84 THE TRADE WINDS. 



"all our winds are derived." These matters are,, 

 however, very fully discussed in meteorological works, 

 and we shall therefore merely venture, in these pages, 

 to offer a few remarks upon some of the more specially 

 remarkable effects which the winds exercise upon 

 climate. 



There can be little question that the " Trade Winds * 

 stand first in this respect ; and that these winds which, 

 from the parallels of about 30 or 35 north and south 

 of the equator, are unceasingly sweeping round the 

 equatorial regions at a speed of some 10 or 12 miles 

 an hour, exercise a most powerful influence upon 

 climate, everywhere throughout the world, as the chief 

 rain-producing winds. Observations show that from 

 the belt of calms, or light airs, which prevail in the 

 neighbourhood of the equator we have two zones 

 of originally dry hot, and therefore evaporating winds, 

 whose average temperature is from 78 to 80 Fahr., 

 extending entirely round the earth viz., the Zone of 

 the N.E. trade, to the northward of the equator; 

 and that of the S.E. trade, to the southward of it; 

 and that, 



"with slight interruptions these winds blow perpetually, and 

 are as steady, and as constant, as the currents of the Mis- 

 sissippi River; always moving in the same direction, except 

 where they are turned aside by a desert, or a rainy region, 

 here and there, to blow as monsoons, or as land and sea 

 breezes." * 



Another fact worthy of note is that though those 

 winds are, as we have said, in all probability the chief 



* The Physical Geography of the Sea, by Lieut. Maury, U.S.N., 

 1877, I7th edit., p. 78. 



