382 THE DEPTHS OF THE SEA. [CHAP. VIII 
received from the sun by the Arctic regions, and, 
reduced by a half to avoid all possibility of exaggera- 
tion, it is still equal to one-fifth of the whole amount 
received from the sun by the entire area of the North 
Atlantic. The Gulf-stream, as it issues from the Strait 
of Florida and expands into the ocean on its north- 
ward course, is probably the most glorious natural 
phenomenon on the face of the earth. The water is 
of a clear crystalline transparency and an intense 
blue, and long after it has passed into the open sea it 
keeps itself apart, easily distinguished by its warmth, 
its colour, and its clearness; and with its edges so 
sharply defined that a ship may have her stem in the 
the clear blue stream while her stern is still in the 
common water of the ocean. 
“The dynamics of the Gulf-stream have of late, 
in the work of Lieutenant Maury already mentioned, 
been made the subject of much (we cannot but think 
misplaced) wonder, as if there could be any possible 
ground for doubting that it owes its origin entirely 
to the trade-winds.”’' Setting aside the wider ques- 
tion of the possibility of a general oceanic circulation 
arising from heat, cold, and evaporation, I believe 
that Captain Maury and Dr. Carpenter are the only 
authorities who of late years have disputed this 
source of the current which we see, and can gauge 
and measure as 1t passes out of the Strait of Florida ; 
for it is scarcely necessary to refer to the earlier 
speculations that it is caused by the Mississippi river, 
or that it flows downwards by gravitation from a 
‘head’ of water produced by the trade-winds in the 
Caribbean sea. 
1 Herschel, op. cit. p. 51. 
