§ 828. THE WINDS OF THE SOUTHERN HEMISPHEUE. 443 



western slopes of Patagonia — a physical impossibility, because 

 the peculiar combination of conditions required to produce a Pata- 

 gonian rain-fall are wanting on the polar side of 45° N. There is 

 not in the North Atlantic water surface enough to afford vapor 

 for such an amount of precipitation. In the North Pacific the 

 water surface may be broad and ample enough to afford the va- 

 por, but in neither of these two northern sheets of water are the 

 winds continuous enough from the westward to bring in the 

 requisite quantities of vapor from the sea. Moreover, if the west- 

 erly winds of the extra-tropical north were as steady and as strong 

 as are those of the south, there is lacking in the north that con- 

 tinental relief — mountain ranges rising abruptly out of the sea, 

 or separated from it only by lowlands — that seems to be necessarj^ 

 to bring down the rain in such floods. Colonel Sykes^ quotes the 

 rain-fall of Cherraponjie at 605.25 inches for the 214 days from 

 April to October, the season of the southwest monsoons. Com- 

 puting' the Cape Horn rains according to the ratio given by King 

 and Fitzroy for their 41 days of observation, we should have a 

 rain-fr.ll in Patagonia of 825 inches in 214 days, or a yearly 

 amount of 1368.7 inches. Neither the Cape Horn rains, nor the 

 rains any where at sea on the polar side of 45° S., are periodical. 

 They are continuous; more copious, perhaps, at some seasons 

 than at others, but abundant at all. 



828. Now, considering the extent of water surface on the polar 

 Influence of hi-hiands ^Idc of thc southcast tradc-wind belt, we see no 

 upon precipitation. I'eason why, OH thcsc parallels, the engirdling air 

 of that great watery zone of the south should not, entirely around 

 the earth, be as heavily charged with vapor as was that which 

 dropped this flood upon the Patagonian hills. If those mount- 

 ains had not been there, the condensation and the consequent 

 precipitation would probably not have been as great, because the 

 conditions at sea are less apt to produce rain ; but the quantity of 

 vapor in the air would have been none the less, which vapor was 

 being borne in the channels of circulation toward the antarctic 

 regions for condensation and the liberation of its latent heat ; and 

 we make, as we shall proceed to show, no violent supposition if, 

 in attempting to explain this activity of circulation south of the 

 equator, we suppose a cloud region, a combination of conditions 



* Report of the British Association for 1852, ]}. 256. 



