394 THE DEPTHS OF THE SEA. [CHAP. VIII. 
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 France, 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, 
