ed. The evening was fine and clear, the wind westerly. The aurora first appeared in the north, and gradually extended in a luminous arch across the zenith, almost to the southern horizon. A dim sheet of light then suddenly appeared, and spread over the whole of the heavens to the eastward of the magnetic meridian, while only a few insulated specks were visible to the westward. The eastern aurore were grey and obscure, and exhibited little motion; but the arch extending across the zenith, showed an uncommon playfulness of figure and variety of form. Sometimes it exhibited a luminous edge towards the west, in some places concentrated into a fervid brilliancy. The rays were a little oblique to the position of the arch; but generally parallel to each other, and commonly ran in the direction of the magnetic north and south. At one time they extended sideways against the wind; at another in the contrary direction. Now they shot forward numerous luminous pencils, then shrunk into obscurity, or dispersed into the appearance of mere vapour. The colours were yellowish-white and greyish-white. All the stars of the fourth magnitude were visible through the meteor, even in its most vivid coruscations. Ursa Major was at one time encircled with such a characteristic blazonry of light, that the Bear seemed to spring into figure, and to be shaking his shaggy limbs, as if in contempt of the less distinguished constellations around him. The Pleiades were almost observed by the light produced by the aurora; though Venus, and all the superior stars, shone with becoming splendor. I have never been sensible that the shooting of the aurora was accompanied by any noise; the turbulence, indeed, of the water at sea, or noise of the sails during calms, prevent the light sounds from being heard. Earthquake in Chile.-A government Gazette of Chile, published at Santiago on the 27th of November, contains an account of this dreadful calamity. A despatch of the supreme director, who happened to be at Valparaiso at the time of the earthquake, is dated at 10 at night on the 20th of November, and is addressed to the ministers, of whom he asks a report respecting the state of the capital. He says, that, on the preceding night, at 15 minutes before 11 o'clock, Valparaiso had received so severe a shock, that in two or three minutes all the buildings were either considerably damaged or thrown down ; the sea receded and fell more than 12 feet; the movement of the earth, although weak, did not cease for an instant till half-past four in the morning, after which shocks more or less strong were felt every five or seven minutes. The inhabitants had retired to the heights, where they had encamped on the 20th. Fifteen or twenty individuals, being mostly soldiers, women, and children, were known to have perished in the ruins; it was, however, difficult, on account of the confusion, to ascertain the number of the victims, which it was feared would be found to be much larger. No public officer nor person of note had perished. The reply of the ministers is dated Santiago, 22nd November; and states, that the capital had not experienced the same terrible catastrophe which had ruined Valparaiso. On the 19th November, at ten minutes before eleven o'clock at night, a low heat and an extreme rarefaction of the air, having been previously observed for three or four hours, a horrible noise announced, and by a few seconds preceded, an earthquake such as had not been experienced in Chile since 1730: its explosion showed itself by two strong shocks, which lasted two minutes and a half or three minutes; the latter, stronger than the first, was only of about twenty seconds. It was at first thought that the whole city was destroyed: the consternation was general, but fortunately no lives were lost, and only a few persons were hurt by falling fragments or tiles. The action of the earthquake was of the trembling description, and its direction from N.E. to S.W. walls of the churches of La MerSome ced, San Augustin, San Francisco, &c., have fallen down; the Mint, the interior of the Cathedral, the directorial Palace, the steeples of the Treasury, and of the prison, are also damaged, and in some places threaten to come down. The walls of houses which were not very solid are much damaged. earth was almost constantly in The motion, though slight and only perceptible by the pendulum; but at times there were smart and sharp shocks. strong twilight. It is reported, that various other small meteors were 24m., there was another slight shock, seen towards the Cordillera. At 5h. preceded by considerable noise, Shocks succeeded each other rapidly, and increased the consternation, especially amongst women; most families have abandoned the city and retired to the neighbouring country houses; the lower classes are encamped in the public squares, the dikes, and aqueducts. morning, and at 11h. 5m., other On the 21st, at 4h. 25m. in the slight shocks were felt. families came to town to spend the Several day in their houses, with an intention to return to the country and to sleep there. The moon was full at 6h. 30m. p. m. morning, and 9h. 12m. and 9h. This day, at 4h. 20m. in the 22m. three smart shocks; they in the afternoon; but some of them continue to this hour, seven o'clock almost imperceptible. Scheme for sending Despatches Packet.-The Royal George, sir to the East Indies by a SteamJohn M. Doyle, ran from Vigo to Plymouth in 84 hours, being nine and a half degrees, 570 geographic to Portsmouth in 20 hours, being or sea miles; and from Plymouth 135 miles; the former was at the rate of six miles six furlongs and a quarter, the latter nearly at the lation in smoother seas is at eight same rate. The following calcumiles, and on land at the rate of five miles an hour: On the 20th, at 3h. 8m. in the morning, there was a slight shock, without any sensible noise: at 3h. 42m., a meteor ran in the same direction as the earthquake, from N.E. to S.W., in the form of a large train of fire, which for about four seconds produced a sort of From London to Marseilles, or Toulon, in France 540 From the coast of France to Malta.. 4 12 by land. 600 3 3 by sea. From Malta to Alexandria in Egypt by sea. From Alexandria, by Cairo, to Suez 120 1 0 by land. From Suez to Mocha, in the Arabian Gulf... 1020 7 0 by sea. 1.500 7 19 by sea. 4260 24 6 If by sea, and round the southern coast of Africa, it will stand thus→→ nearly seven geographical miles an hour:From Plymouth to Lisbon From Lisbon to the Cape Verd Islands ... .... ...... 720 6 4 6-7 1430 8 12 2-7 2160 12 17 4-7 1800 10 17 1-7 1800 10 17 1-7 2100 12 12 10,010 61 CHEMISTRY. A new Fluid, with remarkable Physical Properties, discovered in the Cavities of Minerals.-A new fluid, of a very singular nature, has been recently discovered by Dr. Brewster, in the cavities of minerals. It possesses the remarkable property of expanding about thirty times more than water; and, by the heat of the hand, or between 75° and 83°, it always expands so as to fill the cavity which contains it. The vacuity, which is thus filled up, is, of course, a perfect vacuum; and at a temperature below that now mentioned, the new fluid contracts, and the vacuity re-appears, frequently with a rapid effervescence. These phenomena take place instantaneously, in several hundred cavities, at the same time. The new fluid is also remarkable for its extreme volubility; adhering very slightly to the sides of the cavities; and is likewise distinguished by its optical properties. It exists, how ever, in quantities too small to be susceptible of chemical analysis. This new fluid is almost always accompanied with another fluid like water, with which it refuses to mix, and which does not perceptibly expand at the above-mentioned tem cavities in crystals, such as those opened by sir Humphrey Davy, which contain only water, and which, of course, never exhibit any of the properties above described. Method of forming Three Haloes artificially round the Sun, or any luminous object.-The following experiment, which illustrates in a pleasing manner the actual formation of Haloes, has been given by Dr. Brewster ;-Take a saturated solution of alum, and having spread a few drops of it over a plate of glass, it will rapidly crystallize in small flat octohedrons, scarcely visible to the eye. When and that he attributes it to the same cause that I do, viz. a portion of fixed magnetism in the steel of the balance or its spring. For my part, I think it will not be found possible to ascertain any ship-rate for chronometers which shall correct the errors arising from this cause, from the direction and strength of the attraction of the iron in a ship undergoing such considerable changes as it does in different dips. I always considered the remedy to lie alone in the hands of the maker, who should carefully ascertain that no steel whatever in a chronometer possesses any fixed magnetic quality; and I pointed this out to a chronometer-maker in London in November 1820, shewing him, amongst a number of balances, those which had any portion of fixed magnetism, and those which had not, &c.; but it is requisite, that, in this respect, not only the balance and its spring should be attended to, but that all the steel in the instrument should be deprived of this quality, particularly the steel-spindles of the fusee, barrel, &c. for it is to magnetic attraction, residing wholly in the machine, that I attribute the alteration which takes place in the rates of chronometers on shore in different parts of the world, and which is often very considerable. These attractions may act in several ways. If there is fixed magnetism in the balance, and'variable magnetism in the spindles of the wheels, the rate may be altered by any considerable alteration in the dip, as the direction and strength of the variable magnetism will thereby become changed; the same effect may be produced if the fixed magnetism is in the spindles of the wheels, &c. and the variable magnetism in the steel of the balance. The balance-spring will likewise be acted on under similar circumstances; I should therefore think it absolutely necessary, that all the steel in the machine should be divested of the fixed magnetic quality; the variable ones will have no effect on each other: this can always be done by the action of fire, and if the mechanic, in the process of hardening and tempering the steel, always carefully cools it in a direction at right angles with the dipping-needle, it will rarely be found to possess any portion of fixed magnetism, as, on the contrary, it will be found, that small steel bodies, if heated redhot, and cooled in the direction of the dipping-needle, will often require this quality. I am of opinion, that this fixed magnetism, if carefully excluded from the machine at first, will not be found to return from the continued motion of its parts. A very necessary precaution with respect to the use of these instruments, is always to hang them up on board ship at a considerable distance from the compasses. I have known an excellent chronometer rendered useless for the time, by being kept within two feet of the cabin compass, and which, when removed to a different part of the cabin, performed remarkably well. New Chemical Combination.-M. Dobereiner, professor of Chemistry in the University of Jena, by a series of entirely new experiments, has ascertained that platina, the heaviest of all elementary substances, when reduced into very fine particles, produces by simple contact with hydrogen gas, (the lightest of elementary substances), an electrical or dynamic combination, which, if brought into contact with hydrogen gas or with atmos pheric air, instantly dissolves itself yielding fire and water. To prove this important fact by a brilliant experiment, M. Dobereiner makes hydrogen pass from a reservoir, by a capillary tube, curved below, upon pure platina in powder, which is contained in a glass tunnel, hermetically sealed at the point, so that the gas mingles with the atmospheric air before it touches the platina. The moment that the current of gas reaches the surface of the platina, the power of that metal becomes red and burning, and this phenomenon continues as long as the stream of gas is directed upon it. New compound of Iodine. Iodide of Carbon ?-Messrs. Ferrari and Frisiani, whilst preparing the iodate and hydriodate of potassa, observed the production of a new compound of iodine. It may be obtained thus:-Heat an ounce of iodine, with a little water, on a sand bath, and add to it, by degrees, about two ounces of potash; when the two salts above mentioned will be formed. In order to saturate the excess of alkali, pour in, by degrees, a tincture composed of one ounce of iodine to six ounces of alcohol, specific gravity 837. When the re-action of the tincture on the potash is finished, pour the hot liquor on a filter, and the liquid which passes through will, as it cools, deposit yellow crystals, of the substance; they should be carefully washed in cold water, to remove all the iodate and hydriodate of potash. Another method is, to take the alcoholic solution of the two salts, prepared as above, and distil it and when the fluid which comes over ceases to be coloured, to change the receiver; the colourless liquor then obtained, upon cooling, deposits very pure crystals, of the substance in question. If the distillation be suspended from time to time, and the retort allowed to cool, beautiful crystals of the substance form in it. If strong alcohol be used in the above operations, and but little water, then, upon adding water to the filtered liquor, the substance is precipitated in abundance. This substance is solid, of a lemon yellow colour, tastes like nitric ether, and has an odour like that of saffron. Its form is a compressed hexahedron (esaedro schiacciato). It is insoluble in water, alkalies, or acids, but soluble in alcohol and ether. It fuses and sublimes by a gentle heat, but at a higher temperature becomes discoloured, is decomposed, and evolves vapours of iodine, leaving behind a mere trace of carbon.-Giornale de Fisica. Vegetation in Atmospheres of different Densities.-The following experiments have been made by professor Dobereiner of Jena. Two glass vessels were procured, each of the capacity of 320 cubic inches, two portions of barley were sown in portions of the same earth, and moistened in the same degree, and then placed one in each vessel. The air was now exhausted in one, till reduced to the pressure of 14 inches of mercury, and condensed in the other, until the pressure equalled 56 inches. Germination took place in both nearly at the same time, and the leaflets appeared of the same green tint; but at the end of 15 days the following differences existed. The shoots in the rarefied air were six inches in length, and from nine to ten inches in the condensed air. The first were expanded and soft; the last rolled round the stem and solid. The first were wet on their surface, and especially towards the ex |