Steam engine. Steam engine designed by the British engineer James Watt (1735-1819). Watt's engine was revolutionary in that it drove steam out of the cylinder to be condensed in a separate vessel. Previous engines, based on a design by Newcomen, condensed the steam within the cylinder and were far less efficient than Watt's design. Watt patented his design in 1769 and by 1772 had entered into a highly profitable partnership with Matthew Boulton in Birmingham. Whilst Boulton supplied the business with capital, Watt continously refined his design and made several improvements until his retirement in 1800. Photograph of a 1782 engine.