42 AUSTRALIAN WKATHER. 



Passing from this record of the double burster, it is now neces- 

 sary to consider various facts relating to the time taken by 

 bursters in travelling along the coast. 



RATE OP TRANSLATION OP BURSTERS. 



From the preceding remarks and the figures quoted in the table 

 page 39, as well as other figures appended to page 43, it will appear 

 that no definite relation can be traced between the rate of trans- 

 lation and velocity of the wind in bursters. As already demon- 

 strated, it is quite possible for two bursts to occur on different 

 parts of the coast at the same time, and it is also possible for a 



BURST SIMULTANEOUS OVER A WIDE AREA. 



burst to be felt at the same moment over an extensive area. (See 

 table 28th November, page 43. Since there is no visible con- 

 nection between the velocity of the wind and the ratio of transla- 

 tion of the burst itself, it may throw light on the matter if we 

 look for some explanation of the fact that the southerly change is 

 generally first experienced on the south coast of the Colony. 



BURSTERS FELT FIRST SOUTH OF SYDNEY. 



The most probable explanation is as follows : The high pressure 

 following the \ depression in many cases moves faster over 

 Victoria than it does over this Colony, and thus forces the lower 

 part of the ,\ to the east making the axis of it more or less 

 towards south-east and north-west. Were it not for this swinging 

 of the A depression, the wind, from its natural inclination to the 

 centre of a low pressure, would be south-west instead of due south. 



CONDITIONS GOVERNING THE RATE OF TRANSLATION. 



The southerly isobars of the A depression usually reach the 

 south coast first, hence it follows that the burster touches the 

 coastal stations in rotation, beginning at the south. The rate at 

 which it travels in its northerly course is decided, first by the 

 inclination of the axis of the A to the trend of the coast, and 

 secondly, by the then prevailing rate of the general atmospheric 

 motion to the eastward. 



