302 



THE EXTERIOR OF THE HORSE. 



of the power. The absolute augmentation, however, being equal for both, the 

 preservation of the equilibrium will demand that the power or the muscular 

 contraction be more intense to counterbalance the resistance, or the weight of 

 the body, whose arm has lengthened beyond the limits required by the mechanism 

 of the parts. 



Whence it follows that the elongation of the pastern increases the 

 force R at the expense of the force M, because its effect is to lengthen 

 the arm of the lever by the same quantity, instead of in an inverse 

 ratio to the forces which mo\'e them, 



Durincj locomotion, when the foot has reached the ground, it is no 

 longer the first two phalanges that constitute the phalangal segment, 



as M. Pader ^ believes, but 

 it is the entire digital re- 

 gion, the hoof included. 



These form, it is true, 



a broken lever composed 



of two pieces (1st, the first 



two phalanges ; 2d, , the 



hoof), but their successive 



movements, always in the 



same direction, are so closely 



associated as to give to the 



total displacement a unity 



analogous to that produced 



by a rigid lever, OB (Fig. 



100), extending from the 



soil, B, to the fetlock, 0. 



With a quantity of 

 movement that varies ac- 

 cording to the weight of 

 the body and the velocity 

 of the gait, the extremity. By 

 of this segment comes, at 

 each step, in contact with 

 the ground, xy, which necessarily reacts in proportion to the actioM 

 which it communicates to the hoof. It is easy to convince ourselves 

 that this action is also modified by the variations in the length of the 

 digital region. 



Let the line BH represent the force which, acting at the extremity, B, of the 

 lever, BOA, tends to rotate it around the point 0, and, consequently, to close the 



Fig. 100. 



1 Pader, loc. cit. 



