THAMES (Lat. Tam-esis; the root tam probably meaning broad, and esis or iris, being identical with esk, ex, ouse, etc., all from Cel. uisg, water), the most important river of Great Britain, and the longest in England, flows e.s.e. across the s. portion of the country. Its remotest springs—those of the upper waters of the Churn—rise on the s.e. slope of the Cotswold hills, 3 m. s. of Cheltenham, and 7 m. w. of the Severn at Gloucester. The springs unite about a m. from their sources, and form the Churn, which flows s.e. 20 m. to Cricklade, and there receives the Thames, which joins it from the w. after a course of 10 miles. The Thames, or Isis, then flows e.n.e. for about 35 in., when, curving s.e., it passes Oxford, and flows on to Reading, where, after receiving the Kennet from the w., it again changes its course; and with a generally eastward course, it passes Windsor, Eton, Richmond, London, Woolwich, and Graves end, a few miles below which it expands into a wide estuary, and enters the North sea. The length of the Thames is estimated at 250 m., the area of its basin at upward of 6,000 sq. miles. Throughout the greater part of its course, it is of importance as form ing the boundary-line between several of the southern counties. Passing Cricklade, it forms part of the northern boundary of Wilts, and below this point it separates the counties of Oxford, Buckingham, Middlesex, and Essex on the n. from those of Berks, Surrey, and Kent on the s., except certain outlying bits of some of these coun
ties. Its chief affluents are the Coln, Leach, Windrush, Cherwell, Thome, Colne, Lea, and Roding, on the left; and the Kennet, Loddon, Darent, Mole, and Medway, on the riodu, bank. At Vauxhall bridge, the width of the river is about 230 yards; at London bridge, 290 yards; at Woolwich, 490 yards; at Gravesend pier, 800 yards; 3 m. below Gravesend, 1290 yards; and at its mouth, between Whitstable and Foulness Point, about 8 m. below the Nore, it is 18 m. across. At the Nore Light, the commonly reputed mouth of the Thames, the breadth is 6 miles. The river is navigable for barges to Lechlade, upward of 200 m. above its mouth, and it is connected with the Thames and Severn, Oxford, Wilts and Berks, Grand Junction, and several other important canals, by means of which it maintains free communication with the w. and s. coasts, and with all parts of the interior of the country. Vessels of 800 tons can reach St. Katharine's docks, while those of 1400 tons can ascend to Blackwall, 6 m. below London bridge. The part of the river immediately below London bridge is called the Pool; and the part between the bridge and Blackwell is called the Port. Two embankments have been formed, one on the n. shore from Blackfriars bridge to Westminster, and one on the s. shore from Westminster bridge to Vauxhall. See LONDON.