Sectional drawing (scale 1:12) of Joy's patent Water Pressure Engine

Sectional drawing (scale 1:12) of Joy's patent Water Pressure Engine, framed and glazed in Museum

This drawing shows a water-pressure engine designed for working the bellows supplying air to an organ, but the cylinder in its action resembles the steam cylinder of a direct-acting steam pump. The supply of water is controlled by a valve connected with the air reservoir, so that the speed of working is automatically adjusted to the consumption of wind.