I. 



THE FORCES OF INORGANIC NATURE. 



THE following pages are designed as an attempt to an- 

 swer the questions, What are we to understand by 

 "Forces" ? and how are different forces related to each other? 

 Whereas the term matter implies the possession, by the object 

 to which it is applied, of very definite properties, such as 

 weight and extension ; the term force conveys for the most 

 part the idea of something unknown, unsearchable, and hypo- 

 thetical. An attempt to render the notion of force equally 

 exact with that of matter, and so to denote by it only objects 

 of actual investigation, is one which, with the consequences 

 that flow from it, ought not to be unwelcome to those who 

 desire that their views of nature may be clear and unencum- 

 bered by hypotheses. 



Forces are causes : accordingly, we may in relation to 

 them make full application of the principle causa cequat ef- 

 fectum. If the cause c has the effect e, then c e; if, in its 

 turn, e is the cause of a second effect/, we have e=f, and so 

 on: c=e=f...=c. In a chain of causes and effects, a 

 term or a part of a term can never, as plainly appears from 

 the nature of an equation, become equal to nothing. This 

 first property of all causes we call their indestructibility. 



If the given cause c has produced an effect e equal to it- 

 self, it has in that very act ceased to be : c has become e ; if, 

 after the production of e, c still remained in whole or in part, 



