Eminent French astronomer, geodesist, and cartographer. Worked on various projects that measured and verified the meridian of France. Member of the Académie des Sciences. Director of the Observatoire royal de Paris. Responsible for producing the first modern map of France.

His principal works include: La méridienne de l’Observatoire royal de Paris vérifiée dans toute l’étendue du royaume, … (Paris, 1744); Avertissement, ou Introduction à la carte générale et particulière de la France (Paris, 1755); Description géométrique de la terre (Paris, 1775); and Description géométrique de la France (Paris, 1784).

Born at Thury (Oise). Son of Jacques Cassini, dit Cassini II, and Suzanne-Françoise Charpentier de Charmois. Married to Charlotte Drouin de Vandeuil. Father of the astronomer Jean-Dominique Cassini, dit Cassini IV.