Cornish engine

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The pumping station at Cruquius, showing the beams of the pumping engine emerging from the supporting wall – the engine's cylinder is in the middle of the round building.
Water is pumped 9 metres from the Spaarne, at the level of the arches.

A Cornish engine is a type of steam engine developed in Cornwall, United Kingdom, for pumping water from a tin 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 as man engines for winching workers and materials into and out of the mine.

A Cornish engine pumps by a falling weight that is lifted by the engine. Few remain in their original locations, the majority having been scrapped when their related industrial concern closed.

[edit] Preserved Cornish engines

The Kew Bridge Steam Museum in London, England has the largest collection of Cornish engines in the world. Two also survive in the town of Pool, Cornwall.

The Cruquius pumping station in the Netherlands contains a Cornish engine with the largest diameter cylinder ever built for a Cornish engine, at 3.5 metre diameter (144 inches). The Cornwall-built engine has eight beams connected to the one cylinder, each beam driving a single pump. The engine was restored to working order between 1985 and 2000, although it is now operated by an oil-filled hydraulic system, since restoration to steam operation was economically nonviable.