The chief rivers on the north coast are the Torridge and the Taw, the former of which, rising in the extreme north-west, on the Cornish border, near the source of the Tamar, flows south-west for nearly half its course, and then sweeps round to run in the opposite direction, giving its name to three several Torringtons, and having as its chief tributaries the Walden, the Lew, and the Okement, all on its right bank. The last-named stream is formed of the East and the West Okements, which meet at Okehampton, their namesake. The lower waters of the Torridge form a long and narrow estuary--its shore only ten miles distant from the original source of the river--half-way down which is the once important port of Bideford, built on both sides of the stream, which is here spanned by a very ancient bridge. Near the entrance of the estuary, but neither of them on the open sea, are Appledore, the port of Barnstaple, and Instow, a small but growing watering-place. The Taw is a Dartmoor-drawn river, rising, like so many streams, in the Cranmere bog, giving its name to Tawstock and to three several Tawtons, and receiving on its right bank the Yeo, the Little Dart, and the Mole. The most considerable town on it is Barnstaple, beyond which it becomes a broad tidal estuary, joining that of the Torridge, and flowing out into what is known both as Barnstaple and Bideford Bay. [Illustration: Bideford and the Torridge Estuary] Many small streams fall into the Bristol Channel, among which is the Lyn, renowned for its beautiful scenery and its good trout-fishing. A large proportion of the Celtic words in our language are found in the names of natural features, especially of hills and rivers. This is particularly well seen in Devonshire, where, as has been pointed out, the Saxons came as settlers rather than conquerors, adopting many of the names which they found already in use, and where an unusually large number of towns and villages have been called after the streams on which they stand. The names Exe, Axe, and Okement, from the Celtic _uisge_; Avon, Aune, and Auney, from _afon_; Dart, from _dwr_; and Teign, from _tain_, are all derived from roots meaning "water." Other names are taken from descriptive adjectives, such as Wrey, from _rea_, rapid; Lyn, from _lleven_, smooth; and Tamar, Taw, and Tavy, from _tam_, spreading or still.