Daniel BERTHELOT (1865-1927), physicist, son of Marcellin Berthelot, member of the Académie des sciences; Becquerel's assistant at the Muséum laboratory, he succeeded Pierre Curie as professor at the École de Physique et Chimie. His most important work was on ultraviolet light; he was also one of the main propagators of Einstein's theories on Relativity and published several works on the subject. He was also president of the Société Française de Physique. An archive box containing a set of autograph manuscripts and notes, approximately 150 pages, mainly in-4. Important set of scientific manuscripts, very corrected drafts of texts, articles and letters on Relativity, Quantum Theory, etc., some with mathematical developments and graphs. Attached is a bag containing numerous press cuttings on the work of Daniel Berthelot (+ qq. brochures, qq. handwritten notes and qq. letters addressed to him) and 2 bulletins of the International Society of Electricians (1916) full of Berthelot's manuscripts.