Heat is used to raise steam which either turns a turbine or forces a piston to move up and down in a cylinder.
Engine that uses the power of steam to produce useful work. It was the principal power source during the British Industrial Revolution in the 18th century. The first successful steam engine was built 1712 by English inventor Thomas Newcomen at Dudley, West Midalnds, and it was developed further by Scottish mining engineer James Watt from 1769 and by English mining engineer Richard Trevithick, whose high-pressure steam engine 1802 led to the development of the steam locomotive.
In Newcomen’s engine, steam was admitted to a cylinder as a piston moved up, and was then condensed by a spray of water, allowing air pressure to force the piston downward. James Watt improved Newcomen’s engine in 1769 by condensing the steam outside the cylinder (thus saving energy formerly used to reheat the cylinder) and by using steam to force the piston upward. Watt also introduced the double-acting engine, in which steam is alternately sent to each end of the cylinder. The compound engine (1781) uses the exhaust from one cylinder to drive the piston of another. A later development was the steam turbine, still used today to power ships and generators in power stations. In other contexts, the steam engine was superseded by the internal-combustion engine.