Clyde (Welsh Clwyd, ' strong'), a world-famous river and firth of south-west Scotland. The river rises as Daer Water at an altitude of 1600 feet, and runs 106 miles northward and north-westward, round Tinto Hill (2335 feet), and past Lanark, Bothwell, Glasgow, and Renfrew, till at Dumbarton it merges in the firth. Its drainage area is 1481 sq. m., of which 111 belong to the South, North, and Rotten Calders, 127 to the Kelvin, 200 to the Black and White Carts, and 305 to the Leven and Loch Lomond. Tributaries higher up are Powtrail Water, Little Clydes Burn, Douglas Water, Medwyn Water, Mouse Water with its deep gorge through the Cartland Crags, and, near Hamilton, the Avon. In the four miles of its course near Lanark the river descends from 560 to 200 feet, and forms the four celebrated Falls of Clyde - Bonnington, Corra, Dundaff, and Stonebyres Linns, of which the finest, Corra, makes a triple leap of 84 feet. Above the falls the Clyde is a beautiful pure trout-stream, traversing pastoral uplands; below, it flows through a rich fertile valley, here broadening out into plain, there pent between bold wooded banks. But its waters become more and more sluggish, begrimed, and polluted, the nearer they get to Glasgow. Since 1765 upwards of ten millions sterling has been expended on rectifying and deepening the channel from Glasgow to Dumbarton, no less than 40,000,000 cubic yards of materials having been lifted by steam-dredgers during 1844-1905. The result has been that whereas ' a hundred years ago there was a depth at low-water of 15 inches, now they have at Glasgow from 18 to 20 feet at low-water;' and that whereas even lighters could once 'not pass to and from Glasgow except it be in the time of flood or high-water at spring-tides,' now a steamer has been docked at Glasgow that is second in size only to the Great Eastern. In 1812 Henry Bell launched on the Clyde the first boat in Europe successfully propelled by steam; and since then the river's shipping and shipbuilding (the latter dating from about 1718) have both grown enormously. - The Firth, which some make begin at Glasgow (the highest point of the tide), and some not until Gourock, extends 12 miles westward and 52 southward, and broadens from 1 mile at Dumbarton to 1 3/4 at Dunoon, and 37 at Ailsa Craig. It sends off the Gareloch, Loch Long, Holy Loch, and the Kyles of Bute; contains the islands of Bute, Arran, and the two Cumbraes; is bordered along its ancient sea-margin with an almost continuous fringe of seaports and watering-places (Greenock, Rothesay, Ayr, etc.); and, like the last 14 miles of the river, is one of the world's chief commercial water-ways. See works by Deas (1881-87), Millar (1888), and Pollock (new ed. 1893).