6 " 



g 30, 



g II 



2 ' 10 0-609 0-618 



Intelligence and Miscellaneous Articles. 247 



in each of the external spheres, wires can be introduced by which 

 the sphere is either charged or discharged. The following are the 

 results obtained : — 



Charge obtained Ratio of the Ratio of the 



experimentally. charges calculated 



obtained. charges. 



No '^ i? "I 0-457 0-438 



6 So J 



751 



55 / 



27 1 

 32-6 J 



} 



5 16-4/ 



The differences obtained between the calculated and observed 

 charges are small, considering the imperfections of the modes of 

 measurement ; and we see that the formulas deduced from the 

 theory of propagation may be applied to the case of condensa- 

 tion, as well in the case of spherical condensers as in the case of the 

 cylindrical and plane condensers with which I have been previously 

 occupied. I believe that the proposition may without temerity be 

 generalized, and be considered applicable to condensers of any 

 shape. 



To appreciate the interest of this principle, it is important to ob- 

 serve that the theory of condensers, which has been usually pre- 

 sented as a branch of statical electricity, comprehends really the 

 whole of this subject. When an insulated and electrified conductor 

 is placed in any room, the electricity with which it is charged is 

 usually called free electricity ; but, as Mr. Faraday has shown by 

 numerous experiments, this electricity is no more free than that on 

 the inner coating of a Leyden jar. The insulated conductor is only 

 the inner coating of a large condenser, the external coating of which 

 is constituted by the whole of the adjacent conductors. In fine, all 

 questions relating to the distribution of electricity which is said to be 

 free, depend on the theory of condensers, and may therefore be 

 solved by means of the theory of propagation. By the principle 

 which I have propounded, all questions of statical electricity may be 

 resolved into questions of dynamics, and vice versa 4 . 



The want of apparatus has prevented me from investigating 

 whether the numerous results which Coulomb obtained in his re- 

 searches relative to the distribution of electricity may be made to 

 coincide with the ideas which I have laid down ; but 1 have already 

 been able to verify the very simple law which expresses the free 

 charge. We have just seen that the quantity of electricity accumu- 

 lated on the inner coating of a spherical condenser is proportional to 



Rr 



t) •• This expression is reduced to r if we suppose R to be infi- 



