120 



ANIMAL MECHANISM. 



which lie the minima, and on the sides of which, the maxima 

 terminate tangentially. 



Forward progress of the body. — It is clear that during the 

 act of walking, the body never ceases to advance ; but the 

 forward movement has not always the same velocity. To 

 appreciate these alternate phases of acceleration and retarda- 

 tion, it is necessary to employ a method which would give the 

 measurement of the space passed through during each of the 



Fig. 24.— Showing two successive positions of the arm of the instrument, 

 and the corresponding positions of the tracing points of the levers. The 

 arm of the lever being three metres in length, and the radius of the 

 cylinder being only six centimetres, a similar angular displacement of 

 the person walking, and of the style which writes, will correspond with 

 spaces which will be to each other as 50 to 1. 



movements in the act of walking, and which would also 

 express the time employed in passing through each of these 

 spaces. In order to obtain this double indication, we have 

 recourse to the following method : — 



It is necessary, first, to ascertain how far the body advances 

 at the different instants of the act of walking. This measure 

 of the spaces passed through, is obtained by inscribing the 

 curves of locomotion, no longer on a cylinder turning with a 

 regular motion, but on an immovable one, on which the 



