Some phosphorous fabric, which the mountains screen,
Whose clouds of light above those mountains rise?
Where the winds rattle loud around the foaming sea,
And lift the waves to heaven in thundering revelry?”
The appearances exhibited by the aurora are so various as to render it impossible to comprehend every particular in a description that must be necessarily brief and general. A cloud, or haze, is commonly seen in the northern region of the heavens, but often bearing toward the east or west, assuming the form of an arc, seldom attaining a greater altitude than 40°, but varying in extent from 5° to 100°. The upper edge of the cloud is luminous, sometimes brilliant and irregular. The lower part is frequently dark and thick, with the clear sky appearing between it and the horizon. Streams of light shoot up in columnar forms from the upper part of the cloud, now extending but a few degrees, then as far as the zenith, and even beyond it. Instances occur in which the whole hemisphere is covered with these coruscations; but the brilliancy is the greatest, and the light the strongest, in the north, near the main body of the meteor. The streamers have in general a tremulous motion, and when close together present the appearance of waves, or sheets of light, following each other in rapid succession. But no rule obtains with reference to these streaks, which have acquired the name of “the merry dancers,” from their volatility, becoming more quick in their motions in stormy weather, as if sympathizing with the wildness of the blast. Such is the extraordinary aspect they present, that it is not surprising the rude Indians should gaze upon them as the spirits of their fathers roaming through the land of souls. They are variously white, pale red, or of a deep blood-color, and sometimes the appearance of the whole rainbow as to hue is presented. When several streamers emerging from different points unite at the zenith, a small and dense meteor is formed, which seems to burn with greater violence than the separate parts, and glows with a green, blue, or purple light. The display is over sometimes in a few minutes, or continues for hours, or through the whole night, and appears for several nights in succession. Captain Beechey remarked a sudden illumination to occur at one extremity of the auroral arch, the light passing along the belt with a tremulous hesitating movement toward the opposite end, exhibiting the colors of the rainbow; and as an illustration of this appearance, he refers to that presented by the rays of some molluscous animals in motion. Captain Parry notices the same effect as a common one with the aurora, and compares it, as far as its motion is concerned, to a person holding a long ribbon by one end, and giving it an undulatory movement through its whole length, though its general position remains the same. Captain Sabine likewise speaks of the arch being bent into convolutions, resembling those of a snake in motion. Both Parry, Franklin, and Beechey agree in the observation that no streamers were ever noticed shooting downward from the arch.
The preceding statement refers to aurora in high northern latitudes, where the full magnificence of the phenomenon is displayed. It forms a fine compensation for the long and dreary night to which these regions are subject, the gay and varying aspect of the heavens contrasting refreshingly with the repelling and monotonous appearance of the earth. We have already stated that the direction in which the aurora generally makes its first appearance, or the quarter in which the arch formed by this meteor is usually seen, is to the northward. But this does not hold good of very high latitudes, for by the expeditions which have wintered in the ice, it was almost always seen to the southward; while by Captain Beechey, in the Blossom, in Kotzerne Sound, 250 miles to the southward of the ice, it was always observed in a northern direction. It would appear, therefore, from this fact, that the margin of the region of packed ice is most favorable to the production of the meteor. The reports of the Greenland ships confirm this idea; for, according to their concurrent testimony, the meteoric display has a more brilliant aspect to vessels passing near the situation of the compact ice, than to others entered far within it. Instances, however, are not wanting, of the aurora appearing to the south of the zenith in comparatively low latitudes. Lieutenant Chappell, in his voyage to Hudson’s Bay, speaks of its forming in the zenith, in a shape resembling that of an umbrella, pouring down streams of light from all parts of its periphery, which fell vertically over the hemisphere in every direction. As we retire from the Pole, the phenomenon becomes a rarer occurrence, and is less perfectly and distinctly developed. In September, 1828, it was observed in England as a vast arch of silvery light, extending over nearly the whole of the heavens, transient gleams of light separating from the main body of the luminosity; but in September, 1827, its hues were red and brilliant. Dr. Dalton has furnished the following account of an aurora, as observed by him on the 15th of October, 1792:—“Attention,” he remarks, “was first excited by a remarkably red appearance of the clouds to the south, which afforded sufficient light to read by at 8 o’clock in the evening, though there was no moon nor light in the north. From half-past nine to ten there was a large, luminous, horizontal arch to the southward, and several faint concentric arches northward. It was particularly noticed that all the arches seemed exactly bisected by the plain of the magnetic meridian. At half-past ten o’clock streamers appeared, very low in the south-east, running to and fro from west to east. They increased in number, and began to approach the zenith apparently with an accelerated velocity, when all on a sudden the whole hemisphere was covered with them, and exhibited such an appearance as surpasses all description. The intensity of the light, the prodigious number and volatility of the beams, the grand intermixture of all the prismatic colors in their utmost splendor, variegating the glowing canopy with the most luxuriant and enchanting scenery, afforded an awful, but at the same time the most pleasing and sublime spectacle in nature. Every one gazed with astonishment, but the uncommon grandeur of the scene only lasted one minute. The variety of colors disappeared, and the beams lost their lateral motion, and were converted into the flashing radiations. The aurora continued for several hours.” A copious deposition of dew—hard gales in the English channel—and a sudden thaw after great cold in northern regions, are circumstances which have been frequently noticed in connection with auroral displays.
Aurora Borealis.
The sky of the southern hemisphere occasionally exhibits this strange and mysterious light, contrary to an old opinion upon the subject; and here it must be called Aurora Australis, the southern day-break. Its appearance, however, is far from being so common as in the northern zone, and is much less imposing. Don Antonio Ulloa, off Cape Horn, in the year 1745, witnessed the first appearance of the kind upon record in this region. Upon the clearing off of a thick mist, a light was observed in the southern horizon, extending to an elevation of about thirty degrees, sometimes of a reddish color, and sometimes like the light which precedes the rise of the moon, but occasionally more brilliant. Captain Cook, in the same latitudes, had more distinct views of the luminous streamers adorning the night-sky of the south. In the course of his second voyage he remarks, that on February the 17th, 1773, “a beautiful phenomenon was observed in the heavens. It consisted of long colors of a clear, white light, shooting up from the horizon, to the eastward, almost to the zenith, and spreading gradually over the whole southern part of the sky. These columns sometimes bent sideways at their upper extremity; and though in most respects similar to the northern lights, yet differed from them in being always of a whitish color, whereas ours assume various tints, especially those of a purple and fiery hue. The stars were sometimes hid by, and sometimes faintly to be seen through, the substance of these southern lights, Aurora Australis. The sky was generally clear when they appeared, and the air sharp and cold, the thermometer standing at the freezing point, the ship being in latitude 58° south.”
The history of auroral phenomena goes back to the time of Aristotle, who undoubtedly refers to the exhibition in his work on meteors, describing it as occurring on calm nights, having a resemblance to flame mingled with smoke, or to a distant view of burning stubble, purple, bright red, and blood-color, being the predominant hues. Notices of it are likewise found in many of the classical writers; and the accounts which occur in the chronicles of the middle ages, of surprising lights in the air, converted by the imagination of the vulgar into swords gleaming and armies fighting, are allusions to the play of the northern lights. There is strong reason to believe, though the fact is perfectly inscrutable, that the aurora has been much more common in the European region of the northern zone, during the last century and a half, than in former periods. A very brilliant appearance took place on the 6th of March, 1716, which forms the subject of a paper by Halley, who remarks, that nothing of the kind had occurred in England for more than eighty years, nor of the same magnitude since 1574, or about 140 years previous, in the reign of Queen Elizabeth, when Cambden and Stow were eye-witnesses of it. The latter states in his Annals, that on November 14th, “were seen in the air strange impressions of fire and smoke to proceed forth from a black cloud in the north toward the south—that the next night the heavens from all parts did seem to burn marvelous ragingly, and over our heads the flames from the horizon round about rising did meet, and there double and roll one in another, as if it had been in a clear furnace.” The year following, 1575, it was twice repeated in Holland, but not observed in England; and as a specimen of the tone of thought respecting the aurora, the description of Cornelius Gemma, a professor in the university of Louvain, may be given. Referring to the second instance of the year, and speaking in the language of the times, he remarks: “The form of the Chasma of the 28th of September following, immediately after sunset, was indeed less dreadful, but still more confused and various; for in it were seen a great many bright arches, out of which gradually issued spears, cities with towers and men in battle array; after that, there were excursions of rays every way, waves of clouds and battles mutually pursued and fled, and wheeling round in a surprising manner.” This phenomenon was repeatedly observed in the last century in Sweden, as at present; but prior to the year 1716, the inhabitants of Upsal considered it as a great rarity. Nothing is more common now in Iceland than the northern lights, exhibited during the winter with imposing grandeur and brilliance; but Torfæus, the historian of Denmark, an Icelander, who 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 presented the vivid coloring of the rainbow.