A Cornish engine is a type of steam engine developed in Cornwall, England, mainly for pumping water from a mine. It is a form of beam engine that uses steam at a higher pressure than the earlier engines designed by James Watt. The engines were also used for powering man engines to assist the underground miners' journeys to and from their working levels, for winching materials into and out of the mine, and for powering on-site ore stamping machinery.
The pumping station at Cruquius, showing the beams of the pumping engine emerging from the supporting wall
Section, circa 1877
One of the preserved engine houses at Pool, housing a 30-inch engine
Valve rod of engine at London Museum of Water & Steam
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is most commonly applied to reciprocating engines as just described, although some authorities have also referred to the steam turbine and devices such as Hero's aeolipile as "steam engines". The essential feature of steam engines is that they are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.
A model of a beam engine featuring James Watt's parallel linkage for double action
A mill engine from Stott Park Bobbin Mill, Cumbria, England
A steam locomotive from East Germany. This class of engine was built in 1942–1950 and operated until 1988.
A steam ploughing engine by Kemna