John Playfair
John Playfair (March 10th 1748 - July 20th 1819) is a British scientist born in Benvie (Angus).
Summary biography
Playfair is professor of Mathématiques then professor of Physique to the Université of Edinburgh.
It publishes an annotated edition of the Éléments of Euclide in 1795, in which it uses an algebraic notation to shorten the demonstrations. Its name is also known for the axiom of Playfair, which is a reformulation of the fifth postulate of Euclide. This axiom bears its name although Proclos is the author, which Playfair always recognized.
After the death of his friend James Hutton he writes his biography which with the wire of its composition becomes an answer to criticisms of the geological theories of this one: Illustrations off the Huttonian Theory off the Earth . This book is published in 1802 after five years of work and contains a reformulation and a clarification of the ideas of Hutton. This book, as well as the support of Charles Lyell later, made it possible to make accept the Uniformitarisme. In addition, Playfair was undoubtedly the first required a clear explanation of the formation of the V-shaped valleys by river erosion as well as transport of erratic blocks by old glaciers.
Playfair becomes member of the Royal Society in 1807 and first president of the Astronomical Institution off Edinburgh in 1811.
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