CRUISES OF THE "MICHAEL SARS " 125 

 After completing this section, we proceeded towards the Wyviik 



homs 

 Lidge. 



Wyville Thomson Ridge, and occupied a station (loi) at a Thomson 



depth of 1000 fathoms, where we employed the trawl as well as 

 a number of pelagic appliances, and then concluded our work 

 by taking two sections on the northern side of the ridge (see 

 stations in Fig. 104). 



The Jiydrographical conditions here have often been de- 

 scribed. Fig. 106 gives a general idea of what we found at 

 Station loi south of the Wyville Thomson Ridge, and at 

 Station 106 to the north of it. South of the ridge salinities 

 and temperatures are rather lower than what we found in our 

 northern Atlantic section, but the differences are not very 

 considerable either in deep water or in the upper layers. The 

 upper layers extend with little variation down to the level of the 

 ridge in 500 metres, but the difference in the deep water on the 

 two sides of the ridge is unmistakable, as the ice-cold bottom- 

 water of the Norwegian Sea comes close to the northern 

 margin of the ridge. 



These conditions, however, are generally known, and our 

 attention was chiefly turned in another direction. During our 

 previous investigations in the Norwegian Sea we discovered 

 that the hydrographical conditions often varied very consider- 

 ably within a short distance or in the course of a short period 

 of time. The variations were not always of the same character. 

 A number of eddies, both large and small, occurred apparently 

 during the movements of the water-layers, and there were up 

 and down movements in the boundary-layers^ — possibly big 

 submarine waves or something of that sort — as well as distinct 

 pulsations in certain currents. We resolved, therefore, on our 

 way over to Bergen to make a careful study of these phenomena 

 in the Faroe-Shetland channel. To be able to do so, it was 

 necessary to have our stations very close together and to occupy 

 them in rapid succession, and also to lie stationary for at least 

 twenty-four hours at one of them. 



Altogether we had fourteen stations north of the ridge in the investigations 

 Faroe-Shetland channel (Nos. 103-116; see Fig. 104) along two cVan*nrL'°^ 

 nearly parallel sections, the distance from one station to another 

 being about 20 nautical miles, and the distance between the 

 sections a little over 25 miles. We found that the hydro- 

 graphical conditions varied greatly in the different localities, 

 and that there was an extraordinary difference between the two 

 sections. At Station 115, on the continental edge to the west 

 of Shetland, we anchored a buoy, and remained stationary there 



