Sir John Leslie, Professor of Natural Philosophy

Sir John Leslie (1766–1832), a native of Largo in Fife, rose from a modest background to become one of Scotland’s most distinguished natural philosophers, largely through self-directed study and exceptional talent in mathematics and physical science. After education at St Andrews and Edinburgh, travels in America and Europe, and early literary work, he achieved scientific renown with his invention of the differential thermometer and his influential Essay on Heat, which earned him the Rumford Medals. Despite clerical opposition over alleged religious unorthodoxy, he was appointed Professor of Mathematics at Edinburgh in 1806, and later Professor of Natural Philosophy in 1819, where his inventive teaching apparatus and discoveries, including artificial congelation, greatly extended his influence. A prolific author and contributor to major scientific journals and encyclopedias, he was knighted in 1832 but died later that year; though sometimes criticised for vanity and sharp judgments, he was widely admired for his genius, good nature, and simplicity of character.