of the Fishery Board for Scotland. 



411 



bending ultimately in a north-easterly direction into the Skagerack, where 

 it abruptly terminates. 



The depth of the southern and smaller division of the North Sea is 

 comparatively slight. A band of shallow water, less than 20 fathoms 

 deep, and varying in breadth from about 30-60 miles, extends the whole 

 way along the coast from Calais to the Skaw. From the Straits of Dover 

 a channel of somewhat deeper water runs in a northerly direction for 

 about 130 miles between the shallow waters off the English coast and 

 those of the Belgian and Dutch coasts. To the north of this 

 the water is shallow from coast to coast, deepening gradually however 

 to the north-east and north-west on either side of the Dogger Bank, 

 to the south of which a band of deeper water, broken up, however, 

 by a series of sandbanks and shallows, forms a connecting link between 

 the deeper waters of the northern and southern areas. 



The great influence which the Dogger Bank has on the distribution of 

 temperature in the North Sea is very clearly shown by Dr Meyer's 

 analysis of the temperatures observed during the 'Pommerania' Expedi- 

 tion. 



In the northern area a layer of cold water, of variable thickness was 

 generally found during the ' Pommerania' Expedition underlying a layer of 

 distinctly warmer water, from which it was separated by a comparatively 

 thin intermediate layer. The temperature of the colder layer was fre- 

 quently found lower than 46°'5 F. (8° C), while that of the warmer and 

 upper layer ranged from about 54° to 57° F. (12° to 14° C). 



The passage southwards of the cold bottom water is arrested by the 

 Dogger Bank. 



The temperature of the southern and shallow area was found to be 

 markedly higher than that of the northern area at corresponding depths. 

 The vertical distribution of temperature in the southern area was 

 found to be very uniform, there being no great and abrupt differences of 

 temperature between the upper and lower layers of water as were generally 

 met with in the northern area. Thus in the western portion of the 

 southern area the mean range of temperature observed between surface 

 and bottom was from 60°'0 to 59°'5 F. (16°'7 to 15°-3 C), and even this 

 difference may be attributed to the inflow of colder water from the north, 

 for in the region lying more to the east, and where the inflow of colder 

 water from the north is more completely checked by the barrier of the 

 Dogger Bank, the range in temperature between surface and bottom was 

 only from 64°'6 to 63°'3 F. (18°*1 to 17°'4 C). The relatively higher 

 temperatures of the southern area as compared with those found at similar 

 depths in the northern area were attributed to an inflow of warm surface 

 Atlantic water through the English Channel, and the uniformity of 

 temperature from surface to bottom to the more complete mixing of the 

 shallow waters by wind and currents. The comparatively low temperature 

 of the northern area on the other hand was attributed to the presence of a • 

 mass of cold water of northern or Arctic origin in which the warm 

 Atlantic water flowing in to the north of Scotland is soon lost. 



To these two waters there must be added a third, viz., the outflow from 

 the Baltic, the presence of which, although also indicated by the thermo- 

 meter, was still more clearly recognised by the hydrometer. The specific 

 gravity of the open waters of the North Sea is, generally speaking, not 

 much lower than that of ocean water, and as a general rule the influence 

 of fresh water from the land only becomes marked near the mouths 

 of rivers and in narrow estuaries. 



The most striking instance of the influence of land water in modifying the 

 specific gravity of open sea water was found in the surface water along 



