He performed very little laboratory work till the end of 1844, indulging in the mean time in needful rest. In the beginning of 1845 he made a second series of experiments on the condensation of gases, and about the first of September began the investigation of the magnetic relations of light, which led him to the discovery of the peculiar phenomena of magnecrystallic action. In November he announced his discovery of the "Magnetization of Light and the Illumination of the Lines of Magnetic Force." Whatever doubt there may be as to the soundness of his theory in every particular, his paper is full of the profoundest thought."I have long," he says,held an opinion almost amounting to a conviction, in common I believe with many other lovers of natural knowledge, that the various forms under which the forces of matter are made manifest have one common origin; in other words, are so directly related and mutually dependent, that they are convertible, as it were, into one another, and possess equivalents of power in their action." He always held that the theory of gravitation, not as it existed in the mind of Newton, but as commonly understood, embraced an absurdity, by supposing that when the manifestation of attraction between two bodies decreased in proportion to the square of their distance from each other, an equivalent of energy was lost; thus denying the doctrine of conservation of force," which he considered as established.

In December of the same year he published a memoir addressed to the royal society on the "Magnetic Condition of all Matter," in which he discussed the phenomena presented by diamagnetic bodies, or such as are repelled by the poles of a magnet instead of being attracted, like iron or other paramagnetic bodies, as he termed them. Between this time and 1851 he was much occupied with the magnetic condition of gases, finding, among other facts, oxygen to be powerfully paramagnetic. Among the papers published is one on the diamag-netic condition of flame and gases in the "Philosophical Magazine for December, 1847, and two elaborate memoirs on atmospheric magnetism sent to the royal society on Oct. 9 and Nov. 19, 1850. He applies his theory of the lines of magnetic force to the solution of the cause of the distribution of magnetism in the earth's atmosphere, and of annual and diurnal variations; and although it has been found that the variation in the declination of the magnetic needle is connected with solar spots, it can scarcely be doubted, as Tyndall remarks,that a body so magnetic as oxygen, swathing the earth and subject to variations of temperature, diurnal and annual, must affect the manifestations of terrestrial magnetism." Faraday was opposed to the atomic theory, and it is very difficult, perhaps impossible, to comprehend his idea of the subject.

In the place of an atom as a particle of matter he substituted a point or centre of force, and connected points of force with lines of force. He says:This view of the constitution of matter would seem to involve necessarily the conclusion that matter fills all space, or at least all space to which gravitation extends; for gravitation is a property of matter dependent on a certain force, and it is this force which constitutes the matter. In that view matter is not mutually penetrable; but each atom extends, so to say, throughout the whole of the solar system, yet always retaining its own centre of force." In 1853, at the request of many friends, he was induced to investigate the phenomena of "table-turning," and he prepared apparatus with which to test the reality of the phenomena in question. The investigations were conducted with great care, but he discovered no manifestations of any of the forces, natural or supernatural, which had been suggested as possibly concerned in the phenomena. In 1854 he made a series of experiments connected with submarine telegraphy, which were of great value.

In 1855 he brought his experimental researches on electricity to a close, having followed them, along with his other investigations, during a quarter of a century."The record of this work which he has left in his manuscripts and republished in his three volumes of ' Electrical Researches' will ever remain," says his biographer, Dr. Bence Jones, as his noblest monument: full of genius in the conception; full of finished and most accurate work in the execution; in quantity so vast that it seems impossible that one man could have done so much. Lastly, the circumstances under which this work was done were those of penury. During a great part of these 26 years the royal institution was kept alive by the lectures which Faraday gave for it. He had no grant from the royal society, and throughout almost the whole of this time the fixed income which the institution could afford to give him was £100 a year, to which the Fullerian professorship added nearly £100 more." In 1856 he was again engaged in experimenting for the Trinity house with electric light for lighthouses, and it is thought that his frequent journeys and night excursions in the channel during the winter, when he was 70 years of age, were the remote causes of his last illness.

In 1858 the queen assigned him a house in Hampton Court. In 1860 he resumed his eldership in the Sande-manian church, and held it for the same period as before, resigning in consequence of not being able conscientiously to perform the duties of the office. On June 20, 1862, he gave his last Friday evening lecture, which was on the subject of gas furnaces; in the notes for the lecture he mentions his loss of memory. He was the "prince of popular lecturers," and drew crowds from the theatres to the lecture room of the royal institution on Friday evenings. It was here that he appeared in his glory, absorbed and earnest as a child over his toys, repeating his experiments, in which none were more interested than the lecturer himself. His facility in experimenting was a gift of genius, and his lectures to children are said to have been the most perfect examples of extemporaneous speaking. He was an honorary member of 72 societies, in almost every part of the world. Besides his voluminous manuscripts, papers in the "Philosophical Transactions," and journals, the following works have been published: Chemical Manipulations (1827);

"Researches in Electricity (1831-'55);Lectures on Non-Metallic Elements (1853); Researches in Chemistry and Physics" (1859);

"Lectures on the Forces of Matter (1860); and "Lectures on the Chemical History of a Candle" (1861). The chief biographies of Faraday are: a small memoir by Dr. J.

II. Gladstone; Faraday as a Discoverer," by Prof. Tyndall (1868); and "Life and Letters of Faraday," by Dr. Bence Jones (1869).