HISTORY OF CHRONOPHOTOORAPHY. 



333 



demician, A. Cornu, succeeded in tliis way in rendering perceptible in 

 a coid vibrations of three kinds — the longitudinal, the transversal, and 

 the torsional. A very light little mirror attached to the cord indi- 

 cated these three kinds of motion on a plate having a uniform transla- 

 tion. Fig. 31 is the negative resulting from this experiment. 



Physiology. — It is to the physiological study of the different gaits of 

 animals and to the functional motions of their different organs that 

 chronophotography has prin- 

 cipally been applied. Some 

 types of the experiments 

 which it has rendered possible 

 may here be illustrated. 



Terrestrial locomotion. — 

 The series of photographs 

 taken on moving films have 

 represented all the phases of 

 motion of man and of quadru- 

 peds. Thus tigs. 32, 33, and 

 34 (PI. VI) represent the three 

 normal gaits of the horse. 



One can easily follow the succession of attitudes during the advance of 

 the animal. The sequence of time is from above downward. A dis- 

 puted question of animal mechanics was whether a cat turns over in 

 falling, and, if so, how she does it without any application of external 

 force. Experiment has proved that, as a fact, she does so, thus enabling 

 mechanicians to correct a current error of classical treatises. 



Fig. 35. 



Locomotion in water has also been studied by film photography. 

 These photographs are brought together in order to facilitate the com- 

 parison of them. The locomotion of the eel (tig. 35) shows the pro- 

 gression of undulations of the body of the animal from head to tail. 

 Lines are drawn to show the direction of motion and the advance of 

 the animal. 



