106 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XII.) 



lection of the path, and the solution of the wonder which Harris has so well de- 

 scribed* as existing under the old theory. All is prepared amongst the molecules 

 beforehand, by the prior induction, for the path either of the electric spark or of light- 

 ning itself. 



1408. The same difficulty is expressed as a principle by Nobili for voltaic electri- 

 city, almost in Mr. Harris's words, namely-}-, " electricity directs itself towards the 

 point where it can most easily discharge itself," and the results of this as a principle 

 he has well wrought out for the case of voltaic currents. But the solution of the dif- 

 ficulty, or the proximate cause of the effects, is the same : induction brings the parti- 

 cles up to or towards a certain state (1370.) ; and by those which first attain it, is the 

 discharge first and most efficiently performed. 



1409. The moment of discharge is probably determined by that molecule of the di- 

 electric which, from the circumstances, has its tension most quickly raised up to the 

 maximum intensity. In all cases where the discharge passes from conductor to con- 

 ductor this molecule must be on the surface of one of them ; but when it passes be- 

 tween a conductor and a non-conductor, it is, perhaps, not always so (1453.). When 

 this particle has acquired its maximum tension, then the whole barrier of resistance 

 is broken down in the line or lines of inductive action originating at it, and disruptive 

 discharge occurs (1370.) : and such an inference, drawn as it is from the theory, 

 seems to me in accordance with Mr. Harris's facts and conclusions respecting the 

 resistance of the atmosphere, namely, that it is not really greater at any one dis- 

 charging distance than another;}:. 



1410. It seems probable, that the tension of a particle of the same dielectric, as 

 air, which is requisite to produce discharge, is a constant quantity, whatever the shape 

 of the part of the conductor with which it is in contact, whether ball or point ; what- 

 ever the thickness or depth of dielectric throughout which induction is exerted ; 

 perhaps, even, whatever the state, as to rarefaction or condensation of the dielep- 

 tric ; and whatever the nature of the conductor, good or bad, with which the particle 

 is for the moment associated. In saying so much, 1 do not mean to exclude small 

 differences which may be caused by the reaction of neighbouring particles on the de- 

 ciding particle, and indeed, it is evident that the intensity required in a particle 

 must be related to the condition of those which are contiguous. But if the expecta- 

 tion should be found to approximate to truth, what a generality of character it pre- 

 sents ! and, in the definiteness of the power possessed by a particular molecule, may 

 we not hope to find an immediate relation to the force which, being electrical, is 

 equally definite and constitutes chemical affinity ? 



1411. Theoretically it would seem that, at the moment of discharge by the spark 

 in one line of inductive force, not merely would all the other lines throw their forces 

 into this one (1406.), but the lateral effect, equivalent to a repulsion of these lines 



* Nautical Magazine, 1834, p. 229. t Bibliotheque Universelle, 1835, lix. 275. 



X Philosophical Transactions, 1834, pp. 227, 229. 



