HYDROGRAPHY. 12 , 



and the unequal distribution of the pressure ; this motion is then on account of the friction imparted to the 

 layers underneath, provided that these latter are not acted upon by special powers that are sufficiently 

 strong to give them a direction that is independent of the aforesaid circumstances. The coefficient 

 of friction is as we know, in so far as water is concerned, a very small quantity, so that the moving 

 power with which the upper-layer, during its travel in a southerly direction, is acting on the strata 

 of water that are in a deeper position, must be exceedingly small. Not even the surface waters in 

 the Kattegat, which are flowing in a northerly direction with considerable velocity on account of the 

 afflux from the Baltic, are able to carry the salt under-layer away with them, and gradually take its 

 place. Owing to this, we are led to believe that the extent of the under-layer of the Polar 

 Current north and east of Iceland, on which the influence of the ice-water may 

 be traced, is not determined by the extent of the ice-water at a certain moment, but 

 more likely by the average-value of the extent of this latter during the different 

 seasons of the year; perhaps through several years. 



At station 112, the maximum temperature of the under-layer is high; at the same place the 

 minimum temperature of the ice-water is not very prominent. These circumstances seem to imply 

 that station 112 must be in the vicinity of the eastern boundary line of the ice- water, and nearer 

 than any other station. In addition to the low temperature, we meet with the little degree of salinity 

 that is characteristic of the ice-water, and which manifests itself so openly at the surface, that even 

 if we only take the circumstances at the surface into consideration, we may come to the conclusion 

 that the Polar Current in the vicinity of station 112 has its greatest extent in an easterly direction. 



Hence it can be seen that the extent of the surface and the under-layer of the Polar Current 

 is not the same. The deeper the strata of water are lying, the less they will be effected by the 

 motion of the upper-layer. If we get down to a greater depth than 600 — 700 fathoms 

 (1130 — 1318 metres), the temperatures as well as the salinities will nearly be the same 

 everywhere i 11 the horizontal stratum concerned. It appears from the measurings 

 and investigations of the Norwegian-North-Ocean-Expedition that this, as it were, 

 applies to the whole of the basin of the North Ocean. 



SECTION XIX. 



From Jan Mayen in a southerly direction (west of section XVIII). 



If we compare this section with the foregoing one, it cannot escape our attention that the 

 two sections in their principal features have the same character. That section XIX is situated 

 nearer the axis of the Polar-current, manifests itself by the fact of a cold layer of water near the 

 surface, everywhere with a temperature that is below o°, is stretching itself through the whole of 

 the section. The 35-00 isohaline approaches the surface a little more in section XVIII than in 

 section XIX. 



At station 118 the ice-water has the least thickness, and on an average the highest tempera- 

 ture; at the same station we find the highest maximum temperature for the under-layer. These 

 circumstances prove that station 118 is the one of all the stations in section XIX that is nearest to 



