680 



SCIENCE. 



[YOL. II., No. 42. 



are to be studied, may be taken. These photographs 

 are taken as the walker passes before a black screen. 

 Finally, the dynamographic studies, to measure the 

 energy exerted in the various muscular motions, are 

 possible by means of apparatus which will be de- 

 scribed later. 



Our readers are already familiar with the history, 

 in detail, of the applications of instantaneous pho- 

 tography to the analysis of the locomotion of man and 

 animals. Many have seen the beautiful pictures ob- 

 tained by Mr. Muybridge, who has succeeded In pho- 

 tographing a horse running at full speed. For the 



pear in white the men and animals whose pictures 

 are being taken, as well as the instruments for meas- 

 uring the distance run, and the time consumed be- 

 tween two successive photographs. 



Fig. 2 represents the photographic chamber where- 

 the experimenter is. This room is on wheels, and 

 is arranged on an iron track, so that it may ap- 

 proach or move from the screen, according to the 

 objectives which are employed, and the desired size 

 of the photograph. Generally it is convenient to 

 place the photographic apparatus about forty metres 

 from the screen. At this distance, the angle at which. 



Fis. 1. — Physiological station 



requirements of the physiological analysis of move- 

 ments, we have substituted for the complex apparatus 

 of Mr. Muybridge a simple contrivance, giving on the 

 same plate the successive positions of a man or an ani- 

 mal at various instants of his passage before the black 

 screen. We shall refer to these experiments in order 

 to describe certain imjirovements which make the fig- 

 ures more clear, the time-measurements more exact, 

 and which, by multiplying almost indefinitely the 

 number of images, give a complete analysis of all 

 kinds of movements. 



The apparatus employed at the physiological sta- 

 tion for the instantaneous photography of movements 

 comprises two distinct parts, — first, the photographic 

 apparatus, with the room on wheels, which holds 

 it; and, secondly, the black screen, on which ap- 



the subject to be photographed is presented, changes 

 little during his passage before the black screen. 

 From the outside of this building may be seen the 

 red glass through which the operator can follow the 

 various motions which he is studying. A speaking- 

 trumpet enables him to direct the different move- 

 ments which ought to be made. The front wall of 

 the building is raised in the figure, in order to show 

 a revolving-disk, provided with a little window, across 

 which the light passes intermittently into the ob- 

 jective. This disk is of large size (1.30 m. in diame- 

 ter), and its window represents only a hundredth of 

 its circumference: hence, if the disk revolve ten 

 times a second, the duration of the lighting is only 

 one-millionth of a second. The movemement is re- 

 corded on the disk by wheel-work, which is wound 



