314 THE DEPTHS OF THE SEA. [CHAP. vii. 



47, 90, 49, 50, and 51, are in the warm area, Thei 

 is no great difference in depth between the two seri< 

 of soundings ; and there is no indication of a ridge 

 separating them. The only possible explanation oj 

 these two so widely different submarine climates 

 existing apparently under the same circumstanc 

 and in close proximity to one another, is that th< 

 Arctic indraught which passes into the deeper pai 

 of the Fseroe Channel is banked in at its entrance, 

 by the warm southern stream slowly passing north 

 wards. There is a slight but very constant depres 

 sion of the isothermal lines of surface temperatui 

 in the shallow water along the west coast of Britain, 

 This, I believe, indicates that a portion of the col< 

 Fseroe stream makes its escape, and, still banked 

 close to the land by the warm water, gradually make* 

 its way southwards, so mixed and diluted as only t< 

 be perceptible by its slight effect on the lines of me* 

 temperature. Diagrams 55 and 56 illustrate the dis 

 tribution of temperature in the cold and warm area* 

 respectively ; and in Eig. 57, the results of the serial 

 soundings Nos. 52, 64, and 87, are reduced to curves. 

 Prom these diagrams, taken together, it will be seei 

 that in the first 50 fathoms there is a rapid fall oJ 

 nearly 3 C. Station No. 64 is a good deal farthei 

 north than the other two, and the surface tempera 

 ture is lower, so that the fall, which is nearly to tin 

 same amount, starts from a lower point, The surfac 

 temperature is doubtless due to the direct heat of 

 the sun, and the first rapid fall is due to the rapid 

 decrease of this direct effect, Prom 50 to 200 fathoms 

 the temperature in all three cases falls but little, re 

 maining considerably above the normal temperature 



