86 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
proportional to the distance away, in the direction of out¬ 
crop, at which the bed was saturated, allowance being made 
in this particular case for increase of dip ; whereas, the area 
to be tilled would be proportional to the square of that 
distance. Taking the data already given as sufficiently 
accurate, it follows that about seventy-five millions of gallons 
would be required for the first mile, and it would raise the 
head of water feet, whereas two miles would require about 
four times the amount of water, but would only raise the head 
nineteen feet, and so on. 
Considering, therefore, that the Northampton well resus¬ 
citated itself so well in about two years, without assistance, 
it is evident that the near Marlstone had a considerable 
amount of water left in it when pumping was stopped, 
although the pressure was not sufficient to deliver it in large 
quantities; it thus becomes an indirect proof of the small 
inclination of the bed near the town. 
I have endeavoured to show that there is no natural 
obstacle to a head of 110 feet of water being obtained at 
Northampton. Without the aid of headings, a yield of over 
800,000 gallons per day was obtained when the artesian rest- 
level was ninety feet; therefore, with a rest-level of 110 feet, 
1,000,000 per day would now be obtained. This would be 
sufficient for the present use of the town, and perhaps as much 
as could be expected from a single well. A dozen dumb-icells 
ought to supply this amount of water, and at the same time 
continuously improve the yield up to the greatest limit. 
There is no doubt that one of these wells, when empty, and 
supplied with clear water, could dispose of 1,000,000 gallons 
in a day, but considering that they would not be empty even 
when first made, and that the flow of water would be impeded 
by the filling of sand and gravel, and that that amount of 
water would not be continuously available, I have assumed a 
limit of 100,000 gallons per day on an average, or 1,200.000 
gallons altogether. This amount, together with that im¬ 
pounded naturally, would give an immediate increase of the 
water supply, followed by a continuous improvement in the 
yield up to the maximum amount. A single year would 
suffice to make the supply equal to the bare necessities of the 
town, without extraneous aid, for with a daily loss of 400.000 
gallons, there would be a residue of 865,000,000 of gallons on 
the year. 
In connection with the available supply of water, it is 
somewhat important to know if the river grave taps the river. 
Speaking generally, I should say it does not for the river, in 
most cases, flows over a good thickness of the dirty alluvial 
