THE CENTURY'S PROGRESS IN METEOROLOGY 



Dove classified the winds as permanent, periodical, 

 and variable. His great discovery was that all winds, 

 of whatever character, and not merely the permanent 

 winds, come under the influence of the earth's rotation 

 in such a way as to be deflected from their course, and 

 hence to take on a gyratory motion that, in short, all 



A. WHIRLWIND IN A DUSTY ROAD 



local winds are minor eddies in the great polar-equatori- 

 al whirl, and tend to reproduce in miniature the char- 

 acter of that vast maelstrom. For the first time, then, 

 temporary or variable winds were seen to lie within the 

 province of law. 



A generation later, Professor William Ferrel, the 



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