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Fig Page 1 Piece of roof rock that fell on a miner
Timberman testing roof by the sound and vibration method in presence of foreman
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afterdamp anemometer atmosphere barricade bituminous-coal mines blasting borehole brattice Bureau of Mines carbide lamps carbon dioxide carbon monoxide Cardox cars cause charge circuit clearance coal beds coal dust coal mines coal-mine conductors conveyors crew cross bars dangerous derail detonator devices drilled electrical conductors electrical equipment employees entries explosions and fires explosive gas face falls of roof fatal feet flame safety lamp floor gases gassy hand-loading handling haulage accidents haulage road haulageways hazards ignition inches increase installed loading locomotive machine machinery maintained man-trip material mechanized mines methane method miners misfire motorman necessary nonfatal injuries numerous officials operation oxygen percent persons pillars practice precautions pressure prevent prop proper properly rail railroad car reduce repair result rock dust roof and coal rope safe self-rescuer shelter holes shot firer shot hole shot-firing smoking splice switch testing timbering tion track trailing cables trolley wire underground usually ventilation workmen