wrote in 1706, records his remembrance of the time when the meteor was an object of terror in his native island. It deserves remark, that its more frequent occurrence in the Atlantic regions has been accompanied by its diminution in the eastern parts of Asia, as Baron Von Wrangel was assured by the natives there, who added that formerly it was brighter than at present, and frequently coloured like the rainbow. A work by M. de Mairan, entitled, Traité Physique et Historique de l'Aurore Boreale, published in 1754, records all the observations of aurora from the sixth century down to that date, as far as they appear upon the page of history. From this work, the singular view of an auroral appearance just given is copied, which was observed for a few minutes at Breuillepont, in Normandy, on the 19th of October, 1726. The gross number of distinct phenomena enumerated by M. Mairan, amounts to 1441, distributed as follows: Of course, during the earlier periods, we must suppose that a great many instances occurred which found no record; but the high numbers which appear after the close of the seventeenth century, may be considered as confirming the presumption of auroral exhibitions having become more common in European localities. Distributed according to the different months in which the aurora appeared, the numbers to be assigned to each The instances in the winter half-year amount to 972, and those in the summer to 469, being nearly in the proportion of 2 to 1 in favour of the former. It has been repeatedly affirmed, that auroral displays are attended with sound, variously described as a hissing, murmuring, and crackling noise. Blagden and Gmelin offer several testimonies of a rustling noise having been occasionally heard; Nairne, Cavallo, and others speak of a hissing sound; and Henderson remarks, that in Iceland, when the coruscations are particularly quick and vivid, a crackling noise is heard, resembling that which attends the escape of the sparks from an electric machine. Captain Lyon observes, that the sudden glare and rapid bursts of those wondrous showers of fire that appear in the sky make it difficult to fancy their movements wholly without sound, but nothing was ever heard by him, or by his companion Captain Parry. The latter states, that it was too cold to admit of the ears being long uncovered; but Lyon declares, that he stood for hours on the ice listening, and at a distance from every sounding body, without catching the faintest noise. But the counter testimonies are so numerous, that this point must be deemed at present an open question. Dr. Richardson was an attentive student of the aurora during the arctic land expedition of Sir John Franklin; and though he never heard any sound that could be unequivocally considered as originating with the meteor, yet the united testimony of the natives, both Crees, Copper Indians, and Esquimaux, and of all the older residents at the European ports, induced him to believe that its motions are sometimes audible. It has also been debated, what effect the auroral light produced upon the stars in its path, respecting which, Parry states: “Of its dimming the stars there cannot be a doubt; we remarked it to be in this respect like drawing a gauze veil over the heavens in that part, the veil being the thickest when two of the luminous sheets met and overlapped." Various results of calculation have been given as to the elevation of auroral phenomena. They clearly occur within the limits of our atmosphere, from the fact of the earth's diurnal motion having no effect upon the apparent position of the meteor. M. de Mairan assigns to it a mean height of 175 French leagues, equal to 464 English miles; Dr. Dalton concludes the average elevation to be about 100 English miles; but according to Parry, the auroral appearances seemed to be full as near as many of the clouds commonly seen. In one instance, the aurora appeared to be connected with a very remarkable cloud of a light brown colour, resembling an immense volume of smoke, or a powder magazine in a state of explosion, (the comparison of the gunner,) for upon the breaking up of the cloud the phenomenon was seen in the same part of the heavens. The experience of Beechy is in favour of a comparatively low elevation. "We frequently observed," he states, "the aurora attended by a thin, fleecy, cloud-like substance, which, if not part of the meteor, furnishes a proof of the displays having taken place within the region of our atmosphere, as the light was decidedly seen between it and the earth. This was particularly noticed on the 28th of September, 1827. The aurora on that night began by forming two arches from W. by N. northward to E. by N., and about eleven o'clock threw out brilliant coruscations. Shortly after the zenith was obscured by a lucid haze, which soon condensed into a canopy of light clouds. We could detect the aurora above this canopy by several bright arches being refracted, and by brilliant colours being apparent in the interstices. Shortly afterwards the meteor descended, and exhibited a splendid appearance, without any interruption from clouds, and then retired, leaving the fleecy stratum only visible at first. This occurred several times, and left no doubt in my own mind of the aurora being at one time above, but at another below, the canopy formed about our zenith. The supposition of the light being at no great elevation, is strengthened by the different appearances exhibited by the aurora at the same times, to observers not more than from ten to thirty miles apart; and also by its being visible to persons on board the ship at Chamisso Island after it had vanished in Escholtz Bay, only ten miles distant, as well as by the aurora being seen by the barge detached from the Blossom several days before it was visible to persons on board the ship, about two hundred miles to the southward of her. Captain Franklin has mentioned a similar circumstance in his notices on the Aurora Borealis in his first expedition, when Dr. Richardson and Mr. Kendall were watching for the appearance of the meteor by agreement, and when it was seen by the former actively sweeping across the heavens and exhibiting prismatic colours, without any appearance of the kind being witnessed by the latter, then only twenty miles distant from his companion. Captain Parry also, in his third voyage, describes the aurora as being seen even between the hills and the ship anchored at Port Bowen." Still, it is unquestionable, that the aurora occasionally occurs in the highest regions of the atmosphere, as in the grand example of 1716, which was simultaneously observed in places very remote from each other, and ascertained to be visible from latitude 50° north, all over Europe, between the confines of Russia on the east and Ireland on the west, a sufficient evidence of its very great altitude. -- From optical phenomena belonging to the electric class, or which are supposed to have electrical connections, we proceed to consider the appearances which simply result from peculiar atmospheric conditions. 1. Halos. The simplest form of the halo is that of a white concentric ring surrounding the sun or moon, a very common appearance in our climate in relation to the moon, occasioned by very thin vapour, or minute particles of ice and snow, diffused through the atmosphere, deflecting the rays of light. Double rings are occasionally seen, displaying the brightest hues of the rainbow. The coloured ring is produced by globules of visible vapour, the resulting halo exhibiting a character of density, and appearing contiguous to the luminous body, according as the atmosphere is surcharged with humidity. Hence a dense halo close to the moon is universally and justly regarded as an indication of coming rain. It has been stated as an approximation, that the globules which occasion the appearance of coloured circles vary from the 5000th to the 50,000th part of an inch in diameter. Though seldom apparent around the sun in our climate, yet it is only necessary to remove that glare of light which makes delicate colours appear white, to perceive segments of beautifully tinted halos on most days when light fleecy clouds are present. The illustration shows a nearly complete and slightly elliptical ring around the sun, the lower portion hidden by the horizon, which was distinctly observed during the summer of 1845 in the neighbourhood of Ipswich, of an extremely pale pink and blue tint. When Humboldt was at Cumana, a large double halo around the moon fixed the attention of the inhabitants, who considered it as the presage of a violent earthquake. The hygrometer denoted great humidity, yet the vapours appeared so perfectly in solution, or rather so elastic and uniformly disseminated, that they did not alter the transparency of the atmosphere. The moon arose after a storm of rain behind the Castle of St. Antonio. As soon as she appeared on the horizon, two circles were distinguished, one large and whitish, 44° in diameter, the other smaller, displaying all the colours of the rainbow. The space between the two circles was of the deepest azure. At the altitude of 4° they disappeared, while the meteorological instruments indicated not the slightest change in the lower regions of the air. The phenomenon was chiefly remarkable for the great brilliancy of its colours, and for the circumstance that, according to the measures taken with Ramsden's sextant, the lunar disc was not exactly in the centre of the halos. Humboldt mentions likewise having seen at Mexico, in extremely fine weather, large bands spread along the vault of the sky, converging towards the lunar disc, displaying beautiful prismatic colours; and he remarks, that within the torrid zone, similar appearances are the common phenomena of the night, sometimes vanishing and returning in the space of a few minutes, which he assigns to the superior currents of air changing the state of the floating vapours, by which the light is refracted. Between latitude 15° of the equator, he records having observed small tinted halos around the planet Venus, the purple, orange, and violet being distinctly perceptible, which was never the case with Sirius, Canopus, or Acherner. In the northern regions solar and lunar halos are very common appearances, owing to the abundance of minute and highly crystallised spicula of ice floating in the atmosphere. The arctic adventurers frequently mention the fall of icy particles during a clear sky and a bright sun, so small as scarcely to be visible to the naked eye, and most readily detected by their melting upon the skin. 2. Parhelia. Mock suns, in the vicinity of the real orb, are due to the same cause as halos, which appear in connection with them. Luminous circles, or segments, crossing one another, produce conspicuous masses of light by their united intensities, and the points of intersection appear studded with the solar image. This is a meteorological rarity in our latitude, but a very frequent spectacle in the arctic climes. In Iceland, during the severe winter of 1615, it is related that the sun, when seen, was always accompanied by two, four, five, and even nine of these illusions. Captain Parry describes a remarkably gorgeous appearance, during his winter sojourn at Melville Island, which continued from noon until six o'clock in the evening. It consisted of one complete halo, 45° in diameter, with segments of several others, displaying in parts the colours of the rainbow. Besides these, there was another perfect ring of a pale white colour, which went right round the sky, parallel with the horizon, and at a distance from it equal to the sun's altitude; and a horizontal band of white light appeared passing through the sun. Where the band and the inner halo cut each other, there were two parhelia, and another close to the horizon, directly under the sun, which formed the most brilliant part of the spectacle, being exactly like the sun, slightly obscured by a thin cloud at his rising or setting. A drawing of this parhelion is given by Captain Parry, who remarks upon having always observed such phenomena attended with a little snow falling, or rather small spiculæ or fine crystals of ice. The angular forms of the crystals determine the rays of light in different directions, and originate the consequent visual variety. We have various observations of parhelia seen in different parts of Europe, which in a less enlightened age excited consternation, and were regarded as portentous. Matthew Paris relates in his history: "A wonderful sight was seen in England A. D. 1233, April 8, in the fifth year of the reign of Henry III., and lasted from sunrise till noon. At the same time on the 8th of April, about one o'clock, in the borders of Herefordshire and Worcestershire, besides the true sun there appeared in the sky four mock suns of a red colour; also a certain large circle of the colour of crystal, about two Parhelia. feet broad, which encompassed all England as it were. There went out semicircles from the side of it, at whose intersection the four mock suns were situated, the true sun being in the east, and the air very clear. And because this monstrous prodigy cannot be described by words, I have represented it by a scheme, which shows immediately how the heavens were circled. The appearance was painted in this manner by many people, for the wonderful novelty of it." 3. Paraselena. Mock moons, depending upon the causes which produce the solar image, or several examples of it, as frequently adorn the arctic sky. On the 1st of December 1819, in the evening, while Parry's expedition was in Winter Harbour, four paraselenæ were observed, each at the distance of 211° from the true moon. One was close to the horizon, the other perpendicular above it, and the other two in a line parallel to the horizon. Their shape was like that of a comet, the tail being from the moon, the side of each towards the real orb being of a light orange colour. During the existence of these paraselenæ, a halo appeared in a concentric circle round the moon, passing through each image. On the evening of March 30, 1820, about ten o'clock, the attention of Dr. Trail at Liverpool was directed by a friend to an unusual appearance in the sky, which proved to be a beautiful display of paraselenæ. The moon was then 35° above the southern horizon. The atmosphere was nearly calm, but rather cloudy, and obscured by a slight haze. A wide halo, faintly exhibiting the prismatic colours, was described round. the moon as a centre, and had a small portion of its circumference cut off by the horizon. The circular band was intersected by two small segments of a larger circle, which if completed would have passed through the moon, and parallel to the horizon. These segments were of a paler colour than the first mentioned circle. At the points of intersection appeared two pretty well defined luminous discs, equalling the moon in size, but less brilliant. The western paraselene had a tail or coma, which was directed from the moon, and the eastern also, but much less clearly defined. 4. The Rainbow. The most glorious vision depending upon the decomposition, refraction, and reflection of light, by the vapour of the atmosphere reduced to fluid drops, is the well-known arch projected during a shower of rain upon a cloud opposite to the sun, displaying all the tints of the solar spectrum. The first marked approximation to the true theory of the rainbow occurs in a volume entitled De Radiis Visus et Lucis, written by Antonius de Dominis, Archbishop of Spalatro, published in the year 1611 at Venice. Descartes pursued the subject, and correctly explained some of the phenomena; but upon Newton's discovery of the different degrees of refrangibility in the different coloured rays which compose the sunbeam, a pencil of white or compounded light, the cause of the coloured bands in the rainbow, of the order of their position, and of the breadth they occupy, was at once apparent. The bow is common to all countries, and is the sign of the covenant of promise to all people, that there shall no more be such a wide-spread deluge as that which the sacred narrative records. "But say, what mean those coloured streaks in heaven Or serve they, as a flowery verge to bind The fluid skirts of that same watery cloud, Lest it again dissolve, and shower the earth? To whom the Archangel: Dexterously thou aim'st ; So willingly doth God remit his ire That he relents, not to blot out mankind; And makes a covenant never to destroy The earth again by flood; nor let the sea Surpass its bounds; nor rain to drown the world, |