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18 March 1640 
Paris, France 
21 April 1718 
Paris, France 
Philippe de la Hire was educated as an artist and became skilled in drawing and painting. He visited Italy where he spent four years developing his artistic skills and learning geometry. The interest in geometry arose from his study of perspective in art. La Hire was elected to the Académie Royale des Sciences in 1678. In 1683 he was appointed to the chair of mathematics at the Collège Royale. Four years later he was appointed, in addition, to the chair of architecture at the Académie Royale . Much influenced by the work of Desargues , La Hire worked on conic sections which he treated projectively. He published his first work on conic sections Nouvelle méthode en géometrie pour les sections des superficies coniques et cylindriques in 1673. In 1675 he published a more comprehensive work on conic sections Sectiones conicae which contained a description of Desargues ' projective geometry . In 1708 he calculated the length of the cardioid. Other topics to which he made important contributions included astronomy, physics and geodesy. In astronomy he installed the first transit instrument in the Paris Observatory. He also produced tables giving the movements of the Sun, Moon and the planets. He did much work on surveying, in particular taking measurements of the French coastline. He designed an instrument to find the level at a site. He was also a major contributor to a project to map France. La Hire's maps of the Earth were made with the centre of projection, not at the pole, but at r/√2 along a radius produced through the pole (where r is the radius of the Earth). La Hire also wrote on magic squares .
Source:School of Mathematics and Statistics University of St Andrews, Scotland
