the night of the 9th and 10th November, 1787. In 1813, many were seen in England on the night of the 8th November; in 1818, on that of the 13th November; and in 1832, on the 12th of the same month. From nine in the evening until sunrise many were counted; some had the appearance of small globes of fire. In England, France, Switzerland, Germany, Russia, Mauritius, observers were every where struck with the number and the brilliancy of these meteors. In the United States of America, the shooting stars were still more numerous. November 13, 1833, at 7 P.M. Palmer, at New Haven, in Connecticut, perceived a reddish vapour, which first appeared near the southern horizon, then rose gradually to the zenith; it was very transparent, but yet it concealed the smallest stars. The igneous meteors appeared from nine o'clock, but at four in the morning they appeared in greatest numbers. An uninterrupted succession of fire-balls, like fusees, seemed to originate from a point not many degrees from the zenith; they darted in all directions, but yet always in such a manner, that all their directions produced converged toward the point mentioned. Around this point, which, according to M. Encke, precisely coincides with that toward which the earth is directed in its annual revolution round the sun, a circular space of several degrees is found, in which no meteors are seen. Generally, they leave a luminous train in their passage, and, on disappearing, they burst, and are reduced into smoke; notwithstanding the most persevering attention, the noise of an explosion has never been heard. Besides these isolated masses, the atmosphere was illuminated by phosphorescent lines formed of the succession of a great number of luminous points, and similar to the lines produced in darkness by writing with a pencil of phosphorus.

In the following years, the nights of November were again remarkable for a great number of shooting stars, all of which seemed to come from the constellation Leo, toward which the earth is directed at this period of the year: the same observations are true of the nights of August 10 and 11, during which, also, many shooting stars

are seen.

The balls do not appear to be equally common at all seasons. If we calculate their number for each month, we arrive at the following results :

:

The greatest number occur in November, the least, in June; doubtless the length of the days in summer allows a great number of these meteors to pass unperceived: however, we should observe that their frequency is greater in autumn than in spring. In August, when shooting stars are common, there are also many fire-balls.

APPEARANCES OF FIRE-BALLS.-Their brilliancy surpasses that of the moon; some have been so brilliant, even by day, that they have cast a shadow. Their light is of a dazzling white, or else reddish; other colours are also noticed, having a greater or less degree of distinctness.

Whilst they are traversing the atmosphere, flames, sparks, and smoke, come out from them in all directions; sometimes they seem to be extinguished by falling; they then light up again, after having emitted a quantity of vapour and smoke: when they traverse the atmosphere, they swell up and burst with noise. Chladni explains this rupture by the developement and the dilation of the interior fluids bursting their envelope. When they are not seen to burst, it is because they are too elevated or too far distant from the atmosphere, and have followed their route in space. Sometimes a fire-ball is divided into a certain num. ber of fragments, and each of these fragments forms a small luminous globe, which then bursts in its turn; in some, the mass, after having given issue to the interior gases, sinks on to itself, and then swells out anew, to burst a second time. The balls, that make bounds, generally burst at the point separating the two successive bounds; these explosions are accompanied with vapours and smoke; and the ball is seen to pursue its course, casting forth a new lustre. The crash is sometimes such, that the houses tremble, the doors and windows open, and the assistants fancy that there is an earthquake. Sometimes, says Chladni, the explosion is not noticed, because the mass, after having given forth the gases, is enveloped with a thick smoke that conceals its brilliancy.

AEROLITES OR METEORIC STONES (meteor

steine).-When the globe has burst, the fragments fall to the earth these are sometimes in large quantities; witness those collected near L'Aigle, April 26th, 1803, and near Stannern, May 22d, 1808. However, they may also fall without breaking: these fragments are known by the name of aerolites.

The greater number of aerolites have a general form always the same; according to Schreibers, it is a prism, with four or five unequal surfaces, or an oblique pyramid. Outside they are covered by a black or blackish crust, which appears to have the same chemical composition as the nucleus, although it has passed into the state of scoriæ. This crust, the thickness of which rarely exceeds 0mm,55, presents inequalities; it is black, and not very brilliant, or else of a brilliant blackish brown, as if the stone had been covered with varnish. Sometimes it has a metallic brilliancy like iron melted and slightly oxydised, or rather the aspect of bitumen. The crust may be so hard, that it strikes fire with the flint; on certain stones we find layers, veins, and spots of the same nature as the crust. The aërolite seems already to have been formed when a new swelling has brought a portion of the crust to the interior. This crust does not bear the least analogy to a volcanic product; and we cannot obtain an analogous crust except by melting these stones out of the action of the air; but it is difficult to say which of the constituent principles contributes most to the formation of this envelope. The composition of these stones is different from that of all stones that have been found at the surface of the globe. From the analysis made by M. Gustave Rose, some are found of a greyish mass, in which no other substance beside metallic iron is found; others are composed of different substances, of which some, that are white, are probably labrador (opal feldspar): others, that are brown, resemble a pyroxene.

If they are reduced to powder, we may extract about twenty per cent of iron and nickel; chemical analysis then gives the following principles: oxygen, hydrogen, sulphur, phosphorus, carbon, silica, chromium, potassium, sodium, calcium, magnesium, aluminum, iron, manganese, nickel, cobalt, copper, and tin. According to M. Berzelius, these eighteen elementary substances form the following compounds :

1st. Metallic iron, containing a little nickel, cobalt, magnesium, manganese, tin, copper, sulphur, and carbon.

2d. Sulphuret of iron, with an equal proportion of sulphur and iron.

3d. Magnetic iron.

4th. Meteoric olivine; it constitutes one half of the residue that remains after the metals susceptible of magnetism are removed; its composition is the same as that of terrestrial olivine.

5th. Silicates, combinations of lime, magnesia, oxides of iron, manganese, clay, soda, and potash, insoluble in acids, among which the silicic acid is in double proportion to all the other bodies, and which probably form two minerals, the one pyroxenic, the other analogous to leucite.

6th. Chromate of iron in a small but constant quantity. 7th. Oxide of tin.

METEORIC MASSES OF IRON. - Sometimes the entire aërolite is composed only of metallic iron; however, this case is more rare than that in which it contains only a certain quantity. May 26th, 1751, two masses fell near Hradschina, in the comitat of Agra: one weighed thirty-five, the other eight kilogrammes. They have been found in other countries, though not seen to fall from the sky; but their form and composition must make us regard them as aërolites. One of the best known is that discovered by Pallas, in Siberia, in the year 1771, and which the Tartars regarded as a sacred object fallen from heaven; its weight was 700 kilogrammes. Analogous masses have been found in Bohemia, Hungary, the Cape of Good Hope, Mexico, Peru, Senegal, Baffin's Bay, &c. &c. The iron is full of cavities, filled with more or less perfect crystals of olivine; when these crystals are removed, the residue still contains ninety per cent of iron, a certain percentage of nickel, and the rest needs scarcely being taken into the account.

ORIGIN OF IGNEOUS METEORS.

As they are found in regions inaccessible to man, the imagination has a wide field for framing hypotheses which reason cannot gainsay. Formerly, these shooting stars were affirmed to be composed of gelatinous matter; and it has been frequently said, that the different species of nostoch, found on the banks of rivers, were shooting stars. Chladni was the first to shew, that fire-balls and shooting stars are one and the same thing, and only differ in their size. Since he has also proved that stones do fall from the sky, four principal hypotheses have been put forth, which we will now examine.

VULCANIAN HYPOTHESIS.-It was originally maintained, that these stones were vomited forth by the volcanoes of our globe; but this system is untenable, for our volcanoes cannot hurl them to any great height, and their composition is totally different from volcanic productions.

MOON-STONES.-Some mathematicians, Laplace, among others, have endeavoured to prove that these stones may be projected from volcanoes in the moon sufficiently far to enter into the sphere of our earth's attraction, and so to fall on it. Calculation shews that, in order for this effect to take place, the stone must have an initial velocity of 3250 metres per second, and that it would pass from the moon to the earth in two days and a half.

Notwithstanding the possibility of the fact, it still presents, according to Olbers, grave difficulties; for the body, darted forth by the volcano, is subject to this force of projection, and also to that resulting from the moon's motion, and which acts tangentially to the lunar orbit. Thus, then, the heavy bodies that are darted forth by the lunar volcanoes, and that approach the earth, are attracted by it, and describe a curve. In order that the body may fall to the surface of the earth, there must exist a determinate relation between the direction and the velocity of the projectile; and consequently few of them will fall to the earth. According to Olbers, the initial velocity of from 7000 to 11,000 metres per second, as determined by Brandes, is also contrary to this hypothesis; indeed, let us suppose that the stone is darted forth by the volcano with a velocity of only 2600 metres, it will arrive with an acquired velocity of 11,400 metres. Now, as fire- balls travel with a velocity of about 37,000 metres per second, they must be darted forth by the moon with a velocity of about 23,500 metres, a velocity that may be regarded as altogether impossible.

ATMOSPHERIC HYPOTHESIS.-Other philosophers have admitted that these igneous meteors were a product of our atmosphere; and although Chladni has rejected this explanation, it has yet been sustained by Egen, G. Fischer, and Ideler; the former especially has put forth several important considerations in favour of this opinion. A great number of metals rise into the atmosphere in a gaseous state; and, if chemical analysis does not find them, it is merely because their proportional quantity is very small. These arise annually from the metallurgical forges of Clausthal more than ten millions of kilogrammes of vapours, composed of water, lead, iron, zinc, sulphur, antimony, and arsenic; many of these metals have been recovered by R. Brandes and Zimmerman in rain-water. Then Egen especially rests his hypothesis upon the phenomena that have been observed during the formation of igneous meteors: either the sky has been disturbed by a dark or by a bright cloud, or else white bands have been united into a single mass.

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