110
THE ESSEX FIELD CLUB.
Several members found considerable interest in inspecting the Tyssen
collection of prints and drawings relating to Hackney. These were col-
lected many years ago and form a most valuable record of that older
Hackney which has been for the most part demolished.
Before separating Mr. Whitaker expressed the thanks of those present
to Mr. Wrigley for the trouble he had taken in arranging the meeting,
and for his interesting expositions.
THE 403rd MEETING OF THE CLUB.
Saturday, 30TH March 1912.
A meeting at the Technical Institute as usual, the President in the
chair.
Exhibits.—Mr. D. J. Scourfield, F.R.M.S., exhibited on behalf of
Mr. C. Soar, a beautifully executed water-colour drawing of a Fresh-
water Mite (Arrenurus) which was presented to the Museum.
Mr. W. Cole showed a Museum preparation of the nest of the Great
(or "Horse") Wood Ant (Formica rufa) exhibiting the structure in vertical
section, and with the various "commensals" living in the nest.
Mr. Whitaker spoke of the pugnacious habits of this ant as often ob-
served by him in the Kentish Woods.
Mr. David Howard, F.C.S., exhibited drawings of sections of two
Artesian wells in his works at Stratford, 100 yards apart, and gave some
particulars of the character of the water in the wells.
Paper read.—Dr. Thresh, M.D., D.Sc. (Medical Officer of Health to
the Essex County Council), read a paper on "The Alkaline Waters of the
London Basin." The main subjects touched upon were as follows :—
" The saline constituents of the deep well waters in various parts of
the London Basin, but more especially in Essex—The Thanet sand, analysis
of—Comparison with granite—Peculiar effect of granite upon hard and
soft waters—Comparison with effect of Thanet sand—Action of brine
upon granite and Thanet sand—Origin of the sodium and potassium salts
in the deep well waters—Presence of bromine and iodine and their signi-
ficance."
A long and interesting discussion followed the reading of the paper.
The President first called upon two visitors, Mr. Burgess and Mr.
Matthews, who spoke on the subject from a chemical and engineering
point of view, and Mr. Dymond, Mr. Wood, Mr. David Howard, Mr. Dalton,
and the President, amongst others, continued the discussion.
Dr. Thresh replied to the various questions asked, and incidentally
gave his opinion that waters containing up to So grains of sodium chloride
per gallon were perfectly harmless to health.
The paper was illustrated by many tables of comparative analyses
of the composition of various deep-well waters in Essex (shown by means
of the lantern) and by some experiments.
On the motion of the President, the warm thanks of the meeting were
accorded to Dr. Thresh for his valuable paper.
VISIT TO BLACK NOTLEY AND BRAINTREE.
404th MEETING.
Saturday, 27TH April 1912.
This meeting was of unusual character and interest, its primary object