5 8 HAS NOT VET GENERALIZED. 



receives its explanation in the difficulty always found in 

 fixing attention on what is familiar. Heat and work in no 

 way excited his curiosity. It was the rarer and more occult 

 phenomena of electro-magnetism which first caught his 

 attention, leading him first to pay attention to electricity, 

 thence to heat, and now to "work." 



In the note already mentioned, he says that he had 

 always been " strongly attached to the theory which regards 

 heat as motion amongst the particles of matter." This must 

 have been an instinctive attachment, formed without 

 question or consideration, for a theory of infinite possibility 

 resting on a rational base, as against a dogma opposed to 

 many familiar facts. 



Joule had now discovered and described all the equiva- 

 lences but one on which the conservation of energy is founded ; 

 the heat, and the chemical equivalents of electrical effect, and 

 the heat equivalents of chemical effects. He has not yet 

 generalized, because he has not realized, that the under- 

 lying principle is mechanical effect. But by January 14th, 

 1843, his attention had been arrested by the mechanical 

 character of the effect of that portion of the electromotive 

 force used in electrolysis, which renders the elements 

 gaseous and still more strongly by the constant ratios 

 between the mechanical and heating powers of a current 

 and between these powers and the electromotive force. 

 He looks for further developments, but apparently without, 

 as yet, realizing their true character or importance. 



