this source of loss does not seriously affect the underground 

 supply ; once the water has sunk into the porous soil it is safe. 

 This view of the effect of evaporation is borne out by the fact that 

 the Murray is subject to similar temperature and wind to cause 

 evaporation and they do not there dissipate all the water as some 

 have supposed they do in the Darling country. This is a very 

 strong argument against the view, so often expressed, that the 

 small quantity of water in the Darling is due to the influence of 

 evaporation upon the rainfall. 



On the other hand, in reference to my own statements, I freely 

 admit that they have been based upon measures that might be 

 accurate, if professional men could be employed 



made many years since by officers of the Harbours and Rivers 

 Department ; and the assumptions I have made are, that the 

 section of the river at Bourke has not materially changed since 

 then, and that in floods of the same height, the velocity now would 

 be the same as it was then. So far as the measurements of rain 



basin of the Darling to show with some degree of accuracy what 

 the rainfall is : and as to the section of the river at Bourke I am 

 told that as a matter of fact it has not materially changed since 

 the sections were surveyed, and the only recent measures of the 

 velocity of the current near Bourke confirm the velocities deter- 

 mined 20 years since, that is for the same height of flood water. 

 When I first began to compare the rainfall and the river discharge 

 of the Darling, I was so surprised that I thought there must be 

 some mistake in the velocity and section of the river, and I there- 

 fore used a margin for possible error, which more careful investi- 

 gation since has proved to be amply sufficient. I am quite sure 

 therefore that in all cases, I have rather over than under estimated 

 the quantity of water which is carried off by the Darling. 



For the past ten years upon the assumptions just referred to the 

 discharge of the Darling River has been taken' as a percentage of 

 the rainfall and the yearly amount has varied from 5-81 to 0-09 

 per cent., the mean for the ten years being 1-46 per cent.; a startling 

 result, and one which I believe to be without a parallel in any 

 country in the world. It has been my custom to assume that the 

 oasin of the Darling, for this purpose, was just that part of it 

 enclosed by the great branches which begin al>ove Bourke 

 and spread out towards the mountains like the branches of some 

 jnighty tree. I have done this because I admit that there is some 

 truth in the statement that no rain-water reaches the Darling 

 from the flat country, but as I have shewn, there are remarkable 



