Five years later in 1877 Muybridge resumed the problem of photographing rapid action. Stanford underwrote the experiments, and made available not only his stable, but also the services of one of the engineers of the Central Pacific Railroad, John D. Isaacs. A battery of cameras was built in a shed beside a racetrack to record consecutive phases of motion.
Muybridge first used a mechanical device to trip the shutter-strings were stretched across the track, which the horses broke during their runs before the cameras. These strings were attached to the shutters, which closed, by the action of rubber bands. These shutters Were soon replaced with electrically controlled ones: the circuits were closed by the string method, or by the steel tires of a sulky running over bare wires lying on the ground. Muybridge was awarded two patents in 1879 for these synchronization devices.
The background was covered with rock salt, which gleamed in the sunlight, to give maximum contrast on the slow wet plate. The results were "diminutive silhouettes," not brilliant images but clear enough to furnish evidence for scientific study. A set of prints was deposited in the Library of Congress in 1878, others were published in scientific journals.Stanford formally published the experiments in a handsome quarto The Horse in Motion (1882), with a text by J.D.B. Stillman, and with many drawings after the Muybridge photographs. As Muybridge later complained, they were published "without the formality of his name on the title page."