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SEPTEIrBER 14, 1883.] THE PHOTOGRAPHIC NEWS. 581 a a*#. E K. mefhhauc Sxw A: 732822523/2-34 , . I ' 1--1/4K/MZ 74 . '' 7 : . The beating of this drum obviously Fig. 2. A window of red glass will be seen in the dark-room, permitting the photographer to watch the movements of the living object he is intent on depicting, while a speaking trumpet, which is also shown, serves to convey orders. In the case of fig. 2, it will be seen that the front wall of the laboratory has been removed to show a large disc is of considerable value in forming a scien tific estimate of the movements. Figure 2 represents the movable dark room or laboratory that contains the camera and the photographer. It is a little room mounted on wheels which run along a tramway, as shown in our sketch. In this way it is possible to approach or recede from the background, according to the nature of the lens in use, or the size of the image desired. As a general rule, it is found best to place the camera at some distance from the screen, say about forty yards. At this distance, the angle of view does not alter a very great deal during the passage of the white object in front of the black background. THE NEW PHYSIOLOGICAL STUDIO IN PARIS. Since the month of March last there has been established in Paris a physiological station, or studio, as it may bo termed, which has particular interest to the photographer. It is located in the Avenue des Princes, near the Auteuil Gato, and we may mention that so important was considord the establishment of this observatory, that the Municipal Council of Paris not only granted the necessary land, but gave a contribution towards the installation of the build ings. F urthermore, M. Jules Ferry, the Minister of Public Instruction, interested himself in the matter, and the con sequence was that in the space of a few months the out door studio was not only designed, but perfected. is seen on a tramway at right angles to how he decreases or augments his speed. On the top of the structure, in the centre of the circle, is a drum beaten by means of electricity, so that the beats may be regulated with rigid exactitude. The sketch of the physiological studio which we here present to our readers is taken from La Nature. The station is constructed from a design of M. Marey, of the Institute, whose researches into animal locomotion by means of photography are already familiar. A disciple of Muybridge, M. Marey has now far surpassed his mentor, and, with scientific apparatus at his disposal, he is at present engaged in a long series of investigations by means of the camera. Among the questions which M. Marey has set himself to solve are :—1. To determine the series of motions that go to make up human locomotion during the act of running, jumping, and walking. 2. To examine the external conditions that modify motion—as, for instance, the rapidity of the pace or length of step—and to find out the favourable or unfavourable influence these modifications exert in the locomotion of a man. 3. To measure the work done at every instant during the different phases of loco motion, and to discover the most advan tageous way of utilising this work. In fig. 1 we see the general view of the station. We have already described to our readers how M. Marey works ; how he has recourse to white objects, which are photographed against a black recessed back ground. Only one lens and one camera is employed, a series of exposures, how ever, being made with each plate, so that on development, the moving object is re presented in successive portions of the plate. In the sketch here given is seen the circular path on which the object, whether man or horse, moves, the black background with its overhanging roof being „2 to the left. The camera—or, rather, the movable dark room in which it is located— shown in the picture—through which the view strikes the lens, an exposure being made every time the disc revolves. In this way intermittent exposures are secured, and as the object photographed is in motion, the images impress themselves on different parts of the plate. The disc is of large dimensions, more than four feet in diameter, and the , w ou0w . .g u. slit represents exactly one-hundredth of its circumference. which revolves in front of the lens. This disc has a slit— From this it follows that if the disc revolves ten times Fig. 1. the background. Round the course is an electric wire supported by poles, and every time the moving object passes one of the posts, he transmits a signal to the main building, and thus registers the celerity of his pace, and aids the model in regulating his pace and ——— keeping to the conditions necessary for the experiment. Of course, the process of photographing only goes on when the ob jectpasses in front of the background ; but the tour of the station by the moving object