June i6, 1921] 



NATURE 



493 



searches impressed him greatly. From Weimar 

 he went to Berlin, where he heard Fichte and 

 Schlegel lecture. .\t Weimar he had become ac- 

 quainted with a work by Winterl, " Prolusiones ad 

 Chemiam Decimi Noni," and set himself to make 

 this more widely known, publishing- in 1802 a 

 book, " Materialen zu einer Chemie des neun- 

 zehnten Jahrhunderts," the object of which was 

 to show the common origin of physical and 

 chemical forces. The book was severely criticised 

 everywhere, and Winterl 's chemistry, founded on 

 two mysterious substances, Andronia and 

 Thelycke, has long since been consigned to the 

 oblivion it deserved ; but the root-idea, the 

 common origin of most natural forces, lay at the 

 basis of much of Oersted's future work. 



From Berlin Oersted went to Paris, visiting 

 Ritter at Weimar on the way, and taking 

 part in some of his experiments. On de- 

 scribing these in Paris, especially the inven- 

 tion of what was probably the first storage 

 battery — a storage column, Ritter called it : 

 a pile of copper plates separated by discs of 

 moist cardboard, which retained a charge for some 

 time after it had been connected to a battery, and 

 was capable itself of giving out a current when 

 its extremities were connected by a wire — Biot 

 asked him to write and advise Ritter to compete 

 for a prize of 3000 livres offered bv the First 

 Consul for the most important electrical or gal- 

 vanic experiment which might compare with the 

 invention of the voltaic pile. 



Oersted re-wrote in French the essay Ritter sent 

 in, but the author had stated that his storage 

 column, when placed in a vertical position, became 

 charged through the electrical influence of the 

 earth. Experiments at Paris failed to verify this, 

 and the prize went elsewhere. 



Oersted returned to Copenhagen in January, 

 1804, and was disappointed at not receiving the 

 orofessorship of phvsics, which had been vacant 

 for some time. The warden of the university 

 considered him a philosopher rather than a 

 physicist, and it was not until 1806 that he became 

 professor extraordinarius. In 1807 he repeated 

 and extended Chladni's work on vibrating plates, 

 using Lvcopodium in place of sand. He noted, 

 but could not explain, the action of the Lyco- 

 podium in collecting in the places of maximum 

 vibration ; that was left for Faraday. 



In 181 2 and 181 3 — the years of Moscow and 

 Leipzig — Oersted again visited Berlin and Paris, 

 and, encouraged by the reception he met with, 

 oublished his " View of the Chemical Forces of 

 Nature," in which, while expressing his indebted- 

 ness to Ritter and Winterl, he dissociates himself 

 in many respects from their theories. He avows 

 his continued belief in the essential unity of natural 

 forces, and, while his views are often vague and 

 unsatisfactory, he proposes that " the experiment 

 should be made whether electricity in one of its 

 most latent forms could act on the magnetic 

 bodies as such." The answer came in 1820. The 

 book was well received everywhere. Thomson 

 writes in the "Annals of Philosophy, 1819," deal- 

 NO. 2694, VOL. 107] 



ing with a later French edition: "The book is 

 highly worthy the perusal of all those British 

 chemists who aim at the improvement and per- 

 fection of their science. It is rather surprising 

 that a work of such originality and value should 

 have remained for these four years quite unknown 

 in this country." 



In the years which followed, Oersted was busily 

 occupied with routine work. In 1815 he became 

 secretary of the Society of Sciences, and in 18 17 

 professor ordinarius. In this capacity he delivered 

 a series of monthly lectures to advanced students 

 on the progress of science, and it was at one of 

 these in the spring of 1820 that his great discovery 

 was made. His own description of this will be 

 found in the article in the " Edinburgh Encyclo- 

 paedia" already referred to. .A.fter stating that 

 the luminous and heating effect of the electrical 

 current goes out in all directions, " so he thought 

 it possible that the magnetical effect could likewise 

 eradiate " ; and after referring to magnetic effects 

 produced by lightning," he continues: "The plan 

 of the first experiment was to make the current 

 of a little galvanic trough apparatus commonly 

 used in his lectures pass through a very thin 

 platina wire which was placed over a compass 

 covered with glass. The preparations for the 

 experiment were made, but, some accident having 

 hindered him from trying it before the lecture, he 

 intended to defer it to another opportunity; yet. 

 during the lecture the probability of its success 

 appeared stronger, so that he made the first ex- 

 periment in the presence of his audience. The 

 magnetical needle, though included in a box, was 

 disturbed ; and as the effect was very feeble, and 

 must, before its law was discovered, seem very 

 irregular, the experiment made no strong im- 

 pression on his audience." Nothing further hap- 

 pened for three months ; he delayed his researches 

 until a more convenient time, when a large bat- 

 terv, constructed by his friend Esmark and him- 

 self, was available, and then, during a few days 

 in 1820— July iS~2o — ^^ made the series of 

 experiments which was announced in the Latin 

 circular letter of July 21 already quoted. 



A letter from his pupil Hansteen to Faraday, 

 printed in Bence Jones's "Life of Faraday," gives 

 a fuller account of the original discovery : " At first 

 he had placed the wire at right angles to the 

 direction of the magnet, and found no effect. .After 

 the end of the lecture he said : ' Let us now once, 

 as the battery is in activity, try to place the wire 

 parallel to the needle ' ; as this was made, he was 

 quite struck with perplexity by seeing the needle 

 make a great oscillation almost at right angles 

 with the magnetic meridian. Then he said : 'Let 

 us now invert the direction of the current,' and the 

 needle deviated in the contrary direction. Thus 

 his great detection was made, and it has been 

 said, .not without reason, that he tumbled over 

 it by accident. He had not before any more idea 

 than any person that the force should be trans- 

 versal. But, as Lagrange has said of Newton on 

 a similar occasion : ' Such accidents only meet 

 persons who deserve them.'" Hansteen's remark 



