THAT WHETSTONES ARE OILED TO LESSEN 

 THE FRICTION OF THE METAL UPON THE 

 STONE 



HIS fallacy has become popular owing to a state- 

 ment made by Professor Tyndall in his cele- 

 brated work, "Heat a Mode of Motion." In 

 paragraph 9 occurs the following passage: "When- 

 ever friction is overcome, heat is produced, and the heat 

 produced is the exact measure of the force expended in 

 overcoming the friction. The heat is simply the primitive 

 force in another form, and if we wish to avoid this con- 

 version, we must abolish the friction. We put oil upon 

 the surface of a hone, we grease a saw, and are careful to 

 lubricate the axles of our railway carriages." 



Now since the application of grease to rubbing surfaces 

 for the purpose of lessening friction has been practiced 

 from time immemorial, it is not to be wondered at that 

 Tyndall in his dragnet for instances should have caught 

 the hone or whetstone amongst other things, because the 

 application of oil to hones and whetstones is almost uni- 

 versal. And as his book is a standard authority in its 

 department, this mistake has been quoted over and over 

 again, the latest instance that has come to my notice 

 being found in a most interesting and instructive book by 

 the late Professor Tidy, "The Story of a Tinder-Box." 



Those who are practically familiar with the use of hones 

 and whetstones know that the chief use of the oil is not to 



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