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airway analysis anemometer approximately Assay Office Average production belt conveyor blasting bulb Bureau of Mines butt entries CANADA Cont'd cetane Chemical chute coal bed coal mines cooling crosscut crude oils cubic feet cubic foot deposit determined developed drift drilling driven dry-bulb temperature dust effective temperature electric engineers equipment explosives feet per minute field fuel haulage haulageways heat helium hoist holes ical Idaho inby inches installed Iron County Laboratory names locomotives mechanized units metals methane million particles Minerals Mining method names and addresses operations panel particles per cubic percent petroleum phosphate pillar extraction pressure raw coal reservoir Retsof rock rods roof samples shaft shaker conveyor shale shift silicosis skip station steel stope sulfur surface syncline Testing Laboratories thickness timber tons Total track underground velocity ventilation water gage wet-bulb temperature X X X York