689 



distance southward round the Faeroes, goes between the Shet- 

 land Isles and the Orkneys, and ends on the west coast of Nor- 

 way, a little north of Trondhjem Fjord. In winter and spring on 

 the other hand the water is warmer round the Faeroes than on 

 the west coast of Norway. According to Mohn: »Den Norske 

 Nordhavs Expedition«, 2 vol. Christiania 1883, the isotherm of 6^C. 

 runs in March midway across the Faeroes, then it bends north- 

 ward, then southward, and stops almost in the centre of the east 

 coast of Scotland. 



According to observations made near Thorshavn (see W i 1 1 a u m e- 

 Jantzen 84, p. 29), the annual mean temperature of the surface of 

 the sea is 7,8^C.; from January to March its temperature is 5,5^C., 

 and from July to September 10 — 10,5^ C, in exact accordance with 

 the average observations of 20 years. The lowest mean tempera- 

 ture of the surface of the sea was in one month (March) 4,25 ^C, 

 and the highest in an equally long period (August) 11,75 ^C. These 

 figures clearly show the very small difference of temperature in the 

 sea round the Faeroes, where the greatest difference observed 

 betw^een the mean temperature of the warmest and the coldest 

 months thus only amounts to 7,50 ^C. Ice is also unknown, and 

 it is only in the inmost part of the larger fjords such as Skaale- 

 fjord, little affected by the tides, and where much fresh water streams 

 into the sea, that the water may sometimes be covered by a thin 

 crust of ice. 



The above-mentioned figures only refer to the surface of the 

 sea, but as the marine algae are found down to a depth of about 

 25 fathoms, (for the Faeroes I believe that this may be stated 

 as the lowest limit), it would of course be of interest to our subject 

 to know the temperature as far down as this depth. Such observa- 

 tions, however, do not exist, so far as I know, but on my application 

 the officers of the »Guldborgsund« in 1899—1900 were kind enough 

 to obtain some hydrographical data by aid of a reversing thermometer 

 lent me by the Metereological Institute. The accompanying table 

 shows the results of these observations and indicates that the ditfer- 

 ence of temperature between the surface of the sea and the lower 

 layers of water is exceedingly small. During the warmer period of 

 the year the temperature of the surface rises slightly, yet seldom 

 more than V2^, whereas in winter the water is somewhat warmer 

 deep down than on the surface. In the fjords only, there may be 

 a greater difference (see e.g. the observation ^^/2 Klaksvig); it is due 



