FIG. 4.—CHRONOPHOTOGRAPHIC APPARATUS PRODUCING UPON ONE PLATE
A SERIES OF PHOTOGRAPHS AT EQUAL INTERVALS OF TIME.
The apparatus is open and shows the position of the disk, with its openings moving
in front of the plate.
In Mr. Muybridge’s arrangement, photographic instruments faced a white screen before which passed an animal walking, trotting, or galloping. As fast as the animal advanced, the shutters of the lenses opened and permitted the taking of negatives of the animal. These were, of course, different from each other, because they were taken in succession. They therefore showed the animal in the various attitudes he assumed at different instants during his passage across the field covered by the instruments. The dazzling white light brought out en silhouette the body of the animal. Each shutter is actuated by a powerful spring; the shutter is opened as the animal advances. Threads may be observed across the road; the animal, breaking these threads one after the other, opens the shutters. Mr. Muybridge varied his experiments most successfully. He studied the gaits of different animals, and those of men in jumping, vaulting, and in the handling of various utensils. But since this time the progress of photographic chemistry has wonderfully increased the sensibility of the plates, and at the present day more than mere silhouettes of moving animals and men can be obtained. In a good light full images with all desired relief can be obtained. For example, if an athlete in motion is photographed, all of the muscles of the body are perfectly traced in relief, indicating the parts taken by each of them in the movement executed. The methods used by Mr. Muybridge would always suffice to illustrate the successive phases of the displacement of the members if they were taken at equal intervals of time, but the arrangements adapted for bringing about the formation of the successive phases cause irregularity in the extent of these intervals. The threads give more or less before breaking; moreover, the progress of the horse is not at an even rate of speed. Nevertheless, Mr. Muybridge endeavored to develop from a series of images the trajectory of each leg of a horse, but the curves obtained in these laborious attempts had not sufficient precision. A very simple method enables us to obtain, with perfect fidelity, the trajectory of a body in movement; it is the photographing of this body in front of a black surface. If the photographic apparatus is directed against a black screen, the objective can be uncovered without effect on a sensitized plate, as it will receive no light; but if a white ball strongly illuminated by the sun is thrown across the plane of this screen, and parallel with it, its image will be reproduced upon the plate, which will show the track of the ball in its trajectory, just as the eye receives a momentary impression of lines of fire when a lighted piece of charcoal is waved through the air at night.
FIG. 5.—GENERAL VIEW OF THE PHYSIOLOGICAL STATION AT PARIS.
FIG. 6.—DARK CHAMBER ON WHEELS.