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 
Vni.) 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 which 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 windsj 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. 
E 
