1 1 I- ANIMAL Mi:< 1IAXISM. 



served for the investigation of tin- muscular wave (fi. 7, 

 pajje :17 . If\\e substitute in this ii^-iire an experimental 

 shoe l'..r each <>!' tin- myographical flips 1 ami _', we shall 

 have the arrangement of the apparatus necessary for the study 

 ..)' /' otstept or iiitjxH-ts of the foot on the ground. 



l-'iu-. _'() has lii-cii furnished }>y an experiment in walking. 

 Txvti tracings arc ^iven by tlie intermittent pressure of the 

 fret on the ground. The full line 1) corresponds with the 

 ri-ht loot ; the dotted line with the left. 



Fin. 20. Tnuv'ngs >f the.' impact mid the riseof the two feet in our ordinary walk. 



Knowing the arrangement of the apparatus, we can under- 

 stand that each impact of the foot on the ground will bo 

 represented by the elevated part of the corresponding curve. 



In fact, the pressure of the foot on the ground compresses the, 

 india-rubber sole and diminishes the capacity of the included 

 air-chamber. A part of the contained air escapes by the con- 

 necting tube, and passes into the registering drum. 



\Ve see in 11^-. '_'<) that the pressure of the riijit foot, for 

 in-tance, commences at the moment when that of the left 

 In -ins to decrease; and that in all the tracings then- is an 

 ;.l.ei -nation between the impads of the t\vo feet. The period 

 < f Mi/i/mrt of each foot is shown by a horizontal line which 

 joins the minima, of two successive curves. 



The impacts of the ri^ht and left feet have the same dura- 

 tion, so that the \\eijjit of the lody passes alternately from 

 one foot to the other. It Would not be the same \\itll respect 

 to a lame person ; lamenrss corresponds essentially with the 

 inequality of the impacts of the two feet. 



Then- is a 1 \\ays a very short period during which the body 



i- partially supported by our foot, but \\hen it already lic- 



!i- jest on the cilhcr thi. time is .sraicely ipial to the 



