Former California Governor Leland Stanford, who later founded Stanford University, owned and trained racehorses.
It is said that Mr. Stanford had made a bet that for a moment, all four of a racehorse's hooves are off the ground simultaneously.
He hired photographer Eadweard Muybridge in 1872 to take the pictures to prove him right.
This was difficult to do with the cameras of the time, and the initial experiments produced only indistinct images.
He set up a row of cameras with tripwires's that would each in turn snap a picture for a split second as the horse ran by.
The results proved Stanford right: all four hooves do leave the ground at once as shown in the still photo above and in a continuous GIF image shown below.
Eadweard Muybridge, born in England as Edward James Muggeridge, later filmed a running buffalo as well as people in motion using the same multiple camera technique.