High Quality Content by WIKIPEDIA articles! Les Frères Robert were two French brothers. Anne-Jean Robert (1758-1820), and Nicolas-Louis Robert (sometimes known as Marie-Noël Robert and Robert le Jeune (and sometimes wrongly described as l'aîné, the elder)) (1760-1820), The brothers were the engineers who built the world's first hydrogen balloon for professor Jacques Charles; it 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.