260 PROCEEDINGS OF SECTION A. 



by a comi^lete cliscussion of the characteristics of the month in 

 regard to temperature, pressure, the 'passage of "highs" and 

 " lows," and the weather generally, in which comparisons are 

 made between the month under review and previous seasons, 

 attention being drawn to any abnormal features that may have 

 presented themselves. 



The annual volumes give in detail the observations at Adelaide, 

 the principal results at outstations, and majjs showing in graduated 

 tints the general distribution of rainfall during the year. 



An examination of tlie daily isobar maps extending over a period 

 of eleven years shows that, while we have an infinite variety of 

 details, there are several well-marked types which are frequently 

 recurring. 



No two maps of the same type, perhaps, may exactly agree or 

 resemble each other, but the type to which they belong is at once 

 recognised. We can thus classify our maps into their respective 

 types. 



1 have selected seven well-marked types to accompany this paper 

 (see Plate VI.). 



MAP No. 1— FEBRUARY 18th, 1890, 

 Shows the ordinary summer high pressure over the south coast, 

 having its maximum about latitude 45°, which is further south 

 than usual, covering Tasmania, with gradual falling gradients 

 northwards to the usual low pressure conditions of the tropics. 



The map indicates a cyclonic centre to the north-west of Aus- 

 tralia, where the barque Dorunda reports the barometer down to 

 29-47, in longitude 114° E. and latitude 15° S. 



This cyclone was moving westward when encountered by the 

 Dorunda^ and probably passed through the S.E. trade belt; then 

 recurving to the eastward, may possibly be identical with a south 

 coast depression which appeared off the Leeuwin on the morning 

 of the 24th, but if so it had greatly lost its energy. 



The weather corresponding to this map was — Fine, except on 

 and near the east coast from Caj^e Howe to the Gulf of Carpen- 

 taria, where the weather was everywhere cloudy and unsettled, 

 with rain, heavy rains falling on the coast. Over the whole of 

 Australia the winds were south-east, and strong from the east 

 through Bass's Straits. 



F'ollowing, we had general and heavy continuous rains for 

 several days in both Queensland and New South Wales, the isobar 

 charts showing a V-shaped depression gradually extending south- 

 ward into Queensland fror»i the Gulf of Carpentaria, whilst the 

 high pressure to the south became split up into two parts by a 

 northerly low pressure extension towards our south coast. In 

 Queensland and northern New South Wales many heavy floods 

 Avere reported, Townsville (Queensland) having over 19in. of rain 

 in three days. 



