In 1878, famous industrialist Leland Stanford (yes, that Stanford) wanted the answer to a very important, deeply contested question: do all four of a horse’s hooves ever come off the ground when they gallop? So he did what all millionaires do and he spent money, commissioning the photographer Eadweard Muybridge to photograph a horse in motion. The resulting series, known as Sallie Gardner at a Gallop, is perhaps one of the most famous early images and a precursor to the technology that would be used by the Lumière brothers in the 1890s to produce films. By taking 24 cameras and rigging them around a track,…