between Light and Electricity. 235 



current created by the zinc and lead, to be crossed by the 

 powerful torrents of electricity, I could not change the effects 

 of the last current upon the magnetic needle. 



3. In order to put in opposition the electric currents of 

 two compound batteries, I replaced the pair of lead and zinc 

 by two other plates of brass, equal to those with which I 

 had already armed the two other faces of the cube, and I put 

 them in communication with the poles of a battery of ten pairs, 

 while the first touched also one of the ends of the wire of the 

 galvanometer, and the second was united to the other end of 

 the same wire. I produced the circulation by the ordinary 

 method. The needle deviated 14 degrees. I did not obtain a 

 different effect, when having waited for a sufficient time till 

 the apparatus had recovered its lost energy, I recommenced 

 the experiment, after having caused to communicate the two 

 plates of brass applied against the two other faces of the cube, 

 with the poles of another apparatus a couronne de tasses, of 

 ten, twenty, and even two hundred pairs. 



4. Hitherto, I had always made the two currents which in- 

 tersected each other circulate at the same time, from which 

 perhaps arose the impossibility of proving the influence, either 

 of an increased or of a diminished action upon the magnetic 

 needle, exercised by one of the currents upon the other. For 

 this reason I repeated the latter experiment, and the current 

 of the apparatus of two hundred couples was not developed 

 till after the needle of the galvanometer, put in motion by the 

 apparatus of ten pairs, had become altogether immoveable ; it 

 then indicated a deviation of five degrees. But I thought it 

 right to observe, with the greatest possible attention, the mag- 

 netic needle at the moment when the action due to the second 

 apparatus manifested itself, and I did not perceive the slight- 

 est motion. 



I repeated this experiment several times, by opposing in 

 the manner above specified two currents produced by two 

 batteries, which differed either by the surface of the plates, or 

 by the number of the pairs, but always with the same result. 



5. Convinced by the preceding experiments that the effect 

 of an electric current was not at all altered when it passed 

 through a liquid, which was traversed in a direction perpen- 



