Electro-physiology sessions (Mecanisme de la Physionomie Humaine ou Analyse Electro-Physiologique de L’Expression des Passions, Paris, 1862) conducted by Dr. Duchenne and photographed by Adrien Tournachon (brother of the better known Gaspard Felix Tournachon, aka Nadar). From Luminous-Lint - found via e l e t t r o g e n i c a.