36 PRELIMINARY INQUIRIES. 



There is no impossibility iii this, nor even any very great improbability ; but there is an 

 explanation of its dispersion and distribution [it being once there in some part of the area), which" seems 

 to meet the facts equally well by the phenomena in daily operation, and if there be a sufficient 

 cause already at hand, it would be unphilosophical to abandon it, and refer the residt to another 

 whose former existence is only a sujjposition. 



The phenomena which furnish such an explanation are the currents which surround the Gulf 

 weed bed, and the explanation is that the Sargasso is thrown into and kept in its present position 

 by the eddy or whirl caused by their revolution on every side of it. Hvmiboldt, I think, was the first 

 to notice that it occupied the eddy, and Maury states the theory broadly, that the Sargasso Seas 

 are composed of drift matter, which cannot escape or accompany the current which brings it, in 

 consequence of its being met by another current. " The water that is drifting north on the 

 outside of the Gulf stream turns with the Gidf stream to the east also. It cannot reach the high 

 latitudes, for it cannot cross the Gidf stream. Two streams of water cannot cross each other, 

 unless one dip down and under-run 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 ofi" from a j)assage into higher latitudes. According to this view there ought 

 to be a Sargasso sea somewhere in the sort of middle ground between the grand equatorial flow and 

 reflow, which 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, woidd slough ofi" its drift matter. The forces of diurnal 

 rotation woidd require this collection of di-ift to be in the northern hemisphere, on the right hand side 

 of the current, and in the southern to be on the left. 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 Mozambiqiie current, which runs south along the east coast of Africa from the Indian 

 Ocean, and with the cooler current setting to the north on the Australian side of the same sea. 

 Between these there is a Sargasso on the left, for it is in the southern hemisphere. Again, there 

 is in the South Pacific a flow of equatorial waters to the Antarctic on the east of Australia, and of 

 Antarctic waters (Humboldt's current) to the north, along the western shores of South America ; and, 

 according to this principle, there ought to be another Sargasso somewhere between New Zealand and 

 the coast of Chili. To test the correctness of this view, I requested Lieut. Warley to overhaid our 

 sea journals for notices of kelp and drift matter on the passage from Australia to Cajje Horn and the 

 Chincha Islands. He did so, and found it abounding in small patches, with ' many birds about,' 

 between the parallels of 40° and 50° south, and the meridian of 140° and 178° west. This Sargasso is 

 directly south of the Georgian Islands, and is perhaps less abundantly sujiplied with drift matter, 

 less distinct in outline, and less permanent in position than any one of the others."* 



It thus appears that instead of three, as stated in the former editions of Lieut. Maury's 

 "Physical Geography of the Sea," there are really five Sargassos, and it is from his maps that 

 I have laid them down as shown on MajJ 5*. 



Now the objection to Maury's explanation taken by itself is, that the Sargasso, at least in the 

 Atlantic, is composed of only one ingredient, the Saegassum bacciferum ; whilst any collection of 

 true drift would necessarily be composed of a heterogeneous accunmlation of all sorts of things. If 



* Maury, " Physical Geography of the Sea," 1S60, p. 50. 



