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THE AURORA BOREALIS.-ZODIACAL

LIGHT.

At the North Cape, Acerbi felt as if all the cares of life had vanished; worldly pursuits assumed the character of dreams; the forms and energies of animated Nature seemed to fade away, and the earth appeared as if it were about to revert to its original elements. A solemn magnificence, an interminable space, wearing the aspect of infinity, characterized the scene. The billows dashed in awful grandeur against rocks coeval with the globe; marine birds, wild in character and dissonant in language, skimmed along their girdles; the moon shed her solemn lustre on their dark and frowning pyramids; the stars glowed with burnished brilliancy; and the Aurora Borealis added terrific interest to the gloomy majesty of the whole.

And what can be more awful, and, at the same time, more beautiful, than the wild and mysterious motions and colours which this polar phenomenon presents ? sometimes covering with inconceivable magnificence the concave of the whole hemisphere, changing its positions every moment; now resembling vast pyramids, or stretching into innumerable columns, varying their shapes and hues with astonishing rapidity and with endless caprice; now vanishing in an instant, leaving the heavens sombre and black; and again suddenly returning with increased splendour, shedding a matchless glory over all the sky.

The appearance of this phenomenon has been looked upon by the superstitious and ignorant with no small alarm, as foreboding war, pestilence, or some other direful calamity. Spenser alludes to this in his Faierie Queene, and Thomson, still more particularly, in his philosophic poem of the Seasons.

From look to look, contagious through the crowd
The panic runs, and into wondrous shapes
Th' appearance throws : armies in meet array
Throng'd with aërial spears and steeds of fire,
Till the long lines of full-extended war,
In bleeding fight commix'd, the sanguine flood
Rolls a broad slaughter o'er the plains of heaven.
As thus they scan the visionary scene,
On all sides swells the superstitious din,
Incontinent, and busy Phrensy talks
Of blood and battle, cities overturn'd,
And late at night in swallowing earthquake sunk;
Or hideous wrapp'd in fierce ascending flame;
Of sallow famine, inundation, storm;
Of pestilence, and every great distress;
Empires subversed, when ruling Fate has struck
Th' unalterable hour; even Nature's self

Is deem'd to lotter on the brink of time. With respect to the cause of this phenomenon, many hypotheses have been started by philosophical writers. St. Pierre supposes it may be occasioned by the coruscations of the ice within the polar circles, the approach to islands of ice being frequently indicated some time before they appear in the horizon by the coruscations they emit.*

This hypothesis gains some support from the circumstance observed by travellers in Lapland and Siberia of the aurora being attended by a hissing and crackling sound. An insuperable objection to it, however, is, that if the phenomenon alluded to proceeded from the coruscations of the polar ice, it would make its appearance regularly every year; whereas it is seen only occasionally, and in ancient times was still more rare.t

Some have imagined it to proceed from the ice islands themselves, which float at particular seasons of the year along the Northern and Southern Oceans,

* Ice-blinks are visible at a considerable distance, and by their effulgence may be seen in the thickest fog and in the darkest night. - Mem. Wernerian Society, vol. ii., p. 292.

† The first appearance of it recorded in England is, I be. lieve, by William of Malmesbury, p. 177.

grounding their opinion principally upon Captain Cook's having observed that the ice islands at the South Pole illumined half the horizon to a considerable height. But this hypothesis is even more improbable than the former. It is liable to the same objection we have urged against that, with the addition of the seeming impossibility that any coruscations proceeding from objects so comparatively low as these islands should ascend to an altitude of sev. eral thousand miles ; a height to which, in the opinion of many philosophers, particularly Euler and Mairan, the illuminations of the aurora ascend. To add to the difficulty, it has been observed by different travellers in Iceland, that the northern lights start up from the east and southeast as well as from the north. In Greenland they generally proceed from the east. In Lapland, frequently from the south,* In Hudson's Bay they resemble an umbrella, with streams of light darting from every part of its periphery. At the equator it is seldom if ever seen.

Franklin supposed the aurora to be owing to the vast quantity of electricity accumulated in the atmosphere, and which is unable to pass off into the earth, on account of the non-conducting nature of ice, and the land and seas in the polar regions being incrusted with it. Some have also supposed it to be connected with the magnetic fluid; but Captain Parry, when in the Arctic Regions, could not perceive that it affected the magnetic needle in any degree. It neither altered its polarity, nor even so much as caused a single tremulous motion.t

* The result of Captain Ross's voyage proves that it appears in every direction, and not unfrequently at small distances from the earth.Vid. Voy, of Disc. to Arctic Regions.

+ Professor Hansteen, of Christiana, believes the earth to have four magnetic poles, and that the moon and the sun have mag. netical poles also. He supposes the aurora lights to be magnetical currents flowing from one magnetical pole to the other imme. diately opposite; that they have the form of a luminous cross where they first appear; and that there are four luminous In respect to the iceblink, Martin describes it as an arch formed upon the clouds by reflection from packed ice. This reflection sometimes presents a perfect map of the ice twenty or thirty miles beyond the limits of direct vision.

Some navigators assert that icebergs exhibit green and blue colours by day, but none by night; others, among whom is Captain Ross, that they have most beautiful colours by night as well as by day, displaying a variety beyond the power of art to represent. In these northern regions it is curious that lenses may be formed of ice, which, without melting, will, when the sun is powerful, light matches, fire gunpowder, and even melt lead.

The ZODIACAL Light presents also a very beautiful appearance. It is said to have been first discovered by Cassini in the year 1683; yet who can doubt that it has exhibited itself in all ages ? It is seen only in the zodiac, and best in the month of March, after the setting of the sun. Its figure resembles an inverted pyramid, with its base towards that luminary. Humboldt says it often displays itself in this shape in the Caraccas, as well as among the Cordilleras of Mexico; and La Caille speaks with great admiration of its appearance between the tropics, as he was sailing from Rio Janeiro to the Cape. M. de Marian thinks this phenomenon to be the cause of the aurora borealis, and associates both with the atmosphere of the sun. My own opinion is, that both may be ascribed to the same cause, and that they are occasioned by a peculiar state of the electric fluid,

crosses, two in the northern hemisphere, and two in the southern, elevated from four to five hundred miles above the earth.

FATA MARGANA.

But of all the phenomena of nature, there is none which produces in the mind such an indescribable emotion as the Fata Margana, seen in the Straits of Messina: a phenomenon that surpasses all the fairy phantoms which the imagination conjures up in reading the descriptions of the Arabian poets. The Sicilians therefore consider it to be the most beautiful sight in nature.

Minasi has written a dissertation on this phenomenon, which is thus described by Father Angelucci: “As I stood at my window, I was surprised with a wonderful vision. The sea that washes the Sicilian shore swelled up, and became for ten miles in length like a chain of dark mountains, while the waters near our Calabrian coast in an instant appeared as one clear polished mirror, reclining against the ridge. On this glass was depicted, in chiaroscuro, a string of several thousand pilasters, all equal in altitude, distance, and degree of light and shade. In a moment they lost their height, and bent into arcades like Roman aqueducts; and a long cornice was next formed on the top, and above it rose castles innumerable, all perfectly alike. They soon split into towers, which were shortly after lost in colonnades; then windows; and at last they ended in pines, cypresses, and other trees even and simi. lar. This is the Fata MARGANA, which for twentysix years I thought a mere fable." Such is the account of this surprising phenomenon, derived by Swinburne from Father Angelucci.* It is supposed

* Vernet, says St. Pierre, “was one day greatly surprised to perceive in the sky the appearance of a town turned upside down, and to distinguish perfectly the steeples, towers, and houses. He lost no time in sketching this phenomenon, and, determined to ascertain its cause, he proceeded, following the same point of the compass, into the mountains. But how great

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