Evening Republican, Volume 22, Number 110, Rensselaer, Jasper County, 10 May 1919 — GEOPHONES TO SAVE MINERS [ARTICLE]

GEOPHONES TO SAVE MINERS

War Instrument Will Fix the Location of Men Entombed by Explosions. Washington.—The geophone, invented during the war to determine the exact location of sounds above jind oeneath the surface of the jjgrth, soon will be used extensively in mining operations in this country, the bureau of mines announced. The Instrument proved of great value to the allies before the cessation of hostilities ip determining the’ location of hostile batteries amt in de- ■ tecting the approach of the enemy, j Digging of trenches or tunnels iri. the