xx President's Address 



atmosphere lying over and about Australia, from which, 

 with the assistance of the laws referred to, we can make 

 deductions as to probable coming weather. Examining 

 such a chart in summer time, we shall probably find that 

 over Central Australia the barometer reads low, about 29*8 ; 

 that it reads higher as the east, south, or west coast is 

 approached, indicating a basin or depression in the atmo- 

 sphere over the land. We find from the plotting of the 

 wind directions that it has a tendency throughout to blow 

 from the sea towards the area of low pressure, for, as a rule, 

 winds always blow from a district of low towards a district 

 of high pressure ; therefore, in the north the winds range 

 from N.W. to N.E., and in the south from S.W. to S.E. 

 This is the normal state of affairs in summer, and all around 

 our coast sea breezes prevail. But now if one of the 

 constantly recurring whirls or cyclonic movements of the 

 atmosphere, forming perhaps at the Cape of Good Hope, or 

 on the ocean between here and there, should approach our 

 western or south-western coast, a change of affairs very 

 soon becomes apparent. In Western Australia, or perhaps 

 first at Cape Borda or Cape Northumberland, the barometer 

 begins to fall, the wind coming from N.E., then increasing 

 from north ; then the barometers at Portland, Cape Otway, 

 George Town, Melbourne, Wilson's Promontory, fall in 

 succession with a northerly wind, which increases in force 

 as the pressure gets less ; this wind, blowing from an area 

 of higher to an area, of lower pressure, although still from 

 around the summer low pressure area of Central Australia, 

 comes down to us heated by the tropical sun, and by 

 travelling over regions of heated earth's surface, producing 

 the hot wind of South Australia and Victoria. These hot 

 winds are always in front of cyclonic movements, and are 

 fully explained by them. As the cyclonic area approaches, 

 moving eastwards, the barometer still continues to fall, 

 while the temperature increases. The question now arises, 

 Where is the centre of this area, and where will it pass ? 



