518 G. H. DREW. 



With regard to the accuracy of the work, Mr. Matthews makes the 

 following remarks : — 

 " The accuracy of the observations. 



(a) Salinity. — The method of taking the samples from the water- 



bottle was rather inconvenient, as a siphon was used; the 

 samples were also very small, but well preserved. The 

 water-bottle itself might have leaked or closed at the wrong 

 depth, as was the case with earlier models. That this was 

 not so is shown by : 



1. The sharp fall in the number of bacteria at Ijetween 



200 and 300 fathoms. 



2. The close agreement of the salinities at 400 fathoms, the 



greatest depth at which they were taken on both 

 stations : Station I gave 35-37, Station II 35"34. 



3. The close agreement between the bottom salinity at 



Station I, 34*98 at 822 fathoms, and the salinity 

 found at the same depth at the nearest position at 

 which we have modern observations, i.e. Michael Sars, 

 Station 65, in 37° 12' N., 48° 30' W., June, 1910: 

 according to the curve this is about 34"96. 

 The water-bottle only failed once, at about 890 fathoms at Station II. 



(b) Teinperatures. — The National Physical Laboratory correction 



was given to 0'1° only, but the readings below 15° are com- 

 parable among themselves to 0-05° or possibly less. The 

 curves of temperature for the two stations agree well in 

 shape below 300 fathoms, but the temperature on Station II is 

 generally slightly higher than on Station I : as a rule by an 

 amount corresponding to a difference of depth of about 20 to 

 25 fathoms. 



Below 200 fathoms the curves for both stations agree very 

 closely with that for Michael Sars Station 64, in 34° 44' N., 

 47° 52' W. 



It is almost certain from the above considerations that the 



results are only incorrect by the experimental errors in 



measuring the depth, in determining the salinity (0*02 at 



most), and perhaps 0*1° C. of temperature." 



These observations are sutficient to show that the Tongue of the 



Ocean is an area of considerable interest from a hydrographical point 



of view, and it is much to be regretted that the continued bad weather 



during our stay made it impossible to obtain more observations and 



samples. 



