Jacques A. Cesar Charles (1746-1823)
French Physicist, born in Beaugency (1746) and died in Paris (1823).
In 1783 performed the first flight in an hydrogen balloon (the previous flights were accomplished with hot air). His studies on gas expansion led to the discovery of the law that rules the volume variation of a perfect gas with temperature (1787). The first enunciation of this law was published later (1802) by Gay-Lussac therefore and it is often referred as the Charles and Gay Lussac Law. Charles also determined the water density at different temperatures.