French astronomer and politician. His works on astronomy and on the history of science (notably the Essai sur la théorie des satellites de Jupiter) were distinguished both for scientific interest and literary elegance and earned him membership in the French Academy, the Academy of Sciences, and the Academy of Inscriptions. He was elected (1789) from Paris to the States-General and was chosen president of the National Assembly. Mayor of Paris from 1789 to 1791, he lost favor with the popular elements that pushed the French Revolution onward. He permitted the national guard to fire upon a demonstrating crowd (July 17, 1791). Bailly retired from Paris, but in 1793 he was seized, taken to Paris, convicted of having contrived the July massacre, and guillotined.