Comparison with theory 143 



the plates.it will appear, by calculating according to Prop. XXX [Art. 141], 

 that their charges should be in the following proportion : 



The large circle i-ooo, 



The two small ones at 36 inches distance -933, 

 24 -911, 



18 -890. 



If we suppose that the whole redundant fluid is collected in the cir- 

 cumference, they should be as follows : 



The large circle i-ooo, 



The two small ones at 36 inches distance -890, 

 24 -844, 



18 ,, -805; 



and if we suppose that \\ of the whole redundant fluid is collected in the 

 circumference, and the remainder, or \\, spread uniformly, they should 

 be as follows: 



The large circle i-ooo, 



The two small ones at 36 inches distance -920, 

 24 ,. -890, 



18 -863. 



277] I think this latter proportion of the charges much the most likely 

 to agree with the truth*, as it appears from an experiment which will be 

 mentioned hereafter, that the charge of a circular plate bears the same 

 proportion to that of a globe that it would do if the fluid was disposed 

 in that manner. But it must be observed that in these calculations the 

 circles are supposed to be placed at an infinite distance from the vial by 

 which they are electrified, and also from any other over- or undercharged 

 body, whereas in these experiments the circles were at such a distance from 

 the vial that their repulsion on the canal by which they communicated 

 with it was sensibly less than if it was infinite, and moreover the attraction 

 of the undercharged trial plate on the wire mMNn has some tendency 

 to increase the quantity of fluid in the circles, and the repulsion of the 

 circles tends to diminish the quantity of fluid in the trial plate, and 

 moreover the floor and walls of the room will be made undercharged 

 near the circles and overcharged near the trial plate, which will also have 

 some tendency to alter the quantity of fluid in the circles and trial plate. 

 It was with a view to find out what error could proceed from these 

 causes that I tried the experiment in the two different ways above men- 

 tioned. It will be shewn, however, in the appendix f, that the first two 

 of these causes cannot produce any sensible alteration in the experiment, 

 * I would not be understood by this to suppose that the fluid is actually dis- 

 posed in this manner in a circular plate, but only that the charges will bear the 

 same proportion to each other that they ought to do on this supposition. 



f [Art. 1 88, and Notes 17 and 21.] {Prof. Maxwell has supplied a series of very 

 elegant calculations of capacity, for the cases measured by Cavendish, in Notes 20 to 25.) 



