150 HENRY A. HUNT. 



moment, either in weather or temperature can be anticipated until 

 the barometer shows renewed activity. 



CHANGES OF TEMPERATURE. 



Generally the greatest diurnal range of the temperature re- 

 sulting from bursters occurs in October. The mean minimum 

 temperature for this month is 55*1° so that when the maximum 

 reaches from 85° to 90° and a southerly takes place, the tem- 

 perature in some cases drops as much as 30° to 35° This range 

 is seldom reached in the hotter months, in fact it is only attained 

 when a maximum of about 100° is recorded — an event of very 

 rare occurrence. 



A BURSTER OP THE POPULAR TYPE. 



An anti-cyclone of good energy, and one from which a popular 

 type of southerly burster lasting three days results, has a latitu- 

 dinal axis of approximately two thousand four hundred miles and 

 as it travels at the rate of four hundred miles per diem,* it follows 

 that, if a vertical line is drawn in front of it, an observer stationed 

 in this line will record three days of southerly weather in the front 

 half of it and three days of northerly winds in the rear, due to the 

 normal circulation about an anti-cyclone. This is the actual 

 experience : provided no meteorological agencies affect or modify 

 its symmetrically oval form during its passage over the Australian 

 continent, steady breezes throughout its circulating areas are the 

 rule during the six days it occupies in passing over the compara- 

 tively low lands of Australia, as it travels from west to east. 



ISOBARS FLATTENED BY MOUNTAINS. 



But when the anti-cyclone reaches the mountains of New South 

 Wales, the symmetry is disturbed by a flattening of the front 

 isobars against the mountains, which concurrently show a tendency 

 to spread northwards, aided probably, by the inclination of the 

 mountain chain towards the north east. 



INTENSIFICATION OF THE LOW PRESSURE BY MOUNTAINS. 



While this change is taking place in the high pressure, the 

 isobars of the \ depression in front of it are undergoing a similar 



* " Moving Anticyclones/' in Journ. Meteorol. Society, 1892. 



