44 THE ESSEX FIELD CLUB.
excellent work in this direction, if formed upon somewhat similar lines as the
Underground Water Committee of the British Association. Its function should
be to collect together every possible information and detail of a geological,
chemical, physical, engineering, and structural character. With reference to
wells, springs, and rivers, the mere bringing together of such information, and
tabulating the same in some standard form to admit of comparison, would be a work
of the highest value. This, it appeared to him, could be achieved without much
difficulty if members of the Club could be induced to assist, being distributed
as they are all over the county. Mr. Wood had endeavoured, in a private
capacity, to get information for making a hydro-geological survey of the district
before mentioned, similar to what Mr. Lucas had done for parts of Kent and
Surrey, but met with so many difficulties that he gave it up after six months
work.
Mr. Wood mentioned that the River Stour and valley was highly interesting
from a hydraulic point of view, and that several places existed where gauging
of the daily flow of the river could easily be obtained, as weirs already existed,
especially at Liston near Long Melford, where the mill has been removed and
the flow of the river is passing over a board fixed across the old wheel race ; but
unfortunately he knew of no one in the neighbourhood who would take sufficient
interest to make a daily gauging.
He further mentioned the possibility that a large quantity of Chalk water
was discharged into the bed of the River Stour between Long Melford and
Bures, probably in the neighbourhood of Sudbury, Suffolk, where the Chalk came
to the surface. The river always appeared full between Borely and Bures, how-
ever dry the seasons might be ; and, what was more, the w ater was usually bright
and clear, except in flood time. Interesting results would no doubt be obtained
if the river was gauged between the points mentioned.
From the results of the analyses in Dr. Thresh's paper, it appeared conclusive
that where the Chalk is overlaid with considerable thickness of Tertiaries (Lon-
don Clay, Woolwich Beds, and especially Thanet Sands), the water obtained
from the Chalk by means of a boring contained a much greater quantity of solids
and chlorine, besides being a softer water, than water obtained from a boring or
well sunk in the open Chalk,
Mr. Wood instanced the following eight wells sunk down to the Chalk, and
mentioned in Dr. Thresh's paper, but overlaid with a considerable thickness of
Tertiaries, viz., the three wells of the Southend Water Company, Brentwood
Asylum, Havering, Maldon Water Park Felstead, and Tiptree. The average
solids were 74, average hardness 2-9, average chlorine 21-5 ; whereas if the five
wells in the open Chalk were taken, viz., Saffron Walden, Sudbury (two), Hoddes-
don (two), the average solids were 35'9, average hardness 206, average chlorine
27.
The above differences were remarkable in water derived apparently from the
same formation. The only suggestion that one could offer was that the water
from the sands (especially the Thanet Sands) above the Chalk intermingled freely
with the Upper Chalk waters, due to the absence of impervious beds.
In conclusion, Mr. Wood thought that it would probably be highly interesting
if Dr. Thresh could examine a series of waters (say taken in a line from Haver-
hill to Southend) from the open Chalk to where it is overlaid by a maximum
thickness of Tertiaries, and state the changes in the solids, hardness, and
chlorine, as the case might be.