The reader has now before him the particulars which will enable him to form an idea of the extent and character of the undiscovered region of the Pole. Roughly speaking, it is bounded by the 80th parallel of latitude on the European side, except at a few points where our gallant explorers have succeeded in crossing the threshold; on the Asiatic side it descends as low as 75°; and to the west of Behring Strait as low as 72°. Thus, it varies from 500 or 600 to 1400 or 1500 miles across. Below these parallels, and bounded by the Arctic Circle, or, in some places, by the 60th parallel, extends a vast belt of land and water which is generally known as the Arctic or Circumpolar Regions. These have been more or less thoroughly explored; and it is to a description of their principal features, their forms of animal and vegetable life, and their natural phenomena, that we propose to devote the present volume. [Illustration: A DESERT OF ICE IN THE ARCTIC REGION.] It is important to remember that the northern shores of Europe, Asia, and America are skirted by the parallel of 70°, and that the belt between the 70th and 80th parallels, having been partially explored by the seamen and travellers of various nations, intervenes as a kind of neutral ground between the known and the unknown. We may, indeed, formulate our statement thus; from the Pole to the 80th degree stretches the unknown; from the 80th to the 70th, the partially known; while, south of the 70th, we traverse the lands and seas which human enterprise has completely conquered. The Circumpolar Zone includes the northernmost portions of the three great continents, Europe, Asia, and America; and by sea it has three approaches or gateways: one, through the Northern Ocean, between Norway and Greenland; another, through Davis Strait,--both these being from the Atlantic; and a third, through Behring Strait,--the entrance from the Pacific. It will be seen that the Circumpolar Regions, as they are now understood, and as we shall describe them in the following pages, extend to the south of that imaginary line drawn by geographers round the North Pole, at a distance from it equal to the obliquity of the ecliptic, or 23° 30’. Within this circle, however, there is a period of the year when the sun does not set; while there is another when he is never seen, when a settled gloom spreads over the face of nature,--this period being longer or shorter at any given point according as that point is nearer to or further from the Pole. But as animal and vegetable life are largely affected by climate, it may be justly said that wherever an Arctic climate prevails _there_ we shall find an Arctic or Polar region; and, hence, many countries below even the 60th parallel, such as Kamtschatka, Labrador, and South Greenland, fall within the Circumpolar boundary.