THE HUMAN FRAME. 541 



of the head in the ordinary horizontal attitude of 

 quadnipeds. 



" Pronaque cum spectant animalia csetera terram, 



Os homini sublime dedit, caelumque tueri 



Jussit, et erectos ad sidera tollere vultus."— Ovid. 



The space comprehended by the two feet is 

 extremely narrow, when compared with the ex- 

 tended base on which the quadruped is sup- 

 ported. Hence the stability of the body must 

 be considerably less. The statue of an elephant 

 placed upon a level surface, would stand without 

 danger of oversetting : but the statue of a man 

 resting on the feet, in the usual attitude of 

 standing, would be thrown down by a very small 

 impulse. It is evident, indeed, that in the living 

 body, if the centre of gravity were at any mo- 

 ment to pass beyond the base, no muscular 

 effort which could then be made would avail to 

 prevent the body from falling. But the actions 

 of the muscles are continually exerted to prevent 

 the yielding of the joints under the weight of the 

 body, which tends to bend them. In quadrupeds 

 less exertion is requisite for that purpose ; and 

 standing is in them, as we have seen, a posture 

 of comparative repose : in man it requires nearly 

 as great an expenditure of muscular power as 

 the act of walking Soldiers on parade expe- 

 rience more fatigue by remaining in the attitude 

 of standing, than they would by marching during 



