60 



ANIMAL MECHANICS 



FIG. 13. 



weight of the bird, bending the joint B and C, 



produces the effect 

 of muscular effort, 

 and makes the claws 

 cling. 



But why should 

 the anatomist have 

 recourse to this piece 

 of comparative anat- 

 omy, when he has 

 so fine an example 

 in the human body ? 

 And one which is 

 much more inter- 

 esting, as, in fact, 



it is the foundation of reasoning upon the dis- 

 eases and accidents of the limb. If this beauti- 

 ful arrangement in the healthy and perfect struc- 

 ture of a man's limb be not attended to, it would 

 be easy to prove that many important circum- 

 stances, in regard to disease and accidents, must 

 remain obscure. 



The posture of a soldier under arms, when his 

 heels are close together, and his knees straight, 

 is a condition of painful restraint. Observe, then, 

 the change in the body and limbs, when he is 

 ordered to stand at ease ; the firelock falls against 

 his relaxed arms, the right knee is thrown out, 

 and the tension of the ankle-joint of the same 



