166 HENRY A. HUNT. 



should the burst occur while the northerly wind is in full force — 

 in other words, should it occur in the daytime, for northerly winds,, 

 and particularly those from the north-east, moderate considerably 

 by sunset. 



RELATION OF VELOCITY OF NORTH AND SOUTH WINDS. 



But while it may be said that, as an almost invariable rule,, 

 strong southerlies follow strong northerlies, the mean velocity of 

 the former is generally less than that of the latter, by about ten 

 per cent. 



WITH STRONG WINDS THE BAROMETER RISES SLOWLY. 



And it may be noted, as a peculiar circumstance in a gale with 

 such antecedents, that the barometer rises very slightly after the 

 first short and rapid rise, the accumulation of pressure in the 

 west, no matter how steep the gradient is, seems to be used up in 

 maintaining the gale on the Coast, and along the coast the 

 barometers rise little or nothing. There are remarkable records 

 of cases in which steady high barometric readings have been the 

 precursors of prolonged southerly gales upon the coast, even the 

 diurnal fluctuations being totally ignored. 



GRADIENTS. 



The subject of gradients is a difficult one to touch upon, because 

 our range of latitude is so great, and local geographical features 

 modify it so much, but as a general rule a change of pressure of 

 •4 on the central coast districts of New South Wales may be con- 

 sidered as denoting a steep gradient, while in Tasmania double 

 this range, or *8 would not indicate any more serious change. 



DESCRIPTIONS OF PARTICULAR BURSTERS. 



The past twelve months have, unfortunately, been a most 

 unsuitable season for the study of the subject with which this 

 essay is concerned, and it has been especially unsuitable for the 

 observation of cloud movements. The bursters during the past 

 year have not only been few in number, forty per cent, below the 

 average, but also unusually mild in character, and hence it has 

 been impossible to find a burster of strongly marked character 



