284 THE ARTISTIC ANATOMY OF ANIMALS 



liollowcd in the interior, so that the whole thus constituted 

 forms a sort of hollow cushion which is compressed under 

 the influence of the pressure of the foot on the ground. A 

 tube which is attached to a registering apparatus, which the 

 person who is walking carries in his hand, communicates 

 with this cavity (Fig. ii6). This apparatus is formed of a 

 metal drum, which is closed at its upper part by a flexible 

 membrane. Each time that one of the man's feet presses 

 on the ground, the air contained in the cavity of the sole 

 of the shoe is driven into the drum, which we have just 

 mentioned, and the flexible membrane of this drum is 

 elevated. To this membrane is attached a vertical rod 

 which supports a horizontal style. 

 When the membrane, as we have just seen, is elevated, 



Fig. 115. — Experimental Shoes, intended to Record the 

 Pressure of the Foot on the Ground. 



the style is lifted, and then descends when the pressure of 

 the foot ceases. It traces these displacements on a leaf of 

 paper, the surface of which is covered with a thin layer of 

 lamp-black, which it removes by its contact ; different parts 

 of this surface are successively presented to it, the paper 

 being rolled round a cylinder which is turned on its axis by 

 means of a clockwork movement. It is necessary to add 

 that the inscription is made, in the study of the walk of man, 

 by means of two styles, each corresponding to one of the 

 feet. 



The tracings thus obtained, which are read from left to 

 right, are sufficiently simple ; but to understand them 

 properly, it is necessary to remember that the style under- 

 goes a movement of ascensional displacement during each 

 pressure of a foot, and that, on the other hand, it descends 



