288 On the Magnetism impressed on Metals 



Finally, instead of presenting a conjunctive wire to a magnet, 

 present two conjunctive wires to one another, in parallel posi- 

 tions. Then if the revolutive direction of the force be the 

 same for the two wires, they will both concur in giving one 

 direction to a magnetic needle placed between them ; but if the 

 direction of the revolutive movement be opposite in each, they 

 will tend to turn the needle in opposite directions. These are 

 simple consequences of the law of the forces. Now on trying 

 these two arrangements, M. Ampere has found that in the first 

 the two wires come together, and that in the second, they mu- 

 tually repel each other. Thence we must make two inferences; 

 first, that the wires exert on each other actions perfectly analo- 

 gous to those which they exercise on magnetic needles ; and 

 next that the distribution of these forces in each of their parti- 

 cles is analogous as to direction, with what it is in magnetic 

 needles themselves. These two new conditions relative to the 

 nature of the force, render this experiment very important. 



In the different arrangements which we have just described, 

 the conjunctive wires and the magnets attract or repel princi- 

 pally by their most contiguous parts; for with regard to the 

 rest, their distance rapidly diminishes their action. Hence it 

 is evident that we should augment the energy of the effects, if 

 we approximated together the different parts of the conjunc- 

 tive wire, preserving to them however the same general line of 

 action. M. Ampere has also verified this position, by coiling 

 the conjunctive wire in the form of a flattened spiral, on the 

 plane of whose contours he acts with magnets, as on the side 

 of a single wire. 



M. Ampere's mode of operating, consists in bending a portion of wire, 

 about two or three feet long, into a circular form, recurving its extremities 

 so as to make each point dip into a little cup of mercury, which serves as 

 pivots on which the circle is suspended and round which it may revolve. 

 Into one cup, the ordinary wire from the copper end, and into the other, 

 the wire from the zinc end of the voltaic trough is plunged. The plane 

 of the circle then slowly places itself, according to M. Ampere, at right 

 angles to the magnetic meridian. — Translator. 



