This famous river is navigable up to Welshpool, a distance of 155 miles by water, from the mouth of the Bath Avon river. The extreme branch of this river may be traced for about 45 miles above Welshpool, to Plinlimmon Hill, and numerous other branches extend for great distances into the country on both sides. The whole of this great length of navigation was, till lately, unimproved by art, the river having no locks, weirs, or other erections throughout its whole length, for surmounting the numerous shallows and irregularities which the current over variable strata had formed in its bed. The first or lowest 42 miles of this river, extending to the city of Gloucester, are very wide for a great part of the way, and have a most rapid tide; but the last 28 miles are so crooked, that ships are said to be often several days in passing it; on which account, a ship canal, calculated for vessels of 300 tons burthen, was in the year 1793 projected and begun between Gloucester and Berkeley, of 18¼ miles in length, for avoiding these 28 miles of the river. From Gloucester to Worcester the distance is 30 miles by the course of the stream, the rise in this length being 10 feet, or at the rate of 4 inches a mile; from Worcester to Stourport the distance by water is 13 miles, and the rise 23 feet, or at the rate of 1 foot 9 inches per mile; from Stourport to Bridgnorth it is 18 miles, and the rise 41¾ feet, or 2 feet 4 inches per mile on the average; and from Bridgnorth to the new town at the junction of the Shropshire canal, called Coalport, the distance is about 7 miles, and the rise about 19 feet, being a rate of about 2 feet 8 inches per mile. William Reynolds, the founder of Coalport, caused an account to be daily registered of the depth of the stream in the bed of the Severn at that place, between the 7th of October, 1789, and the 23rd of December, 1800, of which Mr. Telford has given the particulars, except on twelve occasions when the river had overflown its bounds and covered the usual marks (on Sundays during some part of the time), the intervals of frost in which the river was frozen over, and for three short intervals, when, unfortunately, the experiment was by some accident suspended. During all the months of January, in the above period of eleven years, ending the 6th of October, 1800, the river does not appear to have exceeded the depth of 16 feet, that being the greatest depth at any time recorded; and several times, when no depths are inserted to the great floods, it is stated in the table that the water was above all the marks. Besides these, there were thirty-two smaller floods, or times when the water had risen, and was falling again for some days after; the highest of these had a depth of 13 feet (5th January, 1790), the lowest 4 feet, and the mean of the whole of these floods is 7½ feet. In the months of February there were two of these overflowings, one of which (11th February, 1795) followed a frost and continued for five successive days: nineteen floods, the two highest of which were equal (17th and 20th February, 1799) to 12 feet.
The Witham.
On the Witham, for a distance of thirty miles, between Boston and Lincoln, the river is practically a canal. The tide is stopped by a sluice at Boston, and a weir and locks had to be constructed at Bardney and Lincoln. The inland water is held up to a constant height on the sill of this sluice by penstocks, for the purposes of the navigation. The navigation having been taken over by the Great Northern Railway Company, the works are maintained in efficient condition; but the obligation imposed by the original Act of holding up the water seriously affects the drainage. The river Slea, from Sleaford to the Witham, was made into a canal in 1792. The navigation on this river having almost entirely ceased, the company was dissolved by an Act of Parliament. The Bane, another affluent of the Witham, was also canalised, forming a navigation from the Witham to the town of Horncastle; but the dues obtained are insufficient to maintain the works in proper order.
The Nene and Ouse.
On the Nene, which is canalised from Peterborough to Northampton, the navigation is reduced to a few barges. The constant floods on this river are ascribed in a great measure to the defective condition of the works. The proprietors of the navigation, on whom was cast the duty of maintaining the river, no longer have the funds, and there is nobody to take their place. The same thing has occurred on the Ouse between Earith and Bedford.
On some of the affluents of these rivers, which, under legislative powers granted last century, had been converted into “navigations,” the proprietors have obtained Acts of Parliament relieving them of their rights and liabilities, and there is now no jurisdiction over these rivers, or anybody responsible for removing shoals or cutting weeds. The beds of these streams have consequently become shallow, and they are no longer capable of acting as efficient arterial drains. Thus, on the Ivel, an affluent of the Ouse, the navigation trust, created in the reign of George II., was abolished in 1876. The river is said to have since diminished one-half in width, and one-half in depth, and the bottom is being gradually raised to the level of the land. In like manner, the Lark, another canalised affluent, has almost entirely silted up since the navigation of the river ceased. The Ouse itself, above Earith, is obstructed by numerous shoals, and an enormous growth of weeds. These were originally kept down by the constant passage of the vessels, and the shoals were removed by the trustees of the navigation.
The Tees.
The improvements that have been carried out for the purpose of opening up the navigation of the river Tees, although less considerable than those carried out for some of the larger rivers of Great Britain, are yet entitled to take rank as among the most notable river engineering achievements of the century. They are also among the most recent. It was not until 1852 that the Act was passed creating the Tees Navigation Commission. At that time there were three or four channels in the estuary, all of them very shallow. The shifting sandbanks caused great trouble and not a little danger to navigation, and the depth of water near to Middlesbro’ did not admit of the passage of vessels of large size. Since then, about twenty miles of low water training walls have been erected for the purpose of confining the navigable channel. The volume of water and its scour have thereby been much increased. The river has been continuously dredged in order to secure a depth of water that would allow of the passage of vessels of large tonnage into the Middlesbro’ Docks. About 23 million tons of material have been dredged from the bed of the river, and the channel has been generally straightened and widened. Breakwaters have been constructed on both sides, one of them, called the North Gare, being about two miles and a half long. A remarkable feature of the work is that these breakwaters have been constructed of slag, obtained from the blast-furnaces in the neighbourhood. Some millions of tons of slag have been employed in this way, the ironmasters having paid to the Conservancy Commissioners a small sum for removing the slag, the disposal of which had been a great source of difficulty previous to this application.
As a result of the works that have been carried out for the improvement of the navigation of the Tees, the shipping trade of the river, and especially of the port of Middlesbro’, has greatly increased. The main element in this development has been the growth of the iron industry; but the second element has undoubtedly been the increased facilities for navigation. The popular impression about Middlesbro’ is that only a single house stood in 1830, where there is now a busy town of more than 70,000 inhabitants. This may or may not be a legend, but there is no doubt about the fact that in 1850 there were only from two to three feet of depth on the bar of the Tees, where it was possible to wade across at low water; whereas now there is about 20 feet of water, and a harbour of refuge has been provided in which ships can ride in safety whatever the condition of the usually stormy seas outside.