248 E. B. CKOFT ON THE ETVEE LEA BELOW HEKTFORI). 



the Stort flows into the Lea. It consists for the most part of a 

 brown mud or silt, peat or peaty earth also occurring. Hertford is 

 chiefly built on a flat of river-gravel. At Ware and north of 

 Amwell are other similar flats bordering the river, and from St. 

 Margarets southwards is a much broader stratum on an island on 

 which the E,ye House is placed. I have abstracted the above from 

 the Memoir of the Geological Survey on sheet 47 of the map of the 

 Survey, to which valuable and exhaustive work I must refer those 

 who wish further to study the geology of this district. 



Between Hertford and Ponder' s End the Lea is reinforced by a 

 large accession of fresh water from the land- springs which break 

 out from the chalk into the bed of the river. 



The Lea is tidal as far as Lea Bridge, and navigable for barges 

 as far as Hertford, a distance of twenty-eight miles. It has been 

 navigable from time immemorial, and its tidal-reaches were probably 

 embanked at a very early date ; in the reign of Queen Elizabeth 

 the Parliament legislated for the navigation of the river. While the 

 navigation-works on the Thames and other rivers have fallen into 

 ruins through the abstraction of trade by railways and other causes, 

 on the Lea the weirs, locks, and other works are in better order, 

 the navigation is more efficient, and the trade is greater than at 

 any former period. The Stort is navigable as far as Bishop's 

 Stortford, thirteen and a half miles above its junction with the 

 lliver Lea. Two great Water Companies, the New lliver Company 

 and the East London Water Works, supply nearly half of the popu- 

 lation of the Metropolis with water ; 38,000,000 gallons being daily 

 drawn by them direct from the Lea for this purpose, besides the 

 water from various springs in the valley. 



No account of the valley of the Lea would be complete without 

 mention of the New Kiver, the source of which is in the Chadwell 

 springs, half a mile south-west of Ware, but water is now also 

 derived direct from the Eiver Lea, at a point between that town 

 and Hertford. The Chadwell springs vary in volume from 200 

 to 700 cubic feet per minute. Besides the water from the Chadwell 

 springs and the River Lea, the New River Company obtain water 

 from wells and springs at various places lower down the valley. 

 The New River Conduit was commenced by Sir Hugh Myddleton 

 in the reign of James the First. Its length as originally laid out 

 was 38 miles, but by cutting off bends, straightening, and improving, 

 it is now not more than 28 miles. The cross-sectional area is about 

 7o square feet, and the velocity about four-tenths of a mile per 

 hour. The fall is not more than 1 in 10,000, and the flow is 

 checked by gates and sluices ; the bed of the river-conduit is the 

 natural subsoil with clay-puddle when required.* 



* Besides the authorities mentioned in the text I have made use of the following 

 works: — 'Flora Hertfordiensis,' Fuller's 'History of the University of Cam- 

 bridge ' and his ' History of Waltham Abbey,' Holland's ' Camden's Britannia ' 

 (1637 ed.), and the ' Second Report of the Commissioners appointed to examine 

 into the best means of preventing the Pollution of Rivers.' 



