262 PROCEEDINGS OF SECTION A. 



south of New Zealand, with strong south-west gales. Two days 

 after this, the "high " shown on the map of the 12th to the west- 

 ward of Perth had moved eastward and covered the whole 

 continent, with its centre (30-45) off Kangaroo Island (S.A.). 



MAP No. 4, FEBRUARY 5th, 1890, AND MAP No 5, MAY 27th, 1893^ 

 Show low pressure valleys stretching across the continent con- 

 necting the tropical and south low pressure belts. These are 

 frequently productive of good general rains ; the winds on the east 

 side of the trovigh are northerly, and southerly on the west side — 

 strong if the valley is narrow and nipped up between two "highs" 

 with steep gradients on either side. 



With No. 4 map the weather was cloudy and unsettled in the 

 rear or west side of the low pressure trough, with showers all 

 along the coastline of Western Australia ; in advance of the low 

 pressure valley it was partially clouded in central and north 

 Australia, gloomy and sultry in South Australia with steady rain 

 falling over the nirthern areas, very hot (95" at Eucla) over the 

 head of the Great Australian Bight, fine and warm in Victoria and 

 Tasmania, cloudy in eastern Queensland and north-east parts of 

 New South Wales, and thundery in Central Queensland. 



The maps for the previous day or two show that ttie formation 

 of the valley of low barometers was preceded by a general taking 

 off of pressure over the interior of Western Australia on the 3rd. 



Next morning, the 4th, the valley was very well defined, the 

 weather chart for that date being almost identically the same as 

 that on the 5th. Splendid general rains set in over South Aus- 

 tralia during the afternoon and evening of the 4th, extending from 

 Strangways Springs to the Mount Lofty Ranges. Subsequent 

 maps sliow that as the isobars moved eastward the low pressure 

 valley or trough underwent considerable modification, though the 

 valley-like depression was clearly marked in each map. 



The heavy steady rains which fell in advance of the valley in 

 South Australia did not, however, extend to the eastern colonies, 

 and its effect on the weather in New South Wales and Victoria 

 was to produce sultry and oppressive conditions, Avhich culminated 

 later on in heavy thunderstorms and rains over a large part of 

 both colonies. 



The weather with No. 5 map was cloudy to gloomy in southern 

 West Australia, with heavy showers on south coast, fine and clear 

 in the north. All over South Australia (nearly across the con- 

 tinent), Victoria, Tasmania, and the western half of New South 

 Wales it was cloudy to gloomy, and threatening with rain falling 

 in the northern areas of South Australia, and in places in the other 

 colonies ; in Queensland fine but cloudy. 



This map shows a slightly different trough formation to No. 4. 

 In the latter the valley ran north and south across Australia. In 

 this the axis lies north-west and south-east. 



