between Light and Electricity. 233 



of its propagation, will it also present a phenomenon analo- 

 gous to that which we have described ? 



As I am not aware that any one has drawn a similar con- 

 clusion, and made it an object of particular study, and as I 

 conceive also that nothing can now be considered useless that 

 concerns the science of electricity, I have not looked upon it 

 as a trivial occupation to make several experiments, in order to 

 try if the effects of electric currents can be altered when they 

 are obliged to traverse spaces which are already crossed by 

 other electrical currents. 



1. Beginning with the most simple cases, those in which 

 two electric currents cross each other at right angles, 1 took 

 a cube of wood three centimetres in the side, the four faces of 

 which, in parallel pairs, were furnished in their centre with 

 a screw, fixing a rectangular plate of metal eight centime- 

 tres in length, and rather less than two centimetres in 

 breadth. Wishing, in my first experiment, to put in oppo- 

 sition, two electric currents produced by two equal elemen- 

 tary batteries, I applied against one of the faces of the 

 cube a plate of zinc, and against the opposite face a similar 

 plate of copper, and I made them communicate by pressing 

 under the screws which fixed them, the ends of the exciting 

 wire of a galvanometer. The two plates presented on the 

 same side of the cube a projection of about six centimetres. 

 This pair being plunged to the depth of five centimetres in 

 water slightly salted, the needle of the galvanometer deviated 

 twelve degrees. To the two other faces of the cube furnished 

 with screws, I fixed in the same manner two similar plates, the 

 one of zinc and the other of copper, and I put them in com- 

 munication by pressing under the screws which supported 

 them the ends of an exciting wire. The four plates stretched 

 beyond the same base of the cube by an equal quantity. Things 

 being thus prepared, I plunged the two pairs in the fluid above- 

 mentioned, and the deviation of the needle was again twelve 

 degrees. We see by this experiment, that the effect of a pair 

 of plates upon the magnetic needle is not altered, when the 

 electric fluid which it causes to circulate is forced to traverse a 

 fluid which is crossed in a direction perpendicular to its own by 

 an electric current created by a pair of plates equal to the first. 



