Hydrographical Observations from the Danmark Expedition. 



389 



Anneks So (Series LIV). 



This lake lay at a height of 40 m. above the level of the sea in 

 the neighbourhood of Sælsoen. There was no salt bottom-water here, 

 however, though there лvas quite a small quantity of salt (0.07 p. m.) 

 dissolved in the fresh water throughout the whole layer. 



The temperature curve shows a temperature of almost +1%° from 

 20 — 80 m. Towards the bottom the temperature rose a little, whilst 

 it decreased to 0° in the uppermost 20 m. 



The lake has presumably been heated up to ca. 2° in the summer 

 of 1907. Then in the course of the winter the layer from to 20 m. 

 becomes cooled to nearly 0°, probably because there has been a dowTi- 

 flow of cold water from a glacier down to this depth. The cause of 

 the low temperature cannot be the winter cold, as this has scarcely 



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Station LIV. Anneks Sø. 



produced any cooling beyond the uppermost layers of the lake. On 

 cooling below -)- 4^ C. freshwater becomes lighter, so that no convec- 

 tion currents can arise, and the series from the lake at Skibshavn 

 (series LVII) shows, that the cold in this case does not reach down 

 into deep water in calm lakes \sith no wave-movement of importance. 

 The greater thickness of ice in the lake (ca. 2^m.) than in the 

 sea (ca. ly^m.) was probably connected in part with this absence 

 of convection currents, these in the sea constantly bringing up warmer 

 water from the deeper layers to the surface. 



The lake at Skibshavn (Series LVII). 



This lake lay on a plain in the neighbourhood of SkibshaA'n; it 

 received afférents from a small local glacier from the surrounding 

 hills and had outlet through a river, which flowed out near to the 

 anchorage of the ship. The depth of the lake in the summer was ca. 

 5%m. in the middle, in winter ca. 4 m. 



