It is at the equator and the poles that the great system of ocean and aërial currents produces its maximum effects. The influence becomes less and less as we recede from those places, and between them there is a point where the influence of warm currents from the equator and of cold currents from the poles exactly neutralize each other. At this point the stoppage of ocean-currents would not sensibly affect temperature. This point, of course, is not situated on the same latitude in all meridians, but varies according to the position of the meridian in relation to land, and ocean-currents, whether cold or hot, and other circumstances. A line drawn round the globe through these various points would be very irregular. At one place, such as on the western side of the Atlantic, where the arctic current predominates, the neutral line would be deflected towards the equator, while on the eastern side, where warm currents predominate, the line would be deflected towards the north. It is a difficult problem to determine the mean position of this line; it probably lies somewhere not far north of the tropics. CHAPTER III. OCEAN-CURRENTS IN RELATION TO THE DISTRIBUTION OF HEAT OVER THE GLOBE.—(_Continued._) Influence of the Gulf-stream on the Climate of the Arctic Regions.—Absolute Amount of Heat received by the Arctic Regions from the Sun.—Influence of Ocean-currents shown by another Method.—Temperature of a Globe all Water or all Land according to Professor J. D. Forbes.—An important Consideration overlooked.—Without Ocean-currents the Globe would not be habitable.—Conclusions not affected by Imperfection of Data. _Influence of the Gulf-stream on the Climate of the Arctic Regions._—Does the Gulf-stream pass into the arctic regions? Are the seas around Spitzbergen and North Greenland heated by the warm water of the stream? Those who deny this nevertheless admit the existence of an arctic current. They admit that an immense mass of cold water is continually flowing south from the polar regions around Greenland into the Atlantic. If it be admitted, then, that a mass of water flows across the arctic circle from north to south, it must also be admitted that an equal mass flows across from south to north. It is also evident that the water crossing from south to north must be warmer than the water crossing from north to south; for the temperate regions are warmer than the arctic, and the ocean in temperate regions warmer than the ocean in the arctic; consequently the current which flows into the arctic seas, to compensate for the cold arctic current, must be a warmer current.