He rose to pensionnaire by 1746, became professor at the Collège Royal, and was admitted to the Royal Society, the Berlin Academy, and the Academie de la Marine. Grandjean de Fouchy allowed him to observe at the Rue des Postes in Paris, and his first Le Monnier presented an elaborate lunar map to the Academy of Sciences and was admitted as adjoint géomètre on 23 April 1736, at the age of twenty. Le Monnier began his astronomical career early with the assistance of his father. He also constructed a great meridian at the church of Saint Sulpice in 1743. He obtained a telescope by Short and two excellent quadrants by Bird and Sisson. At that time the English instruments were superior to the French ones. The king in turn procured for him some of the best astronomical instruments in France. Le Monnier was presented to Louis XV by the due de Noailles and remained a great favorite of the king, before whom he made important observations of the transits of Venus (1761) and Mercury (1753) across the face of the sun. A second daughter married his brother, Louis-Guillaume Le Monnier. Cussy from a prominent Norman family and had three daughters, one of whom married the mathematician Lagrange. His brother was Louis-Guillaume Le Monnier, also a member of the Academy, professor of botany at the Jardin du Roi and premier médecin ordinaire to Louis XV. Le Monnier’s father, for whom he was named, was professor of philosophy at the Collège d’Harcourt and a member of the Académie des Sciences. Paris, France, 20 November 1715 d, Herils, Calvados, France 3 April 1799)

Le Haschisch by Antoine Monnier