ae a 
e 
‘ a 
‘ : 
until the date of Mr. H. Jus’ Report in 1890,* and were still 
flowing at that time without showing any evidence of diminution 
in yield of water. It is stated however (Joc. cit. p. 10) that the 
artesian wells of the Sahara had almost attained their maximum 
412 T. W. E, DAVID. 
in 1890, and that if the supply were drawn upon any further the 
outflow at the individual wells would probably be diminished. 
The distance of the furthest artesian wells in Algeria from their 
chief source of supply, the Atlas Mountains, is over three hundred 
and fifty miles. 
The water in the Pliocene is evidently in circulation, and its 
pressure is therefore hydraulic not hydrostatic ; but what natural 
outlet there may be for the water from these reticulated subter- 
ranean undersheets is not at present known, as far as the author 
is aware, but the principal direction of the circulation appears to 
be from north to south. Possibly the circulation is partly main- 
tained through the “‘dehour,” just as in the Australian Cretaceous 
strata it was partly maintained through the mud springs, previous 
to the sinking of the artesian bores. One of the largest artesian 
wells, the Fontaine de la Paix yields 1,278,720 gallons per twenty- 
four hours. 
The total quantity of water obtained from artesian and sub- 
artesian wells in Algeria in 1890 was 317,414 litres per minute = 
70,452 gallons per minute = 101,450,880 gallons per twenty-four 
hours. This quantity is almost exactly equal to the total capacity 
of outflow of the Queensland artesian bores as estimated by Mr. 
J. B. Henderson in his report for 1893, already referred to. 
II, Artesian Basin or New South WALES AND QUEENSLAND. 
All the artesian bores of New South Wales, with the exception 
perhaps of the Coonamble Bores and those near Gunnedah, derive 
their supplies of water from the sands and fine gravels of the 
Lower Cretaceous Formation, the equivalent of which in Queens- 
* Résumé Graphique des Soudages Exécutés dans la Provence de Con- 
stantine, De ler Juin 1856 au ler Janvier 1890. Suiveé d’ une Notice 
sur la Region de l’ Oued Rir—Par H. Jus, Constantin 1890. 
