1911] on Biotoi/i/ and the Cinematoyraph. 171 



M. Janssen, Professor Marey, and E. Muyhridge. 



Here I should like to pay my hearty tribute of admiration to the 

 genius of my old master, the late Professor Marey, of the College de 

 France, Paris, who was practically the pioneer of this method in its 

 application to science. A visit to the " Institut Marey" in tiie Pare 

 des Princes, and a survey of tlie numerous beautiful films made by 

 him of botanical, zoological, and purely physiological phenomena, 

 show one what marvellous work he did. He constructed apparatus 

 whereby one hundred images per second could be obtained. 



The late M. Janssen, the eminent astronomical observer in 1874, 

 was the first observer to use an automatic arrangement for obtaining 

 a series of photographs representing successive phases of an object in 

 motion. He inaugurated chrono-photography by photographing on a 

 circular glass plate the transit of Venus, the first chrono-photograph 

 ever made. It was the parent and pioneer of that numerous progeny 

 of various forms of apparatus designed for imprinting on a cellu- 

 loid film "pictures in motion" — "living pictures," if you will — 

 and, indeed, all kinds of movements, even those only visible by 

 means of the microscope. The apparatus he called an "astro- 

 nomical revolver." The plate revolved at regular intervals of 

 seventy seconds through a small angle, and at each turn a fresh 

 impression was made on the plate. He obtained a dark silhouette 

 of the planet on the sun's surface. 



He also suggested the photographic method as one likely to be of 

 value for the study of biological and mechanical problems, such as 

 walking, flight of birds, and other animal movements. At tliaftime 

 the difficulty was the sluggishness of the photographic plates used ; 

 now this and other difficulties have been overcome. This method 

 gives an analytical reproduction of any movement by representing 

 its elementary phases, a method exactly the reverse of that of the 

 phenakistoscope or zoetrope, which reproduces a movement by means 

 of a series of views representing the successive component phase of 

 that movement. 



Some of you may remember the work of Muybridge exhibited by 

 him several years ago by what he called his " Zoo-praxiscope." 



Muybridge did excellent work, more especially in the analysis of 

 the movement of horses and other animals. On one side of a track 

 was placed a screen to reflect the sunlight to the battery of twenty- 

 four cameras placed on the opposite side of the track. The screen 

 was marked at equal distances to indicate the rate of progression of 

 the animal, and across the track at suitable intervals were stretched 

 a series of wires, each of which was connected with an electro-magnet 

 which kept the shutter of its corresponding camera closed. The 

 horse in passing along the track broke the wires one after the other, 

 the corresponding shutters were instantaneously opened, and thus a 

 series of photographs were obtained. Sometimes three batteries of 



