HYDROGRAPHY. j,. 



decreased with 0-15 %o, while the temperature of the water at the same time increased with 3°3, which 

 last circumstance is due to the influence of the heat of summer. Considering the physical conditions 

 south of Greenland in their entirety, it will appear that the ice-water has a greater extent in the 

 month of August than in the month of June. 



We shall now cast a glance on the seas east of Iceland. The chart XXXII with the determina- 

 tions of salinity and temperature that are laid down in it, contains all the surface-observations of the 

 In golf-Expedition for both years 1895 — 1896 in the region of the sea the chart is comprising, as well 

 as a series of observations taken on the route Iceland and the Faroe Islands, and made by the cruiser 

 Heimdal during the 17th and 18* of July 1896. 



The southernmost part of the isohaline 33-00 is stretching as far as 66° 30' L. N. and io° — n° L. W. 

 of Greenwich, a little more southerly we meet with the 33*50 isohaline, and still further south, in 

 65 20' Lat. N., the 3400 isohaline. It will be observed that from 33 - oo the salinity is only increasing 

 slowly to the southward in the western seas, while it is increasing rapidly in the eastern ones. 

 Following the series of observations in a south south-easterly direction from Langena>s, it will be no- 

 ticed that the salinity is decreasing as far to the southward as 65 20' Lat. N., which probably must be 

 due to the influence of the fresh-water current that, as already said, is flowing south along the east- 

 coast of Iceland. 



From the southernmost part of the 34 - oo curve, the salinity remains for a long 

 time constant in a southerly direction, till suddenly it comes up to the salinity of 

 the Atlantic-water. This abrupt transition can plainly be seen from the line 17th — 18th July 96 

 and the line 26* May 96. These transitions are accompanied by considerable variations 

 of temperature, characterising the surface-water east of Iceland as ice-water that is brought hither 

 by a Polar-current, a conception which is backed up by all the observations that have been made. 



While the Atlantic-water has an almost constant temperature of between 8° and 9 during the 

 mouth of May, the temperature of the ice-water is varying between o° and 5 from one place to 

 another. The very irregular variations that appear, may, as has been said before, be accounted for 

 by the fact of the ice being broken into hummocks when melting. Owing to this, we may expect, 

 when in the month of May we are coming from the Atlantic into the East Icelandic Polar Current, 

 to meet with a pretty high change of temperature from at the least 8° (in the Atlantic) to at the 

 highest 4 (in the Polar-current). In the course of the summer, the Atlantic-water and that of the 

 Polar-current is heated, the latter most in consequence of its having the lowest temperature. Thus 

 the difference of temperature between the two species of water will in the course of 

 the summer be less and less, which likewise applies to the variations of temperature 

 in the southernmost part of the Polar-current itself, but for all that the difference of 

 temperature between Atlantic-water and Polar-water will never be perfectly effaced. While in the 

 month of August the Atlantic-water has a temperature of more than n°, that of the ice-water is al- 

 ways below io°. In consequence of this, it is possible on the basis of the temperature alone, to 

 distinguish between Atlantic-water and water from the Polar-current 



Combining the determinations of temperature of the expedition with similar determinations 

 made the whole year round between the Faroe Islands and Iceland, it will be possible to draw approxi- 



