Page:Scientific Memoirs, Vol. 2 (1841).djvu/434

 422 ''places of the circuit, is equal to the sum of all the tensions situated between these two places, and consequently increases or decreases exactly in the same proportion as this sum. When, therefore, one of these places is touched abductively, the sum of all the tensions, situated between the two, makes its appearance at the other place,'' at the same time the direction of the tensions must always be determined by an advance from the latter place. All the experiments on the open pile, with the help of the electroscope, instituted at such length by Ritter, Erman, and Jäger, and described in Gilbert's Annalen, are expressed in this last law.

All the electroscopic actions of a galvanic circuit of the kind, described at the outset, have been above stated; I therefore pass at present to the consideration of the current originating in the circuit, the nature of which, as explained above, is expressed at every place of the circuit by the equation Both the form of this equation, as well as the mode by which we arrive at it, show directly that the magnitude of the current in such a galvanic circuit remains the same at all places of the circuit, and is solely dependent on the mode of separation of the electricity, so that it does not vary, even though the electric force at any place of the circuit be changed by abductive contact, or in any other way. This equality of the current at all places of the circuit has been proved by the experiments of Becquerel, and its independency of the electric force at any determinate place of the circuit by those of G. Bischof. An abduction or adduction does not alter the current of the galvanic circuit so long as they only act immediately on a single place of the circuit; but if two different places were acted upon contemporaneously, a second current would be formed, which would necessarily, according to circumstances, more or less change the first.

The equation shows that the current of a galvanic circuit is subjected to a