4 2 (6) 



lieve that the former is purely phenomenal, and only a 

 manifestation of the latter. Denying the existence of a 

 special vital force as such, they retain the term only to 

 express the sum of the phenomena of living beings. 



In calling your attention this evening to the Correla- 

 tion of the Physical and the Vital Forces, I have a two- 

 fold object in view. On the one hand, I would seek to 

 interest you in a comparatively recent discovery of Sci- 

 ence, and one which is destined to play a most import- 

 ant part in promoting man's welfare ; and on the other 

 I would inquire what part our own country has had in 

 these discoveries. 



In the first place, then, let us consider what the evi- 

 dences are that vital and physical forces are correlated. 

 Let us inquire how far inorganic and organic forces may 

 be considered mutually convertible, and hence, in so 

 far, mutually identical. This may best be done by con- 

 sidering, first, what is to be understood by correlation : 

 and second, how far are the physical forces themselves 

 correlated to each other. 



At the outset of our discussion, we are met by an un- 

 fortunate ambiguity of language. The word Force, as 

 commonly used, has three distinct meanings ; in the 

 first place, it is used to express the cause of motion, as 

 when we speak of the force of gunpowder ; it is also 

 used to indicate motion itself, as when we refer to the 

 force of a moving cannon-ball ; and lastly it is employed 

 to express the effect of motion, as when we speak of the 

 blow which the moving body gives. 4 Because of this con- 

 fusion, it has been found convenient to adopt Rankine's 

 suggestion,* and to substitute the word ' energy' therefor 

 And precisely as all force upon the earth's surface- 



