About this time, Georges Demeny (1850–1917) became associated with Marey in this work. Marey always gave credit to his pupil, aide and collaborator. Eventually, however, they parted company because Demeny was interested in commercializing the work and Marey wished to continue with pure science. Later Demeny asserted that his motion picture ideas were superior to Marey’s and that he was responsible for the actual execution of all the plans. Demeny at thirteen had begun inventing at his home, but his father, a musician, wanted him to be a university professor. In 1874 he went to Paris and at the Sorbonne was a pupil of Marey in physiology and of Mathias Duval--who also worked with Marey--in anatomy. He did some medical studies and opened one of the first physical education establishments called, _Le Cercle de Gymnastique Rationnelle_. From 1880 on he supervised many of the studies at Marey’s Physiological Park. In July, 1882, Marey proposed the use of a band of sensitized paper in the camera. For various reasons the paper was not satisfactory and, of course, was impractical for direct projection as it might be set on fire by the projection lamp. The Langenheims of Philadelphia had solved the problem of projecting photographs in the magic lantern by devising a method of printing the picture on glass. However, a projector equipped, as the original model of Uchatius, with a revolving disk could only hold a few glass slides. This limited the projected pictures to brief action. In 1887 and 1888 Marey achieved his first real success in what he called chronophotography, using a box machine which took eight pictures a second on a single metal plate, or on a sensitized paper band. Marey had difficulty controlling the paper film because it was not perforated and the pictures were not equally spaced. This, however, made no difference to Marey since his main purpose was to obtain data for physiological study, and not entertainment motion pictures. In 1888 Marey obtained a successful series of photographs of fishes swimming, taken with intermittent action on a paper roll film. The images were taken at the rate of either twenty or sixty per second. This method of using paper strips obviates the necessity of operating in a dark camera chamber. At first the paper photographic strips were loaded in a dark room, limiting the scope of the camera, but later light-proof cameras were perfected. Marey also proposed an optical system featuring a turning mirror which would make intermittent action unnecessary. But this method was wasteful of film.