— 66 — 



The components of both M^ and Sg are, at most places in the North 

 Sea revolving currents, i. e. in the course of the tidal period (abt. 12 hours) 

 they turn once round the whole compass, varying at the same time in magni- 

 tude without ever falling to Zero. There are, however, also places where they 

 do not turn; the current then runs alternately in one direction and its oppo- 

 site, becoming nil twice in the course of each period. Consequently, the Mj 

 and S2 minima are at the different places very different fractions of the 

 respective maxima; at some places they are almost as great as the maxima; 

 thus at 30 m. at Horns Rev: Min. of Mg 14,8 cm/sec, max. of M^ 18,9 cm/sec. 

 At other places, however, they disappear entirely. 



The direction of revolution differs at different places; following the sun 

 at some stations, while at others it is against the sun. As a rule, the Mj 

 currents within the same station turn in the same direction at the different 

 depths; it can also happen, however, that the upper layer and the bottom 

 layer revolve in opposite directions; this was for instance the case at Horns Rev. 



The resulting currents found in the period 1 — 14 June 1911 were of 

 very different magnitude at the different places. They were greatest in the 

 Skagerak, where they reached at 10 and 40 m., about 20 cm/sec, and weakest 

 in the deep water along the Scottish and EngHsh coast, where they were found 

 to be only abt. 1/2 cm/sec. 



From the current measurements for the period 1904 — 07 at the Dutch 

 Station Hj, it appears that the alteration of the resulting current in course of 

 time is of the same magnitude as the mean value of the resulting current, and 

 continued current measurements at fixed points (Lightships) are therefore to 

 be regarded as highly desirable. 



2. The Atlantic, the Norwegian and the Barents Sea. 



The international investigations have greatly increased our knowledge 

 of the hydrography of these regions; space will, however, only permit of a 

 very few points among the numerous items of new information being ment- 

 ioned here. 



The existance of great submarine waves in the Fseroe-Shetland Channel 

 has been conclusively shown by series of continued measurements. One of 

 these series, carried out in the course of 67 hours at about 61^2° N, 4^2° W 

 (depth to bottom 780 m.) in May 1910, showed in particular great vertical 

 movements in the intermediate water layers, 300 m., 400 m. and 500 m. below 

 the surface. Thus the temperature at 400 m. moved in the course of 18 hours 

 from a maximum of 4,20° to a minimum of 1,61°, which corresponds to a 

 submarine wave with a height of 50 to 100 metres. Part of the variations 



