very difficult to get any certain information about its speed. Sometimes, especially in the summer months, it is very rapid, but at other times it seems to have a much slower course; the surface speed also, to a great extent, depends on the winds blowing during the time previous to the observation. Taking everything into consideration, I do not think we are entitled to estimate the average speed of the whole current for the year at more than two nautical miles a day. By this calculation we arrive at the conclusion that the polar current between Greenland and Spitzbergen carries southward between 80 and 120 cubic miles of water every twenty-four hours. Whence is all this water taken? It is evident that it cannot originate at the Pole itself; what flows out from the polar basin must be restored by water running in. It is also evident that the influence of a current so considerable as this cannot be limited to a small area; it must affect the polar basin like an immense pump, sucking the water even from the shores of Siberia and Bering Strait. This is the more certain as the polar basin is found to be unusually shallow wherever it has been measured. There are only a few currents known which run into the polar basin. A small branch of the Gulf Stream is known to run northward along the west coast of Spitzbergen. This current is, however, narrow and very shallow, and thus is too insignificant to be of much value in this connection; to some extent it certainly also rounds the north coast of Spitzbergen, and returns southward again toward its eastern coast, partly through Henlopen Strait and Olga Strait and partly east of North East Land. Another branch of the Gulf Stream passes eastward to the north of Norway and enters the polar basin north of Nova Zembla. This current is considerable, and it often runs with a high speed along the coast of Nova Zembla, according to the common experience of Norwegian sailors. Our knowledge of it is not sufficient to enable us to form any certain idea about the quantity of water which it carries along; but according to the calculations of Prof. H. Mohn in his important memoir on the North Ocean* *Prof. H. Mohn, "The North Ocean; Its Depths, Temperature, and Circulation. The Norwegian North Atlantic Expedition, 1876-1878." Christiania, 1887. I think that we may assume that it carries at least sixty or seventy cubic miles of water every twenty-four hours into the polar basin. Next to this Nova Zembla current the most important current running into the polar basin is certainly that which runs northward through Bering Strait. This current seems to be of considerably more importance than former ideas about it would indicate.* From descriptions of it that have recently appeared we learn that it very often runs northward with a speed of two knots and sometimes even of three or four knots. During the spring the current seems to have an average speed of two knots when it is not stirred by winds. It very often gives the impression of being an immense river flowing toward the north and carrying immense quantities of driftwood. Captain Hegemann tells us, for example, that in July, 1860, there was so much driftwood floating through the strait past the Diomede Islands that his ship could advance only very slowly, and that he was obliged to turn and twist about as if he were sailing through masses of floe-ice. We know too little of the speed of this current, during the various seasons of the year, to be able to say anything with certainty about the quantity of water which it carries into the polar basin. But if we assume that the aver age speed is as much as half a knot, and remember that Bering Strait, according to Dall, is 49.33 nautical miles broad and has an average depth of 23.5 fathoms, we must see that about fourteen cubic miles of water is running northward daily. These two currents certainly furnish the most important supplies of water to the polar basin and to the polar current along the east coast of Greenland. A third addition of water to this basin, which I have thought a priori to be of much importance, comes from the American, and especially from the Siberian *According to H. W. Dall's paper, "Hydrologie des Beringsmeeres,” etc. (Petermann's Mittheilungen, Vol. 27, pp. 261, 443; 1881), there should be no constant current running northward through Bering Strait, or at all events only a very slow and superficial one, while underneath a current should be running southward. +Simpson, "Ice and Ice Movements in Bering Sea and the Arctic Basin." Hydrographic Office, Washington, January, 1890. Fr. Hegemann, "Das Eis und die Strömungsverhältnisse des Beringsmeeres," etc. "Annalen der Hydrographie und Maritimen Meteorologie," 1890. rivers that run into it. The drainage area of all these rivers is very considerable, embracing nearly the whole of northern Asia, or Siberia, down to the Altai mountains and Baikal, besides the principal part of Alaska and British North America. The rain and snow of this region is not, however, very considerable, and the whole quantity of moisture falling over Siberia, I have calculated to be no more than about 626 cubic miles in one year. On account of evaporation we cannot assume that more than a small part of this water reaches the polar sea; perhaps not more than one cubic mile every twenty-four hours. This is not much, compared with the size of the ocean currents, but this addition is of special importance, as it consists of fresh and comparatively warm water, which for a very long time keeps at the surface of the sea on account of its lightness, and thus produces surface currents running northward from the Siberian coast. This is also the reason why there is so much open water along this coast every summer. The fresh water thus flowing into the polar sea can only to a very small extent originate from this sea itself, as it is mostly covered by ice, and where open water exists the very low temperature in those regions prevents much evaporation. The moisture of the air over the area draining into the polar sea must consequently originate mainly in the Atlantic and Pacific Oceans. The moisture falling over the Polar Sea itself must certainly to some extent have a similar origin, since warm and moist air is attracted from lower latitudes by the low pressure of the air over the polar regions. This constant addition of fresh water must evidently be the reason why the water of the polar current between Greenland and Spitzbergen contains somewhat less salt, even at considerable depths, than the water of the North Atlantic seas. We thus see that the polar basin is daily receiving a large and constant inflow of water. As little evaporation takes place from its ice-covered surface, there must necessarily be a corresponding outflow, and the most natural outlet is the broad and deep opening between Spitzbergen and Greenland. According to what has already been said, the water running out here seems very nearly to correspond in quantity to the inflow mentioned. Currents also run southward through Smith Sound, Jones Sound, and Lancaster Sound, in the Arctic Archipelago of North America, but as these sounds are very narrow and shallow, the body of water which their currents carry off is of little importance in this respect. The current running southward between Spitzbergen and Franz Josef Land is also insignificant when compared to the East Greenland current. By regarding the before-mentioned contributions of water which the latter current probably receives, it may be possible to form some idea of the probable course of this current through the unknown regions. The waters of the North American rivers form, very likely, a part of the currents through the Arctic Archipelago of North America; a small part of the current through Bering Strait perhaps runs also in this direction. We have left, then, for the formation of the East Greenland polar current the principal part of the current through Bering Strait, the Siberian rivers, the Nova Zembla current, and the moisture falling over the polar basin. It seems quite natural that these sources should converge, and to some extent unite to form the Greenland current. We know also that the Nova Zembla current runs eastward or northeastward, while the current from Bering Strait runs westward. We must expect, therefore, to find the main body of the current which is formed in this way, lying somewhere to the north of the middle of that extended area from which it receives its converging sources, and this placé must consequently be somewhere in the neighborhood of the New Siberian Islands. Here we also have the mouth of the Lena River, which carries a considerable body of comparatively warm water northward into the polar sea. From this region the current must naturally run in a northerly direction by the shortest way to the outlet between Spitzbergen and Greenland, and this must be to the north of Franz Josef Land and across or near the North Pole. But this course of the current may perhaps, to some extent, be disturbed by the winds. Let us examine which winds may be expected to be most prominent in these regions. So far as we know, a belt of low air-pressure seems to extend from the Atlantic Ocean along the south side of Spitzbergen and Franz Josef Land and into the Siberian polar sea. According to well-known meteorological laws, the principal direc |