142 A FRENCH COLUMN IN A DUST STORM. 



a dark, dense cloud arose in the West, and moved towards 

 us with incredible rapidity. Great masses of heavy sand 

 were lifted like so many feathers, and the plains formerly 

 occupied by large hillocks, containing thousand of tons of 

 sand, were swept even as if by magic. None of us could 

 stand against the force and weight of the storm." * 



Even assuming that the quantity of sand thus removed 

 is overestimated, this shows with what fierceness these 

 storms rage when a really bad one occurs. Another 

 instance we may quote is the case of a French column 

 in Algeria, commanded by the Dukes DAumale and 

 Montpensier, which on the -jih of March, 1844, was 

 overtaken in the Algerine Sahara, by the Simoom; in 

 this case the storm " prolonged its furious assaults 

 during 14 hours." Yet on the following day Monsieur 

 Fournel, a mining engineer, who accompanied the force, 

 found that the storm had merely affected a narrow 

 zone parallel to the Aures range, and that at the 

 mountain base the tranquillity of the atmosphere had 

 been undisturbed.! 



This shows how partial such tornadoes often are in 

 their area. At times they assume the ascending form, 

 which we have described as creating vast pillars of 

 eddying sand, or dust, in the desert, which often 

 mount up to an enormous height; thus showing that 

 the direction of the propelling force is upwards; and 

 in their ascending rush through surrounding strata of 

 still air they assume a gyrating motion, exactly as 

 the water in a large bath, let off by withdrawing 

 the plug, forms a vortex. In this case, as we know, 



* Life among the Apaches, by John C. Cremony (Interpreter to the 

 U.S. Boundary Commission), 1868, pp. 125 6. 



j The Desert World, by Arthur Mangin, translated from the French, 

 1869, p. 138. 



