New Britain herald., 1922-07-25

fectlon from which a sound Is com ing through the earth. and thus to
 locate the approximate position of the entombed miner, The bureau gives
 recommendation for signal code of
 poundings by sledges or other means
 which will establish communication
 between the rescuing party and those
 entombed.
 Another promising use of the geo.
 phone Is in the location of leaks in
 water pipes. By means of the in-
 strument, it is possible to hear water
 circulating in the pipes of ordinary
 city mains sitauted 10 to 15 feet below the surface. Tests conducted at a
 busy corner in the downtown district
 Of Pittsburgh located a leak in a
 water main which the water company
 nad TOT two weeks vainly sought to detect.
 Geophone Easily Portable.
 The mine geophone is sensitive, vet extremely simple and easily portable.
 The instrument was invented bv the French during the war to detect san ping and underground mining opera tions It was developed by the United States engineers. and the in- struments now used by the Bureau of Mines were made according to plans drawn by them. except for the intro auction Of different diaphragms. The geophone is essentially small seis- mograph. as it embodies the same principles as the ponderous apparatus that records earthquake tremors. It consists of lead weight suspended between two elastic diaphragms cut ting across small alright box. If the instrument is placed on the ground and anyone is pounding or digging in the vicinity, energy is transmitted as wave motion to the earth, and the earth waves shake the geophone case. The geophone. there fore, transforms the earth wave into nair wave, which is heard by the ear as sound. and at the same time magnif1es the wave so that the sound is louder than if the ears were placed in direct contact with the earth
 The observations of the Bureau of Mines indicate that the geophone should be quite useful in the location of mine fires Usually a mine fire makes enough noise, either by draw ing air or by breaking off slate and | coal to be heard for a considerable l distance through the coal and even through the strata above. The dis tance that these sounds can be heard | depends great deal on the nature of the strata above the mine, yet the | sounds originating at a mine fire. should be detected through 100 to 300 feet of coal.
 Survey Mines.
 Geophones supply quick and fairly accurate method of mine surveying | If two tunnels were being brought to- gether from any direction, the pro- | sress of the tunnels could be observed | by means of the geophone, and their | relative positions determined. Another application of the poss- | biities of the instrument in mine sur veying is in the prevention of acci- dents in blasting through. If two | tunnels are approaching each other, or are passing a short distance apart, it is necessary to determine the rela- tive location in order that men may i be warned to keep away from the point Of danger. AS the sounds transmitted through the eeophone are so characteristic, frequent observa- tions would enable trained observer to follow the progress Of the work in the opposite tunnel. He would thus be able to tell when blasts were to be fired
 Occasionally churn-drill holes are I dropped from the surface to mine workings for running pipes and for ventilation. When these borings come for considerable distances they sometimes drift, and instead of break ing through into the workings, they come down into the solid The question then is to locate them and to determine whether or not the hole is deep enough to come into the work ings. Here the geoephone finds useful field, for not only the direction of the hole, but its elevation can be determined accurately.
 It is well known that when the bit of a diamond drill has disappeared below the surface there is no simple method for determining the course 1t may have taken. AS these bits nearly always drift away from a straight course, any instrument mak- ing 1t possible to follow this drift will obviously be valuable.
 Use in Caye-Ins.
 No attempt has been made to adapt the geophone to determine the earth movements that sometimes occur in 1eep mines and are termed bumps" by the miners. It is probable, how ever, that this instrument may be of Ise in certain parts of the anthracite ,oal fields where cave-ins have de- ,troyed mine workings, causing loss of fife, surface, subsistence. and injury ind destruction of buildings.
 The manifest advantage of the geo. phone for use in mine rescue work 1as led the Bureau of Mines to place he instruments on its mine-rescue .ars, which are constantly being ,alled to assist in the succor of en- ombed men at mine fires and ex- ,lossons.
 Details of the bureaus experiments Ire given in Technical Paper PIT