Joseph Louis Gay-Lussac making a balloon ascent from Paris, 14 September 1804 (1910).

Joseph Louis Gay-Lussac making a balloon ascent from Paris, 14 September 1804 (1910). On this flight, French chemist and physicist Gay-Lussac (1778-1850) reached a height of 7016m and confirmed many of the observations he and Jean Baptiste Biot (1774-1864) made on their flight of 20 August 1804. Theirs was the the first balloon ascent made specifically for scientific purposes and they studied the composition of the air and the effect of altitude on terrestrial magnetism. From La Navigation Aerienne by J Lecornu. (Paris, 1910). (Photo by Oxford Science Archive/Print Collector/Getty Images)