Is possible to hear water cir
culating in the pipes of ordinary city
mains situated 10 to Is feet below the
surface. Tests conducted at busy
corner In the downtown district of
Pittsburgh located a leak In a water
main which the water company had
for two weeks vainly sought to de-
tect.
It's Small Seismogrsph.
The mine geophone is sensitive, yet
extremely simple and easily portable.
The instrument was invented by the
French during the war to detect sap
ping and underground mining opera
tions. 1t was developed by the United
States engineers, and the Instruments
now used by the bureau of mines were
made according to plans drawn by
them, except for the introduction Of
different diaphragms. The geophone is
essentially small seismOgraph. as II
the same principles as the
ponderous apparatus that records
earthquake tremOrs. 1t really consists
Of lead weight suspended between
two electric diaphragms cutting across
a small alright box. If the instru
ment Is placed on the ground and any
Dne Is pounding or digging In the vi
entity, energy Is transmitted as wave
motion to the earth, and the earth
waves shake the geophone case The
seophOne, therefore, transforms the
Earth wave into an air wave, which is
heard by the ear as sound. and at the
same time magnifies the wave so that
he sound is louder than IL the ears
we're placed in direct contact with the
'arth.
The observations Of the bureau of
mines Indicate that the geophone
'hould be quite useful In the location
# mine fires. Usually mine fire
makes enough noise, either by draw
ng air or by breaking Off slate and |
'oal. to be heard for Ii considerable |
distance through the coal and even
through the strata above. The dis |
ance that these sounds can be heard !
depends a great deal on the nature
II the strata above the mine, yet the !
ounds originating at mine fire
hould be detected through 100 to 300
eet of cover and through 500 to 800 |
eet of coal
Used In Mine Surveying
Geophones supply quick and fairly
ceurate method of mine surveying.
two tunnels were being brought to-
ether from any direction. the prog
ess of the tunnels could be observed
y means Of the geophones, and their
elative positions determined.
Another application of the possiblll-
les Of the instrument In mine sur
eying Is In the prevention of acct
ents In blasting through. If two tun-
els are approaching each other, or
re passing a short distance apart. it
necessary to determine the relative
'cation in order that men may be
armed to keep away from the point
danger. AS the sounds transmitted
trough the geophone are so char
rteristlc, frequent observation would
lable a trained observer to follow
he progress of the work in the OPP
osite tunnel. He would thus be able