Xlviii FLORA OF BEEKSHIRE 



navigation on the summit level ; drank it up by means of a steam- 

 engine, which lowered the level of the water-bed in all the adjoining 

 country, so that the natural efflux now takes place half a mile below 

 its former opening. Though diminished and lowered, it still delivers 

 a strong current of sparkling water to a channel almost choked with 

 Avater flowers \ 'Thames Head,' which Leland called ' the very head 

 of Isis,' is only 330 feet above the sea level ; from this point to the 

 Nore the length of the river is 210 miles. For iio miles of its course 

 it forms a boundary for the county of Berks. On the extreme north- 

 west it separates Berkshire from Gloucestershire for about two miles, 

 that is, from St. John's Bridge, where was formerly a priory of Black 

 Canons, near Lechlade to Kelmscott (Kenelmseote^, I Here Oxford- 

 shire takes the place of Gloucestershire, and the Thames separates 

 Berkshire and Oxfordshire from near Kelmscott in the north-west to 

 Henley in the south-east. At Henley, traditionally the oldest place 

 in Oxfordshire, where the river passes under a handsome bridge of 

 Headington stone, Oxfordshire is succeeded by Buckinghamshire, and 

 the Thames continues to serve as a bovmdary between the latter county 

 and Berkshire from Henley to Old Windsor, where Berkshire is in 

 turn displaced by Surrey. During its course of 210 miles the Thames 

 is increased by many tributaries. Some of these enter it before it 

 reaches Berkshire ; the first, therefore, which it is necessary for us to 

 notice is the Cole, a small stream which joins the Thames at its first 

 point of contact with Berkshire. The Cole issues between Chisledon 

 and Idstone from the Chalk hills of North Wiltshire, the streams 

 from which, in time of heavy rain, carry a considerable volume of 

 water across the Upper and Lower Greensand and the Kimeridge 

 Clay, and meet near the county boundary by Hinton Mill ; from this 

 place to the Thames at St. John's Bridge, near Lechlade, a town 

 standing on a tongue of land on the north side of the Thames between 

 the rivers Colne and Leach, the Cole separates Wiltshire from Berkshire, 

 its surface here bei*ng 254 feet above the sea level. From St. John's 

 Bridge to Oxford the Thames receives no stream of any importance 

 from Berkshiie ; but from Oxfordshire it is reinforced by the Charney 

 brook, which drains a portion of flat uninteresting country near 

 Bamptoi^, and by the 'nitrous' Windrush, a stream of considerable 

 charm, the longest affluent of the Thames, which rises like the Thames 

 in the Cotswolds at about 900 feet elevation, and entering Oxfordshire 

 near the old town of Burford, which has a handsome and interesting 

 church, flows by Swinbrook, once the home of the Fettiplaces, and by 



1 Phillips, Geology of the Thames Valley^ p. 26. 



2 The Elizabethan manor house was for some years occupied conjointly by 

 T). G. Rossetti and W. Morris, the latter of whom charmingly describes the 

 place in News from Nowhere. 



