From 1884 to 1886, Eadweard Muybridge produced 781 motion studies, primarily of humans walking, running, dancing, or playing sports. Many of his models were University of Pennsylvania faculty or students, among them Morris Hacker, Jr., a student shown here throwing a baseball. Born in England, Muybridge spent most of his working life in the United States. It was Leland Stanford, a former California governor and horse enthusiast, who first hired him to study the movement of a galloping horse. Using English Dallmeyer lenses, electrically triggered shutters, and a series of specially commissioned cameras, Muybridge was able to prove that a horse was completely in the air at one point in its gait.