125 



The northern watershed of Victoria, during the year, from only a 

 portion of its area (about two-thirds), yields between two to two and 

 a half millions of cubic yards of water, of which one million is available 

 for conservation and use if suitable works are undertaken for that pur- 

 pose ; but at present the large proportion of these waters are wasted in 

 flooding adjacent lands in temporary floodings of the River Murray, and 

 a large proportion is unaccounted for. 



In addition to the watershed of Victoria above referred to, we have 

 the vast area of New South Wales, Queensland, and South Australia, 

 from or into which flow the Murrumbidgee, the Lachlan, and the Dar- 

 ling as feeders of the River Murray ; the Barcoo, Cooper's Creek, and 

 other large streams which empty themselves at nowhere in particular in 

 the interior, and yet in some seasons convey vast volumes of water down 

 their channels. 



It has been hitherto a most convenient explanation of the pheno- 

 menon of the disappearance of these large volumes of water that they 

 are evaporated, and in the case of the River Murray and its tributaries 

 that they pass away to the sea ; but neither of these causes is suffi- 

 cient to produce the results alleged. It is true that on the level 

 plains of the interior evaporation may be a very large element of dis- 

 sipation of the rainfall ; but it does not apply in the same manner to 

 the mountain ranges, where the great bulk of the water falls, 

 and even on the plains evaporation can only take place when there is 

 moisture to be acted upon, consequently during long droughts radiation 

 of heat from the ground may be excessive ; but it abstracts no moisture 

 from that which has already been dessicated, and when heavy rains do 

 fall the ground is rapidly cooled, radiation and its consequent influence 

 in evaporation is checked, and much of the water passes into the ground 

 or away to the natural drainage channels, and on the ceasing of the rain 

 and the return of clear cloudless sky, there is a reduced area over which 

 evaporation can take place. I have more particulary noted these mat- 

 ters owing to the persistence with which the disappearance of our 

 interior river waters have been attributed to evaporation. This last is a 

 large and important item for consideration in all questions of Hydro- 

 graphy in Australia ; but it is only one, and does not account fully for 

 all the observed phenomena. 



The example I have given of the River Murray is a good illustration 

 of the position which I have assumed, namely, that evaporation and sea 

 outlets are but element, but do not embrace the whole. Here we have a 



