The general structore or Cornwall renders it most ac cessible in its southern shores, but the great and neces sary intercourse with Wales has promoted attempts at a more direct intercourse by the northern side. The Heyl river is navigable some distance front St. Ives Bay. A rail-road has been constructed, five miles from the har bour of Portreth, to the mines near Redruth. The harbour of Padstow, or Camel river, has a navigation eight miles to Wade Bridge, where the Polbrook canal commences, (37th George III.) and continues five miles near Bodmin. The engineers were Messrs. Rennie and AIurray. There have been other abortive attempts, as that of Edmond Leach, in 14th George III. ; again, in 1795, for a canal from Bude I laven to the Tamer ; also of Lord Stanhope, in 1793, from the same port to Hots worthy and flatherbigh, in Devonshire. In 1775, a good deal of money was expended near S'. Coluinb, on a nar row canal, but the scheme was abandoned.
On the Devonshire coast there is a natural navigation from the sea, up to Biddeford and Barnstaple, and barges proceed some miles higher.
In Somerset, between the limestone range of Mendip and the red ground in the south of the county, vve have, as usual in that situation, a deep flat, occupied by a bog of peat, which from a very early period has been a field for drainage and navigation. The ridge called the Pol der' Hills, nearly divides this flat into two equal parts, the waters of which pass hy different courses to the sea. On the south side, the Tone and Parret rivers, uniting at Borough Chapel, pass to Bridgewater, which is accessi ble to ships, and from thence pursue a winding course of 10 miles to the sea at Bridgewater Bay. The Tone river is navigable to Taunton, 16 miles above Bridge water, and the Parret to Langport, where thc Ilchestcr and Langport canal (35th Geo. III.) proceeds seven miles to Ilchester. The acts for the Tone and Parret navigations, are 10th and llth William III. 6th Anne, and 44th George III. On the northern side of the Pol den Hills, that part of the level drains by the rivers Brue and Axe ; the latter river has been improved (42d George III ) and is navigable from the Lea, 11 nines, to Axe bridge. See Dugdale; also ilgricultural Report of So merset.
Various projects have been formed for a communi cation across this country, between the Bristol and Eng lish Channels. The transport of coals from South Wales, instead of round the Land's End, has been the principal object. In 1769, a survey was made by James Brindley ; and again, by an act of the 36th George III. for the grand western canal. It was proposed to pass by Taunton, Wellington, and Tiverton, to Exeter, through the great seat of the woollen manufactures. Another project by
Brindley, was by Langport to Axeminster, on the Axe ; but none of these projects have been carried into ef fect.
Leaving these proposed canals, We pass to the river Avon, the root of an extensive navigation, both natural and artificial. From the Severn we proceed by this river, between lofty limestone cliffs, eight miles to the new ba sin at Clifton, with a tide which rises upwards of 30 feet. In 1805, an act of parliament was obtzined tl improve the port of Bristol ; in consequence of which ship locks were constructed adjacent to the hot wells, by wnich the portions of the Avon and Frome which entered the city were converted into extensive floating docks, for vessels of the largest dimensions. A new river course was cut through Radcliff Ieads, into which the river falls over a regulating weir, and is crossed by two iron bridges, each 100 feet span. The engineer for these improve ments was William Jessop.
Above Bristol the Avon continues navigable by locks, for about 20 miles to Bath, where the Kennet and Avon Canal commences, and forms a thoroughfare to the river Thames, with a variety of ramifievicns; which we shall now proceed to describe.
This canal commences in the Avon, a little above the old bridge of Bath, and thence proceeds- It was originally proposed to pass the summit by a tun nel 5000 yards in length ; but this was changed for a steam engine and four locks on each side the summit. The canal is 44 feet wide at the surface of the water, which is about five feet deep. The locks are 80 feet long and 14 wide. There are two considerable stone aqueducts over the Avon. The rugged nature of the county has rendered this canal difficult and expensive. The engineer was John Rennie. The acts are-34th, 36th, 38th, 41st, 45th George III.
From this canal branches off- 1. The Somerset coal canal, for narrow boats, for opening the coal field between the Mendip Hills and the Avon. From Dundas aqueduct to Milford two miles is level ; from this point the northern branch passes eight miles to Paulton engine, rising 138 feet by nine locks. The southern branch has nearly the same length and rise.
2. The Dorset and Somerset canal, or Stour and Avon, by 36th and 43d George III. branches from the Kennet and Avon at Widbrook, near Bradford, passes by Frome, and is intended to proceed by Mineaunton and Stalbridge to thd tideway in the Stour, near Sturnainster. A branch from this canal, of nine miles in length, passes westward from Frome to the collieries of Nettlebridge.