THE ATMOSPHERE. 91 



wet sponge (§ 125), and are abruptly 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 found 

 the astonishing fall of water here of nearly thirteen feet (one 

 hundred and fifty-one inches) in forty-one days ; and Mr. Darwin 

 reports that the sea water along this part of the South American 

 coast is sometimes quite fresh, from the vast quantity of rain that 

 falls. 



142. We ought to expect a corresponding rainy region to be 

 found to the north of Oregon ; but there the mountains are not so 

 high, the obstruction to the southwest winds is not so abrupt, the 

 highlands 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 moisture as at Patagonia, has a 

 greater extent of country over which to deposit its rain, and con- 

 sequently the fall to the square inch will not be as great.* 



143. 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 northeast and 

 southeast trades meet fresh from the ocean, and keep the temper- 

 ature uniform under a canopy of perpetual clouds. 



144. Amount of Evaporation. — The mean annual fall of rain 

 on the entire surface of the earth is estimated at about five feet. 



145. To evaporate water enough annually from the ocean to 

 cover the earth, on the average, five feet deep with rain ; to trans- 

 port 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. This water is evap- 

 orated principally from the torrid zone. Supposing it all to come 

 thence, we shall have, encircling the earth, a belt of ocean three 

 thousand miles in breadth, from which this atmosphere evaporates 

 a layer of water annually sixteen feet in depth. And to hoist up 

 as high as the clouds, and lower down again all the water in a 

 lake sixteen feet deep, and three thousand miles broad, and 



* I have since, through the kindness of A. Holbrook, Esq., United States Attorney 

 for Oregon, received the Oregon Spectator of February 13, 1851, containing the Rev. 

 G. H. Atkinson's Meteorological Journal, kept in Oregon City during the month of 

 January, 1851. The quantity of rain and snow for that month is 13.63 inches, or 

 about one third the average quantity that falls at Washington during the year. 



