FARADAY 83 had been sent to Davy by the duchess of Montrose. In 1817 he gave a second course of lectures before the city philosophical so- ciety, at the tenth of which, on carbon, he used notes for the first time, instead of read- ing his lectures. In 1818 he investigated the subject of sounding flames, showing that they were not dependent, as De la Rive had sup- posed, upon the sudden expansion and con- densation of vapor, but that they were con- nected with musical vibrations produced in a manner similar to the tones of a flute or of an organ pipe. He obtained the sounds as well when using a flame of carbonic oxide gas as when using one of hydrogen. In 1819 he made a tour on foot through Wales, and kept a journal in which there are many passages man- ifesting his intense love of nature and his vivid powers of description. In 1820 he published a paper on two new compounds of chlorine and carbon, and on a compound of iodine, carbon, and hydrogen. It was read before the royal society, and was the first which was published in the " Philosophical Transactions." On June 12, 1821, he was married to Miss Sa- rah Barnard, a daughter of an elder in the Sandemanian church, and, having obtained leave, took his wife to reside at the royal in- stitution, where they remained until they moved to the house assigned them in Hampton Court by the queen in 1858. A month after his marriage he became a member of the San- demanian church. His ideas of religion are indicated by the following quotation from a lecture delivered on medical education in 1854 : "High as man is placed above the creatures around him, there is a higher and far more exalted position within his view ; and the ways are infinite in which he occupies his thoughts about his fears, or hopes, or expectations of a future life. I believe that the truth of the fu- ture cannot be brought to his knowledge by any exertion of his mental powers, however exalted they may be; that it is made known to him by other teaching than his own, and is received through simple belief of the testimony given. Let no one suppose for a moment that the self-education I am about to commend, in respect to the things of this life, extends to any consideration of the hope set before us, as if man by reasoning could find out God." In 1821 there occurred the only unpleasant cir- cumstance that seems ever to have been con- nected with his life. Dr. Wollaston was the first person to entertain the idea of causing a wire to revolve around a magnet, or upon its own axis, and in a visit to Davy at the royal institution made some experiments and con- versed upon the subject, during a part of which time Faraday was present. It greatly excited his interest, and he could not refrain from making experiments, the result of which was that in the months of July, August, and September he wrote a history of the progress of electro-magnetism, which was published in the "Annals of Philosophy." In the latter month he made the discovery of the rotation of a wire in a voltaic circuit round a magnet, and of a magnet round a wire. He says: "I did not realize Dr. Wollaston's expectation of the rotation of the electro-magnetic wire round its axis; that fact was discovered by Ampere at a later date." These experiments and publications of Faraday created consider- able feeling, so much that the matter was dis- cussed two years afterward, when he was pro- posed as a member of the royal society. He was charged with trespassing upon the prov- ince of .another, and with using another's im- plements in cultivating the field ; but his un- blemished character in all other relations, and the great discoveries which he made in this abstruse department of electro-chemistry and electro-magnetism, at last removed all tinge of imputation of wrong intention; and long before he closed his labors all men of science were heartily glad that Faraday had followed his inclinations. About the year 1822 and for some time after he investigated the subject of the liquefaction of vapors and gases, and in 1823 examined a substance which had been regarded as pure chlorine, but which Davy in 1810 had proved to be a hydrate. Faraday first analyzed this hydrate, and then at the instance of Davy subjected it to the action of its own pressure on being heated in a strong sealed tube, by which means he obtained liquid chlorine. Extending his experiments to other gases, he succeeded in reducing a number of them to a liquid state. His first memoir was read before the royal society April 10, 1823, and the second on Dec. 19, 1844. Prof. Tyn- dall says that while making his first series of experiments an explosion occurred by which 13 pieces of glass were driven into his eyes. In 1825 he published a paper in the " Philo- sophical Transactions " on new compounds of carbon and hydrogen, in which he announced the discovery of benzole. But his mind contin- ually reverted from chemistry to physics, and in 1826 he was again engaged upon the subject of vaporization, in which he came to the con- clusion that a limit exists, and that our atmos- phere does not contain the vapors of what are usually denominated the fixed constituents of the earth's crust. During the year he had ten papers in the " Quarterly Journal," one of the principal being on pure caoutchouc, his analy- sis of which is given in the article on that substance in this work. In 1825 Faraday was appointed with Sir John Herschel and Mr. Dolland on a committee to examine the manu- facture of glass for optical purposes. Their experiments continued for four years, when Faraday delivered his first Bakerian lecture "On the Manufacture of Glass for Optical Purposes." This paper required three succes- sive sittings of the royal society, and although the investigation had not much immediate practical use, it led to other and very impor- tant discoveries. In 1831 he published a paper on vibrating surfaces, in which he solved the
