28 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



at the extreme nortli or farthest south, have been found either in 

 the West Indies, on the British Isles, or within the well-known 

 range of Gruli Stream waters. 



87. Of two cast out together in south latitude on the coast of 

 Their drift. .\frica, ouc was fouud ou the island of Trinidad ; 



the other on Guernsey, in the English Channel. In the absence 

 of positive information on the subject, the circumstantial evidence 

 that the latter performed the tour of the Gulf is all but conclusive. 

 And there is reason to suppose that some of the bottles of the gal- 

 lant captain's chart have also performed the tour of the Gulf 

 Stream ; then, without being cast ashore, have retm^ned with the 

 drift along the coast of Africa into the intertropical region ; 

 thence through the Caribbean Sea, and so on with the Gulf Stream 

 again. (Plate YI.) Another bottle, said to be thrown over off 

 Cape Horn by an American ship-master in 1837, was afterwards 

 picked up on the coast of Ireland. An inspection of the chart, 

 and of the drift of the other bottles, seems to force the conclusion 

 that this bottle too went even from that remote region to the so- 

 called higlier level of the Gulf Stream reservoir. 



88. Midway the Atlantic, in the triangular space between the 

 ;rhe Sargasso Sea. AzoTos, Caiiarics, and the Cape de Verd Islands, is the 

 great Sargasso Sea. (Plate YI.) Covering an area equal in extent 

 to the Mississippi Yalley, it is so thickly matted over with Gulf 

 weed (fucus natans) that the speed of vessels passing through it 

 is often much retarded. When the companions of Columbus saw 

 it, they thought it marked the limits of navigation, and became 

 alarmed. To the eye, at a little distance, it seems substantial 

 enough to walk upon. Patches of the vreed are generally to be seen 

 floating along the outer edge of the Gulf Stream. The sea-weed 

 always " tails to " a steady or a constant wind, so that it serves the 

 mariner as a sort of marine anemometer, telling him whether the 

 wind as he finds it has been blowing for some time, or whether it 

 has but just shifted, and which way. Columbus first found this 

 weedy sea on his voyage of discovery ; there it has remained to this 

 day, moving up and down, and changing its position, like the calms 

 of Cancer, according to the seasons, the storms, and the winds. 

 Exact observations as to its limits and their range, extending back 

 for fifty years, assure us that its mean position has not been altered 

 since that time. That the water which comes through the Florida 

 Pass with the Gulf Stream flows in a circle, going to the north on 

 the western side, and returniDg to the south on the east side of the 



