364 Alf Tholle. 



Average density of the Polar Current. 



If we take the boundary of the Polar Current at the depth where 

 the bottom-layer with nearly constant density of 1.02800 begins, 

 the Current increases between the stations IV and VI from ca. 7ö to 

 ca. 200 m. and then to ca. 300 m. at St. VII. 



The average density is as follows: 



Station VI Depth 0—200 m 1.02755 



— LXXVIII — 0—200- .... 1.02747 



— VII — 0-300- .... 1.02734 



— LXXVII — 0—300- .... 1.02712 



The average density is thus greatest in the central part of the 

 Current. 



These average densities are somewhat greater than the average 

 density at Nansen's St. XXIII in the North Polar Basin, which is 

 given by Nansen as 1.02694 (see Fr. Nansen: Oceanography of the 

 North Polar Basin, p. 400, Christiania 1902). 



Remarks on Section I compared viith Section V, PI. VII, 

 Fr. Nansen: Northorn Waters. 



The latter section passes through F. Åkerblom's stations VII 

 and IX, taken on A. G. Nathorst's Expedition in 1899, Ryder's sta- 

 tion XII in 1891 and Roald Amundsen's station XXIII in 1901. 



It is referred to here to show the marked change which occurs 

 in the position of the true Polar Current in relation to land at a la- 

 titude of ca. 75° N., a change which in my opinion is of importance 

 for the spreading of the pack-ice which occurs each year at this la- 

 titude and which permits vessels to pass in through here to the coast. 



On comparing Sect. V with Sect. I it is at once seen, that the 

 true Polar Current, which is revealed in the section by greatly depressed 

 isopykns, in the former section reaches right into land, whereas in 

 the latter it only extends to about 60 km. from land, whereby a region 

 of coastal water in under land is formed. 



This coastal water is thus not found at ca. 75°N. L. ; here the 

 main current itself reaches right into land. This is certainly con- 

 nected with the fact, that the edge of the Continental Shelf approa- 

 ches the land at ca. 75° N. L. (see PI. XII). The eastern boundary 

 of the Polar Current, namely, follows the eastern edge of the Con- 

 tinental Shelf and the Current becomes lost out over the Greenland 

 Sea; this is apparent from both Sect. I and Sect. V. The we.stern 

 boundary of the Current is pushed out to ca. 10° — 12° W. L. at about 

 81° N. L. by the peninsula stretching out here far to the east, and 

 when the coast-line retreats westerly to the south of this, the main 

 Current pesumably does not follow along this but flows at some dis- 

 tance from land with almost unchanged breadth of ca. 175 km., fol- 



