78 First published Paper on Electricity 



the glass, great part of the redundant fluid will be lodged in 68, and in 

 like manner there will be a great deficience of fluid in e<f>. But in order 

 to form some estimate of the proportion of the redundant fluid which 

 will be lodged in 68, let the communication between Ef and the ground 

 be taken away, as well as that by which Bd is electrified ; and let so much 

 fluid be taken from BS, as to make the redundant fluid therein equal to 

 the deficient fluid in E(j>. If we suppose that all the redundant fluid is 

 collected in 68, and all the deficient in e<f>, so as to leave Bd and Ef satu- 

 rated; then, if the electric repulsion is inversely as the square of the 

 distance, a particle of fluid placed anywhere in the plane bd, except near 

 the extremities b and d, will be attracted with very near as much force 

 by the redundant matter in etf>, as it is repelled by the redundant fluid 

 in 68 ; but if the repulsion is inversely as some higher power than the square, 

 it will be repelled with much more force by 68, than it is attracted by e<f>, 

 provided the depth 68 is very small in respect of the thickness of the glass; 

 and if the repulsion is inversely as some lower power than the square, it 

 will be attracted with much more force by e<j>, than it is repelled by 68. 

 Hence it follows, that if the depth to which the fluid can penetrate is 

 very small in respect of the thickness of the glass, but yet is such that 

 the quantity of fluid naturally contained in 68, or e<f>, is considerably more 

 than the redundant fluid in B&; then, if the repulsion is inversely as the 

 square of the distance, almost all the redundant fluid will be collected 

 in 68, leaving the plate Bd not very much overcharged; and in like manner 

 Ef will be not very much undercharged : if the repulsion is inversely as 

 some higher power than the square, Bd will be very much overcharged, 

 and Ef very much undercharged : and if the repulsion is inversely as some 

 lower power than the square, Bd will be very much undercharged, and 

 Ef very much overcharged. 



133] Suppose, now, the plate Bd to be separated from the plate of glass, 

 still keeping it parallel thereto, and opposite to the same part of it that it 

 before was applied to; and let the repulsion of the particles be inversely 

 as some higher power of the distance than the square. When the plate 

 is in contact with the glass, the repulsion of the redundant fluid in that 

 plate, on a particle in the plane bd, id est, the inner surface of the plate, 

 must be equal to the excess of the repulsion of the redundant fluid in 68 

 on it, above the attraction of E<f) on it; therefore, when the plate Bd is 

 removed ever so small a distance from the glass, the repulsion of the 

 redundant fluid in the plate, on a particle in the inner surface of that 

 plate, will be greater than the excess of the repulsion of 68 on it, above the 

 attraction of E(f>; for the repulsion of 68 will be much more diminished 

 by the removal, than the attraction of E<f>: consequently, some fluid will 

 fly from the plate to the glass, in the form of sparks: so that the plate 

 will not be so much overcharged when removed from the glass, as it was 



