202 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 i 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 

 Essey, 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. 



