COAL-MINING BY MECHANICAL APPLIANCES.

Keywords: CAMBRIA MINING, COAL, MINING, MECHANICAL, APPLIANCES, COALFIELDS, ANALYSIS, POWER, MACHINERY, ENGINES, HAULAGE, MINES, WATER, SUPPLY, WATER SUPPLY, WORKING, OUTPUT, WAGES, EQUIPMENT, PLANT, BOILERS, METHODS, ROOM AND PILLAR, PILLAR AND STALL, MACHINES, CAMBRIA, WYOMING, USA, UNITED STATES