Hydrographical Observations from the Danmark Expedition. 353 



The main direction of the section is from E. S. E. to W.N. W., 

 thus almost transversely to the Polar Current and the section gives, 

 therefore, a good picture of the variations in this across the direc- 

 tion of the Current. 



This direction is chosen as a mean between the stations and these 

 are marked off by section of the mean direction plane with the meri- 

 dian plane through the stations. 



The reason for this deviation from the usual method of noting 

 the stations (which is by means of their geographical distance) is the 

 fact, that the greatest changes in the situation of the isotherms and 

 isohalines occur at the edge of the Continental Shelf. 



We are thus able, in my opinion, to give a truer picture of the 

 actual conditions by noting the stations with reference to this edge, 

 the direction of which is nearly N. N. E. (see PI. XII). 



Looking at Sect. I, PI. XV, it will be seen, that the greatest changes 

 in the course of the curves take place at the edge of the Continental 

 Shelf. The stations IV, V and VI are situated here on the steeply 

 ascending ground from 2440 m. to 300 m. 



The true Polar Current can be seen in over the Continental Shelf, 

 with salinities of 32 to 34.80 p. m. and low temperatures. Out over 

 the Greenland Sea deep basin it is very quickly lost. 



As boundary for the Polar Current I have chosen 34.80 p. m. 

 isohaline, which follows approximately the 0° isotherm. 



This boundary is to some extent arbitrary, but it agrees well 

 with the depth of the Polar Current, ca. 200 m., calculated by Hell- 

 and-Hansen in his above-mentioned work on the Duke of Orleans' 

 Expedition. 



The course of the isohalines and isotherms is almost parallel. 



In the south-going Current they are curved down in towards 

 the land, the water-masses owing to the rotation of the earth having 

 the tendency, as known, to bend to the right, in this case, therefore 

 in towards the land where they are dammed up. 



Nearer the land the curves course almost horizontally, which 

 leads one to suspect, that the south-going Current there is less ex- 

 tensive. 



The great break in the 34 p. m. isohaline at St. LXXVIII is cer- 

 tainly due to the fact, that this station was investigated in 1908, whilst 

 the neighbouring stations were taken in 1906. 



Under the true Polar Current there is a layer of warmer and salter 

 water, the existence of which was discovered for the first time by 

 the then First-Lieutenant Ryder in 1891. It has a kernel of water 

 over 34.90 p. m. and +1^ teperature. Further to the west this 

 warm and salt water is gradually pressed deeper down by the over- 

 lying Polar Current and becomes the bottom-layer, and its temper- 

 ature and salinity decrease slightly. We found it again later in the 

 xLi. 23 



