56 Prof. Faraday's Answer to Dr. Hare's Letter 



part of its surface (because of the uniformity of its inductive 

 influence in all directions) and then that difficulty will be 

 removed. A therefore is charged, but not polarly; B 

 assumes a polar condition ; and C is charged inducteously 

 (1483.), being by the prime influence of A brought into the 

 opposite or negative electrical state through the intervention 

 of the intermediate and polarized ball B. 



vii. Simple charge therefore does not imply polarity in the 

 body charged. Inductive charge (applying that term to the 

 sphere B and all bodies in a similar condition (v.)) does (1672.). 

 The word charge as applied to a Leyden jar, or to the whole 

 of any inductive arrangement, by including all the effects, 

 comprehends of course both these states. 



viii. As another expression of my theory, I will put the 

 following case. Suppose a metallic sphere C, formed of a 

 thin shell a foot in diameter ; suppose also in the centre of it 

 another metallic sphere A only an inch in diameter; suppose 

 the central sphere A charged positively with electricity to the 

 amount we will say of 100; it would act by induction through 

 the air, lac, or other insulator between it and the large 

 sphere C ; the interior of the latter would be negative, and its 

 exterior positive, and the sum of the positive force upon the 

 whole of the external surface would be 100. The sphere C 

 would in fact be polarized (v.) as regards its inner and outer 

 surfaces. 



ix. Let us now conceive that instead of mere air, or other 

 insulating dielectric, within C between it and A, there is a thin 

 metallic concentric sphere B six inches in diameter. This 

 will make no difference in the ultimate result, for the charged 

 ball A will render the inner and outer surfaces of this sphere 

 B negative and positive, and it again will render the inner 

 and outer surfaces of the large sphere C negative and posi- 

 tive, 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 

 matter, 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 effectively insulated from 

 its neighbours (1679.), still the same final result will occur; the 

 inductric body A will polarize all these, and having its in- 

 fluence carried on by them in their newly acquired state, will 

 exert precisely the same amount of action on the external 



