Those masses of ice which, towering to a considerable elevation above the surface of the water, are carried hither and thither by the currents of the Polar Sea, are known as _Icebergs_. They are fresh-water formations, originating in the great glaciers of the northern highlands. For as the rivers continuously pour their waters into the ocean, so do the glaciers incessantly glide downward from the head of the valleys which they occupy, until, arriving on the coast, they throw off their terminal projections, to be carried afar by the action of the tidal waves. These bergs, or floating mountains, are sometimes 250 to 300 feet above the level of the sea, and their capacity or bulk is invariably equal to their height. From their specific gravity it has been calculated that the volume of an iceberg _below_ the water is eight times that of the portion rising above it. They are frequently of the most imposing magnitude. Ross, in his first expedition, fell in with one in Baffin Bay, at a distance of seven leagues from land, which had gone aground in sixty-one fathoms water. Its dimensions, according to Lieutenant Parry, were 4,169 yards in length, 3,869 yards in breadth, and 51 feet in height. Its configuration is described as resembling that of the back of the Isle of Wight, while its cliffs recalled those chalky ramparts which stretch their glittering line to the west of Dover. Its weight was computed at 1,292,397,673 tons. Captain Graab examined a mass, on the west coast of Greenland, which rose 120 feet out of the water, measured 4,000 feet in circumference at the base, and was calculated to be equal in bulk to upwards of 900,000,000 cubic feet. Dr. Hayes took the measurements of a berg which had stranded off the little harbour of Tessuissak, to the north of Melville Bay. The square wall which faced towards his base of triangulation was somewhat more than three-quarters of a mile in length, and 315 feet in height. As it was nearly square-sided above the sea, it would be of the same shape beneath it; and, according to the ratio already given, must have drifted aground in a depth of fully half a mile. In other words, from base to summit it must have stood as high as the peak of Snowdon. Its cubical contents cannot have been less than about 27,000,000,000 feet, nor its weight than 2,000,000,000 tons! When seen from a distance, the spectacle of any considerable number of these slowly-moving mountains is very impressive, and it becomes particularly magnificent if it should be lit up by the splendour of the midnight sun. They are not only majestic in size, but sublime in appearance, at one time assuming the likeness of a grand cathedral church, at another, of a lofty obelisk; now of a dazzling pyramid, and now of a cluster of lofty towers. Nature would seem to have lavished upon them all her architectural fancy; and as they are grandly swept along, one might be pardoned for supposing them to be the sea-washed palaces of a race of ocean Titans.