1320 J. T. Jutson: 



that of the normal cyclones, that is, clockwise. Further observa- 

 tions, however, are required, as the records in this paper are too 

 few to come to a definite conclusion on the point raised,. 



A Gigantic Dust Whirl. 



Ihe whirl now to be described has been noted in tlie above list, 

 but its occurrence was so striking that a separate description 

 is warranted. 



This dust whirl was observe<l on 19th February, 1917, at about 

 1.30 p.m., in tlie Comet Vale-Coongariie district, when the sun 

 had not passed a great distance beyond the zenith. The day waa 

 hot and sultry, with a gentle north to north-west Avind. The 

 conditions were, therefore, favourable for dust whirls. This \is.y- 

 ticular wliirl formed a great column of dust, the top of which 

 was above two clouds, which were at different levels in the atmo- 

 sphere, the difference of level apparently Ijeing cnnsiderable. 

 These clouds were of the cumulus type, and were such as may be 

 conunonly observed in the area after midday under the conditions 

 mentioned. The dust column was broken by these two clouds. The 

 column was travelling southward, or south-westwards, at a 

 fairly rapid rate, but the rate of motion could not be deter- 

 mined, and in doing so, passed beyond the clouds, and showed 

 itself as one unbroken, gigantic column, with a pronounced liend 

 forward (i.e., in the direction of its linear movement) at the top. 

 Otherwise it appeared to be approximately vertical. The dust 

 whirl was close to the path of the sun's rays, and as the sun was 

 •obscurcil by the upper cloud, tlie phenonema could l)e closely 

 Avatched. The dust was dull, red in coloui-, and between the 

 two clouds dense masses of dust coiild be seen by the naked eye 

 whirling about and springing upwards. As it moved in the 

 direction mentioned, the columu became invisible within a few 

 minutes. The direction of rotation could not be ascertained, nor 

 could any idea be formed of its diameter, although the diameter 

 appeared to l>e about the same through the wholjo length of the 

 <'olumn. 



The angle of elevation of the top of the column was guessed to 

 be about 80°, but the horizontal distance of the column from the 

 point of obsiervation could not be ascertained, so that it is impos- 

 sible to state its height, even very approximately. Judging by ob- 

 servation, it would certainly not be less than one mile distant, and 

 probably much more; but if it hi assumed th;;t tlie dist^uKe was 



