— 68 — 



were moreover distinctly periodical, the length of period being abt. 12 hours, 

 and the whole phenomenon appears to stand in relation to the tidal phenomenon. 



Bottom water of the Fseroe-Shetland Channel. 



At a depth of 1000 metres and more, the temperature only rarely rises 

 above -^ 1/2°; it lies as a rule between -4- Va" ^^^ -^1°) and the lowest tem- 

 perature hitherto found is ^ 1,19° (at 1250 m. at 61°27' N— 3°42'W, in August 

 1908). The salinity is most often 34,92— 34,96%o, but has also been found 

 to differ considerably from this. Of the extremely extensive material, only a 

 single example will here be quoted, illustrating the variations which occur; the 

 measurements were taken on the 9 — 10 May 1911, at 1300 m. at 61°27' N — 

 3°42'W.: 



9 May, 10 p. m.— 10. May 2,10 a. m. 



^ 0,96°; 34,94 »/oo- 

 10 May, 2,15—4,50 a. m. 



-^ 0,86°; 34,94 %o. 

 10 May, 5,05—8 a. m. 



^0,81°; 35,01 »/oo- 



10 May, 8,30—11,05 a. m. 



-r 0,82°; 35,07 "U. 

 10 May, 11,30 a. m.— 3,15 p. 



^0,84°; 34,96 »/oo. 

 10 May, 3,20—6,10 p. m. 



-4-0,81°; 34,94 »/oo- 



m. 



The bottom salinity can thus change 0,13 "/oo in the course of 6 hours, 

 and one sees that relatively great changes can take place also at the bottom 

 in a short time. This seems to indicate that there is lively movement not 

 only in the upper, but also in the lower masses of water in the Fseroe 

 Shetland Channel. 



By the investigations in the waters around Iceland, a very close rela- 

 tion has been shown between the hydrographical factors and the migrations of 

 fish, especially cod, which again determine the places of the fishery at various 

 seasons. 



The hydrographical investigations in the Norwegian Sea point, as far as 

 can be seen from the material to hand up to the present, in the direction of 

 a relation between the fluctuations, which take place from year to year in the 

 hydrographical condition of the Norwegian Sea and fluctuations in a whole 

 series of phenomena of economical interest. The most important part is here 

 played by the warm and salt water which is brought from the Atlantic by 

 the Gulf Stream, and it has proved possible, — up to the present for five 

 years — to trace the fluctuations occurring from year to year in the Norweg- 

 ian harvest; in the takings of the cod fishery at Lofoten; in the distribution 

 of the ice in the Barents Sea in the spring; and other similar circumstances, 

 back to analogous fluctuations in the quantities of heat which the Gulf Stream 

 brought in to Norwegian Sea in the years immediately preceding. It would 



