6 ON THE EXTERNAL CONFORMATION. 



They who have no knowledge of mechani- 

 cal powers, will, perhaps, ridicule the idea of 

 reducing the animal to any such principle. 

 Anatomical dissection, however, presents a ma- 

 chine of the truest mechanism, capable of loco- 

 motion by means of muscles acting upon bones 

 in various directions. 



This being the fact, it will not be difiicult 

 to discover in what way the power of those mus- 

 cles may be increased or diminished, not entirely 

 by their own susceptibility of stimulus, but 

 simply by their position when in a state of in- 

 action. To explain this theory, will be the ob- 

 ject of the present chapter. 



The body and legs of the horse, exclusively 

 of the head and tail^ may be said to form nearly 

 a square, as represented in plate I. 



This square is divided horizontally into two 

 parts, nearly equal, by the body and legs, as re- 

 presented by the line A A. 



