HOW THE BACKBONE IS BALANCED 27 



wheel is really a great number of legs and feet set together 

 so as to move round in a circle. The wheel of a motor 

 cycle — with its multitude of spokes — is a wonderful 

 invention, and the wheel of the human body with two 

 movable spokes which can serve the same purpose as 

 twenty fixed ones is not only more wonderful but more 

 useful. Human beings go over all kinds of country, 

 jump ditches, get over hedges, climb trees, go upstairs, and 

 do a multitude of things which a motor cycle, although 

 it can travel so fast, cannot do. Indeed man had to make 

 smooth and level roads before wheeled vehicles could be 

 used at all. Instead of using a single strong engine as in 

 the motor cycle, the human machine has been provided 

 with hundreds of them, placed all over the body, where 

 they work the various levers of the limbs and trunk. 



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