to 70 acres; in this part the heathy patches of bog gradually lessen in quantity; the green is lands disappear, and nothing is observed but a thin deposit, consisting of granulated black bogmud, varying from one to three feet in thickness. This, though destructive for the present year, may when dry be burnt, and re

moved for manure to the neigh bouring uplands, or left on the spot to fertilize the valley.

Thus the whole distance which the bog has flowed is about three miles in length, namely, one mile and a half in the bog, and the same distance over the moory valley: and the extent covered amounts to about 150 acres.

New Shetland.-IN October, 1819, the brig Williams, of Blythe, in Northumberland, Smith, master, on a voyage from Buenos Ayres to Valparaiso, stretching to the south, from contrary winds, discovered land, on which the captain landed, and performed the usual formalities of taking possession, in the name of his late majesty, George III. On reaching Valparaiso, and reporting his discovery, and the abundance of seals which frequent its shores, a survey was ordered by captain Shirreff, of the Andromache; and the report reaching England, several vessels were fitted out, whose success has given a stimu lus to other adventurers.-The extent of country explored from East to West, from Clarence Isle to Smith's Cape, is from 54 to 64 deg. west long., and from 61 to 64 deg. south lat., and the land is seen to the southward, as far as the eye can reach. The country already explored consists of numerous islands, without a vestage of vegetation. A species of moss only is found upon the rocks near the shore; eternal snows covering the more remote

parts, which are mountainous Although Nature, in those regions, assumes the most sterile and forbidding features, the thermometer was at no time below the freezing point; but the melting snows near the shore so completely saturate the soil as to check all vegetation. A species of coal was found in abundance, which burnt very well, thus affording the means, if wanted, of replenishing the fuel. The rise and fall of the tide is about twelve feet. Shrimps and penguins are beyond all conception numerous. The islands, headlands, &c. have been named, and the observations ascertaining the latitude and longitude, from repeated experiments, found true; so that we may soon hope to see a correct chart, from the surveys which have been taken, on the arrival of captain Smith, in the Blythe, who is shortly expected.-Part of an anchor-stock, evidently Spanish, being bolted with cop per, and bearing certain marks, was found on shore, and is presumed to be the only vestige now remaining of a 74-gun ship of that nation, which sailed from Spain,

Gelatinous Meteor at Amherst in Massachusets.-On the 13th of August, 1819, between eight and nine o'clock in the evening, a fire ball, of the size of a large blown bladder, and of a brilliant white light, was seen in the atmosphere. It fell near a house, and was examined by Rufus Graves, esq.formerly lecturer of chemistry at Dartmouth College. It was of a circular form, resembling a solid dish, bottom upwards, about eight inches in diameter, and about one in thickness, of a bright buff colour, with a fine nap upon it, similar to that in milled cloth. On removing this nap, a buff

coloured pulpy substance, of the consistence of soft soap, 'appeared, having an offensive suffocating smell, producing nausea and giddiness. After a few minutes exposure to the air, the buff-colour was changed into a livid colour, resembling venous blood. It at tracted moisture readily from the air. A quantity of it in a tumbler soon liquified, and formed a mucilaginous substance, of the consistence, colour, and feeling of starch, when prepared for domestic use. The tumbler was then set in a safe place, where it remained undisturbed for two or three days, and it was found to have all evaporated, except a small dark-coloured residuum adhering to the bottom and sides of the glass, which, when rubbed between the fingers, produced about a thimbleful of a fine ash-coloured powder, without taste or smell. With concentrated and diluted muriatic and nitric acids, no che◄ mical action was observed, and the matter remained unchanged. With the concentrated sulphuric acid, a violent effervescence ensued, a gas was evolved, and the whole substance nearly dissolved.

Volcanic Appearance in the Moon." On Sunday evening, the 4th February," says captain Henry Kater, "I observed a luminous spot in the dark part of the moon, which I was inclined to ascribe to the eruption of a volcano. The telescope used was an excellent Newtonian of 64 inches aperture, with a power of 74. The moon was exactly two days old, and the evening so clear, that I was able to discern the general outlines in the dark part of her disc. Her western azimuth was about 70°, and her altitude about 10 degrees. In this position at

6 hours 30 minutes, the volcano was (estimating by the eye), distant from the northern limb of the moon about one-tenth of her diameter. Its appearance was that of a small nebula subtending an angle of about three or four seconds. Its brightness was very variable; a luminous point, like a small star of the 6th or 7th magnitude, would suddenly appear in its centre, and as suddenly disappear, and these changes would sometimes take place in the course of a few seconds. On the evening of the 5th, having an engagement which prevented my observing it myself, I arranged the telescope for two friends, who remarked the same phænomena as the night before, but in an inferior degree, partly perhaps in consequence of the evening not being so favourable. On the 6th I again observed it; it had certainly become more faint, and the star-like appearance less frequent. I could see it very distinctly with a power of 40. As the moon approached the horizon, it was visible only at intervals when the star-like appearance took place. On the same evening I had the pleasure of showing it to Mr. Henry Browne, F.R.S. I regret that I had no micrometer adapted to my telescope; but I have reason to believe the distance of the volcano from the edge of the moon was about one-tenth of her diameter, and the angle it formed this evening with a line joining the cusps was about 50°. I remarked near the edge of the moon, a well-known dark spot, from which the volcano was distant, as nearly as I could estimate, three times its distance from the edge of the moon. In a

map of the moon published by Dr. Kitchener (and which is the best small map with which I am acquainted), there is a mountain sufficiently near the situation of the volcano, to authorize the supposition that they may be identical. On the 7th I could still see the volcano, and the occasional star-like appearance; but I do not think it was sufficiently perceptible to have been discovered by a person ignorant of its precise situation. I am inclined however to think, that the difficulty of seeing it is rather to be attributed to the increased light of the moon, than to the diminished action of the volcano. The spot in which I observed the volcanic appearance is that named Aristarchus. This spot was par ticularly examined by Hevelius, who calls it Mons Porphyrites, and who considers it to be volcanic. If his drawings are to be relied upon, it has undergone a considerable change in its appearance since his time. Sir Wm. Herschel has recorded in his Philosophical Transactions an observation of three volcanoes, which he perceived in the moon, April 19, 1787, at 10h. 36 m., sidereal. time. One of these, which he says showed "an actual eruption of fire or luminous matter," was distant from the northern limb of the moon 3′ 57′′" 3. the diameter of the burning part being not less than". I find that this observation was made about 9 o'clock in the evening, when the moon was not quite two days old; and from the situation of the spot described by sir Wm. Herschel, I have no doubt of its being the same that I have noticed."

The Compass.-Captain Kater,

in the Bakerian Lecture, has endeavoured to establish the following conclusions:

1. That the best material for compass-needles is clock spring; but care must be taken in forming the needle, to expose it as seldom as possible to heat, otherwise its capability of receiving magnetism will be much diminished.

2. That the best form for a compass-needle is the pierced rhombus, in the proportion of about five inches in length to two inches in width, this form being susceptible of the greatest directive force.

3. That the best mode of tempering a compass-needle is, first to harden it at a red heat, and then to soften it from the middle to about an inch from each extremity, by exposing it to a heat sufficient to cause the blue colour which arises again to disappear.

4. That in the same plate of steel of the size of a few square inches only, portions are found varying considerably in their capability of receiving magnetism, though not apparently differing in any other respect.

5. That polishing the needle has no effect on its magnetism.

6. That the best mode of communicating magnetism to a needle, appears to be, by placing it in the magnetic meridian, joining the opposite poles of a pair of bar magnets (the magnets being in the same line), and laying the magnets so joined flat upon the needle with their poles upon its centre; then, having elevated the distant extremities of the magnets, so that they may form an angle of about two or three degrees with the needle, they are to be drawn from the centre of the needle to the exVOL. LXIII.

tremities, carefully preserving the same inclination, and having joined the poles of the magnets at a distance from the needle, the operation is to be repeated ten or twelve times on each surface.

7. That in needles from five. to eight inches in length, their weights being equal, the directive forces are nearly as the lengths,

8. That the directive force does not depend upon extent of surface, but in needles of nearly the same length and form, is as the mass.

9. That the deviation of a compass-needle occasioned by the attraction of soft iron, depends, as Mr. Barlow has advanced, on extent of surface, and is wholly independent of the mass, except a certain thickness of the iron, amounting to about two-tenths of an inch, which is requisite for the complete developement of its attractive energy.

Meteoric Stones.-A paper, by M. Fleurian de Bellevue, read to the academy of sciences, on meteoric stones, and particularly on those which fell near Jonzac, in the department of Charente, endeavours to establish the following conclusions:

1. The appearances presented by the crust of meteorolites seem to prove, that their surface has been fused whilst rapidly traversing the flame of the meteor, and rapidly solidified into a vitreous state on leaving that flame.

2. They prove that in the first moments the movement of the meteorolites was simple, that is, that they did not turn round on their own axis whilst those two effects took place.

3. That the impulse each meteorolite has received has al2 Y

most always been perpendicular to its largest face.

4. That the largest face is almost always more or less convex. 5. Our meteorolites (those of Jonzac) offer new proofs of the pre-existence of a solid nucleus to bolides or meteors.

This nucleus could not contain the combustible matter which produces the inflammation of the

meteor.

7. It cannot have suffered fusion during the appearance of the phe

nomena.

8. The gaseous matter which surrounds this nucleus is dissipated without producing any solid residuum. No trace of this matter appears ever to exist in the crust of the meteorolites.

9. Meteorolites are fragments of those nuclei which have not been altered in their nature, but simply vitrified at their surfaces.

10. Many of the irregular forms which these fragments present may be referred to determine geometric forms.

11. These latter forms are the consequence of the rapid action of a violent fire, according to a law of the movement of heat in solid bodies, discovered by M. Emer.-Brande's Journal.

Nocturnal increase of Sounds. Humboldt accounts for the increase of sounds during the night, by observing, that the presence of the sun affects the propagation and intensity of sound by the obstacles opposed to its transmission by currents of air of different densities and partial undulation-the result of the unequal heating of various parts of the earth's surface. In air at rest, whether it be dry, or mixed with elastic vapours equally distributed

through it, the sonorous undulation is propagated without difficulty. But when this air is crossed in every direction by small currents of a warmer temperature, the sonorous undulation divides into two waves, at the spot where there is the most sudden change in the density of the medium; thus producing partial echoes, which weaken the body of sound, because one of the sonorous waves is reflected back upon itself. The theory of these partitions of sonorous waves has been explained by M. Poisson.* It is not, therefore, the motion of the passage of the particles of air from below upwards, nor the small oblique currents of this fluid that we consider as opposing, by impulse, the propagation of the sonorous waves. A stroke or impulse impressed on the surface of the liquid will form circles around the impinging centre, even when the liquid is in agitation. Several kinds of waves may cross in air, as well as in water, without interfering with each other; but the true cause of the less intensity of sound in the day-time appears to be the want of homogeniety in the elastic medium. There is at this time a sudden change of density throughout, produced by small currents of air, of a high temperature, rising from portions of the earth's surface that are unequally heated. The sonorous waves are then divided in the same manner as luminous rays are refracted, and form a mirage of sound wherever strata of air of unequal density are contiguous. A distinction must be kept between the intensity of sound or of light, and

Ann. de Chimie, t. 7.