1906. No. 3. AMUNDSEN’S OCEANOGRAPHIC OBSERVATIONS IN 1901. 67 
Even in a section (Sect. X) through Ryders Stations (taken in the 
beginning of July, 1891), north of Amundsen’s region, the isotherm of 
—1° C. and —ı'2° C. lie comparatively low; whilst there is an upper 
minimum, between —1° and —1:5°, at about 60 and 100 metres, extending 
westwards into Mohn’s Stations 350 and 348, where it is lying somewhat 
deeper and underlying a layer of much warmer water. But these 
Stations were taken in August, 1878; z. e. a month later in the season. 
The salinities at Ryder’s minimum have evidently been very low. To judge 
from thé very inaccurate determinations of specific gravity and salinity 
(by K. Rordam) they may have been between 343 and 346% (by 
Knudsen’s Tables), at Ryders Stations IX and X, which is much about 
the typical salinity of the coldest Polar water of the top layers in the 
North Polar Basin as well as in the East Greenland Polar Current. 
The isopycnals of 28-00 and especially of 28-10 also rise to levels 
very near the sea-surface at Amundsen’s Stations, and slope off towards 
the sides, especially towards north and south (see Sections VIII and IX) 
and towards west (Sects. IV, V, VI), but not so much towards east (see 
Sect. IV), where very heavy water obviously occurs in the region of 
Mohn’s Stations 302 and 303 etc. 
The maps, Pl. V, give interesting pictures of the horizontal distri- 
bution of Temperature, Salinity, and Density, in the summer, at 50, 100, 
200, 300 and 400 metres. They show that in the region of Amundsen's 
Stations there are quite peculiar conditions, it forming, as it were, a 
centre of cold and heavy water. 
It is necessary to distinguish between two kinds of cold water in 
these maps, viz. the cold water of the surface layer, between oO and 200 
metres, of the East Greenland Polar Current (and that of the Barents Sea), 
which at some places, e.g. round Jan Mayen and between Jan Mayen and 
Iceland, has sunk down to greater depths, — and the cold bottom-water 
of the Norwegian Sea which in the region of Amundsen’s Stations rises 
so near to the surface that it is in contact with the cold surface water. 
East of Iceland and between Iceland and Jan Mayen the surface of this 
bottom-water rises so high that it is visible in the maps (see especially 
those for 300 and 400 metres). At Ryders Stations II and III, June, 
1891, between Iceland and Jan Mayen, this cold bottom-water was ob- 
viously in contact also with the cold surface water. 
The map for 200 metres gives a good idea of the distribution of 
these two kinds of cold water. In the region of Amundsen's Stations 
the cold bottom-water is surrounded by the isotherms of —1° C. and 
0° C. The former forms a closed ring round Amundsen’s eastern, and 
