122 ANIMAL MECHANISM. 



pressure to which the experimental shoe is subjected (fig. 19), 

 and the other, ten vibrations per second furnished by a chrono- 

 graphic tuning-fork of large size. 



Fig. 2(5. — A large tuning-fork whose vibrations are reduced by masses of 

 lead to 10 per second, acts on the registering lever drum, by an experi- 

 mental drum attached to one of its branches. This also receives at the 

 same time, by a tube with two branches, the influence both of the impact 

 and rising of the foot of the person who walks. 



Fig. 20 shows how these instruments are arranged. It is 

 seen that the drum will be affected by the double influence 



