rTi\r,K WATKU i\ nr.iJTs. 3 



margin can see the bottom at the central part, and on inquiring 

 of Mr. Francis he kindly tells me that " the greatest depth that 

 can be felt by means of a pole is about 18 feet below the water- 

 surface. From this deptli the fissures seem to extend downwards 

 at a considerable angle with the vertical." 



"We have no reason to expect any great thickness of Alluvium in 

 this part of the valley of the Lea ; but, on tlie other hand, we have 

 every reason to expect a very slight thickness close to the edge, as 

 at this site, and it would follow therefore that the greater part of 

 the depth to the Chalk at the spring is taken up by the gravel 

 which underlies the Alluvium throughout. This gravel is highly 

 permeable, perhaps one of the most permeable deposits that we 

 have : it is saturated with water along the whole channel, and 

 is most likely in communication with the river at many places. 

 It seems to me therefore that to dry the Chadwell Spring implies 

 drying the Lea. 



(The above remarks are left as written, with a slight verbal 

 correction. They show the danger of being too sure in such cases, 

 for the Chadwell Spring has since failed so far as water-supply is 

 concerned, though the Lea has not ceased to flow.) 



That there have been great fluctuations in the yield of the spring 

 is certain, as may be seen from tables of gauging, brought before 

 the aforesaid Commission by Mr. Francis, which show that the 

 average daily discharge in weekly periods, from January, 1889, 

 to March, 1892, has varied from 4,698,000 gallons in March of 

 the former year, down to less than a tenth of that amount (450,000 

 gallons) in September and October of 1891. The yield reverted 

 again to very nearly the former figure (4,644,000) in March, 1892, 

 and the figures show many fluctuations. These differences are 

 explained as due to seasonal variations. 



It should be remembered that the spring is simply the overflow 

 of water from the Chalk, forced up through the gravel, etc., and 

 that its discharge is a natural one, unaided by pumping. When 

 the spring lessens in volume so also does the water in the river. 



Chadwell Spring has another peculiarity, in that its water 

 becomes very cloudy soon after a considerable amount of rainfall. 

 On the last occasion that I saw it one could not see anything 

 eighteen inches below the surface, whereas generally in Chalk 

 springs one can see several feet down, indeed to the bottom in any 

 but the deepest springs. 



I believe that it has been suggested that this cloudiness is due to 

 the muddy water, from the clay-slopes, that finds its way into the 

 swallow-holes near Korth Mimms, which has been thought to flow 



