LECTURE III. 119 



Had the vertebral column been formed 

 straight, and the same extent of motion 

 given to the head, the wejght would have so 

 preponderated, that its support would not 

 only have been difficult, but it might have 

 operated injuriously to the fabric of the co- 

 lumn itself. As the column is constructed, 

 when either end of it is projected in one 

 direction, the other can be carried in the 

 opposite, and the balance preserved. Thus, 

 when the loins are brought forward, the 

 neck and head fan be carried backward, so 

 as to preserve t|ie line of gravity perpendi- 

 cular to the basis of support; and vice 

 versa in all directions. 



By constant practice, the muscles are 

 so habituated to produce these opposite 

 and balancing motions, as involuntarily to 

 do so with the greatest exactness, as well 

 as to co-operate with the elasticity of the 

 column, in restoring it to its proper direc- 

 tion and form. The requisite actions are 

 slight, transient, and varied, and therefore 

 produce no fatigue. This circumstance, 



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