129 



"Wales and the Department of Mines of the Government of 

 that colony have taken up the matter. This Society has for 

 the last two years circulated " forms " to be filled up by the 

 recipients with data supplied by the sinking of wells and 

 other subterranean explorations in this country.* Some 

 responses have been received and permanently recorded in its 

 Transactions. The credit which belongs to this Society through 

 its Hon. Secretary, of initiating such a scheme in the interests 

 of the colony at large seems to have induced the Chamber of 

 Manufactures to enter into competition with us. The duplica- 

 tion of effort in this direction must beget incompleteness, if not 

 inefficiency, and the sooner the one or the other withdraws the 

 better for the attainment of the object each has in view. T 

 know well that this Society is fully prepared to transfer its 

 aid to any constituted authority empowered to carry on the 

 record, or to any corporate body which is better able to 

 prosecute the work, and so to deal with the collected infor- 

 mation as to make it practically available. 



I have said that little consideration has hitherto been given 

 to the question of providing permanent supplies of water ; 

 but it must be acknowledged that of late the Government and 

 a few pastoral lessees have experimented after a more deter- 

 mined manner than had characterised their previous eiforts. 



Our great natural water resources are of two kinds — one is 

 derived from the rainfall which has nc^t passed through 

 Nature's filters, and which is obtainable from creeks and other 

 surface drainers, and from lakes and reservoirs ; the other 

 is derived from springs and underground reservoirs. 



Where the soil is impervious the rainfall is thrown off by 

 surface drainage, giving rise to a waterless area. But the same 

 water may elsewhere be impoimded in lakes, swamps, or rock 

 basins. Surface-collected water is usually soft, but it acquires 

 some amount of mineral ingredients in its passage over the 

 surface, the quantity and quality being dependent on the 

 length and duration of the flow and the chemical properties of 

 the surface. AYater thus impounded diminishes in quantity 

 through evaporation, and the ratio of the quantity of saline 

 matter is proportionately increased ; newly constructed dams 

 and saturated salt lakes are the first and last stages between 

 which all impounded waters in arid countries are graduating. 

 At Adelaide the mean annual amount of evaporation for nine 

 years has been ascertained by Mr. C. Todd to be about sixty 

 inches, or about three times that of the mean annual rainfall 

 at the same place, so that, assuming no loss by percolation, to 



* This mode of inquiry was suggested by Mr. T. E. Eawlinson, C.E., in 

 a paper read before this Society, September 17, 1878, and published in the 

 Trans, for 1878. 



