ATMOSPHERIC EFFECTS.

37

Nothing can be more wonderful than the phenomena of the atmosphere dependent on reflection and refraction, which are frequently observed in the Arctic seas, particularly at the commencement or approach of easterly winds. They are probably occasioned by the commixture, near the surface of the land or sea, of two streams of air of different temperatures, so as to occasion an irregular deposition of imperfectly condensed vapour, which when passing the verge of the horizon apparently raises the objects there situated to a considerable distance above it, or extends their height beyond their natural dimensions. Ice, land, ships, boats, and other objects, when thus enlarged and elevated, are said to loom. The lower part of looming objects are sometimes connected with the horizon by an apparent fibrous or columnar extension of their parts; at other times they appear to be quite lifted into the air, a void space being seen between them and the horizon.

A most remarkable delusion of this kind was observed by Scoresby while sailing through the open ice, far from land. Suddenly an immense amphitheatre enclosed by high walls of basaltic ice, so like natural rock as to deceive one of his most experienced officers, rose around the ship. Sometimes the refraction produced on all sides a similar effect, but still more frequently remarkable contrasts. Single ice-blocks expanded into architectural figures of an extraordinary height, and sometimes the distant, deeply indented ice-border looked like a number of towers or minarets, or like a dense forest of naked trees. Scarcely had an object acquired a distinct form, when it began to dissolve into another.

It is well known that similar causes produce similar effects in the warmer regions of the earth. In the midst of the tropical ocean, the mariner sees verdant islands rise from the waters, and in the treeless desert fantastic palm-groves wave their fronds, as if in mockery of the thirsty caravan.

When we consider the intense cold which reigns during the greatest part of the year in the Arctic regions, we might naturally expect to find the whole of the Polar Sea covered, during the winter at least, with one solid unbroken sheet of ice. But experience teaches us that this is by no means the case; for the currents, the tides, the winds, and the swell of a turbulent ocean are mighty causes of disruption, or

strong impediments to congelation. Both Lieutenant de Haven and Sir Francis M'Clintock* were helplessly carried along, in the depth of winter, by the pack-ice in Lancaster Sound and Baffin's Bay. A berg impelled by a strong under-current rips open an ice-field as if it were a thin sheet of glass; and in channels, or on coasts where the tides rise to a considerable height, their flux and reflux is continually opening crevices and lanes in the ice which covers the waters. That even in the highest latitudes the sea does not close except when at rest, was fully experienced by Dr. Hayes during his wintering at Port Foulke; for at all times, even when the temperature of the air was below the freezing. point of mercury, he could hear from the deck of his schooner the roar of the beating waves. From all these causes there has at no point within the Arctic circle been found a firm ice-belt extending, either in winter or in summer, more than from fifty to a hundred miles from land. And even in the narrow channels separating the islands of the Parry Archipelago, or at the mouth of Smith Sound, the waters will not freeze over, except when sheltered by the land, or when an ice-pack, accumulated by long continuance of winds from one quarter, affords the same protection.

But the constant motion of the Polar Sea, wherever it expands to a considerable breadth, would be insufficient to prevent its total congelation, if it were not assisted by other physical causes. A magnificent system of currents is coutinually displacing the waters of the ocean, and forcing the warm floods of the tropical regions to wander to the Pole, while the cold streams of the frigid zone are as constantly migrating towards the equator. Thus we see the Gulf Stream flowing through the broad gateway east of Spitzbergen, and forcing out a return current of cold water to the west of Spitzbergen, and through Davis' Strait.

The comparatively warm floods which, in consequence of this great law of circulation, come pouring into the Arctic Seas naturally require some time before they are sufficiently chilled to be converted into ice; and as sea-water has its maximum of density, or, in other words, is heaviest a few degrees above the freezing-point of water, and then

* See Chapter XXXII.

necessarily sinks, the whole depth of the sea must of course be cooled down to that temperature before freezing can take place. Ice being a bad conductor of heat, likewise limits the process of congelation; for after attaining a thickness of ten or fifteen feet, its growth is very slow, and probably even ceases altogether; for when floating fields, or floes, are found of a greater thickness, this increase is due to the snow that falls upon their surface, or to the accumulation of hummocks caused by their collision.

Thus, by the combined influence of these various physical agencies, bounds have been set to the congelation of the Polar waters. Were it otherwise the Arctic lands would have been mere uninhabitable wastes; for the existence of the seals, the walrus, and the whale depends upon their finding some open water at every season of the year; and deprived of this resource, all the Esquimaux, whose various tribes fringe the coasts in the highest latitudes hitherto discovered, would perish in a single winter.

If the Arctic glaciers did not discharge their bergs into the sea, or if no currents conveyed the ice-floes of the north into lower latitudes, ice would be constantly accumulating in the Polar world, and, destroying the balance of nature, would ultimately endanger the existence of man over the whole surface of the globe.

Populousness of the Arctic Seas-The Greenland Whale-The Fin Whales-The Narwhal-The Beluga, or White Dolphin-The Black Dolphin-His wholesale Massacre on the Faeroe Islands-The Ore or Grampus-The Seals-The Walrus-Its acute Smell-History of a young Walrus-Parental Affection-The Polar Bear-His Sagacity-Hibernation of the She-Bear-Sea Birds.

THE of animate conings to the nakedness HE vast multitudes of animated beings which people the

of their bleak and desolate shores. The colder surface-waters almost perpetually exposed to a chilly air, and frequently covered, even in summer, with floating ice, are indeed unfavourable to the development of organic life; but this adverse influence is modified by the higher temperature which constantly prevails at a greater depth; for, contrary to what takes place in the equatorial seas, we find in the Polar Ocean an increase of temperature from the surface downwards, in consequence of the warmer under-currents, flowing from the south northwards, and passing beneath the cold waters of the superficial Arctic current.