VEG A-EXPEDITIONENS V ET EN S K A P L IG A A R B E T E N. 349 



It seems probable that the direction of the iipper- and under- 

 current in this strait is variable and depends upon causes. 

 ■\vhicli highly require repeated investigation. 



The investigation of the eonditions of the Kära Sea and 

 adjacent parts of the arctic ocean is of course a very compH- 

 cated problem to the metereologists as well as to the hydro- 

 graphers. The climate of the north Asiatic continent in winter 

 is excessively cold and even the sudden change of temperature 

 in the summer months, witnessed b}^ the rise of the June and 

 July isotherms, would be insufficient to break the icy bound- 

 ^ries of the sea, if the warm water from the Siberian rivers 

 did not conduce to the same efFect. Therefore the condition 

 of the Kära Sea in August and September, the only season 

 adapted for navigation, must to a great part be dependent 

 upon the amount of sunshine and rain-fall bestowed in the 

 course of spring and summer upon countries far away from 

 the Yahnal and Taimur coasts. 



Moreover the effect of the heat of the river-water upon 

 the sea is Hmited to its surface, where it is absorbed in the 

 melting of the ice. From a few metres beneath the ice to 

 the bottom, there is an indraught of salt water from the arctic 

 sea north of Siberia, which is sufficiently cold [ — 1°.3 unto 

 — 1°.7 or — 1°.9 C] to prevent the melting of the ice and even 

 to make the inundating superficial stratum of brackish water 

 give up ice, if it does not constantly receive fresh supply 

 from the rivers. 



An excellent illustration of this statement is the curious 

 experiment mentioned by Nordenskiöld in his work »Vegas 

 färd kring Asien och Europa». If a vessel filled with water 

 from the surface of the Kära Sea is immersed deeper into the 

 sea, then the water in the vessel soon freezes into ice. 



Moreover Nordenskiöld asserts that the brackish water 

 at the surface acts like poison upon most part of the animals 

 living below. 



The mechanic reaction of the flowing water makes the 

 cold water below rise nearer to the surface in sorae parts of 

 the Kära Sea, whicli accordinghj are foimd to he more impradicahlc 



30 vadeinen — 1'.5, op 20 vademen — 1".4, op 10 vademen —O'. 4 en aan de 

 oppervlakte + 0'.g .... De bovenstroom liep hier onafgebroken om de west, 

 doch door eene waanieming met den duiker bleek, det het onderwater of 

 om de oost liep of wel stationair bleef. Heet voortdin-end om de west 

 loopen van den stroom in de Matoschkinsharr, waarvan Lutke en andere 

 spreken, hadden wij vroeger, d. i. in 1878 en 1879, niet kunnen waarnemen.» 



