284 



Part III. — Fifteenth Annual Report 



restricted to the Faeroe-Shetland Channel, the distribution shown by 

 parallel straight lines remains practically the same down to 200 fathoms. 

 At '200 fathoms the form of the isotherms changes, and below 300 

 fathoms, i.e., the level of the summit of the Ridge, they follow the con- 

 tour lines of the sea-bottom almost exactly, keeping the central axis of 

 lowest temperature very close to the edge of the continental shelf. At 

 all depths, from 300 fathoms to the bottom, this axis probably passes 

 almost directly through Stations III. and VII. 



Turning next to the isohalines, we find at the surface the line of 35*4 

 })ro mille passing through stations VI., VII., and VIII., and to E.S.E. the 

 lines of 353 and 352 almost parallel to it, the latter passing through 

 station IV. Below the surface the 35*4 line moves slightly to W.N.W., 

 but otherwise the distribution remains altogether unchanged, the isoha- 

 lines running almost at right angles to the isothermals till the summit of 

 the Ridge is again reached, when a sudden change to a curved form, the 

 same as the isothermals, takes place, the axis of greatest salinity remain- 

 ing, however, somewhat to the W.N.W. of the axis of lowest temperature, 

 i.e., more in the centre of the channel. Here the salinity falls to a little 

 less than 34*9 pro mille. 



Comparing these results with those of former expeditions, the salinity 

 observations show at the upper levels fresher waters near the shore side 

 of the channel west of the Orkney and Shetland Islands, and a steeper 

 gradient towards W.N.W., indicating that water of more than usual 

 salinity was to be found to west and south-west of the Faeroe Islands. 

 This point will be settled by the surface observations in the general map 

 when worked up. The 1 Research ' observations are practically the first 

 obtained at levels below 300 fathoms, as the 'Jackal' was not fitted with 

 sounding apparatus that could be safely used at those depths. 



Subtracting the temperature readings of * Knight-Errant ' from those 

 of the 'Research' we get the following differences between August 1896 

 and August 1880. 



Station IV. 'Knight-Errant, No. 33.' 

 At surface - l°-0 C. 

 50 fathoms + 0'1 



100 



>> . 



00 





150 



5) 



0 0 





200 



J) 



1 



Station IVa. 



250 



)5 



-40 



+ 01 



300 



J) 



-3-3 



+ 0-9 



350 



>> 



-2-1 



+ 2-0 



400 



5J 



+ 03 





450 



>> 



+ 0-6 





Bottom 



)) 



+ 0-2 





Station VIII. ' Knight Errant, No. 28.' 



At surface - l°'l C. 



-0 *2 



Station IX. may be compared with 'Knight Errant, No. 5.' 



At surface - 1 0, 4 C. 

 At bottom +0-7 



Station IV. is unfortunately too susceptible to great variations of tem- 

 perature for very slight changes of position to afford any reliable com- 



