When the warm air over the Gulf Stream comes in contact with the floating ice it is chilled, and the moisture which it holds is condensed into fog. The fogs in turn, which are off the Newfoundland coast, being in the line of steamship communication between Europe and America, are a constant menace to navigation. The near presence of ice is usually detected by a greater chilliness in the air. In order to avoid collisions with one another, and also with icebergs, a ship constantly sounds its sirens and fog horns as warnings while in the fog belt. The signal of another steamship is a warning of the one; the answering echo announces the nearness of the other. [Illustration: A large iceberg] The high interior of Greenland, about ten thousand feet in altitude, is thought to result largely from the accumulation of ages of snow and ice, only a part of which melts or moves oceanward to form glaciers. No other part of the world is such an absolute desert as the greater part of this island. Animal and vegetable life are wholly absent. The colony which was planted in Greenland by Eric the Red, and subsequently augmented by other Norsemen, continued to prosper for four hundred years. At the end of that period there were about two hundred villages, twelve parishes, and two monasteries. These, however, disappeared. The hostility of the Eskimos in part accounts for their extinction, but an encroachment of ice from the north, which encompassed the southern part of the island, is thought to have been also a factor. The fact that foreign trade with Greenland was forbidden by the mother country may account in part for the gradual disappearance of the colony. At all events, intercourse with Europe seems to have been cut off. This condition continued for upward of two centuries, and when intercourse with the mother country was again possible there was no Greenland colony. Perhaps the finding of "white" Eskimo in Victoria Land may explain this disappearance. [Illustration: A group of Eskimos in south Greenland] Subsequently the island was again colonized, but concerning the disappearance of the former inhabitants history is silent. The mute testimony of a few ruined buildings and relics is all that has been found to give the least shadow of information as to the final struggle of the wretched colonists. We only know that they mysteriously disappeared. But the great glacial cap is slowly receding and ages hence more ground will be laid bare. The present inhabitants number about ten thousand, most of whom are Eskimos. They are lacking in thrift and live chiefly by hunting and fishing. Among the wild animals living here are the arctic fox, the arctic hare, the musk ox, the seal, the polar bear, the ermine, and the walrus. The principal resources of the island are sealskins, eider-down, oil, and cryolite.