378 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
Along the coast of Greenland the current moves, carrying with it 
the old polar ice noted above, but the masses of water which come 
from the north toward the southwest are not limited to the surface. 
They have a considerable depth and a great complexity, which we will 
now consider (fig. 4). The vertical distribution of the temperatures 
is especially characteristic. In summer the ice floats in a water of 
variable temperature, mostly below 0°, but never going lower than 
—1°. From the surface as far as the depth of about 100 meters the 
temperature decreases progressively. At this depth is found a 
nucleus of very low temperature (as low as —1.8°) which represents 
the center of the polar current. Beyond this the temperature rises 
progressively, and between 200 and 400 meters is found a maximum 
of about +1.2°. It is only below 800 meters that they have observed 
again a negative temperature which is characteristic of the deep 
water. This remarkable distribution of temperature is explained 
very clearly by Helland-Hansen, who agrees in all points with 
‘Nansen. The ice carried by the polar current forms in the polar 
basin, mainly during winter, when the water has a minimum tem- 
perature of —1°. In summer the ice melts and the water warms up 
slowly. This warming makes itself felt only at the surface. The 
cold temperature of winter is maintained in the great depths; it is 
this remnant of the polar winter that is found between 20 and 150 
meters under the ice. 
The region of the maximum intermediate temperature is more 
remarkable. The waters where it occurs have a relatively high 
salinity (84.90 parts to 1,000). By this they show an evident rela- 
tionship with those of the Atlantic current. In fact, these are the 
last traces of the Gulf Stream, which, when it encounters the polar 
current, becomes by reason of the density of its waters, intercalated 
between these and the waters of the great depths. We find then 
here the waters of the returning Gulf Stream. Whether or not they 
have made a complete or a partial tour of the polar basin, they were 
turned aside toward the west at the latitude of Spitzbergen, as shown 
in figure 6. 
We have stated that the Gulf Stream is held against the conti- 
nental platform of Spitzbergen by the rotation of the earth. The 
polar current, some 800 meters in depth, is likewise held against that 
of Greenland; according to the observations of the Belgica its outer 
limit corresponds to the isobar of 1,500 meters, that is to say, it is 
very broad and quiet in the north, while it contracts and gets much 
swifter at the south. 
These Atlantic and polar waters overlie the waters of the great 
depths, the mass of which fills all the basins and by far surpasses in 
volume the superficial waters. The deep-seated waters have a tem- 
perature of —1° to —1.4°, and a salinity between 34 and 35 parts per 
