124 



HYDROGRAPHY. 



SECTION XVIII. 



From Jan Mayeu in a southerly direction. 



This section goes through the most easterly stations of the expedition. According to this we 

 should here have a longitudinal section through the eastern part of the Polar Current and its continua- 

 tion in the East Icelandic Polar Current. The section is not, however, remarkable by any characteri- 

 stical features in so far as the current is concerned. The fact is that many of the stations are lying 

 in the near vicinity of its eastern line of demarcation. It is only at the stations 104 and 105 that we 

 meet with negative temperatures in the ice-water. We see also how the i° isotherms are penetrating 

 underneath the cold ice-water, the usual phenomenon, that the salt and warm water on account of 

 the distribution of the specific gravity is flowing in between the upper and under-layer of the 

 Polar Current 



We have seen that the Irminger Current is sending its water quite into the Polar Current, and 

 that the character of the western under-layer of this latter is due to this circumstance. The fact of 

 the salinities and temperatures in the western part of the under-layer being subject 

 to a decrease when advancing in a southerly direction, proves that this layer fol- 

 lows the motion of the East Icelandic Current, at least in so far as the direction is 

 concerned. The existence of the under-layer cannot be considered as originating from the south, that is 

 to say, from Atlantic water flowing in a northerly direction, as on the assumption of the existence of the 

 cold upper-layer, the temperatures and salinities of an under-layer moving in this direction woixld 

 be gradually increasing to the southward. Even the fact that, upon the whole, there is such a decline 

 in salinity and temperature, proves at the same time that the under-layer has been subject to the 

 influence of the ice-water for a considerable time, so that the velocity of its motion must be 

 very small. Reference is made to all stations in section XVII, station 103 in section XVI. 



That it really must be the cold and fresh ice-water, which is the cause of a decline in the 

 temperature and salinity of the under-layer or its upper part — even to a considerable depth — can 

 be seen from section XVIII. Where the coldest upper-layer is to be found, the o° and — o°5 iso- 

 therms attain their greatest height, while at station 112, where the ice-water is less prominent, these 

 isotherms sink to their lowest position. From station 105, where the ice-water assumes a very promi- 

 nent character, the isotherms sink gradnally towards station 138 which is near the Faroe -Iceland 

 ridge, and thus in the vicinity of Atlantic-water. We cannot consider it as absolutely granted that 

 the isotherms between the two last stations really run as laid down in the chart, but the position of 

 the terminal points is given together with the observations, and this is what it depends upon in this 

 case. It is still more difficult to decide anything with certainty regarding the course of the isohalines, 

 or, upon the whole, to give a description of the transitional amalgamation between the East Icelandic 

 Polar Current and the Atlantic-water, as we are wanting a sufficient number of determinations to 

 this purpose. 



The reason why the under-layer of the Polar Current is moving in a southerly direction together 

 with the Polar Current itself, is probably due to the internal friction in the water. The motion 

 of the Polar-water proper, or I should prefer to say, of the surface-layer, is due to the effects of the wind 



