20 i On the Action of the Voltaic Pile 



agreeable, from having a slight wound near that part of the finger 

 which was plunged in one of the troughs of the pile. 



I endeavoured, at the desire of M. Poisson, but in vain, to ob- 

 tain with my apparatus effects at a distance, by terminating my 

 wires of platina with very sharp points ; contact was always ne- 

 cessary to produce a sensible deviation. 



These facts have led me to conclude that the nullity of action 

 in a Voltaic column of fifty-eight pairs (whether horizontal or 

 vertical) must be attributed st least as much to the imperfect 

 conducting pov.'er of the wrappers of wet cloth, as to the small di- 

 mension of the discs (that of about a six-franc piece). However, 

 this pile gives a shock strong enough. 



I remarked that it is very easy, by means of a battery com- 

 posed of two piles, to establish the conducting power of liquid or 

 gaseous substances interposed in one of the arcs, by placing the 

 needle at the proximity of the other arc. 



Hitherto I made use of a small compass needle suspended ho- 

 rizontally from a vertical pivot of brass. To render the phseno- 

 mena of inclination more sensible, I took a steel wire of very 

 small diameter, and magnetised it by a single touch ■^. It was 

 about two centimetres in length, and manifested diiferent degrees 

 of magnetism, branching nearly from its centre point. I sus- 

 pended this small needle by a very fine silk thread, in such a 

 manner that it was horizontal. 



By observing with attention all the circumstances which at- 

 tended its deviations from the approach of the conducting wire 

 of the pile, I perceived that every time the pole of the needle 

 passed from one side to the other of this wire, though the latter 

 was a little attracted on the passage of the needle, it did not 

 prevent its movement; for the wire of suspension took an oscil- 

 latory movement, which approached and receded from the needle 

 of the conducting wire ; and when it had sufficiently receded, it 

 took then a movement which could no longer affect that wire ; 

 but it avoided encountering the nearest face of the wire to take 

 this new position, and it went, on the contrary,to the face of that 

 side which it lad passed. 



The oscillations of the wire of suspension being modified by the 

 action of a weight which serves to bring the needle to a point of 

 equilibrium, from which another force would remove it ; I thought 

 of placing this small needle slightly coated by a greasy body; 

 because then, the action of the weight being balanced, tiiat of tl>e 

 conducting wire would have all its effect. The experiment suc- 

 ceeded perfectly. 



I may observe in passing, that this small needle became sus- 



* The effects are more marked, and more easily to be produced, with a 

 wire magnetised to saturation by the method of double touch. 



ceptible ' 



_JL 



