162 THE WEATHER, AND WEATHER PK.OPHET5, 



the regions of the earth habitually swept by the trade- 

 winds abound in sandy deserts and arid wastes. When, 

 however, in the progress of that circulation, it descends 

 again to the earth, and becomes a surface-wind (assum- 

 ing the character of an "anti-trade"), it finds itself in 

 precisely reversed circumstances. It is now travelling 

 from a warmer to a colder region. Saturated with 

 moisture in the warmer, and parting with the heat 

 which alone enabled it to retain it, its vapour condenses. 

 Clouds already formed thicken, and descend in rain, 

 and fresh ones are continually forming, to fall in snow 

 at a further stage of its progress ; till all -the superfluous 

 moisture is thus successively drained off, and it is pre- 

 pared to re-assume, while starting on a fresh circuit, the 

 character of a drying wind. 



(25.) We have here the origin of that generally ob- 

 served difference of character between our two most 

 prevalent winds the S.W. and the N.E. The former is 

 our " anti-trade," that which from our geographical posi- 

 tion we are chiefly entitled to expect, and which, in 

 point of fact, is of far the most frequent occurrence. 

 Its prevailing characters are warmth, moisture, cloud 

 and rain, as well as persistence and strength. In the 

 former of these characters it is strongly reinforced by the 

 circumstance of its accompanying across the Atlantic the 

 4ream, which, in fact, it helps to drift upon oui 

 western coasts, and which, retaining a considerable 

 amount of the equatorial heat, sends up along its whole 

 course a copious supply of vapour, in addition to that 

 with which the air above it is already loaded : and this 



