200 LIGHT SCIENCE FOR LEISURE HOURS. 



namely, which extends between the most westerly part 

 of Africa and the West Indies there is a wide expanse 

 of waters unmoved by the flux or reflux of currents. 

 Surrounded on every side by the circulating waters of 

 the Central Atlantic current-system, this region re- 

 mains undisturbed save by winds and the tidal wave. 

 Accordingly its surface is covered with different forms 

 of marine vegetation. My readers will doubtless 

 remember the interest which the Great Sargasso Sea 

 excited in the mind of Christopher Columbus. Oviedo 

 termed this region the ' seaweed meadow.' ' A host of 

 small marine animals,' says Hurnboldt, ' inhabit this 

 ever-verdant mass of Fucus natans, one of the most 

 widely-diffused of the social plants of the ocean, con- 

 stantly drifted hither and thither by the tepid winds 

 that blow across its surface.' 



In the South Atlantic there is a smaller and some- 

 what more sharply-defined Sargasso, covered chiefly 

 with rockweed and drift. A weedy space occurs also 

 about the Falkland Islands, but is probably not a true 

 Sargasso. Maury considers that the seaweed reported 

 there probably comes from the Straits of Magellan, 

 where it grows so thickly that steamers find great 

 difficulty in making their way through it; for it so 

 cumbers their paddles as to make frequent stoppages 

 necessary. 



Such is the distribution of the surface of the Atlantic 

 Ocean. But now the question will at once suggest 

 itself: Is the complete system of oceanic circulation 

 exhibited on the surface ? It seems now quite certain 



