Watt's single acting steam engine, late 18th century.
© Science Museum / Science & Society Picture Library
Plate taken from Rees' Cyclopaedia. This engine was used for pumping at Chelsea Water Works. In 1768, James Watt (1735-1819), in partnership with John Roebuck (1718-1794), invented a separate condenser engine which was patented in 1769. When Roebuck went bankrupt, Matthew Boulton (1728-1809) bought his share of the patent and Watt and Boulton worked together, from 1772 onward, forming a company in 1794.