208 HISTORY OF ELECTRICITY. 



there appeared in the Bulletin des Sciences, an exact solution of tho 

 problem of the distribution of electric fluid on a spheroid, obtained by 

 M. Biot, by the application of the peculiar methods which Laplace had 

 invented for the problem of the figure of the planets. And in 1811, 

 M. Poisson applied Laplace's artifices to the case of two spheres acting 

 upon one another in contact, a case to which many of Coulomb's experi- 

 ments were referrible ; and the agreement of the results of theory and 

 observation, thus extricated from Coulomb's numbers, obtained above 

 forty years previously, was very striking and convincing. 13 It followed 

 also from Poisson's calculations, that when two electrized spheres are 

 brought near each other, the accumulation of the opposite electricities 

 on their nearest points increases without limit as the spheres approach 

 to contact; so that before the contact takes place, the external resist- 

 ance will be overcome, and a spark will pass. 



Though the relations of non-conductors to electricity, and various 

 other circumstances, leave many facts imperfectly explained by the 

 theory, yet we may venture to say that, as a theory whicli gives the 

 laws of the phenomena, and which determines the distribution of those 

 elementary forces, on the surface of electrized bodies, from which ele- 

 mentary forces (whether arising from the presence of a fluid or not,) 

 the total effects result, tha doctrine of Dufay and Coulomb, as deve- 

 loped in the analysis- of Poisson, is securely and permanently esta- 

 blished. This part of the subject has been called statical electricity. 

 In the establishment of the theory of this branch of science, we must, 

 I conceive, allow to Dufay more merit than is generally ascribed to 

 him ; since he saw clearly, and enunciated in a manner which showed 

 that he duly appreciated their capital character, the two chief princi- 

 ples, the conditions of electrical attraction and repulsion, and the 

 apparent existence of two kinds of electricity. His views of attrac- 

 tion are, indeed, partly expressed in terms of the Cartesian hypothesis 

 of vortices, then prevalent in France ; but, at the time when he wrote, 

 these forms of speech indicated scarcely anything besides the power 

 of attraction. Franklin's real merit as a discoverer was, that he was 

 one of the first who distinctly conceived the electrical charge as a 

 derangement of equilibrium. The great fame which, in his day, he 

 enjoyed, arose from the clearness and spirit with which he narrated his 

 discoveries ; from his dealing with electricity in the imposing 1 form of 

 thunder and lightning ; and partly, perhaps, from his character as an 



13 No. li. " Mem. A. P. 1811. 



