Again this green overcame the red; blue and yellow blended with each other in their swift flight; violet-tinted arrows flashed through a broad glow of orange, and countless tongues of white flame, formed of these uniting streams, rushed aloft and clasped the skies. The effect of the many-coloured lustre upon the surrounding objects was singularly wonderful. The weird forms of innumerable icebergs, singly and in clusters, loomed above the sea, and around their summits hovered the strange gleam, like the fires of Vesuvius over the villas and temples of Pompeii. All along the white surface of the frozen sea, upon the mountain-peaks and the lofty cliffs, the light glowed and dimmed and glowed again, as if the air were filled with graveyard meteors, flitting wildly above some vast illimitable city of the dead. The scene was noiseless, yet the senses were deceived, for sounds not of earth or sea seemed to follow the swift coruscations, and to fall upon the ear like
“The tread
Of phantoms dread,
With banner, and spear, and flame.”
Though the details, so to speak, are not always the same, the general character of the aurora changes very slightly, and, from a comparison of numerous accounts, the gradation of the phenomenon would seem to be as follows:—
The sky slowly assumes a tint of brown, on which, as on a background, is soon developed a nebulous segment, bordered by a spacious arc of dazzling whiteness, which seems incessantly agitated by a tremulous motion. From this arc an incredible number of shafts and rays of light leap upwards to the zenith. These luminous columns pass through all the hues of the rainbow,—from softest violet and intensest sapphire to green and purple-red. Sometimes the rays issue from the resplendent arc mingled with darker flashes; sometimes they rise simultaneously at different points of the horizon, and unite in one broad sea of flame pervaded by rapid undulations. On other occasions it would seem as if invisible hands were unfurling fiery dazzling banners, to stream, like meteors, in the troubled air. A kind of canopy, of soft and tranquil light, which is known as the corona, indicates the close of the marvellous exhibition; and shortly after its appearance the luminous rays begin to decrease in splendour, the richly-coloured arcs dissolve and die out, and soon of all the gorgeous spectacle nothing remains but a whitish cloudy haze in those parts of the firmament which, but a few minutes before, blazed with the mysterious fires of the aurora borealis.
THE AURORA BOREALIS—THE CORONA.
The arc of the aurora is only part of a broad circle of light, which is elevated considerably above the surface of our globe, and the centre of which is situated in the vicinity of the Pole. It is not difficult, therefore, to account for the different aspects under which it is presented to observers placed at different angles to the focus of the display. A person some degrees south of the ring necessarily sees but a very small arc of it towards the north, owing to the interposition of the earth between him and it; if he stood nearer the north, the arc would appear larger and higher; if immediately below it, he would see it apparently traversing the zenith; or if within the ring, and still further north, he would see it culminating in the south. It has been supposed that the centre of the ring corresponds with the magnetic north pole in the island of Boothia Felix.
Generally the phenomenon lasts for several hours, and at times it will be varied by peculiar features. Now it will seem to present the hemispherical segment of a colossal wheel; now it will wave and droop like a rich tapestry of many-coloured light, in a thousand prismatic folds; and now it exhibits the array of innumerable dazzling streamers, waving in the dark and intense sky.