KLECTRICITY, MAGNETISM, AND GRAVITATION. 



171 



portion of the coil where it becomes subject to the action of a 

 second ray, its momentum is increased, and probably the 

 quantity of moving force doubled ; and this increase of 

 momentum and force is after the same manner augmented in 

 each succeeding coil by every fresh incidental ray. 



The result of these experiments evince to my mind more 

 than ever the unity of force^ On every band experimental 

 evidence appears to justify the conclusion that there is one 

 universal force in Nature, which is modified by the accidental 

 and varied conditions to which it is subject, but that Us 

 essential nature and characteristics are at all times the same, 

 and evince in every modification constantly the same un- 

 changeable qualities, which are discoverable by man under 

 the denomination of sensations, as well as luminous and 

 calorific properties. 



I believe that these experiments indicate, and indeed prove 

 the identity of caloric and voltaic force, and that now the last 

 required link for the completion of the entire chain of identity 

 of these imponderable forces is obtained. 



