476 SCIENCE PROGRESS 



Gulf Stream drifts, both the annual and the larger periodicities, 

 are also of the greatest importance as causes of the fluctuations 

 in the yield of the harvests and fisheries of certain parts of 

 North Europe. 



The English Branch of the Gulf Stream drift enters both 

 the English and St. George's Channels. Its general distribu- 

 tion is variable from season to season and from year to year. 

 February to April is about the time of the annual maximum. 

 The year 1903 was also a maximum year, but the length of 

 this longer period is not known exactly. Generally speaking, 

 the axial portion of the English Channel is filled with water 

 of truly Atlantic origin, possessing a salinity of about 35 to 

 35'2 per thousand. A narrow tongue of this water passes 

 through the Straits of Dover into the North Sea. The extent 

 of the 35*2 water and that of the North Sea prolongation of 

 the Channel water are very variable. 1 Doubtless the Atlantic 

 water in the Channel is pushed in, to some extent, by the 

 impelling force of the Gulf Stream drift in the North Atlantic, 

 but it is difficult to resist the suggestion conveyed by a glance 

 at fig. i, that this water is actually sucked through the Channel 

 by the action of the cyclonic system of circulation of water 

 in the North Sea. The volume of Atlantic water entering 

 St. George's Channel and the Irish Sea is much less than that 

 entering the English Channel, possibly because an outflow 

 of relatively fresh water from the Bristol Channel sets up a 

 cyclonic circulation off the mouth of this estuary. But, however 

 this may be, we find that the Atlantic water of 35 per mille. 

 salinity does not penetrate farther into the Channel than some 

 distance south of the Fishguard-Rosslare line, as is indicated 

 in fig. 1, where the further limit of this water is shown by the 

 thick black line. 



The Norwegian Branch of the Gulf Stream drift flows on 

 along the west coasts of Ireland and Scotland. Fig. 1 shows 

 that the isohalines lie closely together and very near to the 

 west coast of Ireland, but that there is an area of low-salinity 

 water off the north coast of Ireland and the south-west coasts of 



1 Detailed studies of the variability of the Gulf Stream flow into, and through 

 the English Channel, and in the North Sea, in its southern part, will be found in 

 the papers of Matthews. See Reports on Fishery and Hydrographical Investiga- 

 tions in the North Sea and Adjacent Waters {Southern Area). Bluebooks 

 Cd. 2670, 1905 ; and Cd. 4641, 1909. 



