People obsessed over landscape photos at the time. The images represented the fierceness in American spirit that had settled the frontier, but with the ease of travel brought by train seemed already to have faded. Photographers tried to bring moments of that wildness back to cities as best they could. But while shutter speed could capture stationary lakes and mountains, the passing sky overhead looked like bland white sheets. To make scenes more convincing, photographers sometimes painted or superimposed clouds into their pictures. Muybridge, instead, invented the “sky shade.” This screen shielded the sun’s light enough to capture the landscape, but still rendered the sky’s tones. Now the people in East Coast cities could look into a photo and feel as if they stood in valleys of the Sierra Nevada Mountains, or atop granite peaks. Muybridge signed these photos under the name “Helios,” the Greek personification of the sun.

Eadweard Muybridge

Muybridge looked like a mix of Walt Whitman and Zeus. He was tall and lean, with a long white beard, and bushy brows that shadowed his eyes and made him seem thoughtful and deviant. In six years he’d already gained some fame for his landscape photos, and in 1871, while in his 40s, he married a woman half his age named Flora Shallcross Stone. One year later, Stanford telegraphed Muybridge about an idea he had to photograph his horses, and for three years Muybridge worked on the technology to do exactly that. That work stopped in October 1874, after Muybridge found a letter his wife had written to a drama critic named Major Harry Larkyns.

Muybridge found the letter in his midwife’s home. In it was a photograph of his seven-month old son, upon which his wife had written the boy’s name as “Little Harry,” which led Muybridge to believe his son was not in fact his son.

“He stamped on the floor and exhibited the wildest excitement,” Muybridge’s midwife remembered after he found the letter. “He was haggard and pale and his eyes glassy ... he trembled from head to foot and gasped for breath.”

Muybridge caught a train that afternoon north from San Francisco to Vallejo. It was night when he knocked on Larkyns’ door. As Larkyns stepped forward, Muybridge shoved a revolver at him and said, “I have brought a message from my wife, take it.”

Larkyns died from the gunshot. At trial, Muybridge pleaded insanity. Stanford hired a lawyer to defend him, and friends testified that the stagecoach crash had jarred something loose, had transformed a genial bookstore owner into an emotionally unmoored photographer. A friend and fellow photographer, William H. Rulofson, at trial said Muybridge sometimes slipped into bursts of grief or anger, and just as easily into a placid daze, “immovable as stone.” It’s hard to tell whether this personality change was real or a story conjured by a creative lawyer, but one theory about Muybridge’s injury is that it damaged his orbitofrontal cortex. If that is true, along with altering his emotions, it could explain why Muybridge became so possessed with his work.

Injuries to the orbitofrontal cortex are sometimes connected to obsessive-compulsive disorder, and it was through Muybridge's microscopic fixation on motion that his photos became art. He photographed birds flying, cats leaping, and the American bison galloping at a time when the nation had nearly hunted the animal to extinction. His obsession with all manners of motion drove him to capture women lifting bedsheets, raising cigarettes to their lips, or the quasi-absurd, like in his series Crossing brook on step-stones with fishing-pole and can.

The series consists of 36 pictures taken from three angles, and it follows a woman as she raises her leg, hops onto a stone, then another, then hops off, all the while she holds a fishing pole in one hand and a can in the other, her arms bent like the wings of a bird. Artist have used this work to study motion. Edgar Degas, himself obsessed with the movement of dancers, studied photos like it. As did Marcel Duchamp, particularly in his 1912 painting, Nude Descending a Staircase, No. 2, which became one of the most famous modernist paintings, and looks just like Muybridge’s photo series, Woman Walking Downstairs.