SEA-FISHERIES LABORATORY. 131 



and the end of March, and which is minimal at 4-7°. Such a 

 curve cuts through those of years when the range is less. 



When these smoothed curves for Bahama Bank and More- 

 cambe Bay light vessels are compared it is seen that their 

 general appearance, with respect to each other, are the same, 

 on the whole ; and this is so even when the curves from the 

 same one light vessel, in different years, may be very different. 

 The Bahama Ship temperatures are higher throughout all the 

 years considered except 1907. In that year the temperature 

 at Morecambe Bay Ship was minimal (4-54° C.) on Jan. 31st ; 

 but it rose rapidly, and on February 16th it was higher than 

 at Bahama Ship, not only so but it was higher than at Carnarvon 

 Bay Ship, which is more southerly, and is in the core of the 

 water streams moving from south to north, and is less affected 

 by the influence of the land than is either of the other stations. 



The general similarity, in shape, of the curves for More- 

 came Bay and Bahama vessels, and the higher range of the 

 latter are to be expected when one looks at their respective 

 positions. The latter vessel is just north of the line from 

 Maughold Head and Walney Island, along which line the tidal 

 streams that come through St. George's and North Channel 

 meet, and form an area in which there is little oscillatory ebb 

 and flood, but a large, vertical oscillation. It has been found by 

 study of the salinities along the Maughold Head — Walney Line 

 (Hydrographic Stations I-IIP) that this area is greatly affected 

 by the tidal streams ebbing out from Morecambe Bay. In its 

 gradual transference across, towards the Manx coast, this 

 water is greatly mixed with that which comes up from 

 St. George's Channel because of the resultant tidal drift from 

 south to north. This mixed water, of course, gradually passes 

 out through the North Channel.! 



* Bassett, " Report on Hydrographic Observations," Ann. Rept. 

 Lancashire Sea-Fish. Lab., 1907-14 ; Johnstone, ibid., 1908, p. 79. 



f Knudsen, Publications de Cir Constance, No. 39, 1907. 



