SUMMARY. 



The excessive use of one liand, and of the parts of the 

 body brought into action with it, is the cause of a general 

 deformity among civilized men. 



This so interferes with the central-pivot working of the 

 body as to greatly reduce its power of producing and sus- 

 taining action. 



The working of the spine is the fundamental basis of 

 movement. 



Motion — properly — originates in the spine, is directed by 

 the head, and is only followed up by the limbs. 



The snake presents the simplest type of the spinal working. 



Exemplification of the snake's movement by twisting a 

 cord or elastic rod by counter-turning its two ends. 



These counter-turns, which produce curvatures similar to 

 those of the snake in locomotion, will, when carried beyond 

 a certain limit, originate from their central point of coun- 

 teraction reverse curvatures, which, if allowed to replace 

 the old ones and again to produce a fresh set, would present 

 the shapes of alternately reversed curvatures as they are 

 seen in the locomotion of the snake. 



In displacing one set of curvatures by their alternates a 

 spring is produced. 



The reverse set of curvatures developed from the central 

 point of counteraction of the opposing turns belongs to the 

 nascent alternate curve, but wait to,^ be accepted as such 

 until, by a change of originating points, the old cui-vatures 

 are discharged and the alternate ones adopted. 



The first effect of twisting one of the ends of the elastic 

 rod is to develope a general winding line of shape from one 

 end to the other. 

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