ON THE EXTERNAL CONFORMATION. 21 

 lacy of this doctrine may be easily exposed. 

 In the action of a self-moving body, the poste- 

 rior part generally constitutes the fixed point 

 from whence the motion takes its origin. 

 Thus, if the horse lean forwards, the center of 

 gravity ceases to be supported, and he is oblig- 

 ed to advance one of his fore legs in order to 

 recover the equilibrium. Again, if the chief 

 source of motion exist in the fore quarters, 

 whence does it arise that many good fore-quar- 

 tered horses are bad leapers ? The reason is ob- 

 vious : from weakness in their hinder quarters ; 

 for the principal strength of a horse lies in the 

 muscles of his thighs. Therefore a horse may 

 rise well at a leap, and clear it with his fore 

 legs, but cannot bring his hinder legs over, 

 unless the muscles of his thighs are sufficiently 

 powerful. 



It may be urged, that leaping differs from 

 galloping ; but galloping is, in reality, consti- 

 tuted by reiterated leaps on a plain surface. 

 C 3 Hence 



