Franklin, Dufay and Ampere. 483 



one leads the waves where they would not go, the other im- 

 pedes their going where they would proceed. Both in the 

 case of disruptive discharge through air, producing a spark, or 

 of a deflagrating discharge through wire, causing its explosion, 

 there is a dispersion of intervening ponderable particles ; and 

 yet there is this manifest discordancy, that in one case the un- 

 dulatory process of transfer is assisted, in the other resisted. 

 The waves follow the metallic filament with intense attrac- 

 tion, while they strive to get out of the way of those formed 

 by the aeriform matter, as if repelled. Hence the term dis- 

 ruptive, from dirumpo, to break through, was happily em- 

 ployed by Faraday to designate spark discharges. The zig- 

 zag form of the disruptive spark shows that there is a tendency 

 in the aeriform particles to turn the waves out of that straight 

 course, which, if unresisted or facilitated, they would naturally 

 pursue. On the one hand the aerial filaments being unsuit- 

 able for the conveyance of the electric waves, these are forced 

 by them out of the normal path, first in one direction, then in 

 another; while on the other hand, the finest metallic filament 

 furnishes a channel for the electric waves, so favourable that 

 this chamiel is pursued, although the consequent polarization 

 of the conducting particles be so intense as to make them fly 

 asunder with explosive violence. Even when a bell wire has 

 been dissipated by lightning, it has been found to facilitate 

 and determine the path of the discharge. 



71. The various forms of the electric spark resulting from 

 varying the gas through which it may be made to pass, 

 agreeably to the researches of Faraday, is explained by the 

 supposition that the peculiarities of the spark is parlially the 

 consequence of the polarizability of the gaseous atoms through 

 wliich the discharge is made, and varies accordingly in its 

 appearance. 



Difference between Frictional Electricity and Galvanic does 

 not depend on the one being superior as to quantity, the other 

 as to intensity, but on the different degrees in which the 

 mthereo-ponderable atoms of the bodies affected are de- 

 ranged from their natural state of Neutralized Polarity. 



72. I infer that all magneto-polar charges are attended by 

 an affection of ponderable particles; and that the reason why 

 the most intense statical charge does not afl'ect a galvanometer, 

 is, that it is only when oppositely excited bodies are neutralized 

 by the interposition of a conductor, as during a tlischarge, that 

 a,'lhereo-ponderable particles are sufficiently polarized to en- 

 able them to act upon others in their vicinity, so as to produce 

 a polar affection tiie opposite of their own. In this way dy- 



2 I 2 



