OF ENGLAND. 15 



Hills, in the Bath oolite and lias series ; the head 

 spring is 340 feet above the ordnance datum ; the 

 perennial flow of the Thames is spring water. Some 

 portion of the bed and banks are muddy ; but by far 

 the greater length of the river's banks, and bed, is 

 gravel, rock, clay, and marl. The length from the 

 source to the estuary is 201 miles ; the area is about 

 5,162 miles, of which, the area, above Hampton, 

 there is 3,676 square miles. The Thames' main 

 stream has 61 mills upon it, and upon fourteen other 

 tributaries, 299 mills. It is now navigable from the 

 estuary nominally to Lechlade, but practically not 

 beyond Oxford. Many of the weirs and locks are old 

 and in a ruinous condition, from decay and neglect. 

 The rude and antiquated mode of working the navi- 

 gation by ' flashes/ still prevails, and is highly inju- 

 rious. Some of the weirs retain a head of water, so 

 as to prevent land-drainage, and permanently to 

 waterlog large areas of agricultural land on both 

 margins of the river. At Oxford the suburbs and 

 even urban portions of the city are at times seriously, 

 and as regards the health of the inhabitants, danger- 

 ously, flooded by reason of the impediments offered 

 to the free flow of the flood water, by Sandford and 

 other weirs, etc." 



The area above Oxford appears to be about 600 

 square miles, and is about fifty miles above Hampton, 

 "with a population of 71,520, having three towns 

 with a population of 2,000 and over." " Whereas 

 above the point at which the pumps are placed at 

 Hampton, there is a population of 900,000, within an 

 area of 3,676 square miles, and eighty-nine towns with 

 a population of over 2,000 each." 



" The weirs above Oxford are very similar to the 

 rymer locks, fixed with movable tackle, called flash- 

 boards, overfalls, and ground gates ; in times of flood 

 the whole apparatus can be removed." 



