intersected by numerous water courses, we are fully justified in 

 expecting that a considerable percentage of the rainfall would get 

 into the river, an assumption which is fully borne out by observa- 

 tion and the sudden local Hoods which occur there, and if our in- 

 vestigations had been first turned to the Murray catchment which 

 in outward appearance and rainfall is not unlike that of the 

 Darling, except that it has perhaps a larger proportion of flat land, 

 we should have expected to find something like 25 percent of the 

 rainfall passing Bourke, the fact that we only find 1^ per cent. 

 is, with the facts of the Murray basin before us, still more 

 inexplicable. 



In Europe from 20 to 50 per cent, of the rain flows away in the 

 rivers ; in England about 30 per cent., and here in a river— the 

 Murray, with similar basin and rainfall to the Darling, 25 per 

 cent, of the rain flows down the river. This remarkable condition 

 affecting the dischai;ge of the Darling River is one that calls for 

 investigation, because if it be true as I fully believe, and the 

 observations prove it, then we must have a supply of underground 

 water which is practically inexhaustible for pastoral purposes, 

 and in addition, sufficient to irrigate some of the land. The 

 mean rainfall on the Darling River catchment for the past ten 

 years has been 22-14 inches and of this, as we have seen only 1| 

 per cent, or = 0-33 inches of rain passes Bourke in the river. If 

 25 per cent, of it, which is equal to 5-53 inches of rain passed 

 away in this river as it does in the Murray there would be seventeen 

 times as much water passing Bourke as actually does pass ; but in 

 addition to the water passing down the Murray we know that a 

 certain amount of the Murray rainfall sinks into the ground to 

 supply wells there, and hence 26 per cent, of the Murray rain- 

 fall does not represent all that is available from it. So'much we 

 find in the river, and some more, an unknown amount, is to be 

 found in the soil. We should then De perfectly justified by the 

 analogy of the two river basins, in assuming that the estimate just 

 given of the amount of water which should pass Bourke is below 

 the mark, not above it, and we ought therefore to have an under- 

 ground water supply at least equal to sixteen times as much water as 

 passes Bourke now, and this, or at least a great part of it should 



is to my mind proof that it passes away to underground drainage. 

 For some time past I have been trying to get friends living in the 

 country to undertake percolation observations with a view of 

 measuring what rain actually does sink down into the ground, 

 but so far, I have not succeeded ; and quite recently it occurred 

 to me that Lake George could be made to give one answer to the 

 question which would be much more valuable than ordinary per- 



