There are but two seasons in the Arctic regions――a long, cold winter and a short, dry summer. It is during the summer that the explorers do their work. Throughout the dark winter they can do nothing. Even in the summer, navigators meet with many perils, for Arctic navigation is not an easy matter. Besides the danger that the vessel may be frozen in an ice pack, or crushed between icebergs, the navigator is often blinded by fogs and snows, and has to face unknown tides and currents. [Illustration: DAILY MOTION OF THE HEAVENS AS SEEN AT THE EQUATOR.] The vegetation within the Arctic circle is scanty. During the summer the bright, warm sun causes the plants to spring up and grow rapidly. Willows, dwarf birches, and rush grasses are plentiful in some localities. In southern Greenland, and in some sheltered places along its western coast, yellow poppies and dandelions grow. Farther north only mosses and lichens are to be found, and beyond the moss line there is no trace of vegetation. Nevertheless there are plenty of animals in this land of ice and snow. The polar bear, Arctic fox, blue fox, wolf, ermine, reindeer, and musk ox are plentiful. Seals and walruses come out of the water upon the ice, during the summer, to enjoy the sun, and thousands of snow buntings, auks, and eider ducks visit the shores of the cold seas to build their nests and catch food. When the summer of three months is over, nearly all outward signs of animal and vegetable life disappear and the entire landscape becomes a dreary, white expanse. The inhabitants of this cold land are called Eskimos. They find it hard to get a living, and their dwellings are of the rudest and most primitive sort. Many of the tribes move from place to place, building their snow huts wherever game is most plentiful, but never going far inland, because fish forms a large part of their food. The Eskimos do not mind the bitter weather. They are quite accustomed to a temperature of 50° below zero. Within the Arctic circle are two principal areas of great cold, one in North America and one in Siberia. The mildest winters are at Bering strait and in the Spitzbergen Sea, where there is usually open water. The former is affected by the warm Japan Current and the latter by the Gulf Stream. We have as yet learned but little about the icy North. Nearly three million square miles of our earth lie within the Arctic circle and are unknown to-day. Much more information must be gained before man can hope to understand the physical laws of this mysterious region. [Illustration: THE MIDNIGHT SUN.]