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466 W. A. DIXON. 
On ARTESIAN WATER In connection with IRRIGATION. 
By W. A. Dixon, F.1.C., F.C.S. 
[Read before the Royal Society of N. S. Wales, December 6, 1893. ] 
FoLLowineG on the interesting paper by Prof. David on Artesian 
Water, I have ventured to put down a few remarks in their con- 
nection with irrigation. This is required, because very loose and 
wild ideas as to the results likely to be achieved float through the 
minds of many people, and often find expression through the press. 
Prof. David states as his opinion, that the water which now 
rises in our artesian bores has hitherto been flowing to the sea by 
underground channels, and that the rise of water to the surface is 
caused by the friction of the material of the porous beds on the 
water, the outlet to the sea being much below the level of the land 
surface, He also says that the intake area at the outcrop of the 
Cretaceous beds is about two hundred square miles (so far as the 
drainage into New South Wales is concerned I understand). The 
rainfall on this area is about twenty-two inches per annum on the 
average, and it is stated by Mr. Russell, (Jour. Roy. Soc. N.S.W. 
Vol. xxitl., pp. 57 — 63), that probably half this rainfall percolates 
into the soil. 
It must not be thought that because vegetation exists with a 
rainfall of eight inches per annum, and flourishes with three times 
that amount, that even the larger quantity applied to the ground 
by irrigation would produce the same effect. When rain falls the 
atmosphere is saturated with moisture and evaporation is checked, 
but successful irrigation is practised when the air is dry and 
evaporation at its greatest, so that it is best applied thoroughly to 
small areas instead of to large ones merely watered. The cost of 
laying out channels is kept at a minimum, as is also the loss by 
adycuii»r. relatively to the crop. 
