572 PROCEEDINGS OF SECTION J. 



value without guagings of the flow of water in our rivers and 

 creeks. And I wish here, in passing, to point out the great need, 

 for scientiiic as well as for practical purposes, of this information, 

 which can only be obtained by a systematic guaging of the flow 

 of water in our principal streams. 



The question of the proportion of our rainfall, lost by percola- 

 tion and other causes, is a very difficult one, and yet of the greatest 

 practical importance. From guagings taken by me of the flow of 

 the River Wakefield, and other streams, I find the following are 

 the approximate results: — At Barossa, in 1884, 16|^ inches loss 

 out of a total rainfall of 21^ inches ; at Beetaloo, gauged in 1885, 

 24 7-lOth inches loss out of a total rainfall of 25|^ inches ; andat 

 the River Wakefield, gauged in 1886, 2 lA^ inches loss out of a total 

 i\ainfall of 2l| inches per annum. Assuming the loss by evapora- 

 tion and absorption to be half the above quantities, the loss due 

 alone to percolation underground will be as follows, viz. : — At the 

 Barossa catchment area annually, a loss of 8;^ inches in 1884, 

 and five inches flowing in the river in the hills ; at Beetaloo in 

 1885, loss by percolation 12 3-lOtbs inches, and flowing in the 

 river 6-lOtlis inches ; at the River Wakefield in 1886, loss by 

 percolation 10| inches, and flowing in the river 18-lOOth inches. 



II. THEIE UTILISATION IN OTHER COUNTRIES. 



Such underground water supplies in many other countries have 

 been turned to pi^actical account ; for instance, in California, 

 where tuunelling has been carried out under some of the rivers ; 

 at Seville, in Spain, where water supply is obtained by a tunnel 

 into water-bearing strata, consisting of permeable calcareous rocks 

 resting on impermeable clay. The springs rise and flow away 

 through the tunnel to the city, and some parts ot these tunneling 

 works ai'e said to have been carried out by the ancient Romans. 

 Explorations also were made by tunnels into the hills in the neigh- 

 bourhood of Lisbon, resulting in the obtaining of a supply of about 

 1 20 million gallons per annum; also the city of Florence has obtained 

 water by similar means ; a tunnel has been driven into the valley 

 of the River Arno, and the supply of water, which is of an extra pure 

 quality, for domestic pui'poses, is 1,734 million gallons per annum, 

 or about twice the supply for the city of Adelaide, aud the total 

 cost of these works is only .£268, 000. 



Another instance is that of the Naples water works which 

 draw their supplies from springs in the northern slope of Monte 

 Somma. The waters of these springs are collected by means of 

 infiltration galleries ; the floors of these galleries are not paved, and 

 openings are left in the side walls and arch for the water to flow in. 

 The water-bearing strata are in the hills and situated fifty -two 

 miles from the city, and 1,050 feet above the sea. The whole of 

 the supply thus collected in tunnels is about 38,000,000 gallons 

 per day. 



