144 HENKY A. HUNT. 



is furnished with complete data, both from South Australia and 

 Queensland, it is practically impossible to differentiate the con- 

 ditions. 



DIFFICULTY IN FORECASTING. 



Given these data however, it is possible to foretell accurately a 

 disturbance of the kind above described. So far back as the date 

 of the very first of the series of daily weather charts upon which 

 this essay is mainly founded, the conditions which I have 

 endeavoured to describe have produced the same results without 

 exception. I have thus traced the changes by which the conditions 

 promising a "burster" — i.e. an approaching anti-cyclone with its 

 low pressure a — are modified locally so that we have no southerly 

 burster but in its place a south-east gale. There are other, though 

 less important factors, tending to rob the southerly wind of its 

 velocity. 



RAINFALL IN THE WESTERN COLONIES. 



The first and most important of these is rainfall, only in this 

 instance the precipitation takes place further to the westward. 

 The anti-cyclone appears on the coast of West Australia accom- 

 panied by severe gales and rain, which have, in a great measure, 

 wasted themselves before the disturbance reaches Bass Straits, 

 and on the coast of New South Wales only the last dying breath 

 of the atmospheric upheaval is felt. The barometric evolutions 

 may be related as follows : — In the first place the high pressures 

 both to east and west of the a depression, are in unseasonable 

 latitudes, the summer tracks lying between 36° and 37° south, and 

 never travelling much below that. At first the adjacent isobars 

 of both high pressures are very full and round ; the col between 

 is narrow, subsequently the conditions become intensified, the 

 isobars straighten, and the A becomes acute. 



EFFECT OF COASTAL FORMATION. 



As they advance, the anti-cyclones gradually become separated 

 by a wider space and isobars of the depression open out and 

 become round instead of pointed, grow more obtuse in fact, and 

 were it not for the mountains of the east coast intensifying these 



