Physicist, born in Edinburgh. He studied at Edinburgh and Cambridge, became professor at Aberdeen (1856) and London (1860), and was the first professor of experiemtnal physics at Cambridge (1871), where he organized the Cavendish Laboratory. In 1873 he published his great Treatise on Electricity and Magnetism, which gives a mathematical treatment to Faraday's theory of electircal and magnetic forces. He also contributed to the study of colour vision, and to the kinetic theory of gases, but his greatest work was his thoery of electromagnetic readiation, which established him as the leading theoretical physicist of the century.