506 Sir W. Snow Harris on the Correct Interpretation 



trometers m, n attached to them as in the last case : then, if we 

 charge each of the globes with the same quantity, the electro- 

 meter on the small sphere M will have a much greater angular 

 divergence than the electrometer on the large sphere N ; from 

 which it has been inferred that the electricity on the small sphere 

 is more intense than the electricity on the large sphere, or, in 

 other words, that we have varied the Intensity without changing 

 the quantity. 



3. A further investigation of these phenomena, however, leads 

 to a more definite and simple explanation of them. When we 

 place different quantities of electricity on the three bodies A, C, S, 

 figs. 1, 2, 3, without affecting the angular divergence of the elec- 

 trometer, it is the total quantity which varies, and not the quan- 

 tity in any given point of the surface (that is to say, the absolute 

 quantity affecting the electrometer) : the quantity affecting the 

 electrometer is really the same in each case, although the total 

 quantity upon each of the three bodies may greatly differ. It is 

 in fact quite evident that, since the three bodies vary in extent of 

 surface, the greater the extent of surface the greater the number of 

 points it will contain, and consequently the greater will be the 

 amount of electricity requisite to supply them : hence the quan- 

 tity in any one point of either of the bodies, granting it not to 

 be in the simple ratio of the surfaces, may still be the same, 

 notwithstanding the quantity in each of the bodies is different. 



4. Now the total quantity or charge must be taken to act 

 upon an electrometer projecting from its surface as it would do 

 supposing the electricity were equally distributed ; this is evident 

 from the fact that, in whatever point of the surface the electro- 

 meter be placed, its angular divergence remains the same. Inten- 

 sity in this case, therefore, when rigidly interpreted, is nothing 

 more nor less than the quantity of electricity at a given point of 

 a charged surface acting on the electrometer, and cannot possibly 

 be taken to express any difference in the actual state or condition 

 of the electrical agency. 



5. Let us now take the case of a different angular divergence 

 of the electroscopes, the quantity of electricity being the same. 

 Take, for example, the case of the two unequal spheres M, N, 

 figs. 4 and 5, just adverted to, each furnished with a delicate elec- 

 troscope m, n, and let the same quantity be transferred to each 

 sphere ; the electroscope m of the sphere M will in this case, as 

 already observed, have a much greater angular divergence than 

 the electroscope n of the sphere N. Here we perceive that the 

 quantity in any one point of the two spheres is not the same, 

 because the quantity being the same in each sphere, and the 

 u rface over which it is expanded in the one sphere being of 

 much less extent than the surface over which it is expanded 



