1883.] Soundings and Temperatures in the Faeroe Channel. 205 



weather either the dredge or trawl were usually put out, or the tow 

 nets lowered to such depths as required. 



After completing the work in the Faeroe Channel, the vessel left 

 Stornoway for Oban, and from thence proceeded into the Atlantic 

 about 100 miles north-west of Ireland, to test some pressure gauges in 

 connexion with the observations of Professor Tait on the thermometers 

 of the " Challenger," for which purpose Professor Chrystal, of the 

 University of Edinburgh, accompanied the ship on this section of the 

 voyage. The " Triton " finally returned to Glasgow on the 17th 

 September, and then resumed her ordinary surveying work. 



The Wyville Thomson ridge. — The soundings obtained in the "Triton," 

 combined with those formerly taken in the "Knight Errant," prove 

 conclusively the existence of a submarine ridge in the Faeroe Channel, 

 extending from the edge of the bank north of Rona Island to the 

 fishing bank to the south-west of the Faeroe Islands. To the north- 

 east of this ridge, the temperature of the water at depths exceed- 

 ing 350 fathoms is under 32° F., whilst to the south-west of it the 

 temperature at similar depths is above 42° F., excepting in one 

 part, where, for a short distance south-west of the deepest part of the 

 ridge, a drain of the Arctic water is carried across, and is sufficient to 

 cool the bottom water below 40° for a distance of 8 miles from the 

 axis of the ridge. 



The general depths over the Wyville Thomson ridge, which is 

 100 miles in length, by 10 in width, are from 250 to 280 fathoms, 

 with here and there shoaler heads. In one part, however, there is a 

 saddle or gap 7 miles wide, where the depths are from 300 to 330 

 fathoms. On each side of the ridge the depths increase to 600 

 fathoms or upwards. 



The indications given by the lead as well as the dredge and trawl, 

 show that the Wyville Thomson ridge consists of stones and gravel, 

 whilst to the north-east of the ridge, in the cold area, the bottom is of 

 a hard blue mud, and to the south-west a softer gray mud. 



The ridge seems to be a portion of a chain of hills, mostly sub- 

 merged, which stretch irregularly from the bank off the north-west 

 coast of Scotland to the Faeroe Islands, Iceland, and Greenland, for 

 we know that depths of about 200 fathoms exists between the Faeroe 

 Islands and Iceland, as well as between Iceland and Greenland. As 

 oceanic soundings become more numerous, doubtless many more such 

 chains of submarine elevations will be discovered, for there is reason 

 to believe that the floor of the ocean is not so level as is generally 

 supposed. The absence of mud on the top of the Wyville Thomson 

 ridge may be accounted for by the water flowing over it, washing 

 away all the small particles. 



Flans and Diagrams. — To show the position and form of the ridge, a 

 series of diagrams and a plan have been constructed. The plans shows 



