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is accomplished, I apprehend, in the following way. It is a well known fact, that fresh water, at the temperature of 394, is specifically heaviest ; and that it possesses the strange peculiarity of becoming lighter by the farther reduction of temperature; and at that point where it passes into ice, its expansibility, if we except its vaporous state, is at its maximum. The same law, a little modified, regulates the freezing of salt water; the points of greatest density and consolidation being probably a little lower than in fresh water.

When water is completely frozen, it, like other bodies, contracts by a continued abstraction of calorie. Now, if a body of ice, twenty or thirty feet thick, floats in water at the freezing point, the under surface of that ice will be nearly of the same temperature as the water, and the upper surface may correspond with the temperature of the superjacent atmosphere, which, during winter, in high latitudes, depresses the thermometer to 40° or 50° below zero. Such a difference of temperature must produce a very great difference in specific gravity, and the upper surface must be much more contracted than the under; but as the cold increased progressively, it might happen that no evident effect would be produced by this great difference, as the accumulating mass accommodated itself to the gradual change: but as soon as the summer returns, the temperature of the air is speedily raised, communicating its caloric to the surface of the ice, which begins to expand, and ultimately exerts energy sufficient to overcome the cohesive force of the frozen particles, and a rent is the consequence; which, as soon as it has commenced, runs unrestrained in all directions; and the advancing summer, modifying the winter's sway, prevents reunion, till the attachment is set loose by the currents, or drifted off by the winds.

The effects originating in the influence of the vicissitudes of temperature in tearing asunder the ice, are awfully illustrated by the aspect of the polar glaciers, which are found in the valleys on shore. The ice being upwards of 200 feet thick, the hideous chasm yawns horribly to the very bottom, from the brink of which the beholder turns away with indescribable feelings of horror.

* See Icebergs, Phil. Journ. 1819.

The second effect produced on the ice by the solar rays is solution. When the sun has withdrawn his influence, and the long winter night has spread its shades over the regions of the north, all the dark domain is fettered in tenfold frost,-all is silent and dead,-the torpid bear doses in his icy cave, and the stunted productions of the soil, shrivelled by the cold, shrink into the earth beneath the cover of snow. Ocean is no more; and, except when the changing moon agitates the keen ether, the forlorn scene is never ruffled by the gale. The thermometer, which, during summer, ranged some ten degrees above the freezing point, now sinks to 50° below zero; and half a moon of such intensity produces enough of ice to replace the whole dissolved by the sun's rays. Indeed, that amounts to little; as a thawing temperature is felt only at intervals during a month or two in summer, and can scarce effect the solution of the snow covering the ice-field.

The feeble action of the sun in thawing the polar ice, is abundantly illustrated by the permanency of those ice-shoals which have so long shut up the followers of Eric on the eastern shores of Greenland,―by the annual augmentation of the polar glaciers, reared in ravines on the shores of Spitzbergen, Beerenberg, and even the more southern coasts of Iceland and Cape Farewell.

The presence of these frigid accumulations in so low a latitude, is apt to bias the judgment, leading to an inaccurate estimate of the polar climate; for if, during summer, in a latitude so low as 60°, we find land surrounded by a frozen sea, hills perpetually covered with snow, and valleys filled with solid ice, what picture can our imagination form of those regions 600leagues farther north? None other surely, than that they are in all probability ever in a frozen state.

If, however, during a summer noon, we visit some sheltered bay in Spitzbergen, whilst, through an unclouded atmosphere, shine the bright beams of a never-setting sun, where the calm ether leaves no impress on the placid main, gently murmuring along the shore, from which rises the earthy slope covered with verdure, interspersed with flowers, watered by the streamlet from the mountain rock, which echoes the uncouth screams of myriads of the feathered tribes which annually nestle there,

-amidst a scene like this (and many such there are), heedless of the frowns of huge adjacent icebergs, which diffuse winter around, and often fill the atmosphere with clouds, despite the conviction that, in inland scenes, valleys are filled, and hills buried, with never-melting snow, we would be disposed to esteem the climate mild, and extend the same character to regions still more remote. The impression formed by such Elysian mildness may have divested the ingenious Mr Scoresby of his accustomed acuteness, whilst treating of the " Climate of Spitzbergen," in his "Account of the Arctic Regions;" for, biassed by the indications of the thermometer, he reasons himself into the supposition, that the climate, during summer, is more temperate than even in Scotland, and gives to the circle of perpetual congelation, an altitude of 7791 feet,—a statement contradicted by facts.

2. Action of Tempests.-Having noticed the effects of the sun's direct influence on the ice, I shall next make a few remarks on the action of the tempest. Scarce has the sun risen over the polar horizon, and shed his oblique rays on the hoary regions of the north, than the tempest begins to raise up the billows of the ocean, whose heavings rend the detached ice into fragments, and the west setting current carries off the ruins to be dissolved in a lower latitude.

This process often exhibits a scene truly awful. The mass of thousands of millions of tons, whose farthest verge rounds off the horizon, floats strong and deep, darkening the abyss, and filling the atmosphere with its effulgence, till the storm heaves up the deep. At first, the waves ineffectually dash along the icy barrier, mingling their spray with the drift, but gathering strength, sea rolls after sea; the ice-field labours on its undulating bed; and the reiterated thundering crash proclaims its disruption; and, mixed with the foam, mass reels on mass till the wreck is complete, and the ruins spread along the main.

3. Action of Currents.-The current is a powerful agent in destroying the ice in the North Sea, and is of such importance that, if it did not exert its influence, all the surface of the ocean, within the Frigid Zone, would be crowded with the separated pieces. The currents are rendered very conspicuous in the Greenland Seas, by the drift of the floating substances. They may be divided into two kinds, accidental and permanent. Ac

cidental currents are partial motions in the water, occasioned by the action of the winds, or the movement of the larger bodies of ice. Thus when fields and icebergs are driven from the sea into deep bays, by strong, gales, the dammed up water is sometimes forced many feet above its usual level. Such a phenomenon has been noticed by many navigators. I myself saw decided testimony of such, when on shore at Spitzbergen, near Cross Bay, in the vicinity of the Seven Icebergs. All the low land in that neighbourhood, lying behind Fair Foreland, from its local situation, must be much exposed to inundation. The flat on which I landed, was, in general, ten or fourteen feet above the level of the sea, and some leagues in circumference. All this bore testimony of having been recently covered by the sea, from the pools of salt water, and the remnants of salt water ice, from the drift timber, and the bones of marine animals, which had been bleaching on the beach. Nearly a mile from the shore, I also found a chest made of rough deals, lying high among the gravel, which appeared to have been lashed by the waves, and considerably chafed. opening it, I found it to contain a human skeleton, which had, in all probability, been swept from its superficial grave by the same cause which had transported it thither. On the north of Spitzbergen, Captain Phipps found large fir-trees lying at a distance from the shore, 16 or 18 feet above the level of the sea. And Leonin, who was sent to ascertain the nature of this island by the Grand Marshals of Denmark, found a ship's mizen, about a league inland. The tide there does not rise above four feet.

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that island, sends off a branch towards the north. It then trends to the southward, carrying all the detached ice, throughout its course, in that direction. The quantity thus annually disposed of, has been estimated by Mr Scoresby at 20,000 square leagues, which he notices is three-fourths greater than the area of the sea accessible to the whale-fisher. The opportunity of observation afforded this intelligent gentleman, entitles his remarks to every respect. I do not think he has exaggerated in this calculation. Nay, some are of opinion that if we were possessed of means to ascertain the precise amount, it would be found considerably to exceed his estimate. But though the area of the drifting ice much exceeds that of the fishing ground, I would not consider all the surplus as the produce of unexplored regions. Such an assertion might indeed be consistent, if the sea frequented by the whale-hunter was only once frozen during the year, and if this annual coat alone were broken up, and drifted away; but we must recollect that, by November, the water again begins to freeze, and that the early produce,

tion does not testify its being a tropical production; for, lately examining the bottom of a fishing sloop which had been entirely confined to the banks of Shetland, I found the Teredo navalis rioting in a more fearful extent than I ever observed in the uncoppered planks of vessels which had long traded in the Mediterranean and West Indian Seas. Some specimens of this worm were a foot long, and the largest of their canals were seven-eighths of an inch in diameter.

This northern branch is also the cause of the Whale-fishers' Bight, which is a very deep bay in the ice, found during the early part of the season, extending northward towards Spitzbergen, between the meridian of London and 12° or 13° of eastern longitude. There the sea does not freeze so readily, as the temperature of the water is higher than the adjoining sea. It likewise, with the currents coming from the north, accounts for another anomaly, which, even in our day, has been considered unaccountable. M. de Capel Brook wondered why no ice was formed in the harbour of Hammerfest, in Lat. 70° N. though the temperature of the air was 13° below 0. Others have esteemed it an unaccountable circumstance, that the coast of Newfoundland should be strewed with ice, and the sheltered places on the coast frozen up, whilst the shores of Iceland, and even those of Norway, remained free. Now, it is easily to be accounted for, if we bear in mind the course of the currents. The remnant of the Gulph Stream is continually passing from Iceland along the coast of Norway, on which the intensity of winter has no influence: and, if the currents from Greenland carry not only a great body of cold water, but much frozen ice over to Newfoundland, the climate and temperature of the sea must be much colder than on similar latitudes on the opposite side of the Atlantic.

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