— 58 — 



at in all 150 to 200 different stations, and the measurements have during the 

 past years been repeated from 10 — 30 times at each station. 



Of late years there has been a tendency to carry out investigations 

 more frequently, thus reducing, however, the number of stations investigated; 

 and where possible, continued investigations from fixed stations have been 

 made: An annual extended cruise is, however, considered indispensable. On 

 two occasions investigations have been carried out from a number of anchored 

 ships, which remained 14 days at the place of observation. With these continued 

 measurements chief importance has in particular been attached to measurements 

 of the currents at different depths, and numerous current measurements below 

 the surface are now also carried out from various lightships. 



In the following, a brief description of some of the results hitherto ob- 

 tained will be given. But the work is in progress, and most of the questions 

 are not yet solved, still requiring several years of investigation. 



1. The North Sea and the Channel. 



a. Salinity. 



The mean value of the salinity for the five years 1903 — 7 can in the 

 main be regarded as representative of the typical conditions and will therefore 

 be described here in brief outline. 



Only a small part of the masses of water in the North Sea have a 

 salinity of less than 34,5 "/oo- On the western side of the North Sea, the 

 34,5 "/oo Isohaline both at the surface and at the bottom runs almost parallel 

 with the English coast at a distance which off Flamborough Head amounts 

 to abt. 25 miles; this Isohaline has disappeared however, both off the south 

 coast of England in the Channel and along the greater part of the Scottish 

 coast; the water in both places being, even at a slight distance from land, 

 more than 34V2 "/oo s^lt. Along the eastern side of the North Sea the 

 34,5 %Q Isohaline moves, at the surface, considerable farther from land; it 

 lies about 45 miles both from the Norwegian and from the Danish west 

 coast, running thus a good way outside the mouth of the Skagerak. It 

 further separates the whole of the German Bight from the salt central part 

 of the North Sea, the Isohalines least distant from Heligoland being about 

 80 miles. Finally, it runs along the whole of the Dutch-Belgian coast at a 

 distance of 10 — 20 miles from land. Near Calais it merges with the land, 

 but it is found again in the Channel along the coast of Normandy. South of 

 Lat. 54° N, the 34,5 "/oo Isohaline has practically exactly the same course at 



