French mathematician and astronomer, born at St. Malo; went to Lapland to measure a degree of longitude, to ascertain the figure of the earth; wrote a book "On the Figure of the Earth"; was invited to Berlin by Frederick the Great, and made President of the Academy of Science there; was satirised by Voltaire much to the annoyance of the king, who patronised him and prided himself in the institution of which he was the head (1698-1759).