Marey was the first to synthesize motion from the photographs by mounting them so the action could be reconstructed. Muybridge had no interest in this phase of the subject until he met Marey and learned from him. Even afterwards Muybridge continued to be interested chiefly in taking pictures and not in studying and analyzing them. Technically speaking, Marey analyzed and synthesized the results obtained in the Muybridge photographs. In addition to using the simple Plateau disk which only one person at a time could see, Marey somewhat later had the photographs copied on glass slides, mounted on a revolving disk and projected onto a screen with the Uchatius type projector, equipped with a revolving slit shutter. This scientific demonstration was the first actual motion picture show of real motion and not posed as in the Heyl, Bourbouze and other demonstrations of about 1870. Gaston Tissandier, editor of _La Nature_, in the December 7, 1878, issue wrote on “The Attitudes of the Horse, represented by instantaneous photography,” and discussed the photographs of Eadweard Muybridge of San Francisco which were on display at the firm of Brandon and Morgan Brown, 1, Rue Lafitte, Paris. The early work of Marey was mentioned and the importance of the new pictures was stressed. On December 28, 1878, a letter of Marey’s, published in _La Nature_, expressed the hope that Muybridge would also record and analyze the action of birds in flight as well as animals in motion. Marey mentioned how effective such pictures would be in the Wheel of Life disks and their value in zoology. There also Marey spoke of a photographic gun which he was to invent later. A return letter from Muybridge was published on February 17, 1879 in the same magazine: “Please have the goodness to transmit to Professor Marey the assurance of my highest esteem and tell him that the reading of his celebrated book on animal mechanism had inspired Governor Stanford with the first idea of the possibility of solving the problem of locomotion with the aid of photography. Mr. Stanford consulted me in this matter and, on his request, I decided to undertake the task. He asked me to follow a most complete series of experiments.” Muybridge said also that he was using as many as thirty cameras, mounted twelve inches apart, and that he planned to study all movements, including flights of birds in which Marey was so interested at the time.