Sioux County pioneer. (Fort Yates, Sioux County, N.D.) 1914-1929, 1919-11-20

termfne the distances ut which the shock waves
resulting from the discharge of various explosives
could be heard A brief Investigation of the
factors influencing the transfer of energy from
mining tool to the clay and coal were also made in
order that recommendations could be made us to
the type of mining machine which could be used
to accomplish the most work with the least noise.
In this connection it was found that sounds
were transmitted only about half as far in clay
as in shale strata and about onequarter as far In
clay as In COAL To give some idea of the sensi-
tiveness of the instrument 1t may be said that
pounding with pick on the bituminous coal can
be detected for distance of 900 feet, and the
direction determined and that pounding with
sledge can be heard as far Us $50 feet. These
measurements were made In the Pittsburgh coal
seam in the vicinity Of Pittsburgh where the coal
Is somewhat harder than In most other bituminous
coal beds. The explosion of one-ounce charge
of dynamite was detected distance Of over 1000
feet through the shale strata. 4
Sound Tells the Implement.
One interesting feature of the instrument is
that the sound transmitted to the ear is charac.
teristic of the implement producing the sound. To
illustrate: Twelve mining and carpentering
operations were carried out on the coal rib. An
engineer of the bureau Of mines who had never
used the geophone and who did not know what
tools were to be operated was able to recognize
and name nine of the implements at distance Of
several hundred feet through the strata. The
the tools we're not Identified.
Now that the war Is over, the bureau has turned
ito the development Of the Instruments for peace
time uses thing, 1T is believed that they
/ win be of great value TO- mine-rescue crews who
mag bel entering mines for exploration and to
locate miners who MAJ: have been entombed after
a disaster. THE tests SO far made in the vicinity
I: of Pittsburgh show that ,a man pounding on the
coal fib With pick piece OF timber or sedge cah
he detected and iocated; dtsm point 600 to 1000
feet distant This distance depends greatly on the
achaFactefo COIL which the man is pounding.
, and intervening rooms and entries seem to have
slrprisinglY little effect; upon the distance the
determination tof direction;
Pounding with q sledga can be heard from 200
400 Test mine cover. depending
wind Greatly nterferes; With the successful opera
ton of the instruments. T. will at once be seen
that when mines are not too deep they Gun be
"explored" from the surface ind it will thus be
possibiastos and ind locate miner who is pound
Ing At the experimental mine in Bruceton. Pas
q man has frequently been located through l4O
feet Of cover within SO feet Of the exact point
where he was pounding. saF
study Ii also being made Of the distances that
\ pounding Oh rails and pipes can be heard. Since
rails are generally buried in the earth or dust In
Tie entries of mine and since this dust dampens
. the transmssionof the sound, the sounds are not
transmitted very well. The same is true Of pipe
lines HoYevef,f the pipe lines are not buried
4 hut laid on blocks and ties. the pounding can
be heard great distances. SO far no lines have
been found long enough to show the limit OF the
Y ,aeophone. It is known, however, that the naked
ear can get sounds farther than 1000 feet.
sss:::.ss 4ss Used to Guide Tunnel Work.
i !, In metal mines expensive surveys have some
;. times to be made in order that the approaching
tunnel headings may be brought together ac-
rcusataly.a Since direction can be determined so
we'll with the geophones 1t is thought that they
can be used to- guide such work. It would only
i6e necessary to go into each heading: and locate
the direction from which pounding ii the other
heading was coming. u ~ sfsEsi y
"a observations; made in a metal mine recently
showed that direction can be determined much
J more easily jns rock, than inFcoal This 10 prob
aby due to the fact that there is some reverbera.
ton to the sound from hammer blow on coal.
while on stone the sound Is clean cut 1T 10 hnp-
pened that infthis mine raipe was being driven
IN, shout Six or eight feet distant from Q shaft
observations were made in t. drift Of the sound