a river of England, which rises near Plinlimmon Hill, in Montgomeryshire, and before it enters Shropshire receives about thirty streams, and passes down to Llandrindod, where it receives the Morda, that flows from Oswestry. When it arrives at Monford, it receives the river Mon, passing on to Shrewsbury, which it almost surrounds, and then to Bridgeworth; afterwards it runs through the skirts of Staffordshire, enters Worcestershire, and passes by Worcester; then it runs to Tewkesbury, where it joins the Avon, and from thence to Gloucester, keeping a northwesterly course, till it falls into the Bristol Channel. It begins to be navigable for boats at Welchpool, in Montgomeryshire, and takes in several other rivers in its course, besides those already mentioned, and is the second in England. By means of inland navigation, it has communication with the rivers Mersey, Dee, Ribble, Ouse, Trent, Derwent, Humber, Thames, and Avon; which navigation, including its windings, extends above five hundred miles in the counties of Lincoln, Nottingham, York, Lancaster, Westmoreland, Chester, Stafford, Warwick, Leicester, Oxford, and Worcester. A canal from Stroudwater, a branch of the Severn, to join the Thames, was projected and executed for the purpose of conveying a tunnel sixteen feet high and sixteen feet wide, under Sapperton Hill and Hayley Wood, for two miles and a quarter in length, through a very hard rock, which was lined and arched with brick. This stupendous undertaking was completed, and boats passed through it the 21st of May 1789. By this opening a communication is made between the river Severn at Framilode and the Thames near Lechlade, and is continued over the Thames near Inglesham, into deep water in the Thames below St John Bridge, and so to Oxford and London, for conveyance of coals and goods.