COMPRESSED AIR LOCOMO

TIVES. Compre ed air is used for driving trams in mines and manufacturing plants. Locomotives operated with this motive power in such surroundings have the advantage of freedom from any form of combustion, making them suitable for service in the vicinity of explosives. The air is stored at a high pre ure of 1,000 to 4,000 pounds per square inch in a steel reservoir carried on the locomotive, and admitted therefrom into the engine cylinder at a working pre ure of 100 to 150 pounds. Compre ed air is also used for motor cars. Its employment as a motive power is closely allied to that of steam, and is of marked utility in driving certain types of machinery, especially those at are portable and readily handled, such as rock drills, coal cutters, riveting hammers, sand tampers, saws, crane hoists, air-life pumps and other pneumatic appliances. Compre ed air is adaptable to transmi ion, loses no power from radiation, and in underground work has a discharge that is a healthful instead of a noxious addition te the atmosphere.