PRESIDENTIAL ADDRESS — SECTION E. 235 



There is an important work proceeding in the interior of 

 Austraha, which, although undertaken for purely utilitarian 

 purposes, will yield data of considerable scientific interest if 

 the records be carefully kept. I refer to the artesian wells 

 which are being sunk on the back blocks from the centre of 

 Queensland down towards the mouth of the Murray. Urged 

 to great efforts by the disastrous effects of frequent droughts, 

 the squatters are boring in all directions, and with gratifying 

 results in a large number of instances. Step by step the 

 boring-rod tracks out the flow of those great underground 

 streams ; and if the Government departments in the several 

 colonies will chart down the data obtained from ever}' bore, 

 whether water be tapped or not, with the depths, and the 

 strata passed through, we shall soon have a mass of valuable 

 material out of which a new geographical feature can be elabo- 

 rated and added to our maps — namely, the subterranean 

 drainage of the continent, its principal sources, its extension 

 in streams or shoots, its depth from the surface at different 

 points, and any variation that there may be in its volume 

 from year to year. 



The chief sources of these water-supplies must be looked 

 for in the great eastern cordillera, which sheds the surface- 

 streams that also cross Eiverina. x\long its crests the rainfall 

 is of course greatest, being from 20in. to 40in. per annum in 

 the Queensland portion ; and it is near to the long ribbon- 

 shaped region of heaviest rainfall — that is, along the sides of 

 the watershed — that the superficial dej)Osits, being largely 

 composed of gravel and rock debris, are most pervious. Fur- 

 ther, the continuity of the strata of the plains is broken at the 

 hill-foot, where they die out against the outcropping rocks of 

 the main range, and this line of break affords to the water 

 flowing down the hills a ready passage beneath the sediments 

 of the plains. 



Under these circumstances a large proportion of the rain 

 caught on the raiiges leaks under the subsoil directly it falls, 

 and it flows to the sea slowly indeed, but with its volume un- 

 diminished either by the evaporation which lowers the surface- 

 waters of the Eiverina 6ft. per annum, or by the demands of 

 vegetation, which are much greater upon river water than the 

 public has any idea of. 



As these subterranean waters travel away from tlieir 

 sources they must thin out. Mr. H. G. McKinney, C.E., of the 

 New South Wales Water Commission, estimates that at a dis- 

 tance of a hundred miles from the hills they will have so out- 

 spread that the quantity from any one bore would be too 

 small to warrant the expenditure for irrigation purposes. But 

 it appears to me that in every district of any size there nnist 

 be deeper channels in that ancient land-surface which is now 



