THAMES. The navigation of this most busy of English rivers commences at Lech lade, where the river is about 258 feet above low-water mark at London Bridge. The Thames and Severn Canal, which follows the valley of the Churn and the Thames from near Cirencester, opens into the Thames at Lechlade, thus connecting it with the Severn and the western coat of the island. At Ox ford the Oxford Canal joins the Thames, and opens a communication with the great canal system of the central counties. At Abingdon the Wilts and Berks Canal joins the Thames and, as well as the Kennet and Avon Canal, which joins the Kennet at Newbury (where the navigation of that river commences, 20 miles above its junction with the Thames), opens a communication with the Somerset shire Avon and by it with the Severn. The Theme is navigable from the town of Thame, about 17 miles above its junction with the Thames. The Wey is navigable from Godal ming, about 17 miles from its junction; and is connected with the Wey and Arun Canal, and the Basingstoke Canal, the former of which opens a communication with the river Arun and the Sussex coast. The Grand Junction Canal, which unites with the Oxford Canal at Braunston in Northamptonshire opens into the Thames by the mouth of the Brent, the lower part of which is incorporated with the Canal. Below London Bridge the Lea, which is navigable, chiefly by artificial cuts, for 25 miles, opens into the Thames ; and just above the Lea, the Regent's Canal, which encircles the north and east side of the metropolis, and communicates with the Pad dington Canal, and so with. the Grand Junc tion Canal, also opens into the river.
The Medway is navigable below Rochester Bridge for sea-borne vessels, and from Pens burst, above 43 miles from its mouth, for river craft.
The navigation of the Thames, in its upper part., is kept up by locks and wears, the lowest of which is at Teddington, which is conse quently the limit of the tide. Teddington is about 18 or 19 miles above London Bridge. High-water mark at Teddington is about 1} feet higher than at London Bridge, and the time of high water is about two hours later. Low-water surface at Teddiugton is about 161 feet higher than at London Bridge. At ebb tide there is a depth of from 12 to 13 feet water nearly or quite up to London Bridge, and the rise of the tide is about 17 feet, or at the extreme springs about 22 feet.
Vessels of 800 tons get up to the St. Cathe rine's Docks, and those of 1400 tons to Black wall, about 6 miles below bridge. No other river in the world equals the Thames in its commercial importance. The river for some
2 miles or more below London Bridge is crowded with vessels, chiefly coasters, steam vessels, and colliers, which moor alongside the quays or in tiers in the stream ; others are moored lower down, though not in such num bers ; and for larger vessels there are several excavated on the banks of the Aver.
There is a dockyard for the navy (now litth used) at Deptford, about 4 miles below Lon don Bridge ; one at Woolwich, 9 miles below one at Sheerness, in the Isle of Sheppy, at the junction of the Thames and Medway; and one at Chatham, the most important of the four, on the Medway. The fortifications al Sheerness defend the entrance to both rivers ; the passage of the Thames is further protected by Tilbury Fort, and that of the Medway by Gillingham Fort.
Among many engineering schemes for im proving the banks of the Thames within the limits of the metropolis, is the following by Mr. W. IL Smith :—It is proposed that a ter race, about 12 feet above high-water mark, designed exclusively for the public, and with out any landing places except for passengers, should be carried along the banks of the Thames. The width of the esplanade is to be GO feet, having a parapet and open railing on the side next the river ; thus offering a clear view of the general traffic, but at the same time, by means of the parapet, securing the operations of commerce beneath. This espla nade is connected immediately by carriage approaches with the bridges and main tho roughfares. Where the width of the river is sufficient to admit the space required, it is proposed there should be lines or colonnades of handsome shops, dwellings, or warehouses, according as the situation might require. The goods' traffic of the river is conveyed by trans verse arches beneath, descending to within a foot of high water, which are connected with the property of the wharfs and warehouses on the inner side, the river traffic being thus carried on unimpeded and almost invisibly. Immediately beneath is a railway tunnel, in the base of which the required culverts for pure water, gas, rain water, and sewage, would be formed at about low-water mark. It is proposed that the sewage should be entirely cut off from the river, passed longitudinally under the embankment by means of an iron culvert, and carried into the marshes on the southern side of the river beyond the influence of the tide. The probable expense of this great undertaking, extending from Vauxhall to the West India Docks on the north, and from Vauxhall to Deptford on the south, Mr. Smith estimates at about 3,000,0001.