Dust Whirls. 315 



isand, feet; and Free^ mentiions that they are from a few feet to 

 hundreds of feet in height. I. C. Russell remarks^ that these 



■cohnnns of dust are often 2000 or 3000 feet, or even more, high. At 

 various lieights, according to atmospheric conditions, the dust 

 tends to spread out horizontally, and so becomes invisible. 



Dust columns are slender. Free remarks that they are a few- 

 inches to several feet in diamet^er.^ Various observers have 

 pointed out that when seen at a distance, they resemble water- 



.spouts, and that they mostly occur in calm summer weather. 



Previous Australian Literature. 



Of Australian occurrences, the writer lias found few" records. 



D. W. Carnegieio briefly refel-s to the occurrence of "willy- 

 willies " in arid Western Australia, and states they are sometimes 

 of great violence. J. W. Gregory, with regard to Central Aus- 

 tralia, refers to the " dark w^hirling pillars of sand Avhick slowly 

 travelled up the valley"; also to "three tall columns of dust 

 Avhich were travelling straight towards us"; and again, to "the 

 •dust travelling chiefly in two whirlwinds. "^i D. Mawson has 

 .descril>edi2 the " willy-willy " of the Broken Hill district, 

 pointing out that they are of the nature of small cyclones, like 

 water-spouts in outline, and that they are columns usually alx)ut 

 20 feet in diameter, rising to a height of several thousand feet. 

 A. ^Montgomery has remarked^^ in connection with the Western 

 Australian goldfields country, that "on any fine day in summer 

 it is quite usual to be able to see several whirlwind clouds of dust 

 'dancing over the landscape at one time." 



These are the only Australian rec-ords that the writer is aware 

 •of. 



In sub-arid Western Australia duMt whirls are locally known as 

 "willy-willies." They are a matter of comnxon knoAvledge, but no 

 precise description has, so far as the writer is aware, ever been 

 given of them, and still less is there any record of their mode 

 ■of rotation, their height and other characters. Even in Australia 



T. l^oc. cit. 



8. Monograph XI., U.S. Geol. Surv., Washington. 1885, pp. 9 and 154. 



9. See also Mawson's estimate mentioned below. 



10. " Spinifex and Sand," London, 1898, pp. 254 and 274. 



11. "The Dead Heart of Australia," London. 1906, pp. 26. 120, 121. 



12. "Geological Investigations in the Broken Hill Area," Mem. Roy. Soc. 

 ; South Aust., Vol. II., Part 4. 1912, p. 227. 



13. "The Significance of Some Physiographical Characteristics of Western 

 _j\.ustralia." Journ. Roy Soc. W. Aust., Vol. II., 1915-16, p. 83. 



