Jacques Cassini

Jacques Cassini, known as Cassini II, who lived from 1677 to 1756, was a French astronomer and the son of the famous Italian astronomer Giovanni Domenico Cassini. Born at the Paris Observatory, he studied at the Collège Mazarin, was admitted at the age of seventeen to the French Academy of Sciences, was elected a fellow of the Royal Society of London in 1696 and became maître des comptes in 1706, meeting Newton and Halley while in England. He succeeded to his father's position at the observatory in 1712, and in 1713 he extended the Paris meridian, measuring the arc from Dunkirk to Perpignan and publishing the results in Traité de la grandeur et de la figure de la terre in 1720, where he sided with the Cartesians in favour of a prolate Earth against the Newtonians' oblate spheroid. He also wrote Eléments d'astronomie in 1740 and published the first tables of the satellites of Saturn in 1716. In his last years he worked with his son, Cassini III, on the Carte de Cassini, a very accurate map of France, and historians still debate how original his work on the ballistic pendulum was.