Electrification by induction 45 



42] COR. For the same reason, if the body is undercharged, the de- 

 ficiency of fluid will be greater near the surface than near the center, and 

 the matter near the surface will be entirely deprived of fluid. It is likely 

 too, if the repulsion is inversely as some higher power of the distance than 

 the square, that all parts of the body will be undercharged : if it is inversely 

 as the square, that all parts, except near the surface, will be saturated: 

 and if it is inversely as some less power than the square, that all parts, 

 except near the surface, will be overcharged. 



43] PROP. X. Let the bodies A and D (Fig. 5) communicate with each 

 other by the canal EF; and let one of them, as D, be overcharged; the 

 other body A will be so also. 



For as the fluid in the canal is repelled by the redundant fluid in D, 

 it is plain, that unless A was overcharged, so as to balance that repulsion, 

 the fluid would run out of D into A. 



In like manner, if one is undercharged, the other must be so too. 



44] PROP. XI. Let the body A (Fig. 6) be either saturated or over 

 or undercharged; and let the fluid within it be 

 in equilibrio. Let now the body B, placed near 

 it, be rendered overcharged, the fluid within it 

 being supposed immoveable, and disposed in 

 such manner, that no part of it shall be under- 

 charged; the fluid in A will no longer be in 

 equilibrio, but will be repelled from B: there- 

 fore, the fluid will flow from those parts of A 

 which are nearest to B, to those which are more distant from it; and, 

 consequently, the part adjacent to MTV (that part of the surface of A 

 which is turned towards B) will be made to contain less electric fluid 

 than it did before, and that adjacent to the opposite surface RS will 

 contain more than before. 



It must be observed, that when a sufficient quantity of fluid has flowed 

 from MN towards RS, the repulsion which the fluid in the part adjacent 

 to MAT exerts on the rest of the fluid in A, will be so much weakened, 

 and the repulsion of that in the part near RS will be so much increased, 

 as to compensate the repulsion of B, which will prevent any more fluid 

 flowing from MN to RS. 



Fig. 6. 



