G. H. KNIBBS. ; ; XXV. 
INTRODUCTION—There are four very different aspects to 
the artesian problem, all of which will throw light upon its 
practical solution, viz., the (a) Geological, (b) Chemical, 
(ec) Biological, (d) Hydraulic. All are important, and in 
any thorough investigation of the question, none can be 
omitted. For the key to the solution may happen to lie in 
a suggestion coming from any quarter, and no one who has 
seriously studied the problem will hesitate to avail himself 
of every clue to its solution. Notwithstanding this, the 
problem is fundamentally a _ geological-hydraulic “one. 
The hydraulic aspect is that which is considered in this 
paper. 
I.—NATURE OF THE PROBLEM. 
1. Practical aim to exploit artesian supply.—A large 
supply of underground water beneath the level surface of 
an arid region, means the possibility of considerable 
economic development. If the supply be certainly con- 
tinuous, the places where it is tapped are nuclei of safety 
at critical times of drought, etc., and may be made also, 
centres of intense cultivation, so that if it be possible by 
proper control of the artesian wells to ensure that the 
supply shall be permanent, even at a very limited number 
of stations, this control is important. 
2. Source of artesian waters.—In some parts of the 
world the source of supply of artesian areas is well-deter- 
mined, and the rainfall and intake-area admit of a fairly 
definite opinion being formed as to how far exploitation 
may be pushed. 
The question of source is necessarily largely a question 
of geology; but it may be pointed out that it is also one 
for the hydraulician. If the absolute heights to which the 
water will rise, are known at every point where the artesian 
water is tapped, considerable light is thrown on this ques- 
tion, and the geologist certainly assisted in reaching a 
