Who was the French professor that the Robert brothers built the world's first hydrogen balloon for?
Robert brothers Les Frères Robert were two French brothers. Anne-Jean Robert (1758–1820) and Nicolas-Louis Robert (1760–1820) were the engineers who built the world's first hydrogen balloon for professor Jacques Charles; which flew from central Paris on August 27, 1783. They went on to build the world's first manned hydrogen balloon, and on 1 December 1783 Nicolas-Louis accompanied Jacques Charles on a 2-hour, 5-minute flight. Their barometer and thermometer made it the first balloon flight to provide meteorological measurements of the atmosphere above the Earth's surface.
Louis Robert (historian) Louis Robert (Laurière, 15 February 1904 - Paris, 31 May 1985) was a professor of Greek history and Epigraphy at the Collège de France, and author of many volumes and articles on Greek epigraphy (of all periods, from the archaic period to Late Antiquity), numismatics, and the historical geography of Greek lands. Robert studied at the École Normale Supérieure from 1924-1927, was a member of the École française d'Athènes from 1927-1932, and taught at the École pratique des hautes études (IVth section) in Paris from 1932. He was made full professor at the Collège de France in 1939, where he remained until his retirement in 1974.