able breadth, would be insufficient to prevent its total congelation, if it were not assisted by other physical causes. A magnificent system of currents is continually 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 toward 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's 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 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

CHAPTER IV.

ARCTIC MARINE ANIMALS.

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 Orc, 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

HE vast multitudes of animated beings which people the Polar Seas form a remarkable contrast to the nakedness 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 unfavorable 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 downward, in consequence of the warmer under-currents, flowing from the south northward, and passing beneath the cold waters of the superficial Arctic current.

Thus the severity of the Polar winter remains unfelt at a greater depth of the sea, where myriads of creatures find a secure retreat against the frost, and whence they emerge during the long summer's day, either to line the shores or to ascend the broad rivers of the Arctic world. Between the parallels of 74° and 80° Scoresby observed that the color of the Greenland sea varies from the purest ultramarine to olive green, and from crystalline transparency to striking opacity-appearances which are not transitory, but permanent. This green semi-opaque water, whose position varies with the currents, often forming isolated stripes, and sometimes spreading over two or three degrees of latitude, mainly owes its singular aspect to small medusæ and nudibranchiate molluscs. It is calculated to form one-fourth part of the surface of the sea between the above-mentioned parallels, so that many thousands of square miles are absolutely teeming with life.

On the coast of Greenland, where the waters are so exceedingly clear that the bottom and every object upon it are plainly visible even at a depth of eighty fathoms, the ground is seen covered with gigantic tangles, which, together with the animal world circulating among their fronds, remind the spectator of the coral-reefs of the tropical ocean. Nullipores, mussels, alcyonians, sertularians, ascidians, and a variety of other sessile animals, incrust every stone or fill every hollow or crevice of the rocky ground. A dead seal or fish thrown. into the sea is soon converted into a skeleton by the myriads of small crustaceans which infest these northern waters, and, like the ants in the equatorial forests, perform the part of scavengers of the deep.

Thus we find an exuberance of life, in its smaller and smallest forms, peopling the Arctic waters, and affording nourishment to a variety of strange and bulky creatures-cetaceans, walruses, and seals-which annually attract thousands of adventurous seamen to the icy ocean.

Of these sea-mammalians, the most important to civilized man is undoubtedly the Greenland whale (Balana mysticetus), or smooth-back, thus called from its having no dorsal fin. Formerly these whales were harpooned in considerable numbers in the Icelandic waters, or in the fiords of Spitzbergen and Danish Greenland; then Davis's Straits became the favorite fishing-grounds; and more recently the inlets and various channels to the east of Baffin's Bay have been invaded; while, on the opposite side of America, several hundreds of whalers penetrate every year through Bering's Straits into the icy sea beyond, where previously they lived and multiplied, unmolested except by the Esquimaux.

More fortunate than the smooth-back, the rorquals, or fin-whales (Balanoptera boops, musculus, physalis, and rostratus), still remain in their ancient seats, from which they are not likely to be dislodged, as the agility of their movements makes their capture more difficult and dangerous; while at the same time the small quantity of their fat and the shortness of their baleen render it far less remunerative. They are of a more slender form of body, and with a more pointed muzzle than the Greenland whale; and while the latter attains a length of only sixty feet, the Balaenoptera boops grows to the vast length of 100 feet and more. There is also a difference in their food, for the Greenland whale chiefly feeds upon the minute animals that crowd the olive-colored waters above described, or on the hosts of little pteropods that are found in many parts of the Arctic seas, while the rorquals frequently accompany the herring-shoals, and carry death and destruction into their ranks.

The seas of Novaja Zemlya, Spitzbergen, and Greenland are the domain of the narwhal, or sea-unicorn, a cetacean quite as strange, but not so fabulous as the terrestrial animal which figures in the arms of England. The use of the

enormous spirally wound tusk projecting from its upper jaw, and from which it derives its popular name, has not yet been clearly ascertained, some holding it to be an instrument of defense, while others suppose it to be only an ornament or mark of the superior dignity of the sex to which it has been awarded. Among the numerous dolphins which people the Arctic and Subarctic seas, the beluga (Delphinus leucas), improperly called the white whale, is one of the most interesting. When young it has a brown color, which gradually changes into a perfect white. It attains a length of from twelve to twenty feet, has no dorsal fin, a strong tail three feet broad, and a round head with a broad truncated snout. Beyond 56° of latitude it is frequently seen in large shoals, particularly near the estuaries of the large Siberian and North American rivers, which it often ascends to a considerable distance in pursuit of the salmon. A troop of belugas diving out of the dark waves of the Arctic Sea is said to afford

a magnificent spectacle. Their white color appears dazzling, from the contrast of the sombre background, as they dart about with arrow-like velocity.

The black dolphin (Globicephalus globiceps) is likewise very common in the Arctic seas, both beyond Bering's Straits and between Greenland and Spitzbergen, whence it frequently makes excursions to the south. It grows to the length of twenty-four feet, and is about ten feet in circumference. The skin, like that of the dolphin tribe in general, is smooth, resembling oiled silk; the color a bluish-black on the back, and generally whitish on the belly; the blubber is three or four inches thick.

The full-grown have generally twenty-two or twenty-four teeth in each jaw; and when the mouth is shut, the teeth lock between one another, like the teeth of a trap. The dorsal fin is about fifteen inches high, the tail five feet broad; the pectoral fins are as many, long and comparatively narrow; so that, armed with such excellent paddles, the black dolphin is inferior to none of his relatives in swiftness. Of an eminently social disposition, these dolphins sometimes congregate in herds of many hundreds, under the guidance of several old experi