tions, including magnetic storms. Whether in these inquiries Faraday succeeded in establishing the points at which he aimed is more than can be asserted, but that a body so magnetic as oxygen, swathing the earth, and subject to local variations of temperature, diurnal and annual must influence the manifestations of terrestrial magnetism can hardly be doubted. The air that stands on a square foot of the earth's surface is equivalent in magnetic force to 8,160 pounds of crystallised protosulphate of iron. Such an envelope can hardly be absolutely neutral as regards the deportment of the magnetic needle.
Faraday's speculations on matter and force are in the highest degree curious and interesting. He sought, among other things, to liberate himself from the bondage of the atomic theory, and his views have probably had a serious influence on his chemical successors. Some of these consider, as he did, 'that the words definite proportions, equivalents, primes, &c.…express all the facts of what is usually called the atomic theory in chemistry.' Outside chemistry proper, however, domains of philosophy exist where the words quoted by Faraday would have no meaning, and which the conception of the atom is essential. We cannot, for example, put a definite proportion or an equivalent number as the origin of a train of waves in the luminiferous ether. Here the vibrating atom must be regarded as the real source of the motion. Still Faraday's reasonings are in the highest degree curious and ingenious. Grappling with the notion that matter is made up of molecules separated from each other by intermolecular spaces, he observes that 'space must be taken as the only continuous part of a body so constituted.' He turns to electricity in search of a test for this notion. Consider, he argues, the case of a nonconductor like shellac. Space must here be an insulator, for if it were a conductor it would resemble a 'fine metallic web' penetrating the lac in every direction. But the fact is that it resembles the wax of black sealing wax, which surrounds and insulates the particles of conducting carbon, to which the blackness is due. In the case of shellac, therefore, space is an insulator. But in the case of a conductor we have, as before, space surrounding every atom. If space be an insulator, as proved a moment ago, there can be no transmission of electricity from atom to atom. But there is transmission, hence space is a conductor. Thus he hampers the atomic theory. 'The reasoning ends in a subversion of that theory altogether; for, if space be an insulator, it cannot exist in conducting bodies, and if it be a conductor, it cannot exist in insulating bodies. Any ground of reasoning,' he adds, abandoning his usual temperate caution, 'which tends to such conclusions as these, must in itself be false.' Like Boscovich, Faraday abolished the atom, and put a 'centre of force' in its place.
Another strange speculation is embodied in a letter to Mr. Phillips published in the 'Philosophical Magazine' for May 1846. It is entitled 'Thoughts on Ray Vibrations,' and seems to show that Faraday looked upon what he called the lines of gravitating force as so many fine strings capable of vibration. Along these lines he supposes the undulations of light to be propagated. He concludes that 'this notion, as far as it is admitted, will dispense with the ether,' adding that his view 'endeavours to dismiss the ether, but not the vibration.' There was a vast vagueness, and an immeasurable hopefulness in Faraday's views of matter and force. A strong imagination is required to understand him and to sympathise with him. His views had to him almost the stimulus of a religion, and they urged him to work with expectation and success in regions where a less original, though better trained, man of science would have laid down his tools in despair.
His 'lines of magnetic force' took possession more and more of Faraday's mind. The last three papers of his experimental researches are occupied with this subject. In these papers experiments of exquisite beauty, on wires moving round magnets, are described. At first regarding them as a mere 'representative idea,' he leaned in after years more and more to the notion that the 'lines of force' were connected with a physical substratum. In this connection the title of his last paper is significant: 'On the Physical Character of the Lines of Magnetic Force.' He has been known to hold up a magnet in one of his lectures and, knocking it with his knuckle, to exclaim: 'Not only is the force here, but it is also here, and here, and here,' passing at the same time his hand through the air round the magnet. For the sake of reference Faraday numbered all the paragraphs in his memoirs, the last number being 3299.
Remarkable testimony as to Faraday's power as a lecturer is given by the late Sir Frederick Pollock in his 'Remembrances.' To prepare himself for lecturing he took lessons in elocution; his indebtedness to these was, however, small. His influence as a lecturer consisted less in the logical and lucid arrangement of his materials than in the grace, earnestness, and refinement of his whole demeanour. In his juvenile lectures,
