74 Royal Society. 



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 : V 4. 



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

 be inversely as the surfaces, 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 sur- 

 face of the sphere is closed or shut up ; consequently the exposed 

 surfaces, electrically considered, neglecting 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 12°. Charge 

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

 charges, therefore, are as 8 : 1 1, or as 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 to be in an inverse ratio of the exposed surfaces, as in the 

 former experiments. 



Experiment 16. Comparison of a sphere of 7 inches diameter with 

 a circular plate of 14 inches, or double that diameter. In this 

 case the inner and outer surface of the sphere, taken together, 

 are actually the same as the two surfaces of the plate. The inner 

 surface of the sphere being closed, however, as in the last experi- 

 ment, the surfaces of the sphere and plate, electrically considered, are 

 therefore not equal, and the surface of the plate is twice the surface 

 of the sphere. The surfaces, therefore, open to external induction 

 are as 2 : 1 . 



On examining the charges of the plate and sphere, they were 

 found to be as 10 : 14, or as 1 : 1*4, charge of sphere being 10 

 circular inches, under an intensity of 20°, and charge of plate 

 being 14 circular inches, under the same intensity of 20°. The 

 charge of the sphere, therefore, as compared with the charge of the 

 plate, is as 1 : V2, that is, as the square roots of the exposed 

 surfaces. 



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

 found to be, as in the preceding experiments, in an inverse ratio of 



