His reputation as a photographer spread, and he was a approached by the President of the Central Pacific Railroad, Leland Stanford, to attempt to photograph a horse trotting at speed, to settle a long-standing controversy among racing men as to whether a trotting horse had all four hooves off the ground at any point. In May 1872 Muybridge photographed the horse Occident, but without great success, as the wet-collodion process normally required several seconds for a good result.

In April 1873 he managed to produce some better negatives, in which a recognisable silhouette of the horse showed all four feet above the ground at the same time. Soon after, Muybridge left his young wife, Flora, to go on a photographic trip. While he was away, she had an affair with a Major Harry Larkins and became pregnant. Muybridge - an imposing figure in broad-brimmed hat and lengthening beard - discovering that the child was not his, confronted Larkins and shot him dead. Tried for murder in February 1875, Muybridge was acquitted by the jury on the grounds of justifiable homicide; he left soon after on a long trip to South America.

 
 
On his return, he took up the action photography once more. Using a new shutter design he had developed, which operated in as little as 1/1000th of a second, he obtained more detailed pictures in July 1877. He then devised a new scheme, which Stanford sponsored at his farm in Palo Alto. A 50ft long shed was constructed, containing twelve cameras side-by-side, facing a white background marked off with vertical numbered lines. Each camera was fitted with Muybridge's high-speed shutter, released by an electromagnetic catch. Threads stretched across the track were broken by the horse as it moved along, closing electrical contacts which released each shutter in turn. Thus in about half a second, twelve (later 24 or more) photographs were obtained showing all the phases of the movement.

From 1880 he lectured in the USA and Europe, projecting his results in motion on the screen with his Zoopraxiscope projector. This machine, described by the Illustrated London News as a "magic lantern run mad (with method in the madness)", was basically a projecting phenakistiscope, with a contra-rotating shutter. The silhouette images, derived from his sequence photographs, were painted around the edge of a large glass disc (later, translucent coloured paintings were produced).

Kingston Museum

In August 1883 Muybridge - now using the archaic Eadweard form of his first name - received a grant from the University of Pennsylvania to carry on his work there. During 1884 and 1885, using the superior gelatine dry plate process and new camera apparatus, he produced over 100,000 sequence photographs, of which 20,000 were reproduced in Animal Locomotion in 1887. The subjects included animals of all kinds, and human figures, mostly nude, in a variety of activities. His motion sequences were projected in the Zoopraxographic Hall at the Chicago Exhibiton of 1893. The following year Muybridge returned to his birthplace in England; his last publications were Animals in Motion (1899) and The Human Figure in Motion (1901).