OCEAN CURRENTS 155 



west ; the current, however, is north 79° east, The déviation 

 of current from wind (79° to 29°) is hère 50°, which is rather 

 more than would be expected from theoretical considérations. 

 Tlie south-west monsoon has, in thèse régions, an average 

 strength of 3-66 on the Beaufort scale — that is, a drift of about 

 12-3 sea-miles per day, whereas the Guinea Current averages 

 20'6 sea-miles. So that the wind drift only accounts for about 

 three-fifths of the velocity of the current. In winter the south- 

 west monsoon falls entirely, so that at this time the Guinea 

 Current cannot be due to the wind. The Guinea Current 

 is partly a compensation current, a counter equatorial current 

 flowing eastwards between the North and South Equatorial 

 Currents. 



A third cause of the Guinea Current is the différence in 

 density between its waters and those of the neighbourhood. 

 The Guinea Current has a smaller salinity than either of the 

 equatorial currents. The lines joining places of equal density 

 (isohypsal lines) run as a rule from west to east. As a rule the 

 current runs parallel to the isohypsal lines. The compensation 

 current and the différences in density account for two-fîfths of 

 the velocity of the Guinea Current, but of thèse the former has 

 undoubtedly the more important influence. 



Broadly speaking, the Guinea Current is a compensation 

 current between the two equatorial currents, although there are 

 not unimportant différences of density, and in summer the 

 south-west monsoon plays a part in its causation. 



2. The Florida Current (so-called Gulf Stream). — The 

 Florida Current, under its popular but misleading name of 

 Gulf Stream, is the best known, best defîned, and most 

 remarkable of ail oceanic currents. Incidentally it is the 

 current which most influences the climate of the British Isles 

 and the shores of North-Western Europe. First noticed by 

 Juan Ponce de Léon in 15 13 on his voyage through the Florida 

 Straits from Porto Rico, the Florida Current has been ex- 

 tensively investigated, more particularly by American 

 hydrographers, since the middle of the nineteenth century. 



