MECHANICAL PARADOXES. 



power of the machine is confessedly derived 

 from the energy given up to it by each weight 

 in the course of falling from the highest to the 

 lowest point of its course. But in order that 

 it may fall from the top to the bottom, it has 

 had to be lifted previously from the bottom to 

 the top. And in being lifted, it has received 

 from the machine just as much energy as it gives 

 up in falling the same distance. The weights, 

 therefore, consume all the power which they 

 produce, and there is none left over for doing 

 other work by the drum and belt none, even, 

 for overcoming the slightest losses from friction. 

 And so the machine cannot even turn itself 

 round. It cannot move, and if turned by ex- 

 ternal force, will soon be stopped by friction. 



But this is only a general proof that the in- 

 vention must be a fallacy. It does not show 

 just where the fallacy is. And while the in- 

 ventor will not be satisfied with a condemnation 

 on general grounds, thinking that their applica- 

 tion by the critic is as likely to be mistaken as 

 his own application of principles in detail, so 

 also the amateur student of the matter has not 

 learnt all that it is capable of teaching him 

 until it has been shown in what particular 

 points the inventor has misunderstood mechani- 

 cal laws or has wrongly applied them. 



First, then, an exaggerated view is taken 

 of the leverage of the weights at the ends of 

 the extended arms. The force of these weights, 



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