32 THE SHALLOW AND DEEP WELL WATERS OF ESSEX.
such water, and at West Hanningfield there is a similar well. A
brook running from South Hanningfield also contains such magne-
sian waters. What is the source of this magnesia ? and are the beds
of sand yielding such waters limited to the upper portion of the
London Clay ? The importance of this question will be manifest
when we come to speak of the deep well waters. For examples of
such waters, refer to my report on the Chelmsford and Maldon
District Water Supplies. C. Nos. 15, 16, 17, 21, 24, 26, 31, 38,
39, 45. 63, 94, 98, 107, 121, 126, 159, 168, 176, 198, 213. M.
Nos. 62 to 81, 86 to 90, 133 to 146. At Bradwell, Southminster,
Galleywood, and possibly other places, where such waters are found,
the proximity of beds of brick-earth have possibly some connection
with this peculiarity.
Passing on to the consideration of the waters yielded by wells
sunk through the London Clay, here again we meet with serious
difficulties, due to the fact that many of the wells, more especially
the older ones, are so badly constructed that it is quite uncertain
what proportion of surface or sub-soil water they contain. As the
water from these superficial sources is usually, if not always, very
impure, containing much organic matter and nitrates, we can invari-
ably detect its presence, but we can only very roughly estimate the
quantity. According to the varying proportion of surface to subter-
ranean water will the constituents vary on analysis. Take, for
example, the water at Goldhanger Rectory and at Cold Norton
Railway Station. In 1889, the water from the rectory well was
uncontaminated. In 1891, there were reasons for suspecting that
the water was being fouled, and upon analysis such proved to be the
case. Evidently water containing less saline matter and more lime
salts and nitrates (i.e., impure surface water) was gaining access to
the well. At Cold Norton Railway the water obtained soon after
the well was bored contained so much nitrates and lime salts that I
felt justified in condemning it as impure. The well was opened
and some improvements made. The quality of the water also
improved ; but it still was impure. The well was again examined,
and, I believe, some puddling done, or the brickwork cemented.
The result was that when the water was again submitted to analysis
it proved to be pure. At Stow Maries (Hogwell) we have not been
so fortunate. When I examined the water, in 1890, I found it very
impure, and I reported that sub-soil water was entering the well.
The railway company had the water pumped to a low level, and