The towns of Manchester, Kidderminster, and Southampton have been partly tunnelled under by the Bridgwater, the Stafford and Worcester, and the Southampton and Salisbury Canals respectively.
E & F N Spon London & New York “INK-PHOTO.” SPRAGUE & CO. LONDON.
DUDLEY TUNNEL ON THE BIRMINGHAM CANAL
(SHOWING MEN IN POSITION FOR “LEGGING”)
There are several long tunnels on the Birmingham Canal system, having an aggregate length of 6¼ miles. Two of these—the Dudley Tunnel and the Netherton Tunnel—pass under the Rowley Hills, and are each about two miles in length. The former was constructed in the last century. The waterway is about nine feet in width, and there is no towing-path, the boats being propelled by two men, lying on their backs on the boat, their feet performing a sort of walking motion against the sides of the tunnel, this is called “legging.” The Netherton Tunnel was constructed in the year 1858; it has a waterway 17 feet in width on either side. Both of these tunnels have, from time to time, been seriously injured by mining operations, and in the case of the Netherton Tunnel, the injury is stated to have been caused by the mine-owner illegally working minerals that had been previously purchased by the canal company. ([See illustration of Dudley tunnel].)
Viaducts.
Sir Walter Scott spoke to Southey of the viaduct on the Ellesmere Canal as the most impressive work of art he had ever seen. This viaduct is situated about 4 miles to the north of Chirk, at the crossing of the Dee, in the romantic vale of Llangollen. The north bank of the river is very abrupt; but on the south side the acclivity is more gradual. The lowest part of the valley in which the river runs is 127 feet beneath the water-level of the canal; and it became a question with the engineer, whether the valley was to be crossed, as originally intended, by locking down one side and up the other which would have involved seven or eight locks, or by carrying it directly across by means of an aqueduct.
The aqueduct is approached on the south side by an embankment, 1500 feet in length, extending from the level of the waterway in the canal until its perpendicular height at the “tip” is 97 feet. Thence it is carried to the opposite side of the valley, over the river Dee, upon piers supporting nineteen arches, extending for a length of 1007 feet. The height of the piers above the low water in the river is 121 feet. The lower part of each was built solid for 70 feet, all above being hollow, for the purpose of saving masonry as well as ensuring good workmanship. The outer walls of the hollow portion are only two feet thick, with cross inner walls. Upon the top of the masonry was set the cast iron trough for the canal, with its towing-path and side rails, all accurately fitted and bolted together, forming a completely watertight canal, with a waterway of 11 feet 10 inches, of which the towing-path, standing upon iron pillars rising from the bed of the canal, occupied 4 feet, 8 inches, leaving a space of 7 feet, 2 inches for the boat. The whole cost of this part of the canal was 47,018l., which was considered by Telford a moderate sum compared with what it must have cost if executed after the ordinary manner. The aqueduct was formally opened for traffic in 1805. “And thus,” says Telford, “has been added a striking feature to the beautiful vale of Llangollen, where formerly was the fastness of Owen Glendower, but which, now cleared of its entangled woods, contains a useful line of intercourse between England and Ireland; and the water drawn from the once sacred Devon furnishes the means of distributing prosperity over the adjacent land of the Saxons.”
The Barton Aqueduct on the Bridgwater Canal, is about 200 yards in length, and 12 yards wide, the centre part being sustained by a bridge of three semi-circular arches, the middle one being of 63 feet span. It carries the canal over the Irwell at a height of 39 feet above the river—this head room being sufficient to enable the largest barges to pass underneath without lowering their masts. The bridge is entirely of stone blocks, those on the faces being dressed on the front, beds, and joints, and with cramped iron. The canal, in passing over the arches, is confined within a puddled channel to prevent leakage, and is in as good a state now as on the day on which it was completed.