Show Keeping Up I I v 0 ci n erv e Science Service SOr Mine Roof Ins Cave May a Be e Predicted by New Instrument May 1 Mean l Prevention of Future Catastrophes STATE COLLEGE PA A A A Anew Anew new device to detect mine roof ins cave ins cave and the type of disaster disaster disaster ter which occurred recently at fo 1 Moose se River N. N S S. S has been devel developed ped at the Pennsylvania State college here The frantic and spectacular rescue rescue rescue res res- cue efforts which s saved the lives of two men at Moose River lUver emphasIze emphasize emphasize em em- anew the hazard which roof collapse brings to mining operations operations operations opera opera- and recalls the fact that GOper 50 GO per cent of all deaths In well-kept well commercial coal mines occur from this source Dr H H. Landsberg of the School of ot Mineral MineraI Industries has found that In all aU roof Ins cave-Ins so far studied a definite br break k occurs In the overhead overhead overhead over over- head rock strata several hours before before before be be- fore the final cave In takes place The shale and dirt he found support support support sup sup- port the roo roof for some time after the supporting rock has gone beyond beyond be be- yond ond Its breaking point Detects Initial Break The secret of success of Doctor Landberg's device Is to detect the Initial break l In iii time to warn the working miners His Instrument Is called a convergence recorder From its use can be made predictions much like those a weather man may make after reading rending the barometer The he apparatus consists of ot two steel tubes which slide sIlde Inside one another like the tubes on a bone The sliding tubes are kept apart by a spring and are placed In the mine so that one tube touches the roof and the other the floor of the shaft A movement as ns small as 1 of ot an Inch between roof and ceiling can be detected Predicts Time of Crash Following the Initial break Doctor Doctor Doctor Doc Doc- tor Landsberg points out the rates of convergence of the the roof roof am and floor Increase rapidly un until the the entire mine roof collapses B By studying the rates of convergence the exa exact t time at which the Internal rock structure was broken can be detect detect- detected ed and the final ca cave In In e predicted Further work Is being done along this line tine b by both Doctor Landsberg and the United States bureau of mines I In an effort to establish a amore amore amore more definite relationship between the rates of or convergence of the roof root and floor of a mine and the collapse collapse collapse col col- lapse of the roof structure |