SOUTHERLY BURSTERS. 45 



cases are on record in which at Sydney the barometer has fallen 

 0'5 in. in twenty-four hours, and in Tasmania as much as 0'8 in. 

 these differences expressing the ratio of the changes in the same 

 burster at the two places, due to latitude. 



DESCRIPTIONS OP 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 

 for study, of the comparatively small number however, the best 

 have been chosen. 



The first of these occurred on February 15,1894, it has been 

 selected mainly because the clouds admitted of better notes than 

 others, and because I am able, through the courtesy of Mr. Russell 

 to submit photographs of it from the Observatory records. At 

 9 a.m. on the 14th an anticyclone was over Perth in West 

 Australia, another of rather more decided character was over 

 the Tasman Sea, and between these there was a low pressure 

 wanting in intensity ; winds were light and without character, 

 and the weather generally hot and unpleasant, but fine, except 

 some passing showers on the coast of New South Wales. Fresh 

 northerly winds were blowing in Bass's Straits. Diagram No. 1 

 shows the instrumental conditions of this change from 7 p.m. of the 

 14th to 7 p.m. of the 16th. It will be observed that the barometer 

 began to fall steadily at 10 p.m. of the 14th, and reached the 

 lowest point at 2 p.m. of the 15th, two and a-half hours before 

 the burster arrived, at the time of lowest barometer the wind was 

 from east, and attained its greatest velocity for the day, seventeen 

 miles per hour, at 3 '30 p.m. Temperature was highest 79, 

 between 1 and 2 p.m. of the 15th, and the coming of the southerly 

 at a quarter to six p.m. made but little difference ; light rain 



