■328 Prof. Oersted on Electro-magnetism. [Nov. 



{C.) Explanation of the Attractions and Repulsions which Gal- 

 vanic Conductors excite among each other. 



As soon as I had suspended a small galvanic apparatus in the 

 manner of the torsion balance, I tried whether the connecting gal- 

 vanic wire would act upon that of the suspended apparatus ; but 

 on account of the too weak action and great weight of this appa- 

 ratus, I had no sensible effect. The same thing has happened 

 to several other philosophers who have tried the same process, 

 ■as I have seen in several treatises published upon electro-magne- 

 tism. M. Ampere selected a better process. He made a 

 moveable conductor which he communicated with an apparatus 

 ■of considerable strength , and thus he succeeded in discovering 

 the attractions and repulsions of the galvanic conductor. Hk 

 memoirs upon electro-magnetism are already too well known to 

 Tender it necessary forme to say, that this distinguished philoso- 

 pher has evinced the same extraordinary sagacity in the applica- 

 tion of the discovery, as in his preceding labours, all of which 

 evince great penetration; and if I adopt a theory of magnetism 

 differing from his, I shall never cease to acknowledge the great 

 merit of his labours. 



My present apparatus for experiments upon the reciprocal 

 effects of the galvanic conductor, appears to me to be sufficiently 

 simple ; and 1 shall now describe it. A B C D E F, fig. 5, is the 

 moveable conductor, made of brass wire, of one-fourth of a line 

 in diameter ; N C is a small wooden cylinder, to prevent as much 

 as possible any alteration in the form given to the brass wire. 

 The two points, o, p, move in two conical iron cups, q and r, 

 filled with mercury. In q, the point rests upon the bottom, and 

 upon this, the whole of the conductor; in r, on the contrary, the 

 point moves freely in the mercury. G H and I K are brass wires 

 which support q and r. L M is a little bit of wood, in which these 

 wires are inserted, and which, by means of a screw, are fastened 

 to any support. When G and I are put into the requisite com- 

 munication with the conductors of the galvanic apparatus, the 

 wire A B C D E F forms a part of the communicating wire, and 

 arranges itself in the direction of the magnetic east and west, as 

 "was discovered by M. Ampere, and may be subjected to the 

 principal experiments upon the action which the connecting 

 ■wires exhibit. But in order to render the effect imperceptible, 

 which the conductors, designed only to convey electricity, pro- 

 duce upon the moveable conductor, it is requisite to make G H 

 and I K a foot or more in length, and especially to prevent the 

 conductors of the apparatus approaching the moveable conductor. 

 It will be understood, that in more delicate experiments this 

 apparatus may be inclosed in a glass case, provided only that the 

 wires G H and 1 K are passed through it by means of a cork ; 

 but for the greater number of experiments this precaution is not 

 necessary. 



