d 
bes a 
’ é 
; 
414 T. W. E. DAVID. 
is largely increased, and the practice of allowing a large proportion 
of them to continuously flow at their full capacity is persevered 
in, it is probable that the demand will soon overtake the supply, 
and that there will be a diminution of flow. Indeed it may.be— 
but I do not advance what I am about to say as probable but — 
merely as a possibility—that now the output of the wells equals, 
nay exceeds, the inflow, and that the output is maintained by 
accumulations of water stored in the porous beds. Supposing 
either of these possibilities to exist, it is only a question of time 
when the higher wells will, one by one, cease to flow with the 
lowering water-level, until there is an approach to an adjustment 
between the supply and demand. At all events, whether either 
of these probabilities exist or not, there seems to me to be a strong 
element of danger, and as there does not appear to me to be any 
sound reason why injudicious and wasteful use of the water should 
be allowed, I venture to submit the matter for serious consider- 
ation before such a calamity as the failure of the supples should 
happen.” 
The above passage has been quoted at length as being of grave 
importance to those who are interested in the artesian water 
supply of New South Wales. Mr. R. L. Jack substantially agrees 
with the views expressed by Mr. Henderson, as to the compara- 
tively limited extent of the artesian water supply of Queensland, 
and if these statements are applicable to Queensland, it would be 
interesting to consider how far they may be applicable to New 
South Wales. 
Mr. Henderson cautiously states that it is impossible to measure 
at present with any degree of accuracy the superficial area of the 
outcropping edges of the porous beds of the Rolling Downs 
Formation, owing to their being to a great extent overlapped by 
newer formations. In order to form an accurate estimate of this 
superficial area it is obviously necessary to know (1) the thickness, 
(2) the angle of dip, and (3) the angle of slope of the surface of 
the outcrop of the porous beds, (4) the actual area available for 
intake, 7.¢e., not covered by newer and impervious beds. 
