INTE'^NATIONAL FISHERY INVESTIGATIONS. 389 



November, 1903, siiniiltaneously willi similar cruises undertaken else- 

 where by other countries. Samples of the surface water wore obtained 

 from time to time in the periods between the quarterly cruises, chiefly 

 through the co-operation of officers of the mercantile marine. 



Complete records of the observations made on the periodic cruises 

 have been sent to the Bureau of the International Council, and have 

 been published in the quarterly bulletins issued by that authority.* 



The hydrographical observations during 1903 appear to show that the 

 direction of the flow of the waters of the English Channel was from west 

 to east, and that they were derived from a northerly current of about 

 35'6 per thousand salinity from the Bay of Biscay and from a southerly 

 current of about 35'2 per thousand salinity or less from the Irish Sea 

 and Bristol Channel. The meeting place of these waters may be roughly 

 fixed as south of the Scilly Islands in mid-channel, and it was generally 

 found that the salinity of the water increased as this point was passed 

 from west to east. 



Owing to the varying salinity and teinperature of these two currents, 

 it has been found that at the entrance to the Channel the water is often 

 divided into distinct layers, whilst the changes of their relative velocity, 

 combined with the general drift up Channel, give rise to alternate areas 

 of liigb and low salinity which follow one another eastward. On the 

 line between the Isle of Wight and Cape BarHeur the salinity has been 

 low on all four cruises, a state of things due, in all probability, to the 

 amount of fresh water discharged from the Hampshire basin and 

 the Seine. The presence of denser water south of Beachy Head, 

 however, points to the occasional passage of a high salinity current 

 across this line. 



It would appear that during the summer and early autumn of 1903 

 the Channel waters were derived largely from the Irish Sea, while 

 during the rest of the year the high-salinity water of the Bay of Biscay 

 preponderated. 



The plankton observations show that a large proportion of the more 

 oceanic organisms found off the mouth of the Channel do not penetrate 

 for any considerable distance up Channel, even along a central axis, the 

 percentage of oceanic species having on each cruise fallen below 40 at 

 the stations on the line from the Isle of Wight to Cape BarHeur. When 

 compared with those taken by other countries in the southern part of 

 the North Sea, the observations indicate that conditions very similar to 

 those found in the southern part of the North Sea, between a line from 

 the Wash to Heligoland and the Straits of Dover e.xist in the eastern 



* Bidlelin des Rtisultats acquifi pendant les Courses I'criocUqucs, Conseil Perv)ancnt 

 International pour V Exploration de la Mer. Ania-e 190"J-1903, Nos. 3 ct 4. AiiiiOe 1903- 

 1904, Nos 1 et 2. 



