THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
251 
they had or not, the objections have been valuable to me in 
indicating the nature of the evidence desirable to offer in its 
favour. 
In reference to the matter indicated by the above heading, 
it has been suggested by some that the area to be filled is so 
vast that the water would be almost as completely lost as if 
poured into the sea ; by others that the water would flow 
entirely away from the district, owing to the dip of the beds, 
forgetting that if it could, it would have done so years ago, 
and so left us without water. 
It has been stated previously that the height to which 
water will rise in a well, its artesian rest-level , as it is called, 
is directly proportional to the height of intake, and inversely 
proportional to the resistance of the bed, where there is no 
intermediate relief of pressure. A local depression is always 
caused by local pumping, the extent of which varies with the 
porosity of the bed, and the pumping power. The difference 
in height of the artesian rest-level at different pumping 
stations gives the artesian gradient , and affords a measure of 
the resistance of the bed. Such being the case then, an 
equality of depression over a large area is a sign of extreme 
porosity. 
There is scarcely a doubt that the continuous pumping of 
large quantities of water from the Marlstone, for the supply 
of Northampton, has been the main cause in reducing the 
water-level of the bed over a considerable area, say a sector 
of a circle having a radius of fifteen miles or more, because 
the amount extracted has been in excess of the natural intake 
in an equal time. 
The importance of this consideration is, that it gives a 
good idea of the distance at which feeding wells may be con¬ 
structed, for it is perfectly certain that if the pumping at 
Northampton has reduced the artesian rest-level over a 
certain area, that same area can again contribute any water 
which gets into it, whether naturally or artificially. 
In 1881, the late Mr. Samuel Sharp contributed a paper 
to the “ Journal of the Northamptonshire Natural History 
Society,” entitled, “ Some Remarks upon Local Wells 
and Borings, and upon the Consequences of Excessive and 
Indiscriminate Agricultural Drainage,” in which he showed 
how the water-level of the county had fallen considerably. 
I cannot agree with his contention that it was due to 
excessive agricultural drainage ; indeed the remarks to follow 
will show conclusively that that is not the cause, but the 
facts lie cites are quite relevant to the subject under dis- 
