Disturbing influence of adjacent bodies 169 



the proportion of the charge of the double plate to that of the globe. 

 With regard to the two first, it appears that the charge of the globe and 

 double plate will neither of them be sensibly different from what they 

 would be if they were placed at an infinite distance from the jar by which 

 they are electrified, and moreover, in trying the globe, the repulsion of 

 the redundant fluid in the globe increased the deficience of fluid in the 

 trial plate as much as the attraction of the trial plate increased the quantity 

 of redundant fluid in the globe*, so that it required the same size to be 

 given to the trial plate as it would have done if the globe and trial plate 

 had exerted no attraction or repulsion on each other; and in trying the 

 coated plate, the coated plate could not sensibly increase the deficience 

 in the trial plate, nor could the attraction of the trial plate sensibly increase 

 the redundance in the coated plate, so that neither of these two causes 

 had any tendency to alter the proportion of the charges of the globe and 

 coated plate to each other. 



335] But the third cause will have a sensible effect, for in trying the 

 globe the floor and sides of the room near it would be made undercharged, 

 which would increase the charge of the globe, whereas in trying the coated 

 plate the floor would not be made sensibly undercharged, nor, if it was, 

 would it have any sensible effect in increasing the charge of the plate. 



So that the charge of the globe bore a sensibly greater proportion to 

 that of the coated plate than it would have done if it had been placed 

 at an infinite distance from any other bodies. 



How much the charge of the globe should be increased hereby I can 

 not tell, but I should imagine it should be at least by -J^th part, for if 

 the room had been spherical and 16 feet in diameter (about its real 

 size) and the globe placed in its center, it should have been increased 

 as much as thatf, and as the globe was really placed three times as 



* [Note 17.] 



f Let the globe Bbfi, whose centre is C, be insulated in the hollow globe Dd8 

 concentric with [it]. Let the inner globe be pos. electrified by the canal BE not 



communicating with the outer globe, and let the outer globe communicate with the 

 ground. The quant, dene, fluid in the outer globe must be equal to the redundant 



