LECTURE III. 135 



their children's shoulders backwards; nor 

 do I think the practice wrong, where it is 

 required, and when it is conducted with 

 moderation ; but surely we ought to caution 

 the public against the absurdity of bracing 

 the shoulders back, beyond what is natu- 

 ral, till the blade bones come in contact 

 with the vertebral column, for this destroys 

 the natural balance of the body, and is 

 more likely to produce than to prevent 

 deform it V. 



The joint by which the arm is connected 

 with the shoulder, is a ball and socket 

 joint, admitting of motion in every direc- 

 tion. Even those animals, whose pectoral 

 extremities seldom move in any other direc- 

 tion but forwards and backwards for the 

 purposes of progression, have a similarly 

 constructed joint. The advantage derived 

 from this mechanism seems to be, that it 

 admits of the motion of the limb, or of the 

 body singly. Thus, when at rest, the limbs 

 may be moved without disturbing the posi- 

 tion of the body, and when the limbs are 

 injured, slight variations in the posture of 



