90 The Hydrography of the Faeroe- Shetland Channel 



surface of the eastern Atlantic, and in the subsequent months the area 

 of low temperature gradually narrowed, until in October it had entirely 

 disappeared. 



I hope to obtain data with regard to atmospheric pressure similar 

 to those embodied in the Pilot Chart for October, for the earlier 

 months, and to discuss their relation to the observations in the Faeroe- 

 Shetland Channel in a later paper. The Pilot Charts in their present 

 form will be an invaluable help in interpreting the observations to be 

 made under the international scheme, and, as Dr. Wolfenden informs 

 me that he intends to make simultaneous observations at depths down 

 to 1,000 fathoms to the west of Ireland, the mechanism of the currents 

 flowing from the central region should be completely and finally 

 determined. 



The conclusions arrived at up to the present may be stated thus : 



1. Northward movement of water originating as a drift current is 

 strongest in the Faeroe-Sbetland Channel during winter. 



2. Northward movement of water originating as a stream current 

 is strongest in summer, being probably due to the extension of the 

 ' Atlantic anticyclone.' 



3. The northward movement 2 is the more uncertain, and varies 

 most in different years. 



4. In the transition stages between 1 and 2, or when 2 is abnor- 

 mally weak, the water in the Faeroe- Shetland Channel may remain 

 practically motionless for extended periods. If the channel is filled 

 with water from the south, this water will gradually cool down and 

 sink, being cooled by, and mixing with, the cold underlying waters. 



5. To the north of the Faeroe- Shetland Channel the waters of the 

 Norwegian sea consist of a mixture of waters of Arctic origin with 

 those of Atlantic origin, the latter very similar to 1. The mixture is 

 in most cases fairly complete, but during summer water of Arctic 

 origin, set free by the melting of ice, may form a surface layer of 

 considerable thickness. 



6. The waters of the Norwegian sea make their way southward, 

 under favourable conditions, into the Faeroe- Shetland Channel and 



