SEA-FISHERIES LABORATORY. 241 



sea-temperature to the North-west of the Isle of Man, the 

 distribution of warm and cold water appears to be quite 

 normal. 



General Observations. 



A study of the charts showing the approximate 

 courses of the isothermal lines during 1909 appears to me 

 to afford additional arguments in favour of the view of 

 the circulation of water in the Irish Sea, taken up by 

 Dr. Bassett in the preceding paper, that the general drift 

 of water, both at the surface and bottom, is from North 

 to South through St. Greorge's Channel, to the East close 

 to the coast of Anglesey, and then to the North-west 

 round Point of Ayre through, the North Channel. This 

 view is supported both by the study of isohaline and 

 isothermal contour lines, and it will be seen that these 

 mutually confirm each other when we remember that each 

 series may vary independently of the other. 



One sees quite clearly (1) that in St. Greorge's 

 Channel the isotherms, except so far as they run parallel 

 to the coast lines, are convex towards the North ; and, 

 particularly in February and May, are bent over to the 

 East towards the coast of Anglesey, where the tempera- 

 ture gradient is steeper than on the Irish side; (2) that 

 this convexity of the isotherms is greatest to the North 

 and North-east of Anglesey, a condition again best 

 marked in February, March and May; and (3) that the 

 isotherms East of a line joining Calf of Man and 

 Holyhead are convex towards the English coast in the 

 southern part of the area, and convex towards the Isle of 

 Man in the northern part of the area. It is only in 

 September, when the temperature throughout is very 

 uniform, that this arrangement of the isotherms is 

 obscured. 



