LECTURE III. 139 



part of the pelvis, and of the muscular 

 buttocks is placed behind the sockets, so 

 when we stand upright, the whole of the 

 incumbent weight is perfectly balanced on 

 the rounded heads of the thigh-bone, and 

 the most trivial variation in the direction 

 of the weight occasions the body to in- 

 cline towards that part, at which it takes 

 place. 



The hip-joint is the most complete ball 

 and socket joint in the human skeleton, 

 and the socket can move upon the ball with 

 the most perfect facility, and with the nicest 

 gradation and variation. Thus, when we 

 stand upon one leg, we have the power of 

 balancing the weight upon the rounded 

 head of the thigh-bone. There are two 

 modes of balancing, either by moving the 

 incumbent weight upon the area of sup- 

 port, or by moving the basis of support 

 under the incumbent weight. By the con- 

 nection of our lower extremities with the 

 pelvis, we possess the ability of balancing 

 our weight in both these ways. No better 

 demonstration of this need be given, than 

 what is exhibited in those amphitheatres, 



