ARTESIAN WATER IN N. S. WALES AND QUEENSLAND. 421 
not only by the amount of water present in the surrounding sand 
beds and the pressure to which it is subjected, but also by the 
amount of frictional resistance which the sand offers to the passage 
of the water. The effect of multiplying the number of large bores 
in a restricted area would be undoubtedly to drain the water out 
of the sands faster than it can drain into that particular district, 
and so all these wells might become sub-artesian instead of artesian, 
just as the Native Dog Bore in New South Wales has had the 
effect of drying up the adjoining mud springs; and at the same 
time it might be the case that the total outflow from all the 
artesian bores in the artesian water basin did not amount to more 
than one per cent. of the total annual supply. 
In the future, therefore, if the hydraulic grade is found to fall 
in a special district, there should be no widespread panic amongst 
all the proprietors of artesian wells lest the whole supply of artesian 
water should fail, as such a failure will affect that district only 
where the wells have been overcrowded, and will not necessarily 
make its effects felt over the whole basin. 
(2) As regards the angle of dip of the Rolling Downs strata, this 
must be but slight, If the case of the Muckadilla Bore be taken 
as an example, the bore is 3,262 feet deep, and it is distant about 
fifty miles from the base of the Rolling Downs Formation at the 
nearest point, there being little difference in the surface levels 
between these points and the Muckadilla Bore being in Cretaceous 
strata throughout. The maximum dip might therefore in this 
case be 3,262 feet in fifty miles, that is a dip of about one in eighty- 
one, provided the amount and direction of dip between these two 
points is uniform. A bed of porous rock, therefore, one hundred 
feet thick would have an outcrop, if the surface were level, 8,100 
feet wide, that is a trifle over a mile and a half in width. At the 
Darr River the Rolling Downs Formation, as judged from the tem- 
perature of the water, may be as much as 6,000 feet thick, but as 
this is over one hundred and thirty miles from the edge of the 
Cretaceous basin at the nearest point, the general dip, (allowing 
that the surface level at the bores at the Darr River is about five 
