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NOTES—ORIGINAL AND SELECTED.
began by suggesting that scientific records should be prepared and kept of all
wells and springs yielding large supplies of water. In Essex, where the
supply was chiefly dependent upon deep wells, and where the water varied so
extraordinarily in character, a record of this kind was of such importance
that he had been accumulating data for several years past. The chalk under-
lay all portions of Essex. Most of the waters were exceedingly soft, but
there was much variation. They all contained much less carbonate of
calcium (chalk) than waters taken from the chalk elsewhere. What was the
source of the carbonate, sulphate, and chloride of sodium ? And what had
reduced the hardness of the water or removed so much of the calcium and
magnesium salts which were found in all other chalk waters ? His view was
that this water was practically stagnant under the county, and that in the course
of ages the action between the water which entered on the west from the
chalk outcrop, and the sea water which entered on the east from the opposite
outcrop under the ocean, had resulted in the formation of these particular
constituents. On both the south and east, wells had been sunk into the
chalk and abandoned on account of the brackish character of the water
obtained. The normal water level in these wells was now below ordnance
datum, and was sinking from 1 ft. to 2 ft. every year. Everything appeared
to indicate that very little of this water came from the outcrop to the west,
and such being the case, the multiplication of deep wells would continue to
reduce the water level, and sea water would travel inland at a rate faster than
the reactions which had produced the saline constituents of the water now in
the chalk could keep pace with, and the supply would gradually become
brackish. He could discover no indications of this alkaline water travelling
in any direction, and, in his opinion, it was a vast and practically stagnant
underground reservoir which, if drawn from, was much more likely to be fed
with sea water from the east than by the rainfall on the outcrop to the west.
The river water entering the chalk at or near Barking underwent some
change before arriving at the wells, since the deeper well yielded a water con-
taining no calcium sulphate, and in both the proportions of the various salts
differed considerably from those in Thames water. At Greys the wells
yielded no sulphate of magnesia, while common salt and chloride of mag-
nesium, the chief constituents of the tidal water, were increasing. At Orsett
the water contains both these salts. Such great variation over so limited an
area points to a condition approaching stagnation. The water was impri-
soned here. It passed from Kent under the Thames towards Essex, but,
finding no outlet towards the north, it was forced through fissures into the
bed of the Thames. Excessive pumping might reduce the level of the water
at the Essex side, so that water from Kent, or even from the river, might flow
in to restore equilibrium. Certain of the wells at Barking yielded a water
containing carbonate of sodium, and resembling that found under Central
Essex, and possibly any little flow that existed of this water was in the direc-
tion of Barking. The water level in these wells, however, had fallen with
such extraordinary rapidity during the last two years that it could not be long
before the pressure from the Thames side would make itself felt by the influx
of calcium and magnesium salts, since the chalk near the Thames was
admittedly infiltrated with river water. This over-pumping from the chalk in
the South of Essex was likely to have very serious consequences, for the con-
tinued depression of the water level below that of the sea will lead to infiltra-
tion of sea water on the east and of tidal water on the north and south.