PERPETUAL MOTION 65 



would turn the wheel half round and sink to the bottom, 

 because it is so heavy: and when the little weights reach 

 the top they would sink down, because they are so many; 

 and thus the wheel would turn round for ever.' 



The child's fallacy is a type of all the blunders which 

 are made on this subject. Follow a projector in his 

 description, and if it be not perfectly unintelligible, which 

 it often is, it always proves that he expects to find certain 

 of his movements alternately strong and weak not 

 according to the laws of nature but according to the 

 wants of his mechanism. 



2. FALLACIES 



Fallacies are distinguished from absurdities on the one 

 hand and from frauds on the other, by the fact that with- 

 out any intentionally fraudulent contrivances on the part 

 of the inventor, they seem to produce results which have 

 a tendency to afford to certain enthusiasts a basis of hope 

 in the direction of perpetual motion, although usually not 

 under that name, for that is always explicitly disclaimed by 

 the promoters. 



The most notable instance of this class in recent times 

 was the application of liquid air as a source of power, the 

 claim having been actually made by some of the advocates 

 of this fallacy that a steamship starting from New York 

 with 1000 gallons of liquid air, could not only cross the 

 Atlantic at full speed but could reach the other side with 

 more than 1000 gallons of liquid air on board the power 

 required to drive the vessel and to liquefy the surplus air 

 being all obtained during the passage by utilizing the 

 original quantity of liquid air that had been furnished in 

 the first place. 



V ' OF THE 



UNIVERSITY 



OF 



