Double Exposure
"The Horse in Motion is a series of cabinet cards by Eadweard Muybridge, including six cards that each show a sequential series of six to twelve "automatic electro-photographs" depicting the movement of a horse. Muybridge shot the photographs in June 1878. An additional card reprinted the single image of the horse "Occident" trotting at high speed, which had previously been published by Muybridge in 1877. Stanford also had an interest in art and science, in which he looked for illustration and for affirmation of his own ideas and observations about the horse's motions, but got frustrated with the lack of clarity on the subject. Years later, he explained: "I have for a long time entertained the opinion that the accepted theory of the relative positions of the feet of horses in rapid motion was erroneous".
This does not explain how you record horses at an accurate speed. The two below do not either.
