"Ille etiam exstincto miseratus Cæsare Romam, And pitied Rome, when Rome in Cæsar fell; Temporary darknesses have been occasionally recorded, one of the most striking of which, both for intensity and duration, occurred in 1547,—a year memorable for the battles of Mühlberg on the 24th of April, at Pinkie on the 10th September, and not to be forgotten, as already observed, for blood-spots in Germany. On the 17th June 1777, Messier observed for about five minutes at noon, a very large number of black globules cross the sun's disc. We instance this observation because of its importance in aiding the conjectures regarding these temporary darknesses, that they have arisen from the interposition of bodies between the sun and the earth. The 11-13th May have been described as cold days. Kepler sought the cause of the phenomenon, in solar emanations; Chladni explained it by the interposition of meteoric bodies; and to Professor Erman' it seems owing to the transit of the asteroids which we have described. If we suppose that these bodies revolve round the sun in a very eccentric ellipse, cutting the orbit of the earth in two parts of its circumference like Biela's comet, and performing their solar revolution in the same time as our globe, their conjunction will take place when the earth has completed one half of its revolution, and thus the phenomenon of showers of fire and cold days, periodically recurring, will be explained. The conjunction of the November meteors with the sun and the period of the cold days recorded, is a coincidence almost warranting this explanation, and connecting them by cause and effect. But we are not limited to the belief that only one group of asteroids exists. We have several minor planets revolving in orbits suigeneris, and certain comets bearing a closer connexion with Pog. Annal. 1839. "The eccentricity in parts of the semi-axis of Vesta -0.0891; Juno - 0.2578; Ceres = 0.0784; Pallas = 0.2416; Astræa = 0.195. ourselves than any of the others.' May we not have more than one cluster of asteroids, similar, yet independent, subject to perturbations by telluric and atmospheric influences? 348. May not the passage of such bodies also explain the well-known fact, that though our atmosphere may seem equally clear, the moon does not always shine with uniform lustre? We know that the comet of 1770, whose path was calculated by Lexell, and subsequently by Burkhardt,2 passed in 1767 and 1779, between Jupiter and his satellites, and was drawn from a parabolic curve to an ellipse and then thrown by their attractions into a different orbit. Float on, thou wandering mystery, in the chill depths of infinity, for thou art no longer ours! Astonish another world with thy spectral appearance, but return to tell us of thy destiny. We may be sleeping with our sires, but a new generation rejoicing in their youth, will hail thee from afar, and welcome thy presence in their fathers' sky! But, perchance, thou art revolving with thy great disturber, and adding thy feeble light to his already gorgeous night-vault. How strange if true! Is it unphilosophical to suppose that meteors occasionally pass between our earth and moon, and thus eclipse a portion of her clear cold beams? We venture this suggestively, for nevertheless some beautiful, and as yet unaccountable phenomena attending the occultation of stars by our statellite, it is doubtful, we had almost said certain, that that body has no atmosphere like ours To dim, by flitting clouds her silvery light. The eccentricity of the orbits of the comet of Biela=0.751; of Encke=0.845; of Faye = 0.551. 2 Mém. de l'Inst. 1806. Since writing this we have read the following note by Sir David Brewster :"Our astronomical readers will be gratified to learn that M. Leverrier has found that the periodical comets of 1770 and 1844 are two different bodies; that two of the comets of Faye, Vico, and Lexell, passed close to Jupiter; and that all these comets, now permanently attached to our system, have come into it and been detained by the action of Jupiter and other bodies. M. Leverrier proves that the comets of Faye and Lexell have been in our system for at least a century, and have come a dozen of times near the earth without being observed. The comet of 1844 he proves to be the same as that of 1678, which has travelled into our system from the depths of infinite space, and been fixed among us centuries ago. It will revisit us in 1849."-North Br. Rev. No. xvi. p. 51, note, Feb. 1848. CHAPTER XIV. 349. Aurora borealis. 350. General appearances. 351. Examples. 352. Features at the Bay of Alten. 353. Appearances during present century. 354. Visible over great extent. 355. Aurora australis. 356. Corona borealis. 357. Fixed order of progression of the Polar Lights,-dark segment, arc, rays, wreath. 358. Hues, and Lustre. 359. Height. 360. Periodicity,-secular, mensual, diurnal. 361. Magnetic influence. 362. Magnetic storms. 363. Odour,-ozone. 364. Sound. 365. Hypotheses. 366. Magnetic theory. 367. Zodiacal light. 368. Cause. 369. Ignis Fatuus. 370. Appearances. 371. Luminous appearances unconnected with evolution of heat. 372. Cause of the Ignis Fatuus; Sepulchral lamps. "In Fancy's eye encount'ring armies glare SAVAGE. 349. The aurora borealis, or polar lights, is one of those beautiful luminous meteors which in all ages since its first appearance, has attracted notice, and names, fanciful as numerous, have been applied to it. It is the nordlichter or nordscheine of the Germans, the merry-dancers of the Shetlanders, and the streamers of others, associated in the minds of the vulgar, who inherit by descent the opinions of their ancestors, with all that is terrible and portentous. To the ancients it was known according to its peculiar appearance by the names of trabes, bolides, chasmata, capra-saltans or skipping goats, and when the beams resembled the staves of a cask, pithias. Flying dragons, hostile armies, and other signs and prodigies have been traced by the superstitious, in the bloody rods and burning spears of the aurora, no difficulty being found in accommodating the modes of celestial warfare to the ideas of the beholders and the times. The untutored Indian views in it, the spirits of his fathers roaming in the land of souls. 350. The aurora borealis is a luminous meteor of much beauty, appearing in the northern sky, seldom stationary, often flitting about with great velocity, or breaking out in fantastic corruscations. Sometimes it spans the earth, enclosing in its arc, a gloomy segment through which the stars may be observed this was termed by the ancients Bothynoë, a cave or chasm, and is mentioned by Aristotle. At other times, it appears in concentric arcs; and sometimes assumes the form of nebulous or curdled masses, or bands. In hue and shade there is no little variety, from a smoky-black, or a steel-grey, to a deep yellow; from a violet to an orange, or from a russet-brown to a fiery red. So vivid occasionally is this meteor, that it was seen by day on the 29th January 1786, by Lowenorn, and subsequently by Sir W. E. Parry.' The aurora borealis is most brilliantly exhibited in the polar regions, enlivening the long absence of sun, and aided by the protracted twilight, enabling the inhabitants of those dreary climes to engage in occasional pursuits, so that "Even in the depth of polar night they find THOMSON, Winter, v. 863. 351. The aurora borealis has been described by Aristotle," and referred to by Pliny,' Seneca, and others. Frobesius records appearances of this meteor in the years 502, 465, and 463 before the Christian era, beside many others down to modern times. Holinshed' mentions several undoubted appearances in England, in the years 1194, 1204, 1564, 1574, and 1575; Stow notices those of 7th October 1564, and 14th and 15th November 1574; the latter is mentioned by Camden. Halley 1 Jour. of Voy. 1821-23, p. 156. 2 For notices of this meteor in the Phil. Trans. of last cent., see vols, for the years 1716, 1717, 1719-24, 1726-31, 1734, 1736, 1740, 1741, 1750, 1751, 1762, 1764, 1767, 1769, 1770, 1774, 1781, and 1790. Nat. Hist. ii. 27, 33. Cat. pub. at Helmstadt, 1739. 3 Meteors, book i. ch. iv. v. Quæst. Nat. lib. i. cap. 15. Chron. vol. iii. pp. 143, 166, 1207, 1260, 1261. 8 Ph. Tr. No, 347, p. 406. quotes its appearance on the 30th January 1560 at London.' Those of 1575 were seen in Brabant, and have been described by Gemma of Louvain. In 1580, Mæstlin of Tubingen, the preceptor of Kepler, witnessed the polar lights seven times, at Baknang, in Wurtemberg; in the following year they were seen several times, but particularly in February and September. On the 13th and 15th September 1606-the day before and after the royal baptism at Fontainbleau, where the court of Henry IV. of France were assembled,-the aurora borealis appeared, and continued to excite fears till the savans of those days agreed among themselves that the apparitions were only exhalations! It was upon the appearance of this meteor, on the 2d September 1621, that Gassendi gave it the name aurora borealis. In November 1623, an appearance of the polar lights in Germany, is noticed by Kepler. Cotes notices that one which was seen at Cambridge, on the 20th November 1706. It was observed in 1707 in Ireland;3 and was witnessed the same year by Romer at Copenhagan, and Kirch at Berlin; in 1708 it was seen at London by the Bishop of Hereford; and in 1710, at Leeds, by Thoresby. Halley says he waited till he almost ceased to hope, before he was gratified with the spectacle at last, on the 6th March 1716, an aurora borealis of great beauty appeared, and attracted general attention : it was visible from the west of Ireland to the confines of Russia. It became the theme of the vulgar, and though our illustrious Hanoverian kings had began to reign two years before, that was no objection in their minds to its connection. with the new dynasty. Several other appearances are recorded between that year and 1723, when the phenomenon was seen at Bologna. On the 19th October 1726, a very singular one was witnessed at Breuillepont in Normandy, and figured by Mairan.' In November 1765, the whole horizon in the lat. of 57° was overspread with a red aurora. Maupertuis saw one at Oswer Zornea, very vivid and forming a A Descrip. of Meteors by W. F.-D. D. Lond. 1654. 2 Lib. de Cometa, 1580. Miscellanea Berolinensia, 1710. 3 Neve,-Ph. Tr. No. 320; Abr. ii. 112–123. Phil. Tr. No. 331, p. 322; Abr. ii. 114. "Ib. No. 347; see also Nos. 351, 352,—Aur. observ. by Barrel and Foulkes. Traité dé l'Aur. Boréale, 1754. |