Answer to Dr. Hare's Letter. Ill 



positive, and it again will render the inner and onter surfaces of 

 the large sphere C negative and positive : the sum of the positive 

 forces on the outside of C being still 100. 



X. Instead of one intervening sphere let us imagine 100 or 

 1000 concentric with each other and separated by insulating mat- 

 ter, still the same final result will occur ; the central ball will act 

 inductrically, the influence originating with it will be carried on 

 from sphere to sphere, and positive force equal to 100 will appear 

 on the outside of the external sphere. 



xi. Again, imagine that all these spheres are subdivided into 

 myriads of particles, each being effectually insulated from its 

 neighbors (1679), still the same final result will occur ; the in- 

 ductric body A will polarize all these, and, having its influence 

 carried on by them in their newly acquired state, will exert pre- 

 cisely the same amount of action on the external sphere C as be- 

 fore, and positive force equal to 100 will appear on its outer sur- 

 face. 



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

 ducteous 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 individually 

 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 pre- 

 sume I am saying no more than what any electrician will admit. 

 Were it not so, then positive and negative electricities could exist 

 by themselves and without relation to each other (1169, 1177); 

 or they could exist in proportions not equivalent to each other. 

 There are plenty of experiments, both old and new, which prove 

 the truth of the principle, 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 between the cen- 

 tral ball A and the external sphere C being occupied by a uniform 

 distribution of the equal metallic particles, 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 through 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 



