INFLUENCE OF THE GULF STREAM UPON COMMERCE. 65 



traveled and as unknown as the great Amazonian wilderness of 

 Brazil, or the inland basins of Central Africa. To the south of a 

 line extending from Cape Horn to the Cape of Good Hope (Plate 

 VHL) is an immense waste of waters. None of the commercial 

 thoroughfares of the ocean lead through it ; only the adventurous 

 whaleman finds his way there now and then in pursuit of his 

 game ; but for all the purposes of science and navigation, it is a 

 vast unknown region. Now, were the prevailing winds of the 

 South Atlantic northerly or southerly, instead of easterly or west- 

 erly, this unplowed sea would be an oft-used thoroughfare. 



87. Nay, more, the sea supplies the winds with food for the 

 rain which these busy messengers convey away from the ocean 

 to "the springs in the valleys which run among the hills." To 

 the philosopher, the places which supply the vapors are as sug- 

 gestive and as interesting for the instruction they afford, as the 

 places are upon wdiich the vapors are showered down. There- 

 fore, as he who studies the physical geography of the land is ex- 

 pected to make himself acquainted with the regions of precipita- 

 tion, so he who looks into the physical geography of the sea should 

 search for the regions of evaporation, and for those springs in 

 the ocean which supply the reservoirs among the mountains with 

 water to feed the rivers ; and, in order to conduct this search 

 properly, he must consult the winds, and make himself acquainted 

 with their " circuits." Hence, in a work on the Physical Geog- 

 raphy of the Sea, we treat also of the Atmosphere. 



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