THE GULP STREAM. 49 



currents. — Here I am reminded to turn aside and call attention to 

 another fact that militates against the vast current-begetting 

 power that has been given by theory to the gentle trade-winds. 

 In both oceans these weedy seas lie partly within the trade-wind 

 reo-ion ; but in neither do these winds give rise to any current. 

 The weeds are partly out of water, and the wind has therefore 

 more power upon them than it has upon the water itself; they 

 tail to the wind. And if the supreme power over the currents of 

 the sea reside in the winds, as Sir John Herschel would have it, 

 then of all places in the trade-wind region, we should have here 

 the strongest currents. Had there been currents here, these 

 weeds would have been borne away long ago ; but so far from it, 

 we simply know that they have been in the Sargasso Sea (§ 88) 

 of the Atlantic since the first voyage of Columbus. But to take 

 up the broken thread : — 



135. The drift matter confined to sargassos hy currents. — The w^ater 

 that is drifting north, on the outside of the Gulf Stream, turns, 

 with the Gulf Stream, to the east also. It cannot reach the high 

 latitudes (§ 80), for it cannot cross the Gulf Stream. Two 

 streams of water cannot cross each other, unless one dip down 

 and underrun the other; and if this drift water do dip down, as 

 it may, it cannot carry with it its floating matter, which, like its 

 weeds, is too light to sink. They, therefore, are cut off from a 

 passage into higher latittides. 



136. Theory as to the formation of sargassos. — According to this 

 view, there ought to be a sargasso sea somewhere in the sort of 

 middle groimd between the grand equatorial flow and reflow 

 Avhich is performed by the waters of all the great oceans. The 

 place where* the drift matter of each sea would naturally collect 

 would be in this sort of pool, into which every current, as it goes 

 from the equator, and again as it returns, would slough ott" its 

 drift matter. The forces of diurnal rotation would require this 

 collection of drift to be, in the northern hemisphere, on the right- 

 hand side of the current, and, in the southern, to be on the left. 

 (See Chap. XVIII. and Plate IX.) 



137. Sargassos of southern seas to the left of the southern, to the 

 right of the great polar and equatorial floio and reflow. — Thus, with 

 the Gulf Stream of the Atlantic, and the "Black Stream" of the 

 Pacific, their sargassos are on the right, as they are also on the 

 right of the returning and cooler currents on the eastern side of 

 each one of those northern oceans. So, also, with the Mozam- 



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