DYNAMICAL SIGNIFICANCE OF "WORK." 93 



has a still higher interest in that it shows how and by what 

 means the skin of familiarity was at last pricked, and Joule's 

 curiosity excited as to the dynamical significance of "work." 



His papers have shown how little Joule thus far owes to 

 whatever knowledge he may have initially had other than that 

 resulting from his own familiarity with the subjects and 

 means of his research : how he has been guided entirely by 

 the curiosity which his own observations and discoveries 

 have excited in his mind ; and how successively having his 

 attention turned on to the relations between the, to him, 

 initially familiar mechanical power as measured by " work," 

 and the several physical quantities, magnetism, electricity, 

 heat, and chemical affinity, and as to the inter-relations, 

 between these physical quantities, he has succeeded in 

 realising an intimate knowledge of these physical quantities,, 

 of the inter-relations between them, and of the several 

 relations between them and mechanical power — a knowledge 

 including all that was known at his time, but extending far 

 beyond. 



Now, for the first time, his attention is directed to the 

 relations between mechanical effect, as measured by the 

 product of motion multiplied by resistance and other 

 measures of mechanical action applicable to express the 

 mechanical effect represented by a moving body in terms 

 of its weight and motion. 



That such measures had been fully investigated, and were 

 known to all mathematicians, must have been known to 

 Joule, and he must have had some vague ideas of these 

 measures ; but he had received no education in the only 

 language in which they were expressed, and they had not 

 hitherto excited his curiosity. 



He proceeds in this case as he has proceeded in all the 



