316 LIAS OF ENGLAND AND WALES : 
A shaft sunk in 1836 at Kingsthorpe, near Northampton, 
penetrated the Middle Lias, which yielded about 864,000 gallons 
of water per day. No use was made of this water, for the sinking 
was earned (in search of coal) to a depth of 967 feet, and then 
encountered saline water. Mr. B. Thompson remarks (1888) that 
the salt water fills the old shaft to within 270 feet of the surface. 
Northampton was about 10 years later (184 6) supplied by a well 
(near the Billing Road), sunk and bored 168 feet into the Marl- 
stone. About 500,000 gallons per day were at first obtained, 
and the water rose to within 60 feet of the surface. Later on a 
second well was sunk. In 1871 about 280,000 gallons of water 
were daity supplied ; but the total amount available was found 
steadily to decrease. Some temporary increase was obtained by 
means of headings, but many old wells were rendered dry, as the 
water-level was reduced, and in 1884 the water did not rise above 
the Marlstone rock-bed. As pointed out by Mr. B. Thompson, 
more water (from this and other wells in the neighbourhood) 
was pumped from the Marlstone than it received from natural 
sources. He proposed a scheme to supply the deficiency by 
means of dumb-wells constructed to take surplus waters from 
the Nen and tributaries. This scheme Avas not adopted.* 
A reservoir intended to hold 400 millions of gallons of water has now been 
constructed on the Upper Lias Clay in the valley between Ravensthorpe and 
Guilsborough. The brooks in this valley form one of the tributaries of the 
Nen, and they derive their waters from the Northampton Sands. 
The dam is near to and nearly parallel with the road from Ravensthorpe to 
Teeton, so that the reservoir is sometimes spoken of as the Teeton reservoir, 
and sometimes as the Ravensthorpe reservoir. The Upper Lias clay was used 
in the construction of the dam. 
Mr. Beeby Thompson, to whom I am indebted for the above particulars, 
informs me (1891) that the reservoir has probably never received half the 
amount of water which it was constructed to hold. 
At the Midland railway-station at Wellingborough, a boring 
was carried through the Upper Lias to a depth of 150 feet, when 
the Rock-bed (Marlstone) was struck, and plenty of water was 
obtained.f Good water (used for brewing) was obtained from the 
Middle Lias (at a depth of 80 feet), one mile west of Oakham).J 
(See p. 238.) 
The water obtained from the Lower Lias limestones is as a rule 
much harder than that obtained from the Marlstone, and it is 
sometimes contaminated with sulphuretted hydrogen. This is also 
the case with wells that are sunk through the Middle Lias into 
the clays at its base. In waters not subject to artificial pollution, 
the hardness, as might be expected, is usually less in the spring 
water than in the water obtained from wells, and it increases 
according to the depth of the well. The hardness is mostly of a 
u temporary " character, and can be removed by Clark's process. 
* B. Thompson, Middle Lias of Northamptonshire, pp. 78, 82, 84, 100, &c. ; and 
B. Latham, Trans. Soc. Eng., 1864, p. 244. 
f From notes made by H. W. Bristow. 
j De Kance, Rep. Brit. Assoc. for 1879. p. 161. 
