§ 407, 408. CURRENTS OF THE SEA. 201 



in all parts, holds in solution the same kind of solid matter ; that 

 its waters in this place, where it never rains, are not Salter than 

 the strongest brine ; and that in another place, where the rain is 

 incessant, they are not entirely without salt, may be taken as evi- 

 dence in proof of a system of currents or of circulation in the sea, 

 by which its waters are shaken up and kept mixed together as 

 though they were in a phial. 



407. Currents of the Atlantic. — The principal currents of 

 Currents of the At- ^hc Atlantic havc been described in the chapter on 

 ^^°'^^' the Gulf Stream. Besides this, its eddies and its 

 offsets, are the equatorial current (Plate YI.), and the St. Roque or 

 Brazil Current. Their fountain-head is the same: it is in the 

 warm waters about the equator, between Africa and America. 

 The former, receiving the Amazon and the Orinoco as tributaries 

 by the way, flows into the Caribbean Sea, and becomes, with the 

 waters (§ 103) in which the vapors of the trade-winds leave their 

 salts, the feeder of the Gulf Stream. The Brazil Current, coming 

 from the same fountain, is supposed to be divided by Cape St. 

 Roque, one branch going to the south under this name (Plate IX.), 

 the other to the westward. This last has been a great bugbear to 

 navigators, principally on account of the difficulties which a few 

 dull vessels falling to leeward of St. Roque have found in beating 

 up against it. It was said to have caused the loss of some En- 

 glish transports in the last century, which fell to leeward of the 

 Cape on a voyage to the other hemisphere ; and navigators, ac- 

 cordingly, were advised to shun it as a danger. 



408. This current has been an object of special investigation 

 The St. Roque current, during my Tcscarches connected with the Wind 

 and Current Charts, and the result has satisfied me that it is nei- 

 ther a dangerous nor a constant current, notwithstanding older 

 writers. Horsburgh, in his East India Directory, cautions navi- 

 gators against it ; and Keith Johnston, in his grand Physical At- 

 las, published in 1848, thus speaks of it: "This current greatly 

 impedes the progress of those vessels which cross the equator 

 west of 23° west longitude, impelling them beyond Cape St. 

 Roque, when they are drawn toward the northern coast of Bra- 

 zil, and can not regain their course till after weeks or months of 

 delay and exertion." So far from this being the case, my re- 

 searches abundantly prove that vessels which cross the equator 



