A letter to Prof. Faraday. — 3 
ous experiments, and especially those of Davy, was inconsistent 
with the idea that ponderable matter could be a necessary 
the process of electrical induction. I therefore inferred ‘that your 
efforts would be primarily directed to a re-examination ot that 
question. 
If induction, in acting through a vacuum, ee 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 be, 
known phenomena of electricity require ; especially acco he 
to your opinion that the only difference between the fluid evolved 
by galvanic apparatus and that evolved by friction, is due to op- a: 
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 difference of 
intensity in inductive power, can be create 
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- 
eg 
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