The difficulties that make the quest of the pole so arduous have been discovered by slow degrees. It is marvellous how soon nearly the full limits of northward attainment were reached. In 1596 Barents discovered Spitzbergen in about 78 deg. north; in 1770 Hudson reached 80 deg.; in 1827 Parry, by sledging on the ice when his ship became fast, succeeded in touching 82 deg. 45'. Since then all the enormous resources of modern science--steam, electricity, preserved foods and the experience of centuries--have only enabled forty miles of additional poleward advance to be made. The accompanying map gives a fair idea of the form of the Arctic regions, and remembering that the circle marked 80 deg. is distant seven hundred miles from the pole, the reader can realize the distances involved. The Arctic Basin, occupied by the Arctic Sea, is ringed in by land; the northern coasts of America, Europe, and Asia, forming a roughly circular boundary broken by three well-marked channels communicating with the ocean. Bering Strait between America and Asia is the narrowest, Baffin Bay between America and Greenland is wider, branching into a number of ice-blocked sounds to the westward, and tapering off into Smith Sound in the north-east. The widest channel of the three lies between Greenland and Europe, and this is bisected just south of 80 deg. North by the island group of Spitzbergen. The whole region is one of severe cold, and the sea is frozen for the greater part of the year, land and water becoming almost indistinguishable, but for the incessant movement and drift of the sea-ice. In summer the sea-ice breaks up into floes which may drift away southward and melt, or be driven by the wind against the shores of continents or islands, leaving lanes of open water which a shift of wind may change and close in an hour. Icebergs launched from the glaciers of the land also drift with tide, current, and wind through the more or less open water. Possibly at some times the pack may open and a clear waterway run through to the pole, and old whalers tell of many a year when they believed that a few days' steaming would carry them to the end of the world, if they could have seized the opportunity. At other times, routes traversed in safety time after time may be effectively closed for years, and all advance barred. Food in the form of seals or walrus in the open water, reindeer, musk ox, polar bears or birds on the land, may often be procured, but these sources cannot be relied upon. Advance northward may be made by water in a ship, or by dog-sledge, or on foot, over the frozen snow or ice. Each method has grave drawbacks. Advance by sea is stopped when the young ice forms in autumn, and land advance is hampered by the long Arctic night which enforces months of inaction, more trying to health and spirits than the severest exertion.