Cutaway view of the gondola of the hot-air balloon in which Joseph Louis Gay-Lussac and Jean-Baptiste Biot are sitting.
On August 24, 1804, Gay-Lussac goes on his first balloon ascent in the company of Biot to study terrestrial magnetism. He’ll go on a second one alone on September 16 for further investigations of the Earth’s atmosphere.
The caption reads in the original French:
Gay-Lussac et Biot font des expériences de physique à 4 000 mètres de hauteur.