26 THE PHYSICAL GP:OGRAPHY OF THE SEA. 



Their drift. Africa, one was found on tlie 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 returned 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 VI.) Another bottle, said to be thrown over off 

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

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

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

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

 called higher level of the Gulf Stream reservoir. 



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

 The Sargasso Sea. Azorcs, Cauarics, and the Cape de Yerd 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 

 weeds {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 weed are always to be seen 

 floating along the outer edge of the Gulf Stream. Now, if bits of 

 cork or chaff, or any floating substance, be put into a basin, and a 

 circular motion be given to the water, all the light substances will 

 be found crowding together near the centre of the pool, where 

 there is the least motion. Just such a basin is the Atlantic Ocean 

 to the Gulf Stream, and the Sargasso Sea is the centre of the 

 whirl. Columbus first found this weedy sea in his voyage of dis- 

 covery ; 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. 

 This indication of a circular motion by the Gulf Stream is corrob- 

 orated by the bottle chart, by Plate YI., and other sources of in- 

 formation. If, therefore, this be so, why give the endless current 

 a higher level in one part of its course than another? 



