HISTORY OF COLCHESTER CORPORATION WATER WORKS. 3 I 
form a small stream or tributary of the Colne, and had from 
time immemorial been the only motive power for driving 
Lexden Corn Mill; after passing through the mill the stream 
discharged into the main river. (See Plan of the Lexden 
Springs. Plate II.) 
The source or gathering ground is a large plateau of gravel 
and sand to the south vest, extending to Stanway in the west, 
to the limits of the Roman river in the south, which river runs 
in an easterly direction around the plateau to a junction with the 
river Colne nearly opposite Wivenhoe. The area of this enormous 
bed of sand and gravel is about 13 square miles, and the bed 
falls both towards the main valley of the Colne and the Roman 
river. The plateau rises to a maximum altitude of about 
130 feet above O.D. The springs rise or show themselves at 
an elevation varying from 40 to 50 feet above O.D. to the 
south-west of the Malting Farm. From the left of the springs 
the gravel rises rapidly, the 100 feet contour being only a 
short distance away. The water escapes from/four or five well 
defined springs, and yields considerable quantity, even after 
abnormal dry periods; in fact the discharge has been looked upon 
in the neighbourhood for ages past as practically constant, 
but such is not quite the case, as it varies with wet and dry 
periods. The beds are of a porous nature, and of considerable 
thickness, and due to their porosity a considerable portion of the 
rainfall percolates into the soil, and ultimately finds its way 
in the shape of springs into the valleys before mentioned, 
especially at Lexden. The beds undoubtedly form a most efficient 
natural filter, as at the points of collection the formation is 
practically all clean sand, and even after heavy rain the water 
always comes av T ay perfectly bright and clear ; there is very 
little doubt that the beds form an underground reservoir of no 
mean capacity. The water is collected by cutting a trench in 
the water-bearing bed at right angles to the direction of the flow 
of the w r ater, well at the back of each spring and bekvv the level 
of the natural discharge or lip, and laying therein special per¬ 
forated stoneware pipes, around which is packed shingle. The 
trench is then refilled with the material in the order it was taken 
out. The collecting pipes are then led to a pit common to each 
spring, and each pit is connected by an iron pipe controlled by a 
valve to the main gravity aqueduct. By this means each spring 
