CAN A MAN LIFT HIMSELF BY THE STRAPS 

 OF HIS BOOTS? 



THINK it was the elder Stephenson, the famous 

 engineer, who told a man who claimed the 

 honor of having invented a perpetual motion, 

 that when he could lift himself over a fence by 

 taking hold of his waist-band, he might hope to accomplish 

 his object. And the query which serves as a title for this 

 article has long been propounded as one of the physical 

 impossibilities. And yet, perhaps, it might be possible to 

 invent a waist-band or a boot-strap by which this apparently 

 impossible feat might be accomplished ! 



Travelers in Mexico frequently bring home beans which 

 jump about when laid on a table. They are well-known as 

 "jumping beans" and have often been a puzzle to those 

 who were not familiar with the facts in the case. Each 

 bean contains the larva of a species of beetle and this af- 

 fords a clue to the secret. But the question at once comes 

 up : " How is the insect able to move, not only itself, but its 

 house as well, without some purchase or direct contact with 

 the table?" 



The explanation is simple. The hollow bean is elastic 

 and the insect has strength enough to bend it slightly ; 

 when the insect suddenly relaxes its effort and allows the 

 bean to spring back to its former shape, the reaction on 

 the table moves the bean. A man placed in a perfectly 

 rigid box could never move himself by pressing on the 

 sides, but if the box were elastic and could be bent by the 

 strength of the man inside, it might be made to move. 



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