62 



THE SEVEN FOLLIES OF SCIENCE 



the strength of the loadstone) will make it fall into that 

 hole at E; and the force it receives in this fall will carry it 

 with such a violence unto the other end of this arch, that 

 it will open the passage which is there made for it, and by 

 its return will again shut it ; so that the bullet (as at the 



Fig. 15. 



first) is in the same place whence it was attracted, and, 

 consequently must move perpetually." 



Notwithstanding the positiveness of the "must " at the 

 close of his description, it is very obvious to any practical 

 mechanic that the machine will not move at all, far less 

 move perpetually, and the bishop himself, after carefully 

 and conscientiously discussing the objections, comes to the 

 same conclusion. He ends by saying : " So that none of 

 all these magnetical experiments, which have been as yet 

 discovered, are sufficient for the effecting of a perpetual 

 motion, though these kind of qualities seem most conduci- 

 ble unto it, and perhaps hereafter it may be contrived from 

 them." 



It has occurred to several would-be inventors of perpet- 

 ual motion that if some substance could be found which 

 would prevent the passage of the magnetic force, then by 

 interposing a plate of this material at the proper moment, 



