260 Mr. Smee's New Definition of the Voltaic Circuit, 



voltaic circle, might possibly vary in some new manner, for 

 which further experiments are wanted. In that case it would be 



I'A— 151 • 



"W" = ' the old English 1& standing for the new 



resistance afforded to the whole current. The tunnel might be 

 cut away at any other part besides (R), thus it might be de- 

 ficient at (F), (a), (c), (r), or (e) ; but the student will readily 

 perceive the expressions for these cases. 



The algebraic formula for (W) is replete with interest, for it 

 accurately defines the value of (W) in determining the so-called 

 power of any battery. The power of a battery is the inten- 

 sity multiplied by the quantity, in other words, I' x A ; but our 

 equations show that W is not equal to I A but to I A — R A, 

 and from that we deduce that I A = W + R A ; therefore it is 

 impossible by Faraday's voltameter to ascertain the value of 

 I' A at once, and it is necessary first to find the value of A. 

 The immense mass of experiments in which the voltameter 

 has been assumed to be equal to I' A, must now be discarded 

 as inaccurate, and no deductions drawn from them ; but all 

 future experimenters, by attending to these equations, may 

 make the results obtained by the voltameter absolutely 

 correct. 



The symbol (A) I have before noticed stands for the value 

 of atoms of the compound fluid exposed to the action of a body 

 removing one of its elements. It sometimes becomes an incon- 

 stant quantity, as in the cases where non-conducting substances 

 incase the poles of the battery. A is tolerably constant in Da- 

 nielPs and in Grove's battery, most so in the former. It is less 

 constant in mine, and very inconstant in most smooth metal 

 batteries. A is analogous to what experimenters formerly very 

 properly called the quantity of a battery. The contact theorists 

 indeed would fain make us believe that there is no such thing as 

 either quantity or intensity, but they have erroneously multi- 

 plied intensity (I') with quantity (A), and called it electromotive 

 power, and then denied the existence of the several parts of that 

 power, which is nothing but the I' A of my equation with the (c) 

 and (r) abstracted from the (I'), and considered separately. 

 This is the point on which Ohm and his followers have 

 perplexed all English philosophers ; still, notwithstanding this 

 mystification, to Ohm is due the hearty thanks of every elec- 

 trician for showing that voltaic force is diminished by resist- 

 ances, and doubtless his doctrine of resistance is a most im- 

 portant and lasting discovery. Ohm's equation, in the complex 

 mannerin which he has given it, presents fewest difficulties when 

 applied to solid connecting resistances ; thus those who used bat- 

 teries with connected wires could appreciate it in many cases, but 



