HISTORY OF COLCHESTER CORPORATION WATER WORKS. 27 
contained no water I have never been able to ascertain, 
except that it was unfavourably placed as regards elevation, 
the chalk below being compressed due to the pressure of super¬ 
incumbent mass above. The result of my experience is that 
wells placed in the floors of valleys, yield water more freely 
than when placed high up the flanks, or on the top of the 
plateau ; the reason appears to be that the beds are much 
more broken up and fissured in the valley, and besides the 
underlying chalk is not so compressed. 
Nearly all the wells and bore holes which have been sunk in 
the Borough and neighbourhood from the floor of the valley 
yield water freely, and several of them are practically 
artesian. 
There is undoubtedly a large quantity of water travelling 
from the outcrop of the chalk on the north-east, beneath the 
floors of both the valleys of the rivers Colne and Stour, on its 
way to the sea, that being probably the line of least resistance 
due to greater Assuring and because the beds are less compressed. 
It must not be lost sight of that the water does not travel 
through the whole mass of the chalk, but along planes of 
bedding, beds of flints, and through a network of vertical and 
horizontal fissures. It also flows more easily down the dip than 
across it on the way from the water-shed down to the lowest 
point, which is the sea. It would be interesting to know whether 
the water yielded by the wells in Colchester is derived directly 
from the chalk outcrop to the north-west in Cambridgeshire 
and Suffolk, or is connected in any way with the River Stour 
between, say, Borely and Henny about twelve miles distant, 
through which district the river intersects the open chalk. 
Although the Chalk is of great thickness in East Anglia and 
Essex, say about 850 feet, and is practically water-logged 
throughout its thickness, it is only the Upper Chalk or porous 
zone, say from 300 to 400 feet thick, which yields water in this 
district. This Upper Chalk contains in its mass, locked up in its 
capillary pores, so to speak, some two to three gallons of water 
per cubic foot, which cannot readily be got out by pumping, but 
only by pressure, and has been described as Capillary Water. 
The water we obtain by wells and bore holes in the Chalk an 
this neighbourhood is not this capillary water, but water flowing 
in undefined channels and fissures. 
