52 THE SEVEN FOLLIES OF SCIENCE 



He then suggests some difficulties which the ball, seen 

 just under the letter E, is intended to overcome, but he 

 confesses that he has never tried it, and to any practical 

 mechanic it is very obvious that the machine will not work. 



Fig. ii. 



But we give the description in the language of the inventor, 

 as a fair type of this class of perpetual-motion machines. 



In the year 1790 a Doctor Schweirs took out a patent 

 for a machine in which small metal balls were used instead 

 of a liquid, and they were raised by a sort of chain pump 

 which delivered them upon the circumference of a large 

 wheel, which was thus caused to revolve. It was claimed 

 for this invention that it kept going for some months, but 

 any mechanic who will examine the Doctor's drawing must 

 see that it could not have continued in motion after the 

 initial impulse had been expended. 



