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DESCRIPTION OF THE AURORA BOREALIS.
coruscations were paler than the laminæ observed in the southern parts of the heavens : they were, when first seen, about a degree in breadth, and they increased in height very rapidly. While these appearances were taking place in the north, several laminæ were succeeding each other in the south. The zenith as yet was clear; but the coruscations in the north, though decreasing in breadth, were rapidly ascending to it, accompanied with others from those parts that were to the south of it, but from a region more elevated than that in which the lamina moved. Such was the rapidity with which they were formed, and the lamina themselves quickly vanishing, that the writer could not ascertain whether those coruscations to the south of the zenith were given out by the lamina: but he would suggest that should laminæ again be observed of the description here given, the observers would do well to pay particular attention to them, and especially to notice if any coruscations proceed from them.
It was about six o'clock, when the scene, that the observer had been contemplating, arrived at its greatest splendour. The extremities of the arch above mentioned assumed a red appearance; the coruscations were exceedingly numerous both above and below it, their breadth being very small; and there was not a spot from the east to the western point of the northern hemisphere that was not covered with them. The appearance they presented was similar to the representation of falling rain; or they might fitly be compared to a numerous army with their weapons gleaming in the solar beams.
They had now extended to the zenith, and met there, forming a most splendid coloured corona. The colour of this part of the phenomenon was a lively crimson, or blood colour. The laminæ had now vanished, but a considerable quantity of luminous matter was seen extending to the south from the west; the south-eastern being the only portion of the heavens, that did not at this time display some of the varied forms of this meteor: this part, however, had not been exempt, as several laminæ had previously traversed it, which occasioned the observer to think, that the luminous matter, which was seen near the south, would quickly pass the planet Mars, then near the meridian, and thus succeed them. But this was not the case, for the phenomenon having arrived at a degree of splendour, an adequate idea of which it is impossible for language to convey, began now to decline, as if it had spent all its strength in producing the splendid spectacle that the writer witnessed. The coloured corona in the zenith
first faded; the coruscations diminished both in extent and number; the luminous matter, that before extended over a considerable portion of the heavens, now settled down in the northern horizon; and about a quarter before seven nothing was left of this beautiful phenomenon but a luminous appearance in the northern part of the heavens, that formed an arch, the highest part of which was in the direction of the magnetic pole.
About this time a lamina appeared a little to the east of north, similar in appearance to that observed across the constellation Orion, with the exception of the extremities not being so well defined: this moved with a moderate rapidity across the northern meridian, and about the same distance to the west disappeared. Nothing new in the appearance took place until half-past seven, with the exception of the arch of luminous matter gradually increasing in altitude, and occasionally sending forth a coruscation or two. At the time above-mentioned it had arrived at the zenith; and the whole of the northern hemisphere, bounded by a line drawn from a little to the north of east, and terminating a little to the south of west, had the appearance of an attenuated film or sheet of light, which was brightest in the east and western extremities, and also in the north near the horizon.
Hitherto the meteor had been unattended with that shooting, or tremulous motion, which has frequently been observed in other phenomena of the same nature; and which was very conspicuous in an Aurora observed by the writer on the 12th of Decem. ber last. But an appearance now took place similar to that observed in the Aurora of March 6th, 1716, by Dr. Halley, and which he termed nubecula.
A thin luminous substance arose from the east and western extremities of the arch, perpendicular to the horizon; and passed along the heavens towards the zenith with great rapidity. Its duration was momentary; for it was no sooner formed, than it vanished. This appearance was repeated incessantly for the space of nearly half an hour; during which time the luminous matter of the northern hemisphere had extended beyond the zenith towards the south; and several lucid portions which were constantly formed, as rapidly disappeared in the southern portion of the heavens.
A most interesting part of the phenomenon now began to present itself. The meteor nearly occupied every portion of the heavens, and the brilliant extremities of the arch above-mentioned, especially the eastern, began to throw out, or rather separate, into
long and thin coruscations, similar to those observed previous to the formation of the corona before alluded to. These were soon attended with a separation of the luminous matter in the northern hemisphere into coruscations of the same nature. This appearance was noticed a little after eight, when those portions of the heavens, which before were the most luminous, presented a coloured appearance.
The writer noticed three distinct portions of coloured coruscations: one in the direc. tion of the magnetic meridian, and one on each side, at the east and western extremities of the arch, which, at this time, was lost in the multitude of coruscations that now presented themselves to the sight of the admiring spectator. The coloured portions were not contiguous throughout the whole length of the coruscations, but arose only to a determinate height above the horizon; their breadth being nearly equal to their length. The summits of the coruscations were white, and they now met at some distance to the south of the zenith, where they formed a second corona. This magnificent appearance continued about a quarter of an hour, when the corona and coruscations, with their superb colours, gradually became fainter, and, at last, were lost to view.
About a quarter before nine, a new phenomenon presented itself. The luminous matter had again settled down towards the northern horizon; but instead of forming an arch, as on the former occasion, it assumed the appearance of a bright streak, or lamina, which had a serpentine form; the eastern part being more elevated than the western: it was also remarked, that the eastern extremity was curved towards the horizon. This appearance gradually assumed the arched form, which was again complete at half-past nine, when it had a considerable elevation. The luminous matter had also arrived at the zenith; but the appearance now was different to that noticed, as the luminous arch approached the zenith between the formation of the two corona. The whole of the northern portion of the heavens was then overspread with nearly an uniform sheet of luminous matter; a line drawn from the zenith to the east and west points of the horizon (nearly) forming the southern boundary thereof.
At the present time, the luminous substance appeared to be divided into two portions: one bounded by the arch, which was considerably the brightest; and the other extending to the zenith, which appeared rather faint and diluted, compared with the former observation. It was about ten o'clock when nubeculæ were again seen
darting from the east and western points of the horizon towards the zenith, but not to the extent and variety they were before observed. At a little past ten, the eastern extremity of the arch began to show signs of again separating into coruscations; but the substance shortly united, and thus continued until half-past ten, when some clouds arose from the north-west point of the horizon. At eleven the eastern extremity of the arch assumed a copper-coloured hue, which gradually became a pink, and extended to the zenith. A few coruscations now shot from the horizon near the east; but the meteor was evidently decreasing; and the clouds at this time overspreading it, put an end to further observations.
Having endeavoured as accurately as possible to describe the various appearances he saw, the observer will proceed to classify them, in order to facilitate the comparison of them with others of the same nature. The Aurora above described may naturally be resolved into three distinct parts: the first, comprising the appearances previous to the formation of the coloured corona: the second, the space of time occupied between the two corona: and, the third, the phenomena presented after the disappearance of the second corona.
In considering the first portion, there are four objects that present themselves to our notice. The luminous arch, and the coruscations observed in the north; the lamina in the south, and the coloured corona in the zenith. Of these the arch claims considerable attention; as it shows the manner in which the luminous matter has a tendency to arrange itself.
As all fluids, when isolated, form a sphere or globe, so the luminous matter of the Aurora appears to have arranged itself in a form something allied to this, although there are circumstances that prevent its taking a globular shape. It is also probable, that the luminous matter observed in the Aurora, to be contiguous to the northern horizon, was vertical to some portion of the earth's surface. If so, we may inquire, what would be the appearance at that spot? It is evident, the luminous matter would be seen in the zenith, spreading therefrom in every direction towards the horizon. Therefore, if the luminous matter takes a circular form (which is very probable) at those portions of the earth's surface considerably removed from the central part thereof, it would assume the form of an arch; the heights of which, above the horizon, would depend partly on the extent of the luminous matter, and partly on the distance from the central point. This hypothesis may, probably, be
DESCRIPTION OF THE AURORA BOREALIS.
confirmed; if, on future occasions, observers are diligent to notice the appearances presented to them, and, as Dr. Halley directs, in his account of the Aurora of 1716, set their clocks to apparent time, and note especially the altitudes and azimuths of every remarkable portion of the pheno
The coruscations are the next objects that demand our attention: these may in the present example be divided into two kinds, viz. those that were observed to shoot from the horizon, and those that resulted from a separation of the luminous matter. The coruscations that shot from the horizon appeared to the writer to consist of the same Juminous matter as the arch, but under a different form, and those that resulted from a separation of the luminous matter, were evidently composed thereof. The laminæ in the south appeared to consist of detached portions of the same luminous matter, that was generated in the regions in which they were observed. Their situation, with respect to the earth's surface, may easily be ascertained, if their altitudes have been observed at various places, especially to the south of this.
Their motion from west to east is an interesting feature, and demands the attention of every philosophic observer, especially as it is the direction in which the heavenly bodies perform their revolutions. The coloured corona appeared to be formed from an union of the coruscations in the zenith; and when the meteor had arrived at this stage, the coloured appearances were produced.
The writer having briefly considered the first part of the phenomenon, will proceed to enumerate the objects presented in the second. These are, a similar luminous arch; the nubecule that darted from the east and western portions of the horizon towards the zenith; the separation of the luminous matter into coruscations; and the formation of a second corona, attended with the colouring of the coruscations. It was this portion of the Aurora that particularly interested the observer; for here he had an opportunity of tracing the formation of this brilliant spectacle, and observing the growth thereof immediately under his eye.
After the superb corona, and brilliant coruscations of the former part, had vanished, nothing was presented to the view, but a small portion of luminous matter, which had again arranged itself in the form of an arch. This apparent focus of the phenomenon, in consequence of receiving fresh supplies of Juminous matter, was continually increased in size; and thus was occasioned the ap2D. SERIES, NO. 3.-VOL. I.
pearance of the arch, extending gradually to the zenith. The luminous matter at this time was evidently extended over a very considerable portion of the earth's surface; and the boundary now passing over the place of observation, gave an opportunity of noticing the manner in which the additions to the arch were performed, viz. by the action of the nubecula; for as these phenomena were darting across the heavens, the luminous matter was increasing in size; and as it approached the south, the nubeculae were noticed still more southerly. From this it appears, that the luminous matter, when first generated, assumed the form of nubeculæ, which darted with considerable velocity around the circumference of condensed luminous matter that formed the arch.
The substance that gave birth to these nubeculæ, although seen under that form but for an instant, was, probably, attracted by the matter composing the arch, with which it united; and upon its becoming more condensed, appeared to increase that portion of the meteor. The lucid portions in the southern parts of the heavens appeared to be of the same nature as the nubeculæ ; but in consequence of their distance from the central mass, they continued to be separated therefrom. When the operation of the nubeculæ ceased, the separation of the luminous matter into coruscations began to take place: there was, therefore, at this period of the phenomenon, an evident change. A very considerably quantity of luminous matter had collected together, which, in three distinct parts, was considerably condensed. There appeared now no more luminous matter to augment the arch; and, when it attained a certain extent and intensity, an internal motion appeared to take place in the meteor, by which the luminous matter was separated into filaments, of which the coruscations were formed.
It was remarked, that these coruscations, as well as those observed in the former part of the phenomenon, were not contiguous throughout their length, but appeared broken in several places. It was the union of their extremities in a point, situated on the boundary of the luminous matter, that occasioned the appearance of the corona: and it must be remarked, that both the coronæ were seen in the direction of the meridian. Their formation will illustrate the manner in which the separation of the luminous matter into coruscations was effected. This appeared to be twofold; one in a direction diverging from the centre; and one, by which the filaments were arranged in concentric lines. By the separation first taking place in the extremities of the arch, it appears, that
portions which were the most luminous, and, consequently, the most condensed, were first resolved into filaments; the direction being concentric of those near the circumference, and divergent of those near the centre of the luminous matter. Those that were differently situated appeared to follow a direction between the two just mentioned.
Now, the union of these differently directed coruscations would occasion the appearance of the coronæ. These would appear in or near the zenith, according as the boundary of the luminous matter passed over or near thereto, and would also be noticed in the direction of the meridian, if the centre of the luminous matter coincided therewith. It was at this stage of the phenomenon that the coruscations became coloured; from which it appears, that the colours really belonged to the luminous matter, and were not dependent on that atmospherical medium through which it was seen: for it may be remarked in the present Aurora, that no portion of it assumed a coloured appearance until the luminous matter was resolved into coruscations; and shortly after this display of colour took place, in both instances, the substance of which the Aurora was composed subsided.
In the third part of the phenomenon, there is only one particular different from what has been before noticed, viz. the curved lamina observed in the north, after the disappearance of the corona and coruscations. This, most probably, arose from those portions of the luminous matter that, previous to the formation of the corona, were more condensed than others. Upon the subsiding of the luminous matter, these condensed portions would prevent its taking that regular form which it otherwise would have done, and which it ultimately did, in the formation of another arch. The circumstance of there being a distinction between the arch and the luminous matter showed, that the phenomenon, in the third stage, was not near so active as in the two former.
In closing these remarks, the writer will refer the reader to several accounts of this interesting meteor, that have been published, which will materially assist him in his researches into the natural history thereof.
In the Philosophical Transactions, No.347, page 406, he will find an account of the brilliant Aurora of March 6th, 1716, observed and described by Dr. Halley, who has suggested some ideas as to the cause thereof. Nos. 351 and 352, of the same Transactions, contain accounts of Aurora observed by Mr. Barrel and Mr. Foulkes. Forster, in the account of his voyage round
the world with Captain Cook, describes a similar phenomenon observed towards the South Pole. The London Encyclopedia contains an interesting article on this meteor, in which M. Libes theory of its production merits attention. And the Quarterly Journal of Science, part 2, 1827, page 385, contains a most interesting paper on the Aurora of the 25th of September, 1827, by E. A. Kendall, Esq. F.S.A.
The writer will only add, that the present is the fifth Aurora that he has observed since the beginning of September last; and he has also been informed, that there have been four besides, which he did not see. One, that he observed on the 12th of December, was very considerable; but having had his attention directed to it only for a short time, he is unable to give that accurate description of it which he could wish. It was, however, attended with a very distinct arch, of considerable elevation. The coruscations were powerful, and had an altitude of about 70°. The observer noticed on this occasion a quick, tremulous, or flashing motion in the luminous matter composing the arch; first on one side, and then on the other. These appearances arose from the lower parts of the arch, and ascended to its boundary. The extremities of the arch became tinged with a copper colour, during the time the writer was observing it: and after this took place, he noticed that the phenomenon decreased. It may be remarked, that the breadth of the coruscations in the Aurora just mentioned was much greater than of those in the phenomenon above described; and that the latter was unattended with the tremulous motion of the former.
VIGIAS, OR ROCKS, IN THE ATLANTIC. ANOTHER of these thorns in the sides of navigators is said to have sprung up in the Atlantic, but fortunately, on authority which, although founded on ocular demonstration, is not sufficient to overcome our scepticism as to its reality.
The master of a ship and his mate, on their way to the island of Ascension, from England, say they saw a rock in lat. 6° 0′ S. and lon. 12° 57' W. Now, we are not for adding another to the long list of these "said to be" rocks, to create uneasiness to our seamen, nor are we for altogether adopting so bold a course as to pay no attention to them, but we decide according to circumstances. The position, however, assigned to this has been so often traversed by ships of all nations, that, had such a rock existed, it must have been known long ago; nay, almost from the time of the Portuguese
TRAVELS IN PERU.
voyages along the coast of Africa, in search of Cabo Tormentoso. There are few wellauthenticated vigias, of the many said to exist; and if all were marked on the charts, the commander of a ship would scarcely
venture to sea.
The reality of Aitkin's rock on the north coast of Ireland, had never been doubted until its existence was proved to be impossible by the vessels sent to look for it last summer; and when the authority on which it is laid down in the charts is investigated by a seaman, it turns out to be vague and indeterminate.
The Devil's rock in the middle of the entrance to the bay of Biscay is not yet found, although a ship has been sent to look for it. The sand-bank between Bermuda and Halifax has been stated to exist, but on very doubtful authority: yet there is no doubt that a very dangerous rock, about a hundred miles to the westward of Bermuda, does exist.
A PERUVIAN DINNER PARTY.
(From Temple's Travels in Peru.)
I AVAILED myself this day of a general invitation to dinner, given with unfeigned cordiality by Donna Juliana Indalesias, the rich widow of a man who, before the revolution, was one of the first among the many wealthy merchants then esiding in Potosi. Donna Juliana never omits daily attendance at mass, nor absents herself from any procession or particular ceremony of her church, and would consider it a crime to conceal her veneration for the images and paintings of saints which hallow and adorn her apartments. She also highly respects, and distinguishes from all her other friends, those whose peculiar calling it is to instruct mankind in the sacred doctrines of religion, seldom sitting down to dinner unaccompanied by a priest or friar, who have free admission to her plentiful table. That, however, which may excite surprise, because so seldom in accordance with ostentatious acts of devotion, is the fact, that she possesses the kindest heart in the world, and dispenses charity with true benevolence. She is known by the appellation of "La buena Cristiana," and never was distinction more deservedly bestowed.
Donna Juliana, Cura Costas, (the respectable head of the church at Potosi,) Padre Francisco, (a Dominican friar, whose portly corporation excited in my mind a malicious suspicion of his being more accustomed to feasting than fasting,) were the party with whom, at two o'clock, I sat down to dinner. Three Indian girls, the
children of old domestics, clean and tidy; an Indian boy, as may be sometimes seen in another "land of potatoes," shirtless, shoeless, and stockingless; a very fine negress slave, and an elderly woman, evidently the confidential servant, were the attendants. For nearly an hour, immense silver dishes were carried in and carried out, with the various compositions of our repast. The first course consisted, as is usual in the country, of cheese and fruit, such as melons, apples, figs, chyrimoyes, tunas, membrillos, &c. Then came two or three kinds of soup or porridge, with rice prepared in different ways. After these were removed, there was no regularity observed in the courses; for, whilst some of the attendants carried off the dishes that had been helped from, or, if not yet touched by us, that had remained long enough upon the table to gratify our view, others were at hand instantly to replace them: there was no opportunity given to remark, that
"There was the place where the pasty was not."
Each dish contained sufficient for a party of twice our number; and from every one I observed Donna Juliana take a large plateful, sometimes two platefuls, and, saying something in Quichua, hand them to one of her Indians, who placed them in a distant corner of the room. When the more substantial subjects of the feast were discussed, then followed custards, and compotes, and sweetmeats, from which small portions were also taken, to be husbanded, as I imagined, for to-morrow's fare. A dish of very good potatoes, accompanied with very bad butter, concluded the dinner. When the cloth was removed, all the attendants, without any word of command, ranged themselves in a rank in the middle of the room, and, suddenly dropping on their knees, sung, or said aloud, a grace that lasted full four minutes, in which the deep-toned voices of Padre Costas and Friar Francisco, nothing mellowed by their hearty meal, and ample goblet of Cinty wine from the estate of our hostess, chimed in like bass-viols, whilst Donna Juliana, pressing her cross and beads to her bosom, her eyes devoutly fixed upon a beautiful painting upon the Virgin and Child, which hung opposite to her, in a large massive silver frame, accompanied the others in all the fervency of thanksgiving. "Amen!" with the sign of the cross, as a benediction upon the company, by Padre Costas, ended this appropriate ceremony, in the solemnity of which the most obdurate heretic could not have refrained from joining.