Water engine

The water engine is a positive-displacement engine, often closely resembling a steam engine, with similar pistons and valves, that is driven by water pressure. The supply of water was derived from a natural head of water, the water mains, or a specialised high-pressure water supply such as that provided by the London Hydraulic Power Company. Water mains in the 19th century often operated at pressures of 30 - 40 psi, while hydraulic power companies supplied higher pressure water at anything up to 800 psi.