Engine

Engine, the generic term for any converter of energy from one form to another. Such arrangements are very numerous and widely different in principle and construction. Hence their classification brings the study of special examples under totally different headings. Thus the conversion of the heat-energy in steam to mechanical motion is effected by the steam-engine; the heat is supplied by the chemical combination of coal, petroleum, or other such fuel, with oxygen. The similar conversion of the heat-energy in the products of combustion of coal-gas is effected by the gas-engine; and of the heat-energy in hot air by the air-engine. Such engines producing mechanical motion are termed prime-movers, a term which also includes water-wheels and turbines. Such may further be classified as stationary or locomotive engines, the former including all those that remain in the same place giving rotatory or oscillatory motion to various mechanisms, and the latter all those that supply the energy for their own transference and perhaps that of a train of dependent carriages.