John Playfair
He is perhaps best known for his book Illustrations of the Huttonian Theory of the Earth (1802), which summarised the work of James Hutton. It was through this book that Hutton's principle of uniformitarianism first reached a wide audience. The idea was later taken up by Charles Lyell and Charles Darwin. Playfair is also remembered for his proposal of an alternative to Euclid's parallel postulate.