[Proc. Rot. Soc. Victoria 34 (N.S.), Pt. II., 1922]. 



Art. XII. — Local Rain Producing Influences under' Human 

 Control in South Australia. 



By E. T. QUAYLE, B.A. 



(With Map.) 

 [Kead 8th September, 1921]. 



In a previous paper the author has brought several Unes of 

 proof to show that various influences in Victoria were having a 

 marked effect upon the rainfall. The chief of these were the 

 substitution in the Mallee of crops and grass for the drought- 

 resistant forest covering, and irrigation, both natural and 

 artificial. One of the proofs relied upon was a map showing 

 for all stations available the departures of the mean rainfall for 

 the decade 1910-1919 from that of a standard 30-year period.. 

 1 885- 1 91 4. This appeared to show remarkably well the effects 

 looked for, that is, all areas in lee of, or S.E. from one with 

 increased cultivation or irrigation, showed a marked increase in 

 the rainfall, up to 15 per cent, in the most favoured cases. But 

 there were increases just beyond the Victorian border in South 

 Australia for which no explanation was available. In order 

 to see if any light might be thrown upon this, I undertook the 

 task of analysing the South Australian rainfalls in the same way 

 as I had already done those of Victoria and the southern and 

 western parts of New South Wales. This revealed an area of 

 marked rainfall improvement, lying south-east from Lake 

 Torrens, ' and embracing more especially the eastern portions 

 of the Upper North, where it ranged as high as 20 per cent. 

 This area seems to be continuous with the Victorian areas of 

 improvement, in which case we have a long strip lying north- 

 west and south-east, stretching from the sources of the Murray 

 to Lake Torrens, or at least to the highlands of the Upper 

 North, giving a total length of over 600 miles. It was found too^ 

 that as in New South Wales', north from this area the rainfall 

 had markedly decreased, deficiencies of 14 per cent, being 

 common, and that to south-west, as in Victoria, the areas 



