A letter to Prof. Faraday. 3 



ons experiments, and especially those of Davy, was inconsistent 

 with the idea that ponderable matter could be a necessary agent in 

 the process of electrical induction. I therefore inferred that your 

 eflforts would be primarily directed to a re-examination of that 

 question. 



If induction, in acting through a vacuum, be propagated in 

 right lines, may not the curvilinear direction which it pursues, 

 when passing through " dialectrics," be ascribed to the modifying 

 influence which they exert ? 



If, as you concede, electrified particles on opposite sides of a 

 vacuum can act upon each other, wherefore is the received theory 

 of the mode in which the excited surface of a Leyden jar induces 

 in the opposite surface, a contrary state, objectionable ? 



As the theory which you have proposed, gives great importance 

 to the idea of polarity, I regret that you have not defined the 

 meaning which you attach to this word. As you designate that 

 to which you refer, as a "species of polarity," it is presumable 

 that you have conceived of several kinds with which ponderable 

 atoms may be endowed. I find it difficult to conceive of any 

 kind which may be capable of as many degrees of intensity as the 

 known phenomena of electricity require ; especially according 

 to your opinion that the only difference between the fluid evolved 

 by galvanic apparatus and that evolved by friction, is due to op- 

 posite extremes in quantity and intensity ; the intensity of elec- 

 trical excitement producible by the one, being almost infinitely 

 greater than that which can be produced by the other. What 

 state of the poles can constitute quantity — what other state inten- 

 sity, the same matter being capable of either electricity, as is well 

 known to be the fact ? Would it not be well to consider how, 

 consistently with any conceivable polarization, and without the 

 assistance of some imponderable matter, any great diflference of 

 intensity in inductive power, can be created ? 



When by friction the surface is polarized so that particles are 

 brought into a state of constraint from which they endeavor to 

 return to their natural state, if nothing be superadded to them, it 

 must be supposed that they have poles capable of existing in two 

 different positions. In one of these positions, dissimilar poles co- 

 inciding, are neutralized ; while in the other position, they are 

 more remote, and consequently capable of acting upon other mat- 

 ter. 



