From Chambers' Journal. Among the navigators and scientific men of former times, it was disputed whether salt water was capable of being frozen. Experience—in many cases a stern teacher—has set that question at rest, proving that within the polar circles tha sea is,' for hundreds of miles, covered with masses of ice, which form a sullen, unyielding barrier to the poles. Maury describes the agencies at work in these terrible solitudes in a famous passage: "There icebergs are framed and glaciers launched; there the tides have their cradle, the whales their nursery; there the winds complete their circuits, and the currents of the sea their round in the wonderful system of oceanic circulation; there the' aurora is lighted up, and the trembling needle brought to rest; and there too, in the mazes of that mystic circle, terrestrial forces of occult power and of vast influence upon the well-being of man are continually at play. Within the arctic circle are the pole of the winds and the poles of the cold; the pole of the earth imJ of the magnet. It is a circle of mysteries; and the desire to enter it—to explore its untrodden wastes and secret chambers, and to study its physical aspects—has grown into a longing." Marine ice is whitish opaque, and rough on the surface, and consists of thin flakes of a porous spongy texture. From the quantity of strong brine enclosed in its substance, it is very heavy and dense, and projects only one-fifth above water. When sea-water begins to freeze, it partially deposits its salt, which, thus set free, retards the process of congelation below. Old floes are almost fresh, but a thaw renders them brackish. The polar seas do not congeal until the temperature falls to I 28 degrees of Fahrenheit, which takes place in September in the north, and March in the south; though even in summer, a slight increase of cold is sufficient to form young ice several inches thick. The sun sets early in November, and the severity of the arctic winter begins in December, continuing to the end of January, during which time the thermometer ranges to about 40 degrees below zero. A week or two of milder weather comes on; but the middle of February brings with it the sun, immediately followed by the most intense cold of the whole winter. After that, the sun's influence begins to be felt, and in July the ice breaks up. During the three summer months, the sun never sets, but noon and midnight are equally illumined by brilliant sunshine. A few stars appear in Scp-I tember. The darkest part of the winter is from the middle of December to the middle of January, when the aurora transforms the sky into a vault of fire, and paraselene appear, surrounding the moon with blazing cresses, circles, and mock-moons, scarcely surpassed by the wonderful deceptions of tho solar rays. The intense cold of February is accompanied by considerable twilight; and in the, latitude of Banks' Land, i there is even at the end of January tolerable light from 9.30 A.M. to 2.80 P.M., so much so, that at noon Arcturus is the sole star unquench by the increasing daylight. The only naviga-! ble time is from July to September within the northern, and January, February, and part of March within the southern circle. During the rest of the year, the arctic regions are im-I penetrably sealed by vast fields of ice, both " floe " and " pack," covering every foot of water, from the shallowest inlet to the wide expanse of Baffin's Bay or Melville Sound. The interior of Greenland is occupied by vast glaciers 179 which encroach on the coast, filling the deep dark fiords with I frozen snow. As summer advances, those portions of the , glacier that project into the sea are undermined by the waves, f and fall with tremendous noise, rocking in the foaming water. till they gain equilibrium, when, perfect icebergs, they float i here and there, impelled by winds and currents. Many are j borne by the polar current southward. They meet the warm waters of the Gulf-stream in latitude 50 degrees, where they melt, and deposit the loads of earth and stones borrowed from j the Greenland soil. According to Maury, this has probably,; in course of time, formed the Grand Bank of Newfoundland. They are in incredible numbers. As many as five hundred j have been counted in sight together, ranging from fifty to j three hundred feet in Mght, and of all sizes up to a mile in extent. Their appearance is very beautiful and no less extraordinary. Gothic churches, Egyptian temples, aerial palaces -with pillars and archud windows festooned with crystal draperies, are only some of the inconceivable varieties of form displayed, while they gleam under the summer sun like mountains of burnished silver, with pinnacles and cliffs of clear sapphire or the palest green, from which rush cataracts of limpid water mingled with fragments of ice. These various hues arise from several causes. Bergs are originally composed of fresh water ice of different ages, but that formed from salt water frequently overlays it in parts. A great deal of snow lies on their summits, and forms large ponds of fresh water, when dissolved by the heat of the sun. Finally, the solar -rays touch the bergs with colors, changing with the position of the spectator. Only one-eighth of their total thickness is seen above water. Frequently bergs capsize in consequence of the sea undermining their base. An ominous rolling motion gives notice of this event; it continues for some time, and at last the berg heels over and disappears with a terrific plunge, sending up columns of spray. It reappears bottom upwards, balances itself, ana floats quietly on with a changed face. All the antarctic land yet discovered consists of gigantic cliffs without a single opening, three thousand feet high in some places, descending in others to one hundred feet. The whole is faced with ice of enormous thickness, and covered with snow, so that at a glance the eye can scarcely imagine it to be land at all, but for spots showing the dark stone where the cliff is too perpendicular to admit of even ice maintaining its hold. Nothing is so tenacious as the cold of the antarctic regions. In February, the warmest summer month of 1841, the thermometer never rose above 14 degress at noon near the continent. It is rarely above 30 degrees in the sun at mid-day during summer, and fells in winter more than 50 degrees below zero. The sun stays a week longer north of the equator tUan it does south, making tho winter and night of the antarctic regions longer. South Georgia, in a latitude corresponding with that of Yorkshire in the northern hemisphere, is always covered with frozen snow, and produces scarcely anything but mosses and lichens. The immense preponderance of water south of latitude 50 degrees, allows the fierce westerly winds to blow round and round the world, a perpetual cyclone, keeping the sea in constant agitation. The two polar circles differ greatly in physical conditions. Tho antarctic has a marine climate, that is to say, it is equable. Though wet and stormy, it is not subject to extremes of temperature, and it is believed that the south pole must be warm-1 er than the north in winter. Arctic sunshine raises the ther- ! inomoter to 66 degrees or 70 degrees, and hung in the shade immediately after, the mercury falls to the freezing point. The arctic climate is continental—dry, calm, and variable. The thermometer has a range of about 120 degrees; and while the round of the seasons brings but little change in the f right-fiul antarctic wastes, nothing can surpass the beauty of the j arctic summer—" an endless blaze of light, the air and sea and earth teeming with life," plains glowing with richly tinted j flowers, and strange, glittering forms sailing past " in stately and solemn procession." Its currents are strong, and bear large numbers of bergs to meet the warm Gulf-water, and, as it is natural to suppose, bergs are found to be most numerous where the drift is strongest. The antarctic seas are in direct opposition to this. Not only are its currents sluggish and feeble, but the most powerful of them, Humboldt's Current, carries few bergs along the Chilian coast, while the main ice-drift is towards the Falklands on one side, and the Cape of Good Hope on the other, where there is scarcely any motion of the water. This is a fact which no navigators are able to explain, except perhaps on the supposition that there may be strong submarine currents at a great depth below the surface. Bergs have been observed in Baffin's Bay drifting rapidly to the north, where there was a powerful surface-current running tigainst them, showing that in consequence of their weight and immense draft of water (in some instances more than a thousand feet), they must be influenced by some " resistless undertow " yet stronger.