ON MATTER AND FORCE. 35 



then cease to act, then act, then cease to act, 

 without being otherwise disposed of." 



In another manuscript, he says : " What I 

 mean by the word force is the source or sources 

 of all possible actions of the particles or 

 materials of the universe; being often called 

 the powers of Nature, when spoken of in respect 

 of the different manners in which these effects 

 are shown." 



In order to avoid the indistinctness and con- 

 fusion which come from using the word force at 

 one time as the cause of an effect, and at 

 another time as the effect itself ; and, in order 

 to confine ideas to the effect which alone can 

 be the object of experimental research, the term 

 conservation of energy is now adopted, instead 

 of the term, conservation of force. 



Thus, force, which we assume to be indestruct- 

 ible and inseparable from matter, is the cause of 

 energy, and energy is the effect of force. 



This diagram may perhaps render the use of 

 these terms more clear : 



CAUSE. EFFECTS. 



Force or power, total 

 quantity of which is 

 as constant as the total 

 quantity of matter. 



Actual energy = Motion _ 

 Potential energy = Tension [ 



= o 



