born July 5, 1753, Chacewater, Cornwall, Eng. died March 1815, Penryn, Cornwall British inventor. He and his father, Jonathan (1717-80), worked for James Watt. Seeking to improve on Watt's steam-engine design, he devised the first reciprocating compound steam engine (patented 1781); his engine had two cylinders (see piston and cylinder), a significant contribution to efficiency. In 1799 it was judged an infringement on Watt's patent