Racking (pacing); saddle; brown horse, Pronto, from the series Animal Locomotion. An Electro-Photographic Investigation of Consecutive Phases of Animal Movements

Eadweard Muybridge first started photographing horses in 1872, when Leland Stanford, the railroad magnate and founder of Stanford University, encouraged him to prove whether all four hooves leave the ground at once during a gallop. (They do.) The challenge led Muybridge to invent a system by which the horse’s movement tripped wires that then released the camera’s shutters. He succeeded in his experiments by 1878, leading him to publish Animal Locomotion with the backing of the University of Pennsylvania. This magnum opus included 781 collotypes—photomechanical prints—that sequentially show how horses and other animals, including humans, move.