308 MOVEMENT 



Application of the Zootrope to the Study of Horses' 

 Paces. — In the year 1867 we made use of the zootrope 

 for the purpose of representing the various paces of a 

 horse in motion, and also for showing how the various 

 paces differed from one another. The latter could be 

 shown by merely altering the sequence of the move- 

 ments of the fore and hind limbs. This was the 

 concrete demonstration of the sequence expressed by 

 the chronographic charts. 



At this time instantaneous photography had not 

 been thought of, and so we used simple drawings to 

 show the successive positions, our data were derived 

 from the registered charts and from the actual foot- 

 tracks. 



We chose first the simplest case, namely, the paces 

 of an ambling horse, in which the two limbs on the 

 same side acted simultaneously. Twelve positions were 

 drawn on a long strip of paper, six to represent the 

 rise of the two feet on the right-hand side, the other six 

 to represent their period of contact on the ground, the 

 two feet on the left-hand side were of course in the 

 opposite phases. 



By arranging this strip of paper in tne zootrope, the 

 paces of an ambling horse could be easily recognized 

 through the slits. 



Now, for the purpose of showing how the other paces 

 could be derived from those of ambling, we had recourse 

 to the following device. Vertical lines were drawn 

 through the middle of the horses' bodies, and square 

 frames were constructed round the posterior halves of 

 the figures containing the hind limbs of the animals. 

 The squares of paper were then cut out, and the 

 original strip of paper then remained, representing a 

 series of positions of the fore quarters, and behind 

 each of these mutilated images there appeared a square 

 hole in the paper. The strip of paper was then placed 



