...There is the guy taking the academic standpoint and who wrote a film school master's thesis about this early experiment as a review. At the other end of the spectrum there is the guy who wrote his review as satire as though he'd seen this in a movie theater and was very upset for having wasted his time and money on it. So what's left to say at this point but - "Look at the pretty horsie"? Well, I'll try.
Leland Stanford was a horse enthusiast, industrialist, and railroad baron who became governor of California later in the 19th century and was the founder of Stanford University. He wanted to settle a bet as to whether or not all four hooves of a horse were off the ground at any point in time when running. He turned to noted photographer Eadweard Muybridge for that task.
Muybridge used multiple cameras to photograph Stanford's Kentucky-bred Sallie Gardner, galloping at the businessman's farm in Palo Alto, in the presence of the press. The shutters were controlled by trip wires triggered by the horse's legs. However, to correctly display the horse in motion required an invention by Muybridge that was completed the year after the photos were taken - the zoopraxiscope. It projects images from rotating glass disks in rapid succession to give the illusion of motion, and is considered the oldest movie projector. The 24 photos Muybridge took of Sallie Gardner running were shown using this device. This invention inspired Edison's invention, the Kinetoscope, the first commercial film exhibition system. And the answer? Yes, there is a point when all four hooves are indeed off of the ground.
Later, when Muybridge was in Europe touring and demonstrating his technique and his images in motion, he was told that back in the United States Leland Stanford had published a book entitled "The Horse In Motion", basically claiming credit for the early motion studies as his own, with no mention of Muybridge. This left Muybridge bereft of reputation. This was a rather dangerous thing for Stanford to do since Muybridge had, in 1874, committed the premeditated murder of a man he suspected to be his wife's lover and yet was acquitted with a verdict of justifiable homicide. Stanford would have known about this because, among other reasons, he paid for Muybridge's defense.
If all of the colorful characters that went into this forerunner to moton pictures had not existed, then the motion picture industry would have eventually invented them. I give this an 8/10 for its importance to the history of motion pictures.