Whenever ships have sailed southwards, except at a few places where land has been met with, they have come at last to a wall of ice, from fifty to four hundred feet high. In those regions it snows, if not incessantly, at least very frequently, and the snow melts but little. As far as the eye can reach nothing is to be seen but snow. Now this snow must gradually accumulate, and solidify into ice, until it attains such a slope that it will move forward as a glacier. The enormous Icebergs of the Southern Ocean, moreover, show that it does so, and that the snow of the extreme south, after condensing into ice, moves slowly outward and at length forms a wall of ice, from which Icebergs, from time to time, break away. We do not exactly know what, under such circumstances, the slope would be; but Mr. Croll points out that if we take it at only half a degree, and this seems quite a minimum, the Ice cap at the South Pole must be no less than twelve miles in thickness. It is indeed probably even more, for some of the Southern tabular icebergs attain a height of eight hundred, or even a thousand feet above water, indicating a total thickness of the ice sheet even at the edge, of over a mile. Sir James Ross mentions that--"Whilst measuring some angles for the survey near Mount Lubbock an island suddenly appeared, which he was quite sure was not to be seen two or three hours previously. He was much astonished, but it eventually turned out to be a large iceberg, which had turned over, and so exposed a new surface covered with earth and stones." The condition of the Arctic regions is quite different. There is much more land, and no such enormous solid cap of ice. Spitzbergen, the land of "pointed mountains," is said to be very beautiful. Lord Dufferin describes his first view of it as "a forest of thin lilac peaks, so faint, so pale, that had it not been for the gem-like distinctness of their outline one could have deemed them as unsubstantial as the spires of Fairyland."