146 HENRY A. HUNT. 



diverted from its easterly course to a south-east direction, and 

 instances are recorded where, so far as it is possible to trace its 

 movements it has disappeared travelling almost due south. 



ANOTHER CONDITION MODIFYING BURSTERS. 



There is yet another condition, or set of conditions, which not 

 only modifies the southerly burster but retards it to a considerable 

 extent. As a general rule when there is a \ depression lying 

 with its centre approximately south of Wentworth, it may be 

 confidently anticipated that the southerly will reach the sea-board 

 after a period varying from twelve to eighteen hours. 



EFFECT OF ELECTRICAL CONDITIONS. 



But should the front of the \ develope more than the normal 

 electrical activity, it will inevitably be delayed for another 

 day, and in the meantime the barometric conditions advance but 

 slightly. A southerly of this type is almost invariably only one 

 of a series. The local weather features which herald its advent 

 are the same as those which foretell the coming of the ordinary 

 burster, except that the temperature on the day of thunderstorm 

 is higher than that of the day on which the burster reaches us. 

 The isobaric curves accompanying this particular form of dis- 

 turbance are notably disorganised and irregular to the east of the 

 y\, while on the high pressure to the west they remain smooth 

 and even. 



TYPES OF LOW PRESSURE. 



Southerlies have been observed to result from three distinct 

 types of low pressure. The first of these is the familiar y\ depress- 

 ion, resulting in the true southerly burster. This is the one most 

 commonly experienced, and as a rule, the sharper the \ the more 

 sudden is the change. 



THE MONSOONAL DEPRESSION. 



The second variety is the tropical depression or tongue which 

 may be looked upon as an inverted \, which only occurs during 

 the monsoonal season, and even then only on rare occasions ; in 

 fact the tongue has never been observed to exist east of the moun- 



