AVHIRLWINDS OF DUST. 



299 



myriads of locusts in their tourbillons, and carry them either to 

 other parts of the continent, where these insects instantly devour all 

 the crops, or towards the ocean, where they are swallowed up. Some- 



Figs. 122, 123.— Whirlwinds of Dust. 



times the navigators encounter, at considerable distances from the 

 coast of Africa, real clouds of them, that the tempests have raised 

 from the ground and then consigned to the north-east trade-winds.* 

 In the deserts of the Sahara, Arabia, Khorassan, India, and South 



* Lartiguo, Systeine dcs Vents, pp. 70, 71. 



