before and qfter completion of the Voltaic Circiiit. 2d\ 



f^llowance for loss of electricity, or, as it would be better to 

 express it, loss of tension through insufficient insulation, admits 

 but of one interpretation : the interpretation itself is generally 

 allowed, but the force of it is not, I believe, generally ad* 

 mitted ; it is, that the elejnents constituting the voltaic battery ^ 

 "when arranged in series^ assume polar tension before the circuit 

 is completed; and that in the apparatus above mentioned, this 

 tension is such that a spark will pass before the circuit is com- 

 pleted. 



16. When the micrometer electrometer, described in my 

 former paper*, was introduced between the terminal wires, 

 sparks, through the space of j^th of an inch, were obtained ; 

 and when the double electroscope (fig. 4) was included in the 

 circuit, and the discs a and b were approximated, an uninter- 

 rupted succession of sparks would pass between the discs. 

 These effects, which 1 have repeatedly shown to many friends, 

 are most brilliant. On one occasion they were continued un.- 

 interruptedly day and night for upwards of five weeks ; and 

 although some months have now elapsed since this battery 

 was completed, it still exhibits the same effects. 



17. When the experimenter was standing on the ground, 

 and consequently, as has been already explained, in actual, 

 although imperfect connection, with the battery, he could draw 

 sparks from either terminal. We shall, in the sequel, be en- 

 abled to trace, with more precision, the rise of this tension ; 

 for the present, we are only concerned in establishing its ex- 

 istence, and thereby proving the first fact, that tension or 

 electro- static effects precede, and are independent of the com- 

 pletion of the voltaic circuit. 



18. Hitherto we have not obtained any insight into the 

 condition of the dynamic effects under such circumstances of 

 antecedent tension. For testing the presence of what is usu- 

 ally termed the current, or in other words, obtaining the 

 means of observing the electro-dynamic effects, I used the in- 

 strument which is best suited for examining such phaenomena, 

 and which invariably attests the instant completion of a voltaic 

 circuit. An exceedingly delicate galvanometer was introduced 

 at B (see fig, 1 ), and the two condensing plates a and b of the 

 double electroscope (fig. 4) were respectively attached by wires 

 to the terminals Nand P of the battery, fig. 1. If great care 

 was taken not to make any connection with the ground, the 

 party manipulating being himself well insulated on shell-lac, 

 no action could be perceived on the needle in the galvano- 

 meter, although the gold leaves of the electroscope immedi- 

 ately diverged to a very considerable extent. 



* Philosophical Transactions, 1840, p. 184, § }2. 

 U2 



