IX. CONCLUDING EEMAEKS. 



I HAVE now gone through the affections of matter for 

 which distinct names have been given in our received 

 nomenclature : that other forces may be detected, differing as 

 much from them as they differ from each other, is highly 

 probable, and that when discovered, and their modes of 

 action fully traced out, they will be found to be related inter 

 se, and to these forces as these are to each other, I believe 

 to be as far certain as certainty can be predicted of any future 

 event. 



It may in many cases be a difficult question to determine 

 what constitutes a distinct affection of matter or mode of 

 force. It is highly probable that different lines of demarca- 

 tion would have been drawn between the forces already 

 known, had they been discovered in a different manner, or 

 first observed at different points of the chain which connects 

 them. Thus, radiant heat and light are mainly distinguished 

 by the manner in which they affect our senses : were they 

 viewed according to the way in which they affect' inorganic 

 matter, very different notions would possibly be entertained 

 of their character and relation. Electricity, again, was 

 named from the substance in which, and magnetism from the 

 district where, it first happened to be observed, and a chain 

 of intermediate phenomena have so connected electricity with 

 galvanism that they are now regarded as the same force, 



