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D AY Y 847 appeared in 1812 ; and in 1813 he pxiblished his Elements of Agricultural Chemistry, the substance of his leceures delivered to the Board of Agriculture. Having obtained from the French emperor permissio.i to travel in France, Davy, on October 13, 1813, went thither with his wife and Faraday, the latter in the capacity of " assistant in experiments and writing." Faraday had been engaged on the 1st of March previous to help Davy in the laboratory of the Royal Institution. On the 29th of October, after a detention of six or seven days at Morlaix, Davy arrived in Paris, where he stayed two months, and began the course of investigations on iodine which enabled him to prove its elementary character. This body had hitherto been regarded as a compound by the French chemists. On the 13th of December Davy was elected a corresponding member of the first class of the Imperial Institute at Paris. From Paris he proceeded, in the end of December, to Montpellier, and thence to Italy. At Genoa and Florence he continued his experiments on iodine ; and at the latter place he effected the combustion of the diamond by means of the great lens in the cabinet of natural history, and discovered that, when once ignited, it will continue to burn in pure oxygen. He next pro ceeded by Rome to Naples, where he collected specimens of the colours used by the ancients in their pictures, which formed the subject of a memoir presented to the Royal Society. After spending the winter in Italy, he returned to London on April 23, 1815. The year 1815 is memorable in the history of Davy, as that in which he turned his attention to the frequent occurrence of accidents from explosions of fire-damp in coal mines. At his request specimens of the gas were sent from Newcastle to London for him to examine. He ascer tained that it would not explode when mixed with less than six or more than fourteen times its volume of air, with one-seventh its volume of carbonic acid gas, or with one- sixth its volume of nitrogen ; that in tubes one-seventh of an inchin diameter explosive mixtures of air and fire-damp could not be fired ; and that metallic tubes prevented explosions better than glass tubes. On November 9, 1815, Davy made known to the Royal Society these results of his experi ments ; and before the close of the year he had completed the invention of what has since been known as the Davy safety- lamp (see p. 72 of the present volume). In this a cage of wire-gauze, by its cooling action, prevents the flame from igniting an explosive atmosphere exterior to the lamp, even though the flame reach as far as the gauze. Of this invalu able aid to the miner the coal-owners of Newcastle and its vicinity were not slow in availing themselves ; and on the llth of October 1817 they testified their appreciation of the boon disinterestedly conferred upon them by Davy, who had taken out no patent for his invention, by present ing him with a suitably inscribed service of plate. In the succeeding year Davy was created a baronet. For his various communications to the Royal Society on the subject of fire-damp, and on the nature of flame, in 1815, 1816, and 1817, he received the Rumford medals. In 1818 and 1819 he produced four memoirs, "On the Fallacy of the Experiments in which Water is said to have been produced by the Decomposition of Chlorine," " On some Combinations of Phosphorus," " Observations on the Formation of Mists over Lakes and Rivers," and " On Electro-Magnetism." In 1818 he was sent by the British Government to examine the papyri of Herculaneum in the Neapolitan Museum, his remarks on which are con tained in a paper in the Philosophical Transactions for 1821. In 1820 Davy returned to England, and on the death of Sir Joseph Banks, in that year, he was elected president of the Royal Society ; in this position, however, it cannot be said that he always appeared to advantage, or on every occa sion acted in a manner calculated to render himself popular amongst the members. In 1821 he busied himself with electrical experiments, and in 1822 with the investigation of the fluids contained in the cavities of crystals in rocks. In 1823 he read before the Royal Society a paper " On the Application of Liquids formed by the Condensation of Gases as Mechanical Agents." In the same year he in vestigated the cause of the rapid destruction of the copper sheathing of sea-going ships. It occurred to him that, as sea-water acts only on positively electrified copper, the sheathing would be protected if he could render it slightly negative. He found that plates of copper having portions of iron or zinc attached remained unchanged after prolonged immersion in sea-water. In consequence of this discovery directions were given by the Government, after some prelim inary experiments, to apply plates of iron, or " protectors " as they were called, to several ships of the royal navy ; many merchantmen also were supplied with them. Experience, however, showed that the bottoms of the protected ships soon became extremely foul seaweed and shell-fish accumulating in such quantities as seriously to impede sailing ; so that in June 1825, much to the mortification of the inventor, orders were issued for the removal of the protectors. In 1826 Davy s health had so far declined that he was with difficulty able to indulge in his favourite sports of angling and shooting ; and on returning to London from Somersetshire he was unable to attend the anniversary dinner of the Royal Society. In January 1 827 he published his six anniversary discourses, delivered on awarding the Royal and Copley medals. Early in 1827 he was seized with an apoplectic attack, which rendered his removal to the Continent advisable. After some short stay at Ravenna he removed to Salzburg, whence, on account of the continuance of his illness, he sent in his resignation of the presidency of the Royal Society. At the end of autumn he returned to England, and in the winter he published his Salmonia, a book of some interest, written in imitation of Izaak Walton s Complete Angler. In 1828 Davy quitted England, and spent most of thf summer and autumn at Laybach. In the winter he fixed his residence at Rome, whence he sent to the Royal Society, " Remarks on the Electricity of the Torpedo," written in Illyria in October. This, with the exception of a posthumous work, entitled Consolations in Travel, or the Last Days of a Philosopher, was the final production of his pen. While at Rome, he was attacked by paralysis, from which he had already suffered. His wife and brother having hastened to his assistance, he left Rome for Geneva, where he died on the 29th of May 1829. His remains were deposited on the 1st of June in the burying-ground outside the walls of that city. Davy was of a sanguine, somewhat irritable temperament. To all his pursuits he devoted himself with a characteristic enthusiasm and firmness of purpose. His tone of mind, as indicated by his poems, was highly imaginative, attend Davy s lectures," said Coleridge, " to increase my stock of metaphors." The power and perspicacity of his intellect is sufficiently attested by his numerous and brilliant discoveries. He was not 21 years of age when he wrote. It is only by forming theories, and then comparing them with facts, that we can hope to discover the true system of nature." As an experimenter he was remark ably quick; "with Davy," it has been remarked, "rapidity was power." Of the minor observances of etiquette he was careless, and his great frankness of disposition sometimes exposed him to annoyances which the exercise of tact and caution might have obviated. His manner in society, which gave to many the impression

of a haughty consciousness of superiority, is ascribed by