264 PROCEEDINGS OF SECTION A. 



Subsequent maps show that the " high " g-radually increased in 

 energy till the 1st of July ; then decreased slightly during the next 

 day or two, the centre of the anticyclone remaining stationary over 

 the southern part of South Australia. Yevj cold frosty nights 

 were experienced inland over South Australia and New South 

 Wales, the thermometer on grass at the Sydney Observatory on 

 the morning of the 4th reading 24° — the lowest reading there in 

 thirty-five years. 



MAP No. 7, JULY 14th, 1893, 

 Is another typical winter map showing an extended series of low 

 pressure waves passing in rapid succession easterly along the south 

 coast — one rounding the Leeuwin, another to the west of Tasmania, 

 while a third is over southern New Zealand, vvith its centre to the 

 south of the island. A moderate "high" covers Australia from 

 west to east. 



The trend of the low pressure isobars on the south coast is a very 

 general feature. Reaching up northwards into Victoria, they curve 

 abruptly southwards, rounding Tasmania to the south, and then 

 recurving northwards up the east coast. In many maps this is 

 much more marked. The same feature may be seen in maps 3 

 and 6. This abrupt northerly extension east of Tasmania frequently 

 gives rise to strong southerly winds on the New South Wales coast. 



The weather was cloudy to threatening and showery in West 

 Australia ; cloudy to gloomy and threatening, and in a few places 

 showery, with squalls on coast, in South Australia, Victoria, and 

 Tasmania; tine and clear in north-east New South Wales, un- 

 settled in west : cloudy to gloomy in south and east parts of 

 Queensland, clear in centre and north-west districts. 



This map was taken at random from several during a long spell 

 of cyclonic conditions, lasting from the 8th to the 24th. and clearly 

 shows the rapid succession of V-shaped depressions along the south 

 coastlines. With each depression unsettled weather and rain 

 passed along the south coast of the continent. The "low" shown 

 off the Leeuwin when it reached the Bight passed inland over 

 South Australia, causing the rains to be heavier and more general 

 than when the previous depression passed along the south coast 

 further to the south. 



Leaving the maps, and speaking generally, I would point out 

 that in both the Northern and Southern Hemispheres is a belt or 

 zone of high pressure, separating the tropical and polar zones of 

 low pressure at the latitude where the return trade and polar 

 winds descend towards the surface of the earth. 



The southern belt passes over the extra-tropical or temperate parts 

 of Austi-alia. It is made up of long loops, or antioyclonic areas, 

 being broken up at intervals by low pressure intrusions from the 

 tropics and northerly extensions of V-shaped depressions from the 

 south. When these join they form a barometric trough or valley, 

 effecting a complete rupture of the anticyclonic belt. The position 



