206 Royal Society : — 



given degree of the electrometer or what the author calls intensity, 

 he deduces the following : — 



1 . The charges of spheres and circular planes, as also of plane 

 rectangular plates, are as the square roots of these surfaces multiplied 

 into their circumferences or perimeters. 



2. The charge of a cylinder is as the square root of its surface 

 multiplied into the sum of its length and circumference, 



3. The charge of a cube is as the square root of its surface mul- 

 tiplied into twice its side. 



4. The charge of a sphere is to the charge of one of its great 

 circles as 2 : 1 . 



5. The charge of a sphere is to the charge of a plane circle of 

 equal surface as 1 : v'2, or as 1 : 1-41. 



6. The charge of a cube is to the charge of a sphere of equal 

 surface as 1 : 1'47 nearly. 



7. The charge of a square plate is to the charge of a cube whose 

 side equals the side of the square as 1 : 1'6 nearly. 



8. The charge of a circular plate is to the charge of a square plate 

 whose side equals the diameter of the circle as 1 : r28. 



The author examines the charges of cylindrical rods or tubes of 

 small diameter, and finds their capacity to be nearly as the length, 

 the surface being constant ; being quite in accordance with the result 

 arrived at by Volta, who found that an insulated conductor com- 

 posed of gilded rods could receive under the same intensity as much 

 electricity as would produce a shock equal to a given extent of 

 coated glass. 



In referring to the beautiful experiments of Coulomb, the author 

 conceives that the sharing of electricity between a circular plate and 

 sphere of equal area, in proportion to the two surfaces of the plate 

 to the one exterior surface of the sphere, is a different thing from the 

 absolute charging of the plate on two surfaces, and adduces experi- 

 ments to show that when a circular plate charges on both its surfaces, 

 it takes up twice the quantity of electricity under the same intensity, 

 which a plane circular plate in respect of a sphere of equal area does 

 not ; he conceives the sharing of electricity between a sphere and 

 circular plate of equal area to be a pure result of the inductive sus- 

 ceptibility of the plate in consequence of the free exposure of its 

 entire surface ; he further gives some new experiments on induction, 

 with a view of proving that when one surface is opposed as it were 

 to itself, as in the case of the interior surface of a sphere, the induc- 

 tive susceptibility of one-half the surface is reduced to zero. The 

 phsenomena of what the author calls, after Cavendish, electrical 

 charge, he refers to some peculiar arrangement or disposition of the 

 electrical particles on the surfaces of the several conductors, by which 

 they exhibit a greater or less degree of excitement, as observable by 

 the electrometer. 



The remaining portion of this paper is devoted to the laws and 

 phsenomena of electrical attractive force. The attractive force of a 

 given surface under a given charge does not depend on the quantity 



