NOTES OF A JOURNEY ON THE DARLING, 67 
the permeable strata were narrow, and winding about to a certain 
extent as rivers do on the surface; and it is quite possible that 
two wells, comparatively close together, might strike different 
branches of the same drainage system and the water stand in 
them at different levels. The same water which supplies the well 
at Booroora, if tapped at Tourale (although Booroora, where the 
water stands at 10 feet from the surface, is nearly 150 feet higher 
than Tourale), would not there rise 140 feet above the surface, 
but the rise would depend altogether on the freedom of the outlet 
from Tourale to the sea. Wherever the obstructions to the free 
passage of the water were great there would be upward pressure, 
and where the water-way was open there would be no tendency to 
rise above the surface, although the supply to be obtained by . 
pumping would be just as great in one case as in the other. Tube 
wells will have an advantage over open shafts in so far.as the water 
can be prevented from escaping through the sides in any fissure or 
porous strata that may be above the water-bearing strata. 
is will be made clear by supposing a well to have reached a 
supply of water that comes in at the rate of 100 gallons per minute, 
with sufficient force to bring it up to the surface. When the 
area of country in Queensland to the north of this, in which the 
rainfall is comparatively heavy, which seems to have no outlet for 
its waters by surface drainage, and the mud springs which are 
Scattered about the country show, I think beyond question, that 
the water is there and that the force with which it tends to rise to 
the surface is very great. The only part of the western country 
in which I have been where it seems to me improbable that watt 
boring 
oo of dry country between the Darling and Lachlan Rivers 
: estern plai : it Iam inclined to 
: plains, and from what I saw of it Lam inc 
that the older strata in which the clay rests are there above 
