But the history of these rivers does not end when they reach the sea. When their broad and high glassy front touches the water it does not melt away nor fall to pieces, but goes down to the bottom, and if it be a shallow bay or arm of the sea, pushes the water back and fills up the whole space, it may be for many miles. When it reaches water so deep that more than seven eighths of its front is below the surface, it begins to feel an upward pressure, just as a piece of wood when forced below its natural water-line will spring back. So after a while this upward pressure breaks off the massive front, perhaps miles in extent, and many hundred feet in height. As this is launched into the sea its thunder crash is heard for miles, and the water boils like a caldron, while the disengaged mass rolls and plunges until, finding its equilibrium, it sails away a majestic ICEBERG. Hereafter the snow will at times cover it with a mantle of pure whiteness; the fierce storms will beat upon its defiant brow; the beams of the rising and setting sun will display their sparkling glories on its craggy top, or, falling upon the misty cloud which envelopes it, will encircle it with all the varying hues of the rainbow. As it voyages in stately dignity southward, anchored, it may be, at times for months, it will pass in sullen silence the drear, long, dark Arctic night, and emerge into the brief summer to be enlivened as the home of innumerable sea-fowl, who will rear their young upon its cold breast. Ultimately it will go back to the drops of water from which it came, to make a part of the great ocean, and possibly to sail away in clouds over the frozen regions, and to drop again upon its glassy plain in sparkling crystals. CHAPTER XXXI. A STRANGE DREAM AND ITS FULFILLMENT. THE winter was fully settled down upon Port Foulke, but the dwellers in the schooner "United States" knew nothing of the anxieties and suffering from cold and hunger which most of the arctic voyagers have known. There was one foe, however, which they, in common with all who had gone before them, had to fight; namely, depression of mind produced by the weeks of inactivity and darkness. We have seen how many means were used by earlier as well as later explorers to meet and vanquish this foe. Dr. Hayes availed himself of the hints given by his predecessors, and had some devices peculiarly his own. To the "school of navigation," dramatic performances, and the publishing of a weekly "newspaper," was added the pleasant stimulus of a celebration of the birthday of every man on board. Such occasions were attended by special dinners, the passing of complimentary notes of invitations to the intended guests, which included all, and by fun-making, at which all laughed as a matter of course.