^84 On the Magnetism impressed on Metals 



the force, and to have delineated it, agreeably to its pheno- 

 mena, without hesitation and uncertainty, is the praise which 

 truly belongs to M. Oersted, and which constitutes a condition 

 entirely new in the movement of electricity. 



As soon as this beautiful discovery was known in France, 

 England, and Germany, it excited the most lively sensation 

 among men of science. One of our colleagues, in particular, 

 M. Ampere, ardently verified it in all its circumstances. Seiz- 

 ing with sagacity the revolutive character of the force impiessed 

 on the conjunctive wire, he directed it with judgment, and 

 skilfully developed the consequences which flowed from this 

 property. His researches, which preceded those of the other 

 French philosophers, have considerably occupied the Academy ; 

 but as the order of exposition, occasioned by the mutual 

 dependence of the phenomena, hinders me from beginning with 

 them, 1 have endeavoured to compensate for this inversion by 

 rendering justice at once, to labours which have anticipated 

 and facilitated others. 



In the above experiments which M. Oersted had made, the 

 conjunctive wire is presented to steel needles, previously mag- 

 netized. It may be asked, if the action then exercised is 

 proper to the conjunctive wire, as the action of a bar of steel 

 tempered and magnetized is proper to this bar, or if the action 

 is communicated to the wire by the presence of the magnetic 

 needle, as we see soft iron, which exercises no magnetic power 

 of itself, acquire transiently this power in the presence of mag- 

 nets? To decide this question it was necessary to examine 

 whether a body, not magnetic in itself, but capable of becoming 

 so by influence, soft iron for example, would experience a 

 sensible action at the approach of a conjunctive wire, traversed 

 by the voltaic current. This was effected by M. Arago, who 

 shewed that filings of iron are attracted by these wires; a 

 simple but important fact, which defines clearly one of the 

 characters of the force by which the phenomenon is produced. 



I shall now proceed to indicate briefly what has been done 

 towards completing the analysis of the electro-magnetic 

 forces. 



