Preface to The Discovery of Electromagnetism (1920)

On July the 21st 1820 the Danish physicist Hans Christian OerstedF2 published his first pamphlet on the effect of the electric current on the magnetic needle. Realizing the importance of his discovery, he composed his booklet in Latin and sent it to a great many prominent persons and to scientific reviews and societies. It caused an immense sensation everywhere; and it was at once translated and published in the scientific reviews of various countries. Not only were his experiments repeated everywhere, but they also inspired a whole series of treatises on the fascinating subject, now brought within the range of scientific research work.

In commemoration of his discovery, which proved to be of immense importance both scientifically and technically, this brochure is issued on the centennial anniversary of the great event. It contains facsimile reproductions of the Latin pamphlet published by Oersted, and of the French, Italian, German, and English translations, which soon appeared in various reviews, and also a reprint of a Danish translation from 1820.

For a long time Oersted had been deeply interested in the possibility of a connection between electricity and magnetism, two elemental forces that, taken separately, displayed many strange phenomena worthy of scientific research and suitable for a few applications in practical life. But the connection of those two forces must be considered one of the happiest events in the history of science both with regard to scientific and practical results.

Already a few years earlier, Oersted had laid down a theory about light, according to which it was due to an electric conflict between the two different kinds of electricity. Now he was struck by the idea that the connection, hitherto looked for in vain, between electricity and magnetism, might appear not to depend on separate electric forces, but on the conflict that arose between them when they united. His idea was strengthened by the fact, already well-known for more than a hundred years, that lightning will change the poles of magnetic needles without striking them.

Oersted made his first experiments at the beginning of April 1820, and through these the accuracy of his theory was confirmed.

The experiments described in the Latin pamphlet were made with a powerful battery consisting of 20 big elements during the month of July 1820.

The pamphlet is very much condensed, in fact it is so brief that in many parts of it each line can be said to describe an experiment.

The results were certainly most astonishing. In the first place, it was a surprise that the magnetic needle was only moved from its position when the galvanic circuit was complete, and not when it was open. Secondly, that the force was perpendicular to a plane through the wire and the magnetic pole. Thirdly, that it made no difference whether the uniting conductor was made of platinum, gold, silver, brass, iron, lead, tin, or a mass of mercury; even water was employed with equal success. Finally, that the effect of the uniting wire, in contrast to other electric forces known till then, passed through all solids, even water and metals, with the exception of iron.

Oersted made experiments on the direction of the force, when the uniting wire is placed in various positions to the magnetic needle (i. e. whether it is placed to the east or to the west of it, above or beneath it, parallel or perpendicular to it), and he summed up his results in the theory that the effect performs a circular motion round the uniting wire, and that the conflict is not confined to the conductor but dispersed pretty widely in the surrounding space. In many respects Oersted’s idea of electric conflict is broader than a later generation’s idea of the electric current. The recognition made in our days, that electrons are rapidly moving to and fro among the atoms in the conducting wire, seems to be very much akin to Oersted’s theories.

After having published his first pamphlet, Oersted continued his research work. He thus made extremely interesting experiments on the effect of a single element and, by suspending it in a cord so that it was free to revolve, he proved that the conductor is influenced by the magnet.F3

Among his numerous works dealing with physics and chemistry, only a few can be mentioned here, viz. his researches on the compressibility of water, and his preparing of anhydrous chloride of aluminium, which is known to have been of great importance for the syntheses of organic chemistry.

As to details, we shall have to refer to the publication of the works of Hans Christian Oersted, which, on account of the centenary jubilee, is issued by the Royal Danish Society of Sciences, and edited by Kirstine Meyer, née Bjerrum,F4 and also to Mr. Harding’s edition of Oersted’s correspondance with men of science.F5

Hans Christian Oersted, who was born on August the 14th 1777 and who died on March the 9th 1851, was professor of physics at the University of Copenhagen.

He rendered great services to Denmark by spreading the knowledge of the study of physics. In 1824 he founded »Selskabet for Naturlærens Udbredelse« (The Society for the Propagation of Sciences). Until his death he was the head of the Royal Technical College of Copenhagen, which was founded in 1829 according to his plan.

Oersted was a very poetical nature; he stood in close relation to most of the leading intellectuals of the day. He was the good genius of the world-famous poet Hans Christian Andersen, and remained his staunch friend to the last. Through his pamphlet on »The Spirit in Nature« Oersted highly influenced his contemporaries’ view of life.

His inspiring and enthusiastic activity for the spreading of the knowledge of physics has been of decisive importance to several Danish leaders of industry.

With his sensational discovery of electromagnetism Oersted enters the ranks of those world-famous men who have taken prominent parts in the development of electricity both as a science in itself and as a basis for all the wonderful practical applications which have proved themselves to be of such great importance to modern civilization.

No wonder that Oersted’s compatriots are proud to couple his name with Danish names such as that of the astronomer Tycho Brahe, whose astronomic works are known all over the world, and the name of Ole Roemer, who perceived that light takes time to spread, and who first of all measured out its velocity.

The Oersted medal reproduced on the title-page of this brochure, is given as a prize for scientific work. It is only one of the many visible signs of the deep gratitude with which Denmark is always sure to surround the memory of Hans Christian Oersted.