1864.] 



of Electrical Force. 



373 



Charge of 1 8-inch plate, 12 circular inches, under the same intensity of 10°. 

 Here the charges are as 1 : 2, whilst the surfaces are as 1 : 4 ; neglecting 

 the difference of boundary, therefore, the charges, as in the preceding ex- 

 periments, are as the square roots of the surfaces. 



On examining the intensities of these plates, ihey were found to be in- 

 versely as the surfaces ; thus 6 circular inches upon the 9- inch plate 

 evinced an intensity of 10°, as just stated; 6 circular inches upon the 

 18-inch plate had only one-fourth the intensity, or 2°*5 ; being inversely 



as the surfaces, according to the formula E = g • 



Experiment 13. A circular plate of 9 inches diameter, surface 63 '6 

 square inches, compared with a circular plate of 12'72 inches diameter, 

 surface 127" 2 square inches. Here the surfaces are as 1:2. 



Charge of 9-inch plate (surface 63*6 square inches), 5 circular inches, 

 under an intensity of 8°. Charge of 12*72-inch plate (surface 127'2 

 square inches), 7 circular inches, under the same intensity of 8°. The 

 charges here are as 5 : 7, whilst the surfaces are as 1:2; that is to say 

 (neglecting the boundaries), the charges are as the square roots of the 

 surfaces. 



On examining the intensities of these plates, they were found to be, as 

 in the preceding experiments, inversely as the surfaces. 



Experiment 14. Comparison of a sphere of 4*5 inches diameter, surface 

 63-5 square inches, with a sphere of 9 inches, or double that diameter, 

 surface 254 square inches. 



Charge of sphere of 4'5 inches diameter (surface 63*5 square inches), 

 4 circular inches, under an intensity of 9°. Charge of sphere of 9 inches 

 diameter (surface 254 square inches), 8 circular inches, under the same 

 intensity of 9°. Here the charges are as 1 : 2, whilst the surfaces are as 

 1:4. The charges, therefore, are as the square roots of the surfaces, or 

 as 1 : V4. 



On examining the intensities of these spheres, they were found to be as 

 the surfaces inversely, or very nearly ; being as 2°*5 and 9° respectively. 



Experiment 15. Circular plate of 9 inches diameter compared with a 

 sphere of the same diameter. Here the actual surfaces are 63*6 square 

 inches for the plate, and 254 square inches for the sphere, being as 1 : 4. 

 We have to observe, however, that one surface of the sphere is closed or 

 shut up, consequently the exposed surfaces, electrically considered, neglect- 

 ing one-half the surface of the sphere as being closed, are as 1:2; and the 

 exposed surface of the plate is exactly one-half the exposed surface of the 

 sphere. 



Charge of plate 8 circular inches, under an intensity of 1 2°. Charge of 

 sphere 1 1 circular inches, under the same intensity of 1 2°. The charges, 

 therefore, are as 8 : 1 1, or sa 1 : 1*4 ; the exposed surfaces being as 1 : 2. 

 The charges, therefore, are as the square roots of the exposed surfaces. 



On examining the intensities of the plate and sphere, they were found 



2 E 2 



