OCEANOGRAPHICAL RESULTS, MICHAEL SARS, 1900. 157 



any i-ate not more than 2 m., and if all openings and lanes 

 between the floes be considered it is probably even less. 



(2) The low salinity of the Polar water, even in southern 

 latitudes, is not chiefly due to the melting of the ice, but to the 

 rivers draining into the North Polar Basin. The Fram Expedi- 

 tion found the whole North Polar Basin covered with a layer, 

 200 m. thick, of Polar Water with low salinity, and we find the 

 same layer, almost with the same thickness, in the sea east of 

 Greenland as far south as near Iceland. ' This layer of Polar 

 water has considerably lower densities than the Atlantic water, 

 and has consequently a strong tendency to spread over the latter, 

 this tendency in connection with the wind is as proved by the 

 drift of the Fram the chief cause of the Polar Current. The 

 boyancy of this 200 m. thick layer between Iceland and Jan 

 Mayen, has naturally a far greater ability to form the East Ice- 

 landic Polar Current than the relatively thin and insignificant 

 layer of fresh surface-water formed by the melting of the ice. 



(3) The cooling effect of the ice-melting upon the under- 

 lying water-strata, is not as great as assumed by Prof. Petters- 

 son, for as I have mentioned in previous papers, the ice is swim- 

 ming in the originally very cold Polar water, and the heat for 

 the melting process is to a very great extent taken directly from 

 the sun-rays and the air; in which manner the surface-layers of 

 the Polar water is also heated, even to several degrees above 

 zero Centigrade. 



The low salinities of the upper water strata towards Iceland, 

 in the most southern portion of the section, is evidently to some 

 extent due to water formed by ice-melting, but the steep inclina- 

 tion of the isotherms and the conspicuously higher temperatures 



^ It is a common mistake to speak of the Polar water as water arising 

 from the melting of ice (e. g. cf. M. Knudsen, The Banish Ingolf Expe- 

 dition, 'Hydrography'). The authors evidently forget that in high lati- 

 tudes where there is formed much more ice than there is melted, the 

 Polar water has even a lower salinity than in more southern latitudes. 



