Natural philosopher and professor, born at Largo, Fifeshire; educated at St. Andrews and Edinburgh University; visited America in 1788, and returned to London 1790; for fifteen years he was engaged in scientific investigation, invented several instruments, and published his "Inquiry into the Nature of Heat," for which he received the Rumford Medal from the Royal Society; appointed to the chair of Mathematics in Edinburgh in 1805, he was transferred to that of Natural Philosophy in 1819; continued his researches and inventions, and shortly before his death was knighted (1766-1832).