discharged from a sling was heard; and a multitude of mineral masses, exactly similar to those distinguished by the name of mete oric stones, were seen to fall at the same time. The district, in which the stone fell, forms an elliptical extent of about two leagues and a half in length, and nearly one in breadth; the greatest dimension being in a direction from south-east to north west, forming a declination of about 22°. This direction which the meteor must have followed is exactly that of the magnetic meridian; which is a remarkable result. The largest of these stones fell at the south-east extremity of the large axis of the ellipse; the middle.sized ones fell in the centre, and the smallest at the other extremity. It thereby appears that the largest fell first, as might naturally be supposed. The largest of all those which fell weighs 17 pounds. The smallest he saw weighed about two gros, which is the thousandth part of the former. The number that fell is certainly above twoor three thousand. They were friable some days after their fall, and smelled strongly of sulphur. Their present hardness was acquired gradually. [Nicholson's Journal. SECTION VIII. Observations on Fire Balls. By F. C. Falda. Notwithstanding the great progress which the sciences have made in the present century; and though our knowledge of the atmosphere has, in particular, been much enlarged; we are still far from being able to explain all its phænomena, especially those of the luminous kind, in a manner sufficiently satisfactory to the cautious and reflecting philosopher. Though many, in consequence of the important discoveries made respecting the electricity of the clouds, imagine that they have found in the electric fluid, so widely diffused, a certain key to all distant phænomena of a similar kind; yet the greater part of them as mere observations, and the explanations given of them as mere hypotheses, must be left to the decision of posterity. It would be useless, and perhaps it is impossible, to mention all these phænomena in any certain order: but the most 461 singular of them are large fire-balls (bolides), which, on account of their importance in natural philosophy, have in modern times ex. cited universal attention *. Respecting the origin and nature of these phænomena, which are but seldom seen, and always surprise us as it were accidentaly, we can venture conjectures and explanations only when we have com. pared a series of observations carefully made with the circumstances by which they were attended, and have then deduced from them general conclusion †, which in the hands of the mathematician may conduct with the greatest certainty to a knowledge of their nature, and of the causes by which they are produced. I shall endeavour, therefore, to present the reader with such conclusions drawn from a series of observations made in regard to fire-balls, not with the intention of giving any explanation from them myself, but in compli ance with the excellent rule laid down by Le Roy, when he says, speaking of this circumstance: "Let us always collect observations without being too forward to deduce consequences from them, and to explain phænomena respecting which we have at present so little knowledge ." * On the 13th of July, 1797, about 42 minutes after nine in the evening, I had the good fortune, when in company with several of my friends, to see a meteor of this kind. It appeared in the southern part of the horizon, at the height of 8 or 10 degrees; had the form of a perfect globe or sphere well defined at the edges, almost as large as the moon when at full, and proceeded in the space of scarcely a second, while its course was only marked by a fine white streak of light, in an almost perpendicular direction towards our horizon, which was confined by houses, and disappeared behind them. Its colour and splendour near the middle were sometimes of a dazzling white. The heat during the day, and in the evening, was considerable. The thermometer varied from 18 to 20 of Reaumur, and between the hours of four and five in the afternoon there had been a storm in the same quarter of the heavens. At the surface of the earth there was a perfect calm, and in the evening the weather-cocks shewed that a light south-west wind prevailed at some height in the atmosphere. At the time of this phenomenon the earth was overspread by a pale mist, through which no stars could be perceived, and which the following night became a thick fog. + 1 faudroit etudier avec soin les rapports de ces phénomenes avec les autres phénomènes atmosphériques; rechercher l'état du ciel avant et aprés leur apparition, déterminer les tems, les circonstances, et lieux, ou ils sont les plus communs, savoir pourquoi ils sont rares, et pourquoi ils arrivent. Que d'observations faire! Que d'observateurs à occuper !-Sennebier. Memoires de l'Academie des Sciences, 1771. Some of the observations here given, as well as the conclusions drawn from them, have been already employed by Dr. Chladni, in a particular treatise *, to explain the origin of the mass of iron found by Professor Pallas in Siberia†, and other masses of the like kind ; as well as stones which, according to accounts worthy of credit, are said to have fallen from the heavens, and therefore more in a geological than a meteorological view. My object is quite different. I propose, notwithstanding the difficulty of determining properly, from the observations made, to what class of luminous appearances such phænomena belong t, to collect together those accounts which have been considered, at least with some probability, as alluding to the same kind; and in most cases just as they were given by the obser vers, without paying attention to any particular mode of expla nation, in order to assist those whose attention is occupied with the origin and nature of these bodies; to examine the old and new hypotheses formed respecting them, or to support future ones, if necessary. These meteors appear then 1. In every climate. Of fifty observations with which I am ac. quainted, three were made immediately under the equator §; three in a southern ||, and 44 in a northern latitude: and this disproportion * Ueber den Ursprung der von Pallas gefundenen und anderer ihr ähnlichen Eisen-Massen, von C. F. F. Chladni. Riga 1794. + See Philosophical Magazine, Vol. II. p. 1. Henry Barham, as mentioned in the Philosophical Transactions, vol. xxx. p. 837, saw in Jamaica, in the year 1700, a flaming fire-ball, of the size of a bomb, descend towards the earth; but though the ground was dug up around the place where it seemed to fall, nothing could be perceived except burnt grass and a sulphurous smell. A violent storm, it is said, had taken place a little before, which makes it highly probable that this phenomenon was nothing else than lightning; especially as Reimarus relates, that lightning has been seen to fall upon houses and conductors in a globular form, and that a sulphurous smell has been afterwards perceived; see Reimarus vom Bliz, Hamburg 1794, p. 51, 155, 319. An observation of two balls proceeding towards each other before a thunder cloud, made by Hartman, in July, 1758, seems to be of the like kind. See Verwandschaft der Elektrischen Kraft mit den Lufterscheinungen, Hanover 1759, p. 237 ; and also a flash of lightning mentioned by Reimarus, p. 12. Other instances of the two phænomena being confounded, are noticed by Dr. Chladni, in his work, p. 2. { Ulloa's Voyage to South America. Lond. 1760. Vol. i. p. 354, and vol ii. p. 226. || Journal des Observations Physiques, Mathematiques, et Botaniques, par Louis Feuille. Paris 1714. Vol. i. p. 116, 119 and vol. iii. p. 92, arises merely from the greater number of accounts brought to us from the latter, and the greater attention of the observers; for we are assured by Foster, that he saw several fire-balls in the south seas *. 2. At every season of the year. I am acquainted with observa. tions made in every month except September; and of these several were made, but between the 45th and 55th degree of northern lati. tude, in all the months except April, June and September. It cannot, therefore be said that, like storms, they appear more frequently at one time of the year than another. 3. At every period of the day. The hour when these phænomena took place is not indeed given by every observer, but observations have been made both by night and by day. The greater part, however, have been made in the evening; when, being more perceptible to the eye, it was less possible for them to escape notice. 4. They appear, for the most part, when the sky is serene. This remark is expressly made in regard to 26 of the above men. tioned 50; and in regard to the rest, it is to be concluded, from concomitant circumstances, such as their height, &c. The heavens were often covered only with a pale mist,+ and some few were seen to proceed from light clouds ; which gives us reason to suppose that they came from a greater height than these clouds. 5. Most of them were seen to move with a very rapid motion; and of those on the velocity of which observations have been made, that is said to have moved quickest which was seen in the month of November, 1758; and which, according to the calculation of Sir John Pringles, passed over thirty English or seven German miles in one second; a velocity greater by 3 miles in a second, than that of the earth in its orbit. The one said to have moved slowest is that which was seen by Balbus at Bologna, in the month of March, 1719, and which proceeded, according to his reckoning, at about * Forster's Observations on Physical Geography, made during a voyage round the word, &c. p. 119. + Breslauer Sammlungen von Natur-und Medicin-Geschichten. III. Jan. 1716, p. 544. Hanov. Magazin, 1791, p. 1628. Breslauer Sammlungen xxix. Aug. 1724, p. 169. Compare Lichtenberg's Gothaisches Magazin, vol. iii. part 2, p. 92; vol iv. part 2, p. 164. Philosoph. Transactions, vol. li. part 1. p. 218. De Bonon. Scient, Instit. Comment. voli. p. 285. 1530 feet, or 0,067 of a German mile in a second. But there is reason to conclude that the movement of others, the course of which, as might be conjectured from their long train, was not in the direction of the eye, must have been much slower. Some appear also, unless these be refused a place here, to be peculiar to one part of the heavens+. 6. They proceed from, as well as towards, all points of the compass. The greater part of them, however, have beyond all dispute appeared in the northern or southern parts of the horizon; but no general conclusion, in regard to their connection with the northern‡ or southern lights, can be drawn from this circumstance; though some observations made in Sweden § seem to favour such an hypothesis. 7. They do not always move according to the direction of the wind. The third observed by Ulloa makes, perhaps accidentally, an exception; and the spindle-shaped meteor seen by M. Lichtenberg, at Gottingen, on the 12th of November |, was towards the S.S.E. the then direction of the wind, which however near the earth was very little felt. Besides, their velocity was seldom, or never, proportioned to that of the wind; as during the most violent storm it does not move above 100 feet per second. When such meteors have appeared, it has been generally calm; but some of them were followed by wind I; and Forster observed that after each fire-ball which he saw, a violent wind took place. 8. They almost all fell towards the earth, and consequently from a rarer to a denser atmosphere, as in most cases might be concluded from their soon becoming considerably enlarged. Some of them, however, particularly those which moved slowly, seemed to pro ceed in a horizontal direction over the surface of the earth; but Breslauer Sammlungen, iv. May 1718, p. 1777; Phil. Trans. vol. xliii. No. 477, p. 524; and Gothaisches Magazin, vol. iv. part 2. p. 164. + Hof in Acta Litteraria et Scient. Sueciæ, an. 1734, p. 78; and De Genssance in Histoire de l'Acad. des Sciences. Paris 1738. p. 36. Bergman's Physic. Beschreibung der Erdkugel, vol. ii. p. 78. Bernstoff in Rozier's Journal de Physique, 1784, p. 115; and Blagden in the Phil. Trans. for 1784, p. 229. § Hof and Celsius in Acta Litteraria et Scient. Sueciæ, an. 1734, p. 78 and 81. Gisler in Schwedische Abhandlungen, vol. xxv. p. 65. Hannövrisches Magazin, 1791, p. 1626. ¶ Acta Litteraria Sueciæ, 1734, p. 78; and Chladni in Gothaisches Magazin, vol. xi. part 2. p. 712. |
