On the southern coast of Devonshire, from Start Bay, near Dartmouth, the tide flows up the river Dart about 10 miles to the town of Totness.
At Plymouth, the various arms of that excellent har bour accommodate a considerable traffic ; and north of Plymouth a canal was, by an act 43 Geo. III. made from the river Tamer, about 44. miles, to the town of Tavistock, with a rise of 237 feet, and was opened in June 1817. A branch of 2 miles, rising 194- feet, goes to the slate quar ries at MINH Bridge. A tunnel one mile and a half long, has been executed upon this canal, which does great credit to the ingenuity and skill of John Taylor, the en gineer.
The Tamer river is the boundary between the county of Devon and Cornwall. It is navigable from the Ha moaze to near Calstock. At this place the Tamer ma nure navigation, authorized by 36 Geo. III. commences, and was intended to pass along the eastern side of the river for about 22 miles to North Tamerton. There have also been proposals for extending an inland naviga tion from this river to the Bristol Channel.
Along the whole of the southern coast of England, the inland navigations are chiefly employed in importing ar ticles for the supply of the various adjacent districts, particularly coals, and in exporting oak timber and agri cultural produce. From Devonshire are also exported slate,potter's clay, manganese, and the singular substance named Bovey coal.
Severn Diatrict.
The wide estuary of the Severn between Wales and Cornwall, opening to the Atlantic and to Ireland, unfortu nately contains no good port on its shores, excepting Millordhaven. The great rise of tide, however, and the increasing wants of the country, have led to the establish ment of various tide harbours, and, at the mouth of its contributary rivers, towns of considerable commerce have gradually grown up. Caerleon, upon the Uske, though now decayed, was a city of note in the time of the Romans. Gloucester, in the main river, being, in its natural state, too far up for large ships, Bristol, upon the river Avon, became the chief mart for the commerce of the Severn, and although well situated for intercourse with Ireland, the west of Europe, and America, it has of late years !seen outdone by Liverpool. Notwithstanding this, Bris tol contains a population of about 70,000.
The basin of the Severn is richly provided with mines and minerals, which, with the manufactures connected with them, have greatly promoted inland navigation. Cornwall abounds in copper and tin ores, and in slate and porcelain earth. The opposite coast of South Wales possesses coal, ironstone, and limestone, and the working and manufacturing of these create an increasing and ex tensive intercourse. South Wales, also, is the seat of a great proportion of the iron trade. As we ascend the Severn, coal, ironstone, limestone, and lead, continue within its basin, and often upon its yery banks almost to its seurce. The porcelain and potteries of Swansea and Worcester draw their chief supplies from Cornwall and D evon.
The estuary of the Severn at Lundy island, is about 40 miles across ; 60 miles higher, at the.Holmes, it is only 7 miles ; and it is here that the Severn is properly un derstood to commence. The length of its navig..tion from hence to Welch Pool, is reckoned 170 miles; at New Pas sage, 20 niiles above the Holmes,the breadth isnearly tsvo miles ; 18 miles farther up, near Newenham, the river is contracted into a narrow Lhannel, and from thence has a winding course of about 20 miles to Gloucester, where we find the first bridge.
There are no locks nor weirs on this river, and there fore the navigation is frequently interrupted in rainy seasons by flood water, and in dry weather from de ficiency of depth in the fords ; and the inclosing the low lands of Montgomeryshire causes the flood water to run off n-iore rapidly than formerly. The acts of parliament respecting this river are, 19th Henry VII. 23d Henry VIII. 12th, 43d, 49th George The only improve ments under these acts is, the making a horse towing path from Bewdley, by Bridgenorth and the Meadow Wharf, to Shrewsbury. The barges which navigate this river are about 120 feet long, from 16 to 20 wide, and 5 feet deep, carrying upwards of 100 tons. The seven trows are 66 fcet long, 16 wide, and 5 feet deep, carrying 75 tons : thcy are worked by a square sail, with a main and top mast, some of thein 80 feet high. Numerous canals and rail-roads branch off from this fine river into the adjacent rich and productive counties.