Kelvin, William Thomson, 1st Baron (1824–1907). Pioneer of thermodynamics and one of the greatest of classical physicists. Educated in Belfast, Glasgow, and Cambridge, he was in 1846 chosen professor of natural philosophy at Glasgow. He remained there for 50 years, and on retirement signed on as a research student. He said that one word characterized his work, ‘failure’. He was not serious: in fact, he had done fundamental research on electromagnetism and light, on telegraphy, and on heat, where he had come up with the idea of an absolute zero of temperature—the scale based on this is named after him. He was happy to turn his talents to practical use, over telegraph cables, liquefaction of gases, and the construction of instruments. The leading physical scientist in Britain, he was made a peer in 1892.

David Knight

Kelvin, William Thomson, 1st Baron (1824–1907) British physicist and mathematician, b. Belfast, after whom the absolute scale of temperature is named. The Kelvin temperature scale has its zero point at absolute zero and degree intervals the same size as the degree Celsius. The freezing point of water occurs at 273K (0°C or 32°F) and the boiling point at 373K (100°C or 212°F). In thermodynamics, he resolved conflicting interpretations of the first and second laws.