manded by General Putnam. He was distinguished by the facility with which he adapted himself to, and rendered himself useful in this peculiar mode of clerical duty. After the peace, he was chosen to represent the town of Northampton in the general court of Boston. Possessing poetical taste, he published, in 1785, an epic poem, called the "Conquest of Canaan." In 1794, he published "Greenfield Hill," descriptive of the place of his residence, situ. ated on the coast of the Sound of Long Island. His reputation as a preacher was constantly increasing, being distinguished for the clearness of his thoughts, the copiousness and elegance of his diction, and for the distinctness and warmth of his elocution. On the death then of President Stiles, in May, 1795, Mr Dwight was named by the public voice as the fittest person to succeed. He was elected, and discharged his duties with such ability, that the college soon began to flourish beyond former example. His labours seem indeed to have been very great, since, besides the general superintend

ence of the college, he undertook the entire instruction of the senior class in rhetoric, logic, metaphysics, and ethics; and heard each week two disputations. As professor of divinity, he delivered every Sunday forenoon, a Lecture, forming part of a general course of theological science, completed in four years; while in the afternoon, he gave a Sermon on miscellaneous topics. His course of divinity he left revised, and in a state ready for the press. In the same state were found a number of miscellaneous discourses and dissertations connected with the proofs of Christianity and Biblical literature. He left also, ready for the press, another laborious work-an Account of the States of New England and of New York, collected in various tours through this territory, during the last twenty years of his life. He contributed numerous papers to the Connecticut Academy of Arts and Sciences, in the formation of which he had taken a very active part. He died on the 11th Ja nuary, 1817.*

In taking a view of the accessions made during the year to the different branches of physical science, it is not our intention to enter into any detail of minute particulars. The object will rather be to embrace those grand and leading discoveries, which retain a permanent interest, and form an era in the department of human knowledge to which they belong. Among these, the following are the most promi

nent:

DAVY'S SAFETY Lamp, and re

SEARCHES ON FLAME.

While the improvements made in science afford to accomplished minds a high rational pleasure, independent of their application to the useful arts, their influence on the latter contributes materially to those sentiments of respect and of gratitude which mankind at large entertain towards them; and in proportion to their operation as promoting public wealth and the general comfort of society, such sentiments are elicited with the greater promptitude and warmth. On this account, it is with feelings of no common admiration that we congratulate the public on the

discovery of the safety-lamp of Sir Humphrey Davy, by means of which, subterranean mines, which hitherto could not be visited without the risk of ruinous explosions, are rendered accessible without danger.

In the coal mines of Newcastle and most other coal districts, an evolution of inflammable gas, called by chemists carbureted hydrogen, and by the workmen, fire-damp, is liable to take place, and to accumulate in situations in which no regular ventilation is kept up. Wherever a mine, or a division of a mine, has been for some time left without ventilation, it is always dangerous to approach it with a lamp or candle, and in cases in which the rashness of individuals has allowed them to neglect the danger, or in which accumulations of the inflammable gas have been more rapidly formed than they were aware, an immense volume of an explosive mixture, has in many instances been set on fire, and explosions have been produced by which numerous lives have been lost; persons who have escaped immediate death have been miserably scorched, and the machinery connected with the works has been destroyed. Various preventives have been

suggested for destroying or removing these gases, or for lighting the mines where they are lodged, without the risk of explosion.

Sir Humphry Davy, on the invitation of the Sunderland committee formed for the express purpose of obviating these dangers, went to that part of the country to investigate the subject, and the result of his investigations, and the multiplied experiments dictated by his inventive genius, and conducted with unwearied perseverance, havebeen completely satisfactory. It is unnecessary to mention the various expedients previously suggested for lighting the mines. One was that of the steel mill, consisting of a wheel with large steel teeth, made to elicit sparks from flint during its revolutions; light is thus afforded, while the heat generated is not so high as to explode the gas. Plans also were attempted for supporting the flame of a close lamp by air introduced from without by a tube, either with or without machinery. These and other measures, however, were either ineffectual or too cumbersome for general use, or laboured under both disadvantages together.

Sir H. Davy's first experiments consisted in examining the combustibility of this gas, the proportions of mixtures of it with atmospheric air which are combustible, and the circumstances occurring during combustion by which the process is liable to be arrested. He found that this gas differs from other inflammable gases in its combustibility, requiring a much higher temperature to produce explosion. He found also that the flame generated in combustion or explosion, did not pass through metallic tubes of small bore, and a certain proportional length. He ascertained at the same time the quantities of azote and of carbonic acid, which, by their presence, extinguished flame, an effect which he found to arise from their cooling power. On the data thus pro

VOL. X. PART I.

cured, he first constructed a lamp which gave light through glass, but was close in every part, with the exception of two or three small orifices beneath for admitting air to support the flame, and one above to give passage to the smoke and residual gases. These orifices admitted only a limited quantity of aerial fluid into the lamp, and such a quantity of azote and carbonic acid was produced as prevented the explosion of the fire-damp, while the nature of the apertures rendered it incapable of communicating any explosion to the surrounding air.

In this lantern the air admitted was only sufficient to support a certain size of flame: the mixture of fire-damp and air being gradually admitted, the first effect of the fire-damp was to produce a larger flame round that of the lamp, and this flame consuming the oxygen which the flame of the lamp required, and the standard of the power of the air to support flame being lowered by the admixture of fire-damp, and by its rarefaction, both the flame of the firedamp and that of the taper or lamp were extinguished together. The azoté and carbonic acid present, by mixing with the fire-damp, prevented explosion in any part of the lantern. As the air gradually became contaminated with fire-damp, this fire damp was consumed in the body of the lantern, and the air passing through the chimney contained no inflammable mixture. In an experiment made on this point, Sir H. Davy gradually threw an explosive mixture of fire-damp and air into this lantern from a bladder. By a rapid jet of gas he produced an explosion in the body of the lantern. There was no tendency to a communication of the flame through the apertures below; the flame did not appear to extend upwards farther than the lower aperture of the chimney, and the explosion mercly threw out from it a gust of foul air. The principle of this lamp being esta

R

proving that there is oxygen even in its interior part." When this philosopher observed such a result, it must have been a deception arising from some disturbance of the flame, by which Oxygen was admitted to its centre, The uniform effect is, when we convey a piece of burning phosphorus in a platinum spoon into the centre of a flame of alcohol, taking care to avoid agitation, that the combustion of the phosphorus instantly ceases; when we remove it into the open air, it recommences, and so on alternately, as long as any remains unburnt. While it is in the air, it is covered with its peculiarly brilliant flame. While in the interior of the flame of alcohol, we only see the yellow surface of the melted matter, like that of a quantity of melted bees-wax. The interior of a flame arising from an extended surface of a burning body consists entirely of combustible matter in a state of volatilization; it excludes the atmospheric air, which only comes in contact with its exterior surface, and the combustion at this surface forms the flame. The heat evolved at the surface of combustion, is very high, as our philosopher proceeds to observe; it is perhaps as high as any we are acquainted with. Mr Tennant was in the habit of shewing, that a small filament of platinum may be fused in the flame of a common candle. Now it may be remarked that, if such a high temperature were extended through the interior of the flame, it would display much more powerful energies in fusing bodies than it does. Platinum would be fused in larger masses, if quite surrounded with such a temperature; but the limitation of it to a thin superficial stratum subjects it to dissipation, as soon as a body of any considerable thickness of substance is placed in it. Even a long piece of wood, held for some time across a broad flame, is brought out scarcely altered by that situation, ex

cept at the points corresponding to the surface of the flame.

With the exception of this mistaken view of flame, the researches of this author are as instructive as they are curious.

He has investigated, in a beautiful manner, the cause of the light emitted by flame, and the differences of this light as exemplified in the combustion of different materials. He finds by comparing a diversity of facts, that the light of a flame of carbureted hydrogen, for example that produced by the combustion of a stream of gas in our artificial gas-lights, arises from the decomposition of the gas towards the interior of the flame, where, he says, the air is in smaller quantity, (but where we maintain that there is no admixture of air at all;) a portion of solid charcoal in the form of a tenuious powder is there generated, which, first by its ignition, and then by its combustion, increases in a high degree the intensity of the light. The flame produced by an explosive mixture of coal-gas and common air, within a wire-gauze cylinder, emits a much fainter light. This arises from the air being thoroughly mixed with the inflammable gas, as is proved by the following beautiful experiment. Sir H. Davy held a piece of wire-gauze over a stream of coal-gas issuing from a small pipe, and inflamed the gas above the gauze, which was almost in contact with the orifice of the pipe. It now burned with its usual bright light. On raising the wire-gauze, so as to admit more atmospheric air into mixture with it, the light became feebler, and at a certain distance the flame assumed the precise character of that of an explosive mixture burning within the lamp; but the heat was now greater than when the light was much more vivid; and a piece of platinum wire, held in this obscure flame, became instantly white hot. Now this is cer