SS8 M. Marianini on an analogy 



From these two experiments, which I have varied in several 

 ways, we may conclude that the electric currents which inter- 

 sect one another in a fluid at a very acute angle, do not weak- 

 en one another, and do not alter the effect of a third current 

 which crosses it like themselves. 



8. Causing the electricity which traversed the fluid from 

 one extremity of the tube to the other, to pass through the 

 wire of the galvanometer, I directed at the same time across 

 the fluid three electric currents, in such a manner that they 

 were all perpendicular to the direction which the current took 

 which was to act on the magnetic needle ; in this case the de- 

 viation was twelve degrees. 



9- With this tube I wished also to try if the action of an 

 electric current upon the magnetic needle was weakened when 

 it passed through a liquid in which one or two other electric 

 currents moved in a parallel direction to the first ; but on 

 account of the small space of fluid to be run over, and the 

 distance of but 2.7 cent, which separated them, I did not con- 

 sider these trials as sufficiently decisive. I then procured a 

 hollow tube of glass of 5 cent, in the side ; one of the faces had 

 three holes furnished with common metallic bands, the dis- 

 tance between them being 1 cent. ; three other holes disposed in 

 the same manner were on the opposite face. Having filled 

 the tube with water, I made the liquid be traversed with three 

 electric currents in a parallel direction, and one of which acted 

 upon the galvanometer. But whether the two other currents 

 were equal to this last or different, — whether they were made 

 to pass in the same direction as it, or in a contrary one, — the de- 

 viation of the needle was always equal to that which is ob- 

 tained when the liquid is crossed only by the electricity which 

 affects the magnetic needle. 



In similar experiments we must take care that the electric 

 currents of the Voltaic apparatus, not intended to act upon the 

 galvanometer, do not find in the wet conductor which they ought 

 to traverse, a passage more difficult than that presented to them 

 by the battery intended to act upon the galvanometer ; other- 

 wise, a part of this electricity takes its course across the 

 battery and consequently changes its effects. 



10. After all, it may still be uncertain if the electric cur- 

 rents which cross the same conductor affect one another, or 



