of the Electrical Terms Intensity and Tension, 505 



- in which q signifies the quantity of electricity, and 5 the 

 s 



extent of the coating or surface over which it is expanded. 



In like manner it has been commonly observed that in the 

 construction of voltaic batteries a few large plates principally 

 relate to quantity ; whilst in breaking up those plates into a long 

 alternating series of smaller ones, we are supposed thereby to 

 impart to the voltaic currents intensity, or elastic power. 



The term "intensity " has also not been unfrequently employed 

 to signify tension, or reactive force — as when a dielectric medium 

 interposed between metallic coatings becomes ruptured or broken 

 down by polarized molecular action. It has been employed in 

 other senses, all of them conveying hypothetical views of the 

 agency in operation. 



These various interpretations of the term intensity have long 

 since appeared to me unsound and unsatisfactory, and unsub- 

 stantiated by a rigid inductive philosophy, resting entirely on 

 mere assumptions of the occult nature of electricity. 



2. I have in vain sought for experiments which could at all 

 lead us to infer the possibility of effecting a change in the 

 condition of the electric agency (whatever it may happen to be), 

 without at the same time varying the quantity of the agency 

 in operation. We have no means, for example, except by means 

 of induction, of changing the angular divergence of an electro- 

 meter attached to an insulated charged surface whilst the quan- 

 tity, remains the same — that is to say, whilst the quantity affecting 

 the electrometer is invariable ; in other words, we have no means 

 of altering the state, condition, or quality of the electrical force 

 absolutely in operation. On the other hand, we have the means 

 of varying the quantity and yet of preserving the angular diver- 

 gence of the electrometer constant. 



Let, for example, A,C,S, figs. 1,2, 3, PI. VII. be three insulated 

 conducting bodies of different forms and magnitude; let A be a 

 circular plate of small thickness, C a cylinder, and S a sphere, 

 and suppose each furnished with a delicate electrometer of diver- 

 gence, a, c } s (the three electrometers being precisely alike) ; 

 further, suppose these three conductors to be charged with 

 electricity to such an extent as will bring each of the electro- 

 meters to the same angle : in this case, as is well known, the 

 quantity of electricity upon each of these bodies will be very 

 different, notwithstanding the sameness of the electrometer indi- 

 cation. Here the electrical intensity of each of the bodies is said 

 to be the same, and the electrical charge to have the same density 

 in each. Again, take two insulated conducting spheres M, N, 

 figs. 4 and 5, of unequal diameters, and suppose the surface of 

 the one to be three times that of the other, having delicate elec- 



PhiL Mag. S. 4. No. 178. Suppl. Vol. 26. 2 L 



