PHYSICAL AND BIOLOGICAL CONDITIONS IN THE NORTH SEA. 245 



extends from the coast of Norway to the east coast of Scotland, and the 

 Orkneys and Shetlands. The rest of the North Sea is 9° and 10° C, 

 becoming warmer towards the English Channel, at the western entrance 

 of which we have 11° to 13°. On the west coasts of the British Islands 

 the temperature is 9' and 10°, as in the south-western part of the Xorth 

 Sea. Mr. Dickson observes that the low temperature on the east coast 

 of Scotland at this period corresponds to the up-welling of bottom 

 water which has been observed there. 



In February, 1894, we find that the northern and southern tongues of 

 oceanic water have met and joined, so that there is a broad central 

 region of this water extending completely through the North Sea. North 

 Sea water occupies a narrow strip on each side, and extends in a narrow 

 tongue into the Skagerack. Coast water is seen on the south coast of 

 Norway, extending into the Skagerack as far as the Skaw, and as usual 

 in a narrow band along the east coast of the North Sea. 



Surface temperature is now at its lowest for the year. From the east 

 coast of the North Sea nearly to the middle it is only 4^ C, this 

 temperature extending all over the Heligoland Bight. Over the whole 

 of the western part of the North Sea the temperature is only 5° and 

 6° C. On the west coast of the British Islands we have temperatures 

 of 7° and 8°, including the western entrance of the English Channel, 

 but 9° and 10° are found not far to the westward in the Atlantic. 



The yearly cycle has now been completed, but we have also observa- 

 tions and charts for May, 1894, and these show that the conditions of 

 May, 1893, are not exactly repeated. It would naturally be expected 

 that the same conditions do not recur exactly at the same period every 

 year, if ever, though there must be a general similarity in successive 

 years. In May, 1894, the data are incomplete, but they show that 

 oceanic water extended throughout the central part of the North Sea, as 

 in the preceding February, with a narrow band of North Sea water on 

 each side. The temperatures are more similar to those of May, 1893, 

 but are rather higher, that of S" C. extending over nearly the whole of 

 the northern part of the North Sea, while, as in the earlier period, the 

 temperature of 9^ extends on the west coast of our islands beyond the 

 north of Scotland. 



Professor Pettersson has also mapped the distribution of surface 

 salinity over the greater part of the North Sea at the end of November, 

 1894, and the middle of February, 1895. In November, 1894, the total 

 area occupied by oceanic water was but small, and the Baltic outflow, 

 instead of being cut off, as at this time in 1893, extended far to the 

 northward. Absence of winds may account for the weakness of the 

 oceanic streams, and the greater strength of the Baltic stream is ascribed 

 to the mildness of the season. 



