At the present day a fringe of coast lines forming the northern shores of the three great continents, with a deep interior polar sea, are the main features of the Arctic regions, but it was not always so. Looking back into remote geological periods, we have evidence of marvellous changes in the Arctic regions since the globe was a gradually cooling mass of vapour. In this process, extending over vast ages, the polar regions must have been, as they are now, cooler than the equatorial regions, and for the same reason. It was, therefore, in the polar regions that life first became possible, and here the life of the Silurian age arose. There is evidence of a continent in Jurassic and Tertiary (Miocene) times where now there is a polar ocean of great depth, save where Spitsbergen and Franz Josef Land exist as the sole remaining fragments of that continent. There is evidence that forests once flourished where now nothing higher than the dwarf willow can exist. There is evidence, too, of tremendous volcanic eruptions, covering great areas with sheets of basalt. In contemplating these mighty revolutions, and the gradual changes through long æons of ages, the leading fact connected with the polar regions is that here life first became possible. Here it was first possible that man could exist. The evidence that the arboreal vegetation of the miocene period originated round the north pole appears to be quite conclusive. The exploration of the Arctic area has disclosed proofs of wondrous secular changes which no imagination, however vivid, could surpass. Alike in the far south, as in the far north, there is food for the imagination--lights thrown here and there on the history of a marvellous past. Such speculations are a fitting introduction to a study of the existing state of things, which has lasted through the historical period, and probably for ages before the dawn of history. [Illustration: American Quadrant Siberian Quadrant Greenland Quadrant Spitsbergen Quadrant ] The two halves of the Arctic regions may be called the Old World or Eastern, and the New World or Western halves. In the former the water flows in, and in the latter it flows out, thus causing a great oceanic circulation not yet fully investigated, but now clearly understood in its general outline. In the eastern half of the Arctic regions the warm current from the Atlantic flows along the coast of Norway and then bifurcates, one branch going north along the western side of Spitsbergen, the other continuing along the Lapland coast and turning up the west coast of Novaya Zemlya. All the great rivers of Siberia also empty themselves into this eastern half. Thus there is a constant tendency, aided by prevailing winds, for the whole drift from the eastern shores to flow across the Arctic Ocean to the western side.