III.— HYDROGRAPHICAL OBSERVATIONS MADE IN 1905. 



The observations made to the west of Gibraltar during 1904 having 

 established the fact that a regular survey of the region in connection 

 with the international observations was of the first importance, 

 Dr. Wolfenclen sent the Silver Belle over part of the area at the end 

 of 1905. Soundings were made at eleven stations, beginning near 

 Station E4 of the international series, off Ushant, on November 8, and 

 ending in the Strait of Gibraltar on December 20. The line closely 

 follows Section III. of 1904 as far south as Station 51, and then runs 

 south-westward to Madeira, repeating the line of Section II., 1904, to 

 the Strait. From the remarks in Captain Henry's log, it appears that 

 the work was carried out under great difficulties, and its successful 

 achievement is a remarkable example of endurance and skill. 



The total number of temperatures and samples obtained was 

 seventy-six. The chlorines have been determined by Mr. Manley, 

 and all the observations treated in precisely the same way as in the 

 previous years. The results will be found in Table V. 



Sections I. and II., 1905, show the distribution of temperature and 

 salinity disclosed. Section I. is, in its northern part, comparable with 

 Section III. of 1904, as has already been stated, and we have now the 

 advantage of a section showing salinity as well as temperature. 

 Section II. is, of course, comparable with the Section II. of 1904. 



The general type of distribution is the same in both years, and 

 there seems little reason to suppose that the type is not constant, with 

 a wide range of variations. There is, therefore, little to be gained by 

 further detailed discussion of the two years' observations, as they do 

 not supply sufficient material to enable us to ascertain the full extent 

 of the variations, and how far thev are periodic or irregular. 



A few points may, however, be noticed. 



In 1905, notwithstanding a much lower surface temperature (prob- 

 ably chiefly due to difference of season), a larger body of relatively 

 warm water occurred at intermediate depths off the Bay of Biscay than 



107 14—2 



