130 E. F. PITTMAN. 



Taking the mean of the figures in the last columns of the 

 two tables, it will be found that the percentage ratio of the 

 run-off to rainfall of the Murray, at Morgan, is about three 

 times as great as that of the Darling at Wilcannia. But 

 this comparison is unsatisfactory, because, Morgan being 

 below the junction of the Darling with the Murray, the 

 result obtained there will include the run-off of the Darling; 

 and again, Wilcannia being about 230 miles above the 

 junction, the percentage of run-off there is higher than it 

 would be at Wentworth, because the Darling receives no 

 tributaries between the two towns, aud this stretch of the 

 river is subject to great loss from evaporation. I there- 

 fore asked Mr. McKay whether he could give a more exact 

 comparison between the two rivers. In reply he says 1 : — 



"In accordance with your request, I have continued the 

 investigations of rainfall and run-off of the Murray River and its 

 tributaries, and am now able to make a comparison of the Murray 

 and Darling catchments at the junction of the two rivers. It has 

 been asserted that the percentage of run-off of the Darling is 

 about equal to that of the Murray, but such a statement must 

 have been made without a knowledge of the various watersheds. 



"Dealing with the period 1895-1903 inclusive, of the Darling 

 catchment at Wentworth, and the Murray catchment at Went- 

 worth, the following results are obtained : — 



1895 Murray percentage of run-off is 19 times greater than DarJing 



1896 „ „ „ 7 „ 



1897 „ „ „ 9 „ 



1898 ,, ,, tt y , t )t j, 



1899 „ ,, ,. 21 „ 

 190Q „ „ „ 11 „ 



1901 „ „ „ 17 „ 



1902 „ „ „ 180 „ 



1903 „ „ „ 4 „ 



• ' Taking each catchment as a whole, it will be seen for the nine 

 years in question, that every square mile of Murray watershed 



1 Personal communication dated 29th August, 1907. 



