In respect to navigation, the Severn has long been of very great Importance. It supplies the means of transporting the produce of mines and manufactories of various descriptions lying in the vicinity of the river to the sea, to North Wales, and the towns and remote districts of the counties through which it flown. Along the greater part of its course the use of the Severn as a navigable river has been impeded by fordo and shoals, and by the deficiency of water in drought, and the superabundance of it during rainy seasons. The whole of the Severn navigation, extending upwards of 160 miles, is free from toils.
The commercial importance of the Severn has been much Increased by its connection with several canals, which are here enumerated:— the Stroudwater Canal, which commences at the Severn near Fremi load, between Gloucester and Newnhem, and terminates hi the Thames and Severn Canal, thus uniting our two greatest navigable rivers; the Gloucester and Berkeley Canal, which shortens the navigation from the Severn near Berkeley, to Gloucester ; the Gloucester and Ledbury Canal ; the Worcester and Birmingham Canal ; the Dreitwich Canal, which runs along the valley of the Salwarpe; the Staffordshire and Worcestershire Canal, which commences at Stourport, on the Severn, and, following the course of the Stour, the Birmingham and Junction Canal; the Shropshire Canal, which with its is used for transporting the produce of the manufacturing district of Coalbrookdale to the Severn, which it joins at Coalport ; the Shrewsbury Canal, originally formed to convey coal to that town from Ketley in Shropshire, and slue* extended by a branch through Newport to the Birmingham and Liverpool Junction Canal before mentioned ; and the Worcester and Birmingham Canal. The Mont gomeryshire Canal commences in the Severn at Newtown, and pandas Welshpool, oommunicatal with a branch of the Ellesmere Canal, but as the Severn is not navigable as high as Newtown, this canal can !meetly be included as one of the connecting links in the Severn navigation.
The fish found in the Severn are salmon, shad, lampreys, roach, dace, gudgeon, bleak, Bounden, eels, lamperna, elvers, chub, carp, trout, grayling, tench, and perch. Salmon were formerly plentiful, but are now scarce, although there are no weirs upon the river to impale the ascent of the fish.
A short distance above the point where the Severn merges in the Bristol Channel, it receives the Wye, which, although Inferior in its size and the length of its course to the Severn, is ranch superior in point of picturesque scenery. The Wye has its gourds on the border of Montgomeryshire, and on the mountain of Plinlimmon, about 2 miles south-west from the source of the Severn. Taking • south-east direction, it receives a number of little tributaries, and quite Mont gomery:111ra and eaten Radnorshire between the village of Llangerig and the town of Rhayader, at the distance of 18 miles from its source. Its course through Radnorshire la in a generally southern direction, and will be found described under that county. At Glasbury the river inclines to the north, but ou entering HEREFORDSHIRE flows south-east. The river is navigable from Hereford, and indeed in the whiter, and whenever there is a depth of water, barges ascend to within a short distance of Hay, for the conveyance of timber, &c. For a short distance the river divides Herefordshire first from Glouces tershire, and subsequently from Meemouensruaz, and then enters the latter county, under which its further course will be found described.
The spring-tides at Chepstow rise to a great height. [Cuerseow.] The length of the coarse of the Wye is about 130 miles. Its scenery throughout is almost without n rival among the rivers of Great Britain.
Owing to the isthmus or neck of laud above the mouth of the Wye, and the projection of Anst Cliff on the opposite shore, the width of the Severn is here only one mile, while higher up, as was before stated, it expands to between two and three miles. At this narrow part of the ,estuary is the principal passage, called Aust Ferry, or Old Passage, from Somersetshire to Monmouthshire and South Wales. About four miles lower down is the New Passage, which is considerably wider, and not so much frequented.
Tho [estuary of the Severn receives the drainage of about 5900 square miles, namely :—the Severn, 4500; the Wye, 1400. The Severn I. charged with a larger amount of turbid sediment than any other river in Europe, the result of Its own long course and the courses of its tributaries through tracts of marl and soft atudstone. This fine sediment is in some places deposited on its banks towards the mouth, and the quantity thus deposited is increased by artificial means. The mud is encouraged to accumulate upon lines of pile and osier, which, as the tide retreats, retain the sediment. Upon these, other lines of osier-fencing are placed, until new laud is raised to a considerable height. On the other hand, the sudden rising of the tides has occasioned great damage to the low lauds, to guard against which sea-walls, piles, and other precautionary means have been adopted. The Inundation, in the years 1606, 1687, 1703, and 1737, are recorded to have producedgreat devastation.
The Bristol Channel, commencing with the sestuary of the Severn, separate. Monmouthshire and South Wales from the counties of Somerset and Devon, and terminates In St. George's ChanueL Its width from King's Road, the mouth of the Lower Avon, to the opposite coast, is about 5 miles. It then rapidly widens to about 12 miles, but is again slightly contracted between the southern point of Glamorganshire and the western part of Somersetshire. It again expands, forming, on the Wash coast, Swansea and Ceermarthen bays, and, on the coast of Devonshire, Barnstaple, or Bideford Bay. The width at its termination in St. George's Channel, taken from St. Gowan 'e I lead on the coast of Pembrokeshire to Hartlaud Point in Devonshire, is about 40 miles. The coast-line, both on the Welsh and Devon shire sides, is extremely irregular. Lundy Island [DevoNenina], and Caddy Island [Prmnnoessanix], are noticed elsewhere. From Hart land' Point to King's Road is about 90 miles; it appears that the tide travels over this distance In about an hour and a half. The tide increases as It advances. At Chepstow the tide rises 43 feet higher than at Lundy Island.
The ' bore' which enters the Severn 1,10 feet high, and is produced, as in other places, by tho depth and quantity of water on the inland ride not allowing the surface there to be immediately raised by means of the transmitted pressure. The greatest velocity of the tidal current through the 'shoots,' or New Passage, is 14 miles an hour. This occurs lower down two hours after high-water, but as tho Severn is approached the difference of time is diminished, according to the general observations on till,' subject.