Michael Faraday, His Life and Work

by Silvanus P. Thompson

This discovery, which showed what was the geometrical relation between the magnet and the current, also showed why the earlier attempts had failed. It was requisite that the electricity should be in a state of steady flow; neither at rest as in the experiments with electric charges, nor yet in capricious or oscillatory rush as in those with spark-discharges. Faraday, adverting a quarter of a century later to Oersted’s discovery, said: “It burst open the gates of a domain in science, dark till then, and filled it with a flood of light.”

The very day that Oersted’s memoir was published in England, Davy brought a copy down into the laboratory of the Royal Institution, and he and Faraday at once set to work to repeat the experiments and verify the facts.

It is a matter of history how, on the publication of Oersted’s discovery, Ampère leaped forward to generalise on electromagnetic actions, and discovered the mutual actions that may exist between two currents, or rather between two conducting wires that carry currents. They are found to experience mutual mechanical forces urging them into parallel proximity. Biot and Laplace added to these investigations, as also did Arago. Davy discovered that the naked copper wire, while carrying a current, could attract iron filings to itself—not end-ways in adherent tufts, as the pole of a magnet does, but laterally, each filing or chainlet of filings tending to set itself tangentially at right angles to the axis of the wire.

A PARADOXICAL PHENOMENON.

This curious right-angled relation between electric flow and magnetic force came as a complete paradox or puzzle to the scientific world. It had taken centuries to throw off the strange unmechanical ideas of force which had dominated the older astronomy. The epicyclic motions of the planets postulated by the Ptolemaic system were in no way to be accounted for upon mechanical principles. Kepler’s laws of planetary motion were merely empirical, embodying the results of observation, until Newton’s discovery of the laws of circular motion and of the principle of universal gravitation placed the planetary theory on a rational basis. Newton’s laws required that forces should act in straight lines, and that to every action there should be an equal and opposite reaction. If A attracted B, then B attracted A with an equal force, and the mutual force must be in the line drawn from A to B. The discovery by Oersted that the magnet pole was urged by the electric wire in a direction transverse to the line joining them, appeared at first sight to contravene the ideas of force so thoroughly established by Newton. How could this transversality be explained? Some sought to explain the effect by considering the conducting wire to operate as if made up of a number of short magnets set transversely across the wire, all their north poles being set towards the right, and all their south poles towards the left. Ampère took the alternative view that the magnet might be regarded as equivalent to a number of electric currents circulating transversely around the core as an axis. In neither case was the explanation complete.

TWO YEARS WASTED.

Faraday’s scientific activities in the year 1820 were very marked. New researches on steel had been going on for some months. It had been hoped that by alloying iron with some other metals, such as silver, platinum, or nickel, a non-rusting alloy might be found. This idea took its rise from the erroneous notion that meteoric iron, which is richly alloyed with nickel, does not rust. Faraday found nickel steel to be more readily oxidised, not less, than ordinary steel. The platinum steel was also a failure. Silver steel was of more interest, though it was found impossible to incorporate in the alloy more than a small percentage of silver. Nevertheless, silver steel was used for some time by a Sheffield firm for manufacture of fenders. The alloys of iron with platinum, iridium, and rhodium were also of no great use. But the research demonstrated the surprising effects which minute quantities of other metals may have upon the quality of steel. Occasionally in later life Faraday would present one of his friends with a razor made from his own special steel. A paper on the use of alloys of steel in surgical instrument making was published in the Quarterly Journal in collaboration with Mr. Stodart. Faraday also read his first paper before the Royal Society on two new compounds of chlorine and carbon, and on a new compound of iodine, carbon, and hydrogen. He also succeeded in making artificial plumbago from charcoal. In writing to his friend Professor G. de la Rive, he gives a long and chatty abstract of his researches on the alloys of steel. They appear to have originated in some analyses of wootz or Indian steel, a material which, when etched with acid, shows a beautifully damascened or reticulated surface. This effect Faraday never found with pure steel, but imitated it successfully with a steel alloyed with “the metal of alumine,” an element which down to that time had not been isolated. He then describes the rhodium, silver, and nickel steels, and mentions incidentally how he has been surprised to discover that he can volatilise silver, and that he cannot reduce the metal titanium. He is doubtful whether this metal “ever has been reduced at all in the pure state.” [It can now be readily reduced either in the electric arc or by the use of metallic aluminium.] He winds up the letter with the words: “Pray pity us that, after two years’ experiments, we have got no further; but I am sure, if you knew the labour of the experiments, you would applaud us for our perseverance at least.”

In 1821, the year of his marriage, came the first of the important scientific discoveries which brought him international fame. This was the discovery of the electromagnetic rotations. It appears that Oersted’s brilliant flash of insight that the “electric conflict acts in a revolving manner” upon the pole of the neighbouring compass needle had been lost sight of in the discussions which followed, and to which allusion has been made above. All the world was thinking about attractions and repulsions. Two men, however, seem to have gone a little further in their ideas. Dr. Wollaston had suggested that there ought to be a tendency, when a magnet pole was presented towards a straight conducting wire carrying a current, for that conducting wire to revolve around its own axis. This effect—though in recent years it has been observed by Mr. George Gore—he unsuccessfully tried to observe by experiments. He came in April, 1821, to the laboratory of the Royal Institution to make an experiment, but without result. Faraday, at the request of his friend Phillips, who was editor of the Annals of Philosophy, wrote for that magazine in July, August, and September a historical sketch of electromagnetism down to date. This was one of the very few of Faraday’s writings that was anonymous. It was simply signed “M.” This is in vol. iii. p. 107. On p. 117 the editor says: “To the historical sketch of electromagnetism with which I have been favoured by my anonymous correspondent, I shall add a sketch of the discoveries that have been made by Mr. Faraday of the Royal Institution.” In the course of this work Faraday repeated for his own satisfaction almost all the experiments that he described. This led him to discover that a wire, included in the circuit, but mounted so as to hang with its lower end in a pool of quicksilver, could rotate around the pole of a magnet; and conversely that if the wire were fixed and the pole of the magnet free to move, the latter would rotate around the former. “I did not realise,” he wrote, “Dr. Wollaston’s expectation of the rotation of the electromagnetic wire around its axis.” As was so often his custom, he had no sooner finished the research for publication than he dashed off a brief summary of it in a letter to one of his friends. On this occasion it was Professor G. de la Rive, of Geneva, who was the recipient of his confidences. On September 12 he wrote:—

LETTER TO DE LA RIVE.

I am much flattered and encouraged to go on by your good opinion of what little things I have been able to do in science, and especially as regards the chlorides of carbon.