174 MEMOIR OF OERSTED. 



advantage wLicli we may attain over these predecessors of onrs will be, for the 

 greatest part, due to the profound researches of the celebrated Berthollet, and to 

 the grand discoveries of Davy and Berzelius, three illustrious savants on the 

 possession of whom our era can never cease to pride itself." 



There was the more merit on the part of Oersted in thus ranking Berzelius 

 among the great lights of chemistry, inasmuch as Berzelius, rather younger than 

 himself, was his rival in the branch of the science to which he attached the most 

 interest ; and it should never be forgotten that if the honor of having completely 

 unfolded the electro-chemical system reverts to Berzelius, Oersted had arrived 

 before him at a closely analogous result, although one less developed. For the 

 rest, Mdiat at the present day is of most import to the memory of Oersted in rela- 

 tion to this work, is perhaps the palpable proof found therein of his ceaseless 

 preoccupation with the subject of electrical phenomena. He had conferred 

 great improvements on the pile ; ho was one among the most practiced experi- 

 menters in employing it ; he had formally indicated magnetism as one of the 

 phenomena of which it would some day furnish the explanation, and no one was 

 better prepared than himself to advance to the practical realization of this new 

 conquest 



Yet all the attempts thus far made had remained unfruitful. The expedient 

 had been tried of placing the two poles of a battery as highly charged as possi- 

 ble in a parallel line with the poles of a strongly magnetized needle ; no effect, 

 however, had been produced. Nevertheless, the conviction still prevailed, 

 especially with Oersted, that a relation must exist between galvanism and elec- 

 tricity. The route to the discovery was unknown, though hazard might open it 

 unexpectedly. 



Fortune, it might be said, ceased to be blind at the moment when to Oersted 

 was allotted the privilege of first divining that it was not electricity in repose 

 accumulated at the two poles of a charged battery, but electricity in movement 

 along the conductor by which one of the poles is discharged into the other, 

 which would exert an action on the magnetized needle. While thinking of 

 this — it was during the animation of a lecture before the assembled pupils — 

 Oersted announces to them what he is about to try ; he takes a magnetic needle, 

 places it near the electric l)atter3'-, Avaits till the needle has arrived at a state of 

 rest ; then seizing the conjunctive wire traversed by the current of the battery, 

 he plaees it above the magnetic needle, carefully avoiding' any manner of col- 

 lision. The needle — every one plainly sees it — the needle is at once in motion. 

 The question is resolved ! Oersted has crowned, by a great discovery, the 

 labors of his whole previous life. 



It was on the 21st July, 1820, that Oersted communicated to learned Europe 

 the important fact with which his genius had just enriched science. He con- 

 signed it to a small tract written in Latin, of only four pages in 4to, which, not- 

 withstanding its conciseness, presented with perfect clearness, the restilts of, 

 more than fifty experiments, and left scarcely anything to be added on the 

 subject. This composition, entitled Experimeiita circa efcdum, etc. — (Experi- 

 ments on the effect of the electrical conflict upon the magnetic needle) — was 

 addressed the same day by post to all the societies in Europe which occupy 

 themselves with the natural sciences. A French translation of it appeared in 

 the number of the Annales de chimie ef de physique for August, 1820, from which 

 I transcribe a few expressions employed by Oersted on this occasion : 



" The first experiments on the subject I undertake to explain were made in 

 the lectin-es which I gave last winter on electricity and magnetism. They 

 evinced in general, that the magnetic needle changed its direction through the 

 influence of the voltaic apparatus, and that this effect took place when the cir^ 

 cuit Avas formed, and not when it was interrupted ; a process which had been 

 attempted in vain by celebrated physicists, some years before. But, as my 



