John Playfair

John Playfair was a Church of Scotland minister remembered as a scientist and mathematician and a professor of natural philosophy at the University of Edinburgh, born at Benvie near Dundee on 10 March 1748 and dead on 20 July 1819. He is best known for Illustrations of the Huttonian Theory of the Earth of 1802, which summarised the work of James Hutton and brought his principle of uniformitarianism to a wide audience. His textbook Elements of Geometry gave a brief expression of Euclid's parallel postulate now known as Playfair's axiom. He studied divinity at St Andrews and Edinburgh, was a co-founder of the Royal Society of Edinburgh in 1783 and served as its General Secretary from 1798 to 1819.