on certain Theoretical Opinions. 57 



sphere C as before, and positive force equal to 100 will ap- 

 pear on its outer surface. 



xii. Such a state of the space between the inductric and 

 inducteous surfaces represents what I believe to be the state of 

 an insulating dielectric under inductive influence ; the particles 

 of which by the theory are assumed to be conductors indivi- 

 dually, but not to one another (1669.). 



xiii. In asserting that 100 of positive force will appear on 

 the outside of the external sphere under all these variations, 

 I presume I am saying no more than what every electrician 

 will admit. Were it not so, then positive and negative elec- 

 tricities could exist by themselves, and without relation to 

 each other (1169. ]177)> or they could exist in proportions 

 not equivalent to each other. There are plenty of experi- 

 ments, both old and new, which prove the truth of the prin- 

 ciple, and I need not go further into it here. 



xiv. Suppose a plane to pass through the centre of this 

 spherical system, and conceive that instead of the space be- 

 tween the central ball A and the external sphere C being 

 occupied by a uniform distribution of the equal metallic par- 

 ticles, three times as many were grouped in the one half to 

 what occurred in the other half, the insulation of the particles 

 being always preserved : then more of the inductric influence 

 of A would be conveyed outwards to the inner surface of the 

 sphere C, though that half of the space where the greater 

 number of metallic particles existed, than through the other 

 half: still the exterior of the outer sphere C would be uni- 

 formly charged with positive electricity, the amount of which 

 would be 100 as before. 



xv. The actions of the two portions of space, as they have 

 just been supposed to be constituted (xiv.), is as if they pos- 

 sessed two different specific inductive capacities (1296.); but 

 I by no means intend to say, that specific inductive capacity 

 depends in all cases upon the number of conducting particles of 

 which the dielectric is formed, or upon their vicinity. The 

 full cause of the evident difference of inductive capacity of 

 different bodies is a problem as yet to be solved. 



xvi. In my papers I speak of all induction as being de- 

 pendent on the action of contiguous particles, i. e. I assume 

 that insulating bodies consist of particles which are conductors 

 individually (1669.), but do not conduct to each other pro- 

 vided the intensity of action to which they are subject is be- 

 neath a given amount (1326. 1674-. 1675.); and that when the 

 inductric body acts upon conductors at a distance, it does so 

 by polarizing (1298. 1670.) all those particles which occur in 

 the portion of dielectric between it and them. I have used 



