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 w^hich 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 upw^ard 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 



