394 THE DEPTHS OF THE SEA. [CHAP. vm. 



a single month, or for the whole year, instantly 

 declares itself as one of a system of curves which 

 are referred to the Strait of Florida as a source of 

 heat, and the flow of warm water may be traced in 

 a continuous stream, indicated when its movement 

 can no longer be observed by its form, fanning out 

 from the neighbourhood of the Strait across the 

 Atlantic, skirting the coasts of Prance, Britain, and 

 Scandinavia, rounding the North Cape and passing 

 the White Sea and the Sea of Kari, bathing the 

 western shores of Novaja Semla and Spitzbergen, 

 and finally coursing round the coast of Siberia, a 

 trace of it still remaining to find its way through 

 the narrow and shallow Behring's Strait into the 

 North Pacific (see Plate VII.). 



Now, it seems to me that if we had only these 

 curves upon the chart, deduced from an almost in- 

 finite number of observations which are themselves 

 merely laboriously multiplied corroborations of many 

 previous ones, without having any clue to their 

 rationale, we should be compelled to admit that 

 whatever might be the amount and distribution of 

 heat derived from a general oceanic circulation, 

 whether produced by the prevailing winds of the 

 region, by convection, by unequal barometric pres- 

 sure, by tropical heat, or by arctic cold, the Gulf- 

 stream, the majestic stream of warm water whose 

 course is indicated by the deflections of the isother- 

 mal lines, is sufficiently powerful to mask all the 

 rest, and, broadly speaking, to produce of itself all 

 the abnormal thermal phenomena. 



The deep-sea temperatures taken in the ' Porcu- 

 pine' have an important bearing upon this question, 



