198 LIGHT SCIENCE FOR LEISURE HOURS. 



tion, however, of its volume passing probably outside 

 the West Indian Islands, to rejoin the other outside the 

 promontory of Florida. At this point the stream h^s 

 become, probably, somewhat diminished in volume, 

 but being still more diminished in breadth, it flows as 

 a deep, strong, and swift stream, known among sailors 

 as The Narrows of Bernini. From hence the stream, 

 now become the true Gulf Stream, grows gradually 

 wider, less deep, and less swift. Off Hatteras it is 

 already twice as broad as in the Florida Straits, and 

 as it stretches with a wide easterly sweep across the 

 Atlantic towards the shores of Ireland and the Hebrides, 

 the current not only reassumes something of its ori 

 ginal extent of surface, but again bifurcates ; a wide 

 but somewhat sluggish stream is sent southward 

 towards the shores of north-western Africa, to rejoin 

 the equatorial stream. The main portion of the 

 current, however, passes with a north-easterly course 

 up the Atlantic valley, between Iceland and Sweden 

 to the Polar seas. It seems uncertain whether Rennell s 

 current, which passes around the Bay of Biscay, and 

 the current which streams southward past the shores of 

 Spain, are forks of the Gulf Stream. They are usually 

 represented in maps as independent currents, and in 

 Captain Maury s large map of the Gulf Stream the 

 great southern bifurcation already mentioned is repre 

 sented as a current impinging upon the flank of the 

 stream which flows past Sp#in and north-western 

 Africa. Yet, if these streams have not their source in 

 the Gulf Stream, it will be found no easy problem to 



