Jerome County times. (Jerome, Idaho) 1919-1920, 1919-11-13
HzInE RkSCZE 0E0HHOHE SIT

.ernine the distances at 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 maze III
order that recommendations could be made as to
the type OF mining machine which could be useu
10 nccompl;sh the most work with the least noise.
In this connection it was found that SOUNDS
were transmitted only about half as far III cla!
as in shale strata and about onc-quarter as lar III
clay as in coal. To give some idea of the sensl-
tiveuess Of the instrument il may be said that
pourding with Il pick on the btuminous coal can
be detected for distance of 900 feet and the
direction determined, and that pounding with
slcdge can be heard as far as lilo 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 Il one-ounce charge
Of dynamite was detected distance Of over 2OoO
feet through the shule strata.
Sound Tells the Implement.
One interesting feature Of the instrument is
that the sound transmitted to the ear is charac
terisc of the implement producing the sound. To
Illustrate: Twelve mining and carpentering
ouerntions were carried out the coal rib. An
engineer Of the bureau of mines who had never
used the geophone and who did not know what
fools were to be operated able to recognize
and name uine of the implements at distance of
several hundred feet through the strata. The
other three sounds were acCuratelS ueScrlUeu put
the tools were not Identified.
Now that the war is over, the bureau has turned
10 the development Of the instruments for peace
time uses For thing il is believed that they
will he of great value to mine-rescue crews who
,,o, no entering mines for exploration and to
locate miners who may have been entombed after
n DISASTER The tests far made in the vicinity
If Pittsburgh show that man pounding on the
coal rib with pick. piece of timber or sledge can
he detected and located from point COO to l2oo
feet distant This distance depends greatly on the
character Of coal upon which the man is pounding
and Intervening rooms and entries seem 10 nave
surprisingly little effect upon the distance or the
determination OF direction.
Pounding with sledgc can be heard from w
IN roo feet through the mine cover dep'huhE
unon the quctness Of the day outside SINCE any
wind greatly interfcres with the successful "per"
.i, of the instruments. 1t will at once he seer
th,t when mines are not too deep they can o'
"eNplorcd" from the surface ana II VIII 'nuS ~
nossible to find and locate miner VINO Is Pounu
ing Al the experimental mine IN bru'e'o',' :"
q mon has frequently been located throuS" if
feet Of cover Wlthln ~ leV' Va WV ~
where he was pounding 49,
A study is also being made Of the ulsl"lV's ."'
nounding on rails and pipes can ne h''" ."
rails are generally buried in the oarth or aust
,,' ontrios of a mine and since this dust dampen
tho transmission of the sound. the SOUNDS are III
,rsr,ittcd very well. The same is true OF PIP
,tDos However, if the pipe lines are NOT nur'e'
hnt NO laid on blocks and ties. the pounding ca
Inc bsord great distances. )" far II" mes nav
n,o,, round long enough to show the limit 'i III
" II Is KNOWN however. that the make
o',r can vet sounds farther than 1000 feet
Used to Guide Tunnel Work
In metal mines expensive surveys nave S'''
.,,,as to bc n.de in order that the approacmn
mrnc headings may he brought together "
,I. since direction can be determ'heu
D,' win the geophones it is thought that th'
nv uscd to guide such work. 1t would on
~, va" ,ocessnry to 20 into each heading ana 'o','
tho direction from which pounding Ill '''e o''
hcadng coming , rocont
observations made in metal NINE re'en'
w., thot direction can be determined mU
more easily in rock than in coal Inns rs pr,
dvo 70 the fact that there is some reVeroe'
= me- Wv" so,,rd from a hammer blow on co
.,,a no on stone the sound is clean cut 1t so M
pensd that in this mine raise was ,u being a nn
- M about six eight feet distant ir% f ,na som
> observations were made in the drift OIL the 81"