26 HISTORY OF COLCHESTER CORPORATION WATER WORKS. 
This is unusual, but where the water comes from, and how 
it gets into the clay, will probably interest our geological friends. 
The section of the old well is mentioned in the Geological 
Memoir, Colchester (1880), but it does not quite agree with my 
section of the new well, which is now published for the first time. 
Ground surface (Top of Brickwork of New Well) 35 - 7ft. above O.D. 
Soil 
Gravel (Glacial or River) 
Blue Clay 38ft 
London Clav 
1 
thick 
Septaria with water ift. thick 
Dark Blue Loamy Clay 
14ft thick 
Dark Loamy sand with 
water ift. thick 
Thickness. 
6 
4 
) 
t 54 Base of London 
Clay—28*3 
below O.D. 
Woolwich and I Mottled clay perfectly dry for ) 79 Base of Thanet Sand 
Reading Beds J or. J r J J h or Top of Chalk 
& Thanet Sand ( ' —107.3 below O.D. 
To Top of Chalk (authority, late P. Bruff) 143ft. 
Note.— The late Mr. Peter Bruff in his paper already referred to 
states that the level of the top of the chalk was 121 ft. below H.W.M. 
When one is investigating a new underground source of 
supply, the first anxiety is to ascertain the quality of the water; 
secondly, the maximum daily quantity obtainable from the 
source without entrenching on the next day or month’s supply ; 
thirdly, if a well supply, to see that the natural or rest level 
of the water is not permanently affected by pumping. Seeing 
the importance of this latter, an electrical automatic recording 
apparatus was arranged in the. well, so that the level of the 
water is recorded every minute of the day, whether the pumps 
,hre at work or at rest. This record has been continued by Mr. 
Bland, so that he now has an unbroken record for the last 22 
years of the behaviour of the underground chalk water under 
Colchester. I am not aware of any other similar record existing 
in this part of East Anglia, and if it is of interest to the Club, 
the Corporation might be persuaded to supply a copy.. 
Colchester appears favourably situated as regards obtaining a 
supply of water from the chalk, and so far as I have been able 
to ascertain only one bore hole in the Borough has actually 
turned out a failure, and that was the boring put down by the. 
Government at the Cavalry Barracks, but if I am correctly in-, 
formed, there is another boring lately put down on the opposite, 
side of the valley, even at a greater elevation, which does not 
yield the quantity, anticipated. Why this former boring 
