Who was the French professor that the Robert brothers built the world's first hydrogen balloon for?
Jacques Charles Jacques Alexandre César Charles (November 12, 1746 – April 7, 1823) was a French inventor, scientist, mathematician, and balloonist.
Benjamin Ball (physician) Benjamin Ball (April 20, 1833 – February 23, 1893) was an English-born French psychiatrist, Professor of Mental Medicine in the Paris Faculty.