CHAPTER IV. MAGNIFICENT AURORAL DISPLAYS. Most Striking of Optical Splendors-Auroral Arc-Streams of Light Shooting Upward-Trembling Gleams and Flashes—“The Merry Dancers"-Lights of Rainbow Colors-What Parry and Franklin Saw--The Heavens in Gay Attire-Lieutenant Chappell's Auroral Umbrella--Arch of Silvery Light-The Canopy Glowing with Splendid Scenery-Polar Night-Six Months without a Sun-Animals Dying of Gloom-Dazzling Standards Unfurled-Magnetism-Fiery Tempests in the Sun-Magnetic Stones on Earth-Outbreak of Auroral Magnificence-Sir John Herschel's Conclusions-The Jerking Needle-Reference by AristotleNorthern Lights more Common than formerly in the Northern Zones. MONG the remarkable phenomena of the sky must be placed The appearances exhibited by the aurora are so various and wonderful. A cloud, or haze, is commonly seen in the northern region of the heavens, but often bearing towards the east or west, assuming the form of an arc, seldom attaining a greater altitude than forty degrees, but varying in extent from five to one hundred degrees. 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. Lights of Various Colors. 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 towards 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 downwards 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, two hundred and fifty 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 meteor 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. Dalton has furnished the following account of an aurora, as observed by him Attention was first excited by a remarkably red appearance of the clouds to the south, which afforded sufficient light to read by at eight 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 cast. 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. A Spectacle Sublimely Brilliant. The intensity of the light, and 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 great distinction between the polar countries and the other regions of the globe, is their long day and long night. Describing an immense spiral around the horizon, the sun gradually mounts to the highest point of his course; then, in the same manner, it returns towards the horizon, and bids farewell to earth, slowly dying away in a gloomy and ghastly twilight. And, for six months, the Arctic wildernesses know it not. When the navigator, says Captain Parry, finds himself buried for the first time in the silent shadows of the polar night, he cannot conquer an involuntary emotion of dread; he feels transported out of the sphere of ordinary existence. These deadly and sombre deserts seem like those uncreated voids which Milton has placed between the realms of life and death. The very animals are affected by the melancholy which veils the face of nature. Under the influence of the almost perpetual gloominess Dr. Kane's Newfoundland dogs went mad, and died. Six Months' Night. But if the sun for six months of the year deprives the circumpolar countries of the splendor of its fires, an imposing phenomenon frequently illuminates the long nights with dazzling radiance, as if nature sought to compensate for the absence of the orb of day by the most impressive of all her optical wonders. The polar nights are nearly always lighted up by the gorgeous lustre of the aurora; called borealis or australis, according to the poles at which it is produced. Shafts and rays of light shoot upwards to the zenith. These luminous sheaves pass through all the colors of the rainbow; from violet and sapphire to green and purple red. Sometimes the columns of light issue from the resplendent arch mixed with blackish rays; sometimes they rise simultaneously at different points of the horizon, and unite to form a sea of flame pervaded by rapid undulations. On other occasions, fiery dazzling standards are unfurled to float lightly in the air. A kind of canopy of soft and tranquil light, which is known as the corona, announces the close of the phenomenon. Thereupon the luminous shafts begin to wane in splendor, the richly colored arcs dissolve, die out, and soon of all the magnificent spectacle nothing remains but a whitish cloudy haze. The arch of the aurora is only part of a ring of light, which is elevated considerably above the surface of our globe, and whose centre is situated in the vicinity of the pole. It is easy, then, to account for the different aspects it presents to observers placed at different angles to it. A person some degrees south of the ring would necessarily see only a very small arc of it towards the north, from the interposition of the earth between him and the observer; 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 suppose it to culminate in the south. It is supposed that the centre of the ring corresponds with the magnetic north point, in the island of Boothia Felix. Flags and Streamers of Light Fluttering in the Sky. The phenomenon generally lasts several hours, and is frequently diversified by peculiar features; so that sometimes it seems to present the hem ispherical segment of a gigantic wheel; sometimes it waves and droops like a rich tapestry of colored light, in a thousand prismatic folds; and, at other times, it may be compared to a succession of resplendent banners, or streamers, waving in the dark and intense sky. The arch varies in elevation, but is seldom found more than ninety miles above the terrestrial surface. Its diameter must be enormous, for it has been known to extend from Italy to the polar regions, and has been simultaneously visible in Sardinia, Connecticut, and New Orleans. According to some authorities, the phenomenon is accompanied by noises resembling the discharge of fireworks, or the crackling of silk when one piece is rolled over another; but this statement is not confirmed by the experience of our ablest Arctic voyagers. Of the magneto-electric origin of the aurora no doubt can be entertained. When it occurs, the magnetic needle is invariably affected, the perturbation being greatest at the climax of the auroral brilliancy. The vortex of the arch is almost always in or near the magnetic meridian. The lights would seem to result from a discharge at or around the magnetic poles of electricity which has gradually accumulated at these opposite points. Startling Changes on the Sun's Surface. The needle has been found to oscillate through a long cycle of changes, one occupying in its completion a little more than eleven years: that is to say, between the time when the oscillation is least and that when it is greatest there elapses a period of five and a half years, and an equal period before it returns again to its first value. Now, a cycle of changes takes place on the face of the sun agreeing most perfectly with this, not merely in length, but in maximum for maximum, and minimum for mini mum. are not permanent, Sometimes his face And as to their ac To make this clear, the nature of the facts involved must be stated, and this can be done in no better words than those of Sir John Herschel : "One of the first achievements of the telescope was the discovery of black spots on the surface of the sun. These spots but come and go; and their number varies greatly. is quite spotless; at others, the spots swarm upon it. tual size, some are comparatively small, others of stupendous extent. One spot which I measured, in 1837, occupied no less than 3,780,000,000 square miles; another, which was nearly round, would have allowed the earth to drop through it, leaving a thousand miles clear of contact on every side; and many other instances of much larger spots than these are on record. What are we to think, then, of the awful scale of hurricane |