SEA-FISHERIES LABORATORY. 237 



convex towards the English coast : they are now convex 

 towards the North-west, except immediately to the North 

 of Anglesey, where the prevalent drift to the North-east 

 is still indicated. During this cruise there was a marked 

 difference between the temperatures of surface and 

 bottom water, the former being significantly warmer, and 

 this is due, of course, to the heating effect of the sand- 

 banks along the Cheshire and Lancashire coasts. 

 Nevertheless, the direction of curvature of the isotherms 

 indicates that this heated water is gradually being 

 displaced to the North-west, passing round Point of Ayre 

 into the North Channel, and the direction of curvature of 

 the isotherms in the neighbourhood of Anglesey indicates 

 just as clearly that the cause of this displacement is the 

 continual entrance of colder water from St. George's 

 Channel. It will also be seen that there are no longer any 

 indications of a flow of water immediately along the East 

 coast of the Isle of Man, the strength of the Gulf Stream 

 drift being now much less than in the Spring months. 



August 4, 1909. 



Eig. 29, which represents the distribution of surface 

 temperatures during part of this month, has been con- 

 structed from our own and Mr. Holt's observations, and 

 includes the whole area. It represents very nearly the 

 conditions during the period of annual maximum tem- 

 perature. The distribution is now entirely reversed, the 

 colder waters being those of the centre of the Irish Sea, 

 and in the fairway of St. George's and North Channels, 

 while the warmest waters are those off the coasts of 

 England and Wales. All the coastal waters within the 

 territorial limits from Great Orme's Head to the Sol way 

 Firth are over 16 i0 in temperature, and though we have no 



