592 SCIENCE PROGRESS 



may diffuse into each other by the action of winds and tides, 

 forming water bodies of composition intermediate to those 

 of the three main categories I have mentioned above. 



The key to the water circulation of the seas of Northern 

 Europe is to be found in the study of the Gulf Stream. 

 One may still read in the text-books of physiography that 

 this great current reaches the shores of Britain and the 

 Scandinavian countries. It is indeed true that sea water of 

 sub-tropical origin does reach our shores, but the case is not 

 so simple as it is usually stated. The Gulf Stream sweeping 

 up from the Gulf of Mexico forms a closed eddy which never 

 actually impinges on the shores of Great Britain, but turns 

 round, forming a cyclonic circulation or eddy the northern 

 boundary of which is in latitudes 40 to 50 . In the centre 

 of this eddy is the well-known " Sargasso Sea." Now in 

 some way or other a current does take origin in this eddy 

 which reaches the shores of Northern Europe. This is the 

 European Stream. Part of this, but a comparatively small 

 part only, enters the English Channel and, passing through 

 the Straits of Dover, flows into the North Sea. The greater 

 body of water flows to the north, and passing through the 

 Faroe-Shetland Channel enters the North Sea round the 

 north of Scotland, and even the Baltic through the Skagerak 

 and Cattegat. A considerable volume of this comparatively 

 warm and dense water still flows to the north and east, and 

 rounding North Cape enters the Barentz Sea, and soon 

 cooling down, sinks beneath the surface and flows on as a 

 deep current. 



Add to this drift of North Atlantic water into the seas 

 of North Europe a southerly current flowing down the east 

 coast of Iceland into the Norwegian Sea, and we have the 

 general scheme of the water circulation of the north Atlantic 

 and the northern ocean. Now if these streams be attentively 

 studied by means of temperature and salinity observations, it 

 is seen that the flow of water is not uniform. Again, the key 

 to the study of these seasonal variations is to be found in 

 the variations in the extent of the Gulf Stream circulation, 

 the boundaries of which undergo a periodic shifting. In 

 March the northern boundary of the Gulf Stream touches the 

 Azores, but does not impinge on the coasts of Africa or 

 Europe. In November, however, the area of the stream has 



