...A photograph is made by one of the 24 cameras at every 12 inches of progress, made by the animal during a single stride. The length of each stride may be calculated by the line of consecutive numbers arranged parallel with the track, a number being placed every 12 inches of distance.
--Eadweard J. Muybridge
The possibility for moving pictures originated from a rich man's bet: whether or not a galloping horse ever had all four feet off the ground at any time during its stride. Because the unaided eye cannot see such an instantaneous event, Leland Stanford hired Eadweard Muybridge to photograph his racehorse, Occidental. After Muybridge produced the proof to win the bet, he continued his motion experiments and documented them in this album. He wrote the above passage on the album's first page, describing his methodical approach of rigging twenty-four cameras with electromagnetic shutters--tripped by wires as an animal ran across a track.
Photographs of the cameras show how wires were attached to modified lens shutters; others depict the racetrack, where a long shed with the battery of cameras faced a track with a wall behind to silhouette subjects. Most pages depict animals and humans walking, running, and jumping before the cameras. Muybridge later devised the zoopraxiscope, a rotating device that animated sequences of images.