CXXXVI. IRRIGATION GEOLOGICALLY CONSIDERED. 
that a considerable proportion of it is to be accounted for 
in the latter way. 
These facts point to the conclusion that the rise of the 
water in the artesian bores of the western plains must be 
due to either hydrostatic or hydraulic pressure. We 
believe the pressure to be hydraulic rather than hydrostatic 
for the following reasons :—(1) If the pressure were hydro- 
static, that is if there were no outlet for the water which 
accumulates in the porous beds, it stands to reason that it 
would ultimately become saturated with the mineral matter 
dissolved from the rocks through which it had percolated. 
Asa matter of fact, however, the water in the artesian 
wells contains, as already stated, only a small amount of 
mineral matter in solution, and this fact must be regarded 
as evidence that the water has a circulation. There are 
valleys in the artesian area which could intersect the 
porous beds at a sufficient depth to allow of this circulation; 
and the amount of water which escapes from the mound 
springs within this area isso small that it may be regarded 
as negligible. The only other possible way in which circu- 
lation could be maintained would be by leakage to the 
ocean. That there is leakage to the ocean is borne out by 
the fact that the porous beds have been found to extend 
along the eastern and south-eastern shore of the Gulf of 
Carpentaria. It may further be stated that if there were 
no circulation of water in the artesian beds, that is if the 
water were hydrostatic instead of hydraulic, it appears to 
us that the beds must long ago have become saturated with 
water, with the result that numerous strong springs would 
be observable in the valleys intersecting the intake beds. 
No such springs, however are known to exist. 
V. ESTIMATED ANNUAL INFLOW OF WATER INTO THE 
ARTESIAN BEDS OF NEw SOUTH WALES.—The area of the 
intake beds has not yet been accurately surveyed, but it 
