162 HENRY A. HUNT. 



then taking advantage of the easier western slope in the northern 

 districts, and the lower altitude of the mountains generally, to 

 the west of Port Macquarie, protrudes some of the isobars over 

 the mountains, so that they come to the eastward at that point 

 like a nose or easterly extension of the isobars, while the southern 

 half of the anti-cyclone is retarded. This feature was noticeable 

 upon the occasion in question, and, as is invariably the case under 

 such circumstances, thunderstorms were prevalent. These, I think, 

 may be safely accepted as the causes which gave rise to the 

 phenomenon of two simultaneous, yet entirely independent, 

 bursters. 



In speaking of the areas over which the burster exercises its 

 coastal influence, mention has been made of the fact that it is rarely 

 met with north of Port Macquarie. The present case was not, 

 in reality, any exception to the general rule ; the burster did not 

 reach Clarence Heads as such, and the change there was simply a 

 veering of the wind from north-east through west to south-east, 

 accompanied by a thunderstorm and hail. The downfall of hail 

 was heavy and some of the stones were very large. This storm 

 lasted on the north coast until 7 p.m., and was also very severe 

 in the northern highlands. It was accompanied by a rainfall of 

 from one to three inches. 



DESCRIPTION OP THE DOUBLE BURSTER. 



The notes taken of this burster — the second of the season — are 

 as follows : — During the 7th, 8th and 9th October the barometers 

 all over the continent showed little or no grade. The centres of 

 the high pressures were situated, one over the Tasman Sea, and 

 the other off the west coast of West Australia, with a shallow 

 trough of low pressure between. On the 10th the western high 

 pressure had intensified and had made much progress, compressing 

 the low pressure into a sharp \, with its axis lying in a north- 

 west and south-east direction, or from Bourke to a little east of 

 Gabo. Strong north to north-west winds were experienced on 

 the western borders of Queensland and in New South Wales 

 north-east, while exceptionally hot weather was reported from the 



