122 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



nortli--west winds of the southern hemisphere, which correspond to 

 the south-west of the northern. Continuing on to the south-east, 

 they are now the surface winds ; they are going from warmer to 

 cooler latitudes; they become as the wet sponge (§ 292), and are 

 p.bruptly intercepted by the Andes of Patagonia, whose cold summit 

 compresses them, and with its low dew-point squeezes the water 

 out of them. Captain King fomid the astonishing fall of water 

 here of nearly thirteen feet (one hundred and fifty-one inches) in 

 forty-one days ; and Mr. DarT\'in reports that the surface water of 

 the sea along this part of the South American coast is sometimes 

 quite fresh, from the vast quantity of rain that falls. A similar 

 rain-fall occurs on the sides of Cherraponjie, a mountain in India. 

 Colonel Sykes reports a fall there dm^ing the south-west monsoons 

 of 605 J inches. This is at the rate of 86 feet during the year ; but 

 King's Patagonia rain-fall is at the rate of 114 feet dming the 

 same period. Cherraponjie is not so near the coast as the Pata- 

 gonia range, and the monsoons lose moistm'e before they reach it. 

 We ought to expect a corresponding rainy region to be fomxl to 

 the north of Oregon ; but there the mountains are not so high, 

 the obstruction to the south-west winds is not so abiTipt, the high- 

 lands are farther from the coast, and the air which these winds 

 carry in their circulation to that part of the coast, though it be as 

 heavily charged with moistui'e as at Patagonia, has a gi'eater ex- 

 tent of comitry over which to deposit its rain, and, consequently, 

 the fall to the square inch will not be as great. In like manner, 

 we should be enabled to say in what part of the world the most 

 equable climates are to be found. They are to be found in the 

 equatorial calms, where the north-east and south-east trades meet 

 fresh from the ocean, and keep the temperature uniform under a 

 canopy of perpetual clouds. 



300. Amount of Evaporation. — The mean annual fall of rain on 

 amohnt of evapo- the entire surface of the earth is estimated at about 



RATION greatest from n r. , rr\ j_ i. i n i- 



the Indian Ocean, iive icet. lo ovaporato Water enough annually irom 

 the ocean to cover the earth, on the average, five feet deep \vith 

 rain ; to transport it from one zone to another ; and to precipitate 

 it in the right places, at suitable times, and in the proportions due, 

 is one of the offices of the grand atmospherical machine. All this 

 evaporation, however, does not take place from the sea, for the water 

 that falls on the land is re-evaporated from the land again and 

 again. But in the first instance it is evaporated principally from 

 the torrid zone. Supposing it all to be evaporated thence, we shall 



