112 THE PHYSICAL GEOGRAPHY OF THE SEA. 
and continues on toward the coast of South America, in the same 
direction, appearing now as the prevaihng northwest wind of the 
extra-tropical regions of the southern hemisphere. Travehng on 
the surface from warmer to colder regions, it must, in this part of 
its circuit, precipitate more than it evaporates. 
202. Now it is a coincidence, at least, that this is the route by 
which, on account of the land in the northern hemisphere, the 
northeast trade-winds have the fairest sweep over that ocean. 
This is the route by which they are longest in contact with an 
evaporating surface ; the route by which all circumstances are 
most favorable to complete saturation ; and this is the route by 
which they can pass over into the southern hemisphere most 
heavily laden with vapors for the extra-tropical regions of that 
half of the globe ; and this is the supposed route which the north- 
east trade-winds of the Pacific take to reach the equator and to 
pass from it. 
203. Accordingly, if this process of reasoning be good, that 
portion of South America between the calms of Capricorn and 
Cape Horn, upon the mountain ranges of which this part of the 
atmosphere, whose circuit I am considering as a type, first im- 
pinges, ought to be a region of copious precipitation. 
Now let us turn to the works on Physical Geography, and see 
what we can find upon this subject. In Berghaus and Johnston 
— department Hyetography — it is stated, on the authority of 
Captain King, R. N., that upward of twelve feet (one hundred 
and fifty-three inches) of rain fell in forty-one days on that part 
of the coast of Patagonia which lies within the sweep of the winds 
just described. So much rain falls there, navigators say, that 
they sometimes find the water on the top of the sea fresh and 
sweet. 
After impinging upon the cold hill-tops of the Patagonian coast, 
and passing the snow-clad summits of the Andes, this same wind 
tumbles down upon the eastern slopes of the range as a dry wind ; 
as such, it traverses the almost rainless and barren regions of Cis- 
Andean Patagonia and South Buenos Ayres. 
204. These conditions, the direction of the prevailing winds, 
and the amount of precipitation, may be regarded as evidence af- 
forded by nature, if not in favor of, certainly not against, the con- 
jecture that such may have been the voyage of this vapor through 
