Mathematician and inventor.

In 1771, took part in a royal French expedition to study the determination of longitude at sea. Invented a “chaise marine” to enable accurate observations. Invited Franklin to witness a demonstration of the mechanical pulley that he had invented (1778). Author of Mémoire des avantages que procurera la géométrie sublime … (Orléans, 1770) and Précis sur les longitudes résolues tant sur terre que sur mer (London, 1785).