36 Presidential Address 



activities of the material universe are 

 represented by alternations from one 

 of these forms to the other. 



Whenever this transference and trans- 

 formation of energy occur, work is done, 

 and some effect is produced, but the 

 energy is never diminished in quantity: 

 it is merely passed on from one body to 

 another, always from ether to matter 

 or vice versa, except in the case of 

 radiation, which simulates matter, and 

 from one form to another. 



The forms of energy can be classified 

 as either a translation, a rotation, or a 

 vibration, of pieces of matter of different 

 sizes, from stars and planets down to 

 atoms and electrons; or else an etherial 

 strain which in various different ways is 

 manifested by the behaviour of such 

 masses of matter as appeal to our senses. J 



Some of the facts responsible for the 

 suggestion that energy is atomic seem to 

 me to depend on the discontinuous nature 

 of the structure of a material atom, and 



1 See, in the Philosophical Magazine for October, 1879, 

 my article on a Classification of the forms of energy. 



