34 



NATURAL SCIENCE. 



Jan., 



greater warmth of the land. The level of the North Sea is therefore 

 higher, and its surface waters will tend to flow out northward and 

 westward. The outflow will be greater the warmer the summer ; its 

 occurrence was clearly shown by the "Jackal " observations in August, 

 1893. 



It appears therefore that, if the western coasts of the North Sea 



750 



-770 

 760 



770 



Fig. 1. — Chart of the Faeroe-Shetland Channel andthe North Sea. - The solid lines show 

 the salinity, in grams per kilogram, at the bottom or at 200 fathoms ; the dotted lines show the 

 specific gravity at the same depth (in this case the first three figures are omitted, e.g., " 1-02760" 

 is printed "760 "). 



are to receive any part of the oceanic water, it must be by means of a 

 current flowing under the surface. In order to understand the 

 mechanism of such a current, it is necessary to study the conditions 

 obtaining in the North Sea itself in somewhat greater detail. At the 

 end of winter or in early spring, the greater part of the area is 

 occupied by water which, although its salinity has been lowered by 



