French family, originally from Italy, which produced four generations of astronomers, cartographers, and geodesists. The most important astronomically were Giovanni Domenico Cassini (sometimes referred to as Cassini I) and his son Jacques Cassini (Cassini II). César François Cassini (Cassini III), also known as Cesare Francesco Cassini (1714–84), son of Jacques, began a topographic map of France that was completed by his own son, Jacques Dominique Cassini (Cassini IV) (1748–1845). These four Cassinis were successively directors of the Paris Observatory.