sorbed in its pursuit. The activity and suggestiveness of his mind outstripped all formula. He entered upon speculations and inquiries far in advance of the rudiments he was studying. These, in due time, assumed a practical guise in the shape of essays, and, being crude and imperfect, excited the ire of the reviewers. "These critics," he writes, "perhaps do not understand that these experiments were made when I had studied chemistry only four months, when I had never seen a single experiment executed, and when all my information was derived from Nicholson's Chemistry and Lavoisier's Elements."

The early experiments of this philosopher were performed in a small bed-room in Mr. Tomkins's house, with a laboratory consisting of vials, wine-glasses, tea-cups, tobacco-pipes, and earthen crucibles; his materials chiefly the mineral acids, the alkalies, and the other articles common to an apothecary's shop. He had no furnace, and, when he needed heat, was compelled to go into the kitchen, where you may rest assured the cook did not thank him for his devotion to science. Notwithstanding these drawbacks, he made rapid progress in the study of chemistry and the relative sciences, and before he had reached his twentieth year was remarkable for the exactness of his information on many learned subjects. He now left Penzance, having obtained the situation of superintendent of the Pneumatic Institution which had been established at Clifton for the purpose of trying the medicinal effects of various gases. Davy remained here for some time, and was quite enthusiastic about the prospects of curing disease by the use of various gases hitherto unknown to medicine. He describes his occupation as "useful to mankind; pursuits which promise me, at some future time, the honorable meed of the applause of enlightened men." This prophetic feeling of distinction was soon about to be realized. The Royal Institution had been founded a short time previously, after a plan of Count Rumford's, for the purpose of diffusing a knowledge of science and of its application to the common purposes of life, and of exciting a taste for science among the higher ranks. In consequence of the expected retirement of the professor of chemistry, a successor was sought for, and the choice fell upon Davy. The duties on which he entered were those of assistant lecturer on chemistry and director of the laboratory; but, according to the terms on which he accepted the situation, this was merely a tem

porary arrangement, and to last only until he should deem himself fit to fill the professor's chair. On the 31st of May, 1802, he was formally appointed to the office, and, notwithstanding his youth, immediately attracted the attention of the philosophical world. His lectures were eagerly attended by the distinguished in science, literature, and position. Compliments, invitations, and presents were showered upon him in abundance from all quarters; his society was courted by all, and all appeared proud of his acquaintance. His youth, his simplicity, his natural eloquence, his happy illustrations, and well-conducted experiments, were the introductions which gave him welcome every where. In 1803 Davy was elected a Fellow of the Royal Society, and for ten sessions delighted the institution and enriched its Transactions with his lectures. His scientific labors during this time may be divided into two portions, the earlier one terminating with his great discovery of the decomposition of the fixed alkalies, the result and reward of his electro-chemical researches; the latter in the reestablishment of the simple nature of chlorine.

During the first portion of the period, among a great variety of objects of research, his attention was more particularly directed to the following: First, the investigation of astringent vegetables, in connection with the art of tanning; secondly, the analysis of rocks and minerals, in connection with geology; thirdly, the comprehensive subject of agricultural chemistry; and, fourthly, galvanism, and electro-chemical science. In the year 1812, unsolicited by Davy, the prince regent conferred on him the honor of knighthood. It was intended, doubtless, as a mark of respect to a man of unusual genius, and was so accepted. In those days men of genius were flattered by such little trifles. In these later times they despise them. A few days after this event Davy married a charming widow, Mrs. Appreece by name. Honors were showered on him; this happiness he achieved.

It is unnecessary and uninteresting in the present day to recount the innumerable distinctions that were bestowed on Davy by the learned bodies of Europe; to say when he was appointed a corresponding member of this society, and an honorary member of that. It is sufficient for our purpose that he was accepted and received as a man of mark in the scientific world, and to hasten to what he accomplished to give him this distinction.

One of the fruits of his researches was the "safety-lamp," now

familiar to every eye. The object which this simple instrument so happily accomplishes is the prevention of explosions of firedamp in mines. From innumerable experiments, Davy found that this gas required to be mixed with a very large quantity of atmospheric air to produce an explosion; that it was the least readily combustible of all the inflammable gases, or required the highest temperature, being neither exploded nor fired by red-hot charcoal or red-hot iron; and, farther, that the heat it produced when inflamed was less than from any other inflammable gas, and, consequently, that the expansive effect from heat attending its explosion was also less. He found that on mixing one part of carbonic acid gas or fixed air with seven parts of an explosive mixture of fire-damp, or one part of azote with six parts, their power of exploding was destroyed. He found that in exploding a mixture in a glass tube of one fourth of an inch in diameter and a foot long, more than a second was required before the flame reached from one end to the other; and that in tubes of one seventh of an inch in diameter, explosive mixtures could not be fired when they opened into the atmosphere; and that metallic tubes prevented explosion better than glass tubes. These were the facts from which the discovery of the safety-lamp was made. In reasoning upon the various phenomena, it occurred to Davy that, as a considerable heat was required for the inflammation of the firedamp, and as it produced, in burning, a comparatively small degree of heat, the effect of carbonic acid and azote, and of the surfaces of small tubes in preventing its explosion, depended upon their cooling powers, upon their lowering the temperature of the exploding mixture so much that it was no longer sufficient for its continuous inflammation. He says, "This idea, which was confirmed by various obvious considerations, led to an immediate result-the possibility of constructing a lamp in which the cooling powers of the azote or carbonic acid formed by the combustion, or the cooling power of the apertures through which the air entered and made its exit, should prevent the communication of explosion." The prosecution of this idea led to the invention of the safety-lamp-a cage of wire gauze, which actually made prisoner the flame of the fire-damp, and in its prison consumed it; and while it confined the dangerous explosive flame, it permitted air to pass and light to escape; and though, from the combustion of the fire-damp, the cage might become red hot, yet still it acted

the part of a safety-lamp, and restrained the flaming element within its narrow bounds, simply by presenting a surface of network, the temperature of which, under ordinary circumstances, could not be raised sufficiently to explode the surrounding atmosphere of fire-damp, or to allow the flame within to pass unextinguished.

Another useful and valuable discovery was made by Davy, namely, a method of preserving the copper sheathing of ships from the corrosive action of salt water. The principle of protection was found to be perfect, but in its practical application some difficulties arose which Davy did not live to obviate, although he made some valuable suggestions toward that end. Many other useful and eminently practical discoveries were made by Davy, especially in the tanning business, which in those days was carried on with hereditary rather than chemical skill. The experimental character of his mind led him naturally into new fields of investigation, and it is but justice to say that whatever he approached he benefited. Few men possessed a more practical yet thoroughly refined taste than Davy. Philosophers not unfrequently lose themselves in the abstruseness of the subjects they investigate, but with him this was never the case. He was a man of the world; keenly observant; mindful of its wants, and anxious to lend all the force of his character and genius to the onward progress of civilization. He was of a contented and beautiful disposition, fond of innocent amusements, and especially delighted with the ever-varying aspects of nature. He had traveled much, and, at the time when death overtook him, was on the Continent, endeavoring to regain in genial climes the health he had lost by too close application. It was during this time that he recomposed his delightful little book on fly-fishing, called "Salmonia,” a work which justly ranks next to old Izaak Walton's for variety of information and charming picturesqueness of detail. He was also engaged on another work called "The Last Days of a Philosopher," since given to the world. He was a voluminous writer, and it may be doubted if any modern philosopher has contributed more largely to the literature of science than he.

Sir Humphrey Davy died at Geneva on the 30th of May, 1829. He had only arrived in that city the day before, and having been attacked by apoplexy after he had gone to bed, expired at an early hour in the morning.

"I KNEW Darteneuf well, for I was his footman.” Such was the characteristic admission of the subject of this memoir, uttered to that severest of critics, Dr. Johnson, and at a time, too, when the name of Dodsley was a passport to much excellent society. An individual blessed with such strength of character presents many excellent traits worthy of imitation, and we give his biography as an essential element of self-made success.

Robert Dodsley was born in 1703 at Mansfield, in Nottinghamshire. Nothing is known of his parents, except that they were poor, and unable to give him more than an ordinary rudimental education. Early in life he became a male servant, or footman, in the service of the Honorable Mr. Lowther, and continued in that somewhat degrading employment for many years, wearing a livery, and exhibiting his calves in the most approved fashion of the day. He was steady and observant, and his natural abilities gave him some little distinction beyond that awarded to his station. Having made some attempts at versification, he found patrons who induced him to publish them, and exerted themselves to procure a handsome list of subscribers. The title of this work, which was published in 1732, was, "The Muse in Livery. A Collection of Poems. By R. Dodsley, Footman to a Person of Quality at Whitehall." The contents of the volume were not remarkable for poetic beauty or for exactness of measure, but, heralded in such a candid way, they attracted attention, and induced Dodsley to prepare another work for the press, called "The Toy Shop." This was a dramatic satire on the fashionable follies of the day, and had merit. Pope (to whom it was shown) expressed himself warmly in its favor, and exerted himself to get it brought out on the stage. In 1735 it was produced at Covent Garden Theatre, and at once achieved a signal success.

There was now a fair prospect for Dodsley in the literary world. Many men have adopted the profession of letters with much smaller capital. But, although a poet, he was of a practical turn of mind, and could see that commerce was better than literature in a pe