Encyclopædia Britannica, Ninth Edition/Thames

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THAMES, the most important river in Great Britain, has its source in several streams on the Gloucestershire border, the main one having its rise in the parish of Coates, 3 miles south-west of Cirencester. The upper part of the river, until the junction with the Thame near Dorchester, is generally called the Isis, a usage to which Camden per haps gave currency, who derives the word Tamesis or Thames from the junction of the names of the two rivers, the Thame and Isis. The total length of the river from Thames Head to London Bridge is 170 miles, and to Sheerness 228 miles. It drains an area of 6100 miles. It be comes navigable 24 miles from its source, near Lechlade, its waters having been greatly augmented by the junction of the Colne, Leach, and Churn; here also is the junction with the Thames and Severn Canal. The height of its source above sea-level is 370 feet, and that of the stream at Lechlade 250 feet, the average fall between Lechlade and London Bridge (146 miles) being 21 inches per mile. The course is remarkably equable throughout. Above Teddington, 19 miles from London Bridge, the tidal wave may be said to cease, and thence up to Lechlade naviga tion is carried on by the aid of locks. A small steamer plies as high as Oxford. While at Lechlade the daily flow of the ordinary summer level is about 100 million gallons, the flow at Teddington is about 380 million gallons. There are seven hours of ebb tide and five hours of flow tide. From the Nore to London Bridge, a distance of 40 miles, the tidal wave travels in two hours, and in other two hours it reaches Teddington. The width of the river at Ted dington is 250 feet, and at London Bridge the width at high tide is 800 feet, the depth being 30 feet, while at low tide the width is 650 feet and the depth 12 feet. Large barges can ascend the river 150 miles above London Bridge, vessels of 200 tons as high as the bridge, and of 400 tons to the Pool, below which, at Irongate and St Katherine's wharf, deep-sea steamer navigation commences, while vessels of any tonnage can come as high as Deptford.

The Thames leaves the Gloucestershire and Wiltshire border near Btiscot, after which it separates successively Berks and Oxford, Berks and Bucks, Middlesex and Surrey, and, finally, at its estuary, Essex and Kent. Below Lechlade it has a winding course, passing near Farringdon and Bampton. After receiving the Windrush, it passes near the grounds of Blenheim, whence it receives from the left the Evenlode, and at Oxford it receives from the left the Cherwell. It then flows in a southerly direction to Abingdon, where it receives on the right the Ock from the valley of the White Horse, and has a junction with the Wilts and Berks Canal. Turning in an easterly direction it is joined, about a mile after passing Dor chester, by its principal affluent the Thame. Thence, through an opening of the Chiltern Hills, it passes Bensington, and turns southwards by Wallingford and Reading, where it receives the Kennet from the right. It then bends northward to Henley, east ward to Great Marlow, and southward to Maidenhead, where it receives from the right the Loddon. Winding in a-eouth-easterly direction it passes Eton, Windsor, Datchet, Staines, and Chertsey, receiving at Staines the Colne from the left. Flowing through the grounds of Hampton Court it reaches Kingston and Teddington, where its bulk is increased by the tidal wave. From Richmond, where it receives the Mole, it begins to pass the villas and suburbs of London. At Gravesend, 27 miles below London, it has a width of half a mile, and at the Nore lighthouse, 50 miles below London Bridge, the estuary widens to nearly 10 miles. In the tidal reaches the principal affluents of the Thames are the Mole at Richmond, the Brent at Brentford, the Wandle at Wandsworth, the Lea at Blackwall, the Roding at Barking Creek, the Ingrebourne at Rainham, and the Medway at Sheerness. The land adjoining the river is greatly subject to floods, and from above London there were in ancient times wide stretches of marsh land covered by shallow lagoons. The embankments below London Bridge date possibly from the time of the Romans, but their origin is the subject of much dispute (see London, vol. xiv. p. 840). Between London Bridge and Chelsea the bed of the river has been altered artificially, and flooding is prevented by a marine wall (see London, vol. xiv. p. 823). The Thames occupies the bed of a much larger prehistoric river, the gravels of which adjoin its banks at a considerable distance.

The scenery, though scarcely to be called picturesque, and in a certain sense monotonous, has a peculiar charm from the richness of its sylvan beauty and its pleasant alternation of hill and dale. The number of islands that occur in the course of the river add to its interest, and afford convenient seclusion for the erection of boathouses and tents. The Thames vies with the Tyne as the principal river for boat-racing in England, and of course greatly surpasses the latter river as regards amateur boat-racing, the principal fixtures in which are the Oxford and Cambridge boat race and the Henley regatta. The river affords about one half of the water supply of London, and is the principal outlet for its sewage. It is under the government of conservators, originally constituted in 1857, but their duties have been extended by several subsequent Acts.

See The River Thames from Oxford to the Sea, 1859; Cassell's Royal River (richly illustrated), 1885; Huxley's Physiography. 1877; and JDickens's Dictionary of the Thames.