Alexis Clairaut, geometer of the Enlightenment

Alexis Clairaut, a relatively unknown mathematician of the 18th century, is remarkable in more than one way. Entered the Academy at 18, he gave there his first presentation of his work on skew curves at age 13. He was part of the expedition tasked with measuring a degree of meridian in Lapland, which would make it possible to settle the question of the shape of the Earth, in accordance with Newton's calculations. He also devoted a large part of his research to validating the theory of gravitation, in astronomy but also in hydrostatics. Very attached to teaching, which he practiced, among other things, as tutor to the Marquise du Châtelet, he wrote his Elements of geometry and algebra. These would still be referenced a century later.