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Show NEW STEP IN AVNE SAFETY... If r - A3 r l A two-way wireless I B rfV;J) UNDERGROUND MINE I Vy .JiJ 111 M COMMUNICATION r x&t 4 svsrevi 4S r!x W SVtTaj ; DEMONSTRATED BY M 7 'J m r, ' CONSOLIDATION COAL CO. llMtP B ANP PROVEN IN ACTUAL S?- J OPERATION IN ITS MINES. C A Sr I INPUSTRY OFFICIALS '7 ra't ? BELIEVE THAT THESE TESTS $ZrM$m 1 WILL LEAD 7V A SYSTEM r', f t ''& 1 CAPABLE OF BEING USED i ' v" 1 '':5':. w pch of conventional telephone communication.. Of special . ' powle hish power ' -. ' significance in " ' ' ' .' ' . surface transmitter- . i an emergency '".''' ' " cbvr ." ' ', '' when regular i '' WIRE COMMUNl- ''. " Imt cA'" ' ' ' cations faiL . cuENT FLOi, : .';:. THIS NEW , ' t-r-r-.-- .'. :.. ... SYSTEM WORKS '. I "' i'-J -" ". . BY SENDING '' v J . s-. ' . signals l A? ; . . : k , : . PIRECTLV ' ' . t.M THROUGH THE ) ,tK. . EARTH. PORTABLE UNPEROUNO M'NE ELECTRODE TRANSMITTER-RECEIVER Tx Voice signals are sent ,, . r:iSST' BY AN UNDERGROUND TRANS - I Wg-'M T'' trr"'- MTTER WHICH WEIGHS 70 LBS. j ",M yVAt-".-" y :j . COPE SIGNALS : P8MM M:, fo & o- ARE SENT TO THE (3 U 1 AVW I U SURFACE BY A S!A(S'l f. ' f transmitter zi Wy r I . fca .. WEIGHING ONLY rs-VLl 1 U ' |