REPORT OF THE COUNCIL. 403 



November 16th, when 35-30 °/ooS. again appeared on the Plymouth- 

 Guernsey line. During the cruise in November, a narrow tongue of 

 surface water of 3540 7ooS. and over was found stretching north from 

 Ushant to near mid-Channel, when it took a sharp turn to the west. 

 This apparent movement from east to west, against the general Channel 

 drift, was due to a sheet of fresher water entering from the west and 

 nearly covering a broad layer of denser water which extended at the 

 bottom from Ushant at least as far as Parson's Bank. 



About the middle of December the flow of high-salinity water in- 

 creased, and during the first week in January 1905, water of 35-407ooS. 

 appeared in the Channel between Plymouth and Guernsey for the first 

 time since February 1904. In February there was a slight fall here, 

 but the presence of water of 35-50 "/.w S., or possibly 35-60 7onS., a few 

 miles to the west showed that the Atlantic How was still increasing, 

 displacing the whole of the fresher water from surface to bottom. 

 This flow reached its maximum towards the end of February with 

 water of 35-59 "/ooS., between Plymouth and Guernsey, though it had 

 not fallen below 35-40 7..o S- at the end of April. The samples collected 

 since that date have not been worked out. The general results show 

 an increased Atlantic flow during the first few months of 1905. 



The specific gravity of various samples collected in the North 

 Atlantic between Lat. 56° N. and Lat. 20" N. has been determined 

 directly, and so far no reason has been found for doubting the accuracy 

 of the ratio of total halogens to specific gravity as given by Knudsen's 

 Tables. These experiments are still in progress. 



The results of the two years of hydrographic work which have now 

 been carried out show that the western portion of the English Channel 

 is sometimes filled with warm Atlantic water of high density entering 

 from the south, whilst at other times the water is of low density, 

 being derived chiefiy from the Bristol Channel and St. George's Channel, 

 and in the case of the coastal waters being diluted to a certain extent 

 with river water. Occasionally water of both kinds may be found as 

 distinct layers — the water of high salinity usually forming the bottom 

 layer. These changes take place somewhat irregularly and vary in 

 dififerent seasons and from year to year. It seems clear that such 

 changes must have a fundamental influence on all problems connec- 

 ted with the life-history and distribution of the organisms inhabiting 

 the area — including the food fishes. 



Samples of Plankton were collected at each station on the t(tur 



