98 HUGH CHARLES KIDDLE. 
of air should (but do not always), revolve right handedly, while 
those that are produced by opposing winds may revolve indiffer- 
ently in either direction. 
The third section, viz., the atmospheric conditions at the time 
these whirls appear, must be subdivided into (a) prevailing winds, 
(6) height of barometer. (a) These whirls nearly always occur 
when the wind is between the north and south-west points of the 
compass, and are very seldom seen when the wind is blowing from 
the north-east or south-east quadrants. Generally speaking it 
may be said that they occur with the westerly winds ; which, it 
must be remembered, is also the prevailing direction of our summer | 
winds. (6) During the early part of March I noticed no whirls 
at all. At the same time the barometer was exceptionally high 
in this district. The highest local reading noted was on March 
11, 1893, when the 
Aneroid barometer stood at Burrumbuttock 29°54, altitude 700ft. 
Standard barometer stood at Albury 295615 5.) Eadie 
Wagga Wagga 29°56, y),. OOnee: 
This high pressure period was coincident with the cyclonic 
99 99 
disturbance which, after passing the New Hebrides, visited our 
Australian coasts with south-east gales. Possibly our high pressure 
was directly caused by the air being heaped up by the cyclone on 
its outer edge while progressing, but whether or not, my object in 
alluding to this circumstance is to point out that a high barometer 
is not a favourable condition for the formation of these whirls. The 
average local reading from my tabulated list, on page 94, is 
29°30 in. for this district. Our westerly winds are accompanied 
with low barometrical readings as a rule, and as I have already 
said that these dust whirls are usually seen when the prevailing 
wind is westerly, we may look in that direction for their origin, 
and with very good reason suggest the intimate relationship of 
cause and effect, 
The fourth characteristic, viz., the effect produced on these whirls 
by coming in contact with external objects, requires more than 
passing notice. Obstructions in the track of these whirls . will 
