Features of the Canals
The Shrewsbury & Newport Canals featured many remarkable structures. The following have been featured in past issues of our quarterly newsletter, S&News.
The Humber Arm
1. Longdon-on-Tern Aqueduct
Longdon-on-Tern Aqueduct is the oldest cast iron aqueduct in the world. That is not to say that it was the first – quite. It is now commonly accepted that a much smaller cast iron aqueduct opened on the Derby Canal some weeks earlier, but that one no longer survives.
The iron aqueduct at Longdon should in fact never have been. Josiah Clowes was engineer for the Shrewsbury Canal and just like most other canal aqueducts built up until that time he designed, and began to build, a substantial masonry structure sufficient to carry its own weight, that of the water and a thick lining of puddled clay to retain the water. Between 10-12 February 1795 however the works were washed away by an abnormal flood but, perhaps fortunately, Clowes had just died.
So, who did the canal company turn to – yes, Thomas Telford. He was appointed on 28 February 1795 to take over construction of the canal but just 14 days later the company approved the erection of an iron aqueduct at Longdon by William Reynolds & Co., the cost not to exceed £2000. It was stated that the plan was to be approved by Telford and, although often attributed to him, it seems unlikely that the idea was actually his. Indeed he himself later wrote that the idea was that of Thomas Eyton, chairman of the company, and the design determined by Reynolds and Telford – it does perhaps look as if it was designed by a committee!
The fact remains that the aqueduct was designed and built in very quick time. The iron plates were cast at Ketley and the aqueduct built between the surviving masonry ends of Clowes aqueduct by March 1796. The trough was 62 yards long and 16 feet high – or rather the troughs, as the towpath ran in what is virtually a second trough alongside, the horse’s feet being at the same level as the bottom of the canal! Beneath, cruciform-section struts spring in all directions to support the trough.
Even if Longdon was not Telford’s idea, its success certainly gave him the know-how which allowed him to build Pontcysyllte Aqueduct (1007 yards long and 121 feet high – slightly larger!) on the Ellesmere Canal just a few years later.
Today the aqueduct still stands across the Tern but looking rather forlorn without the approach embankments. It is now a listed Ancient Monument. If visiting the site please note that it is on private land and that permission should be sought, although it can be seen from the road to Wellington just outside the village.
It is very unlikely that the original aqueduct could be used again in the restoration. But what an opportunity for a modern day Telford (or Eyton or Reynolds!), to design something equally innovative and spectacular to cross the river alongside. Perhaps in another 200 years that could also be an Ancient Monument!
2. Berwick Tunnel
Berwick Tunnel is the only tunnel on the S&N. It is 970 yards (or for those who prefer such things, 887 metres) long, although originally planned to be slightly shorter with cuttings at each end. The tunnel has finely proportioned portals faced with stone, the keystone being inscribed with the date 1797. The tunnel is brick lined and a slight bend meant that it was not possible to see through. Although of reasonable length the tunnel is fairly shallow and it is likely that if the canal had been built a few years later it would have been completely replaced by a cutting.
Berwick was remarkable for being the first tunnel of any significant length to have a towpath built through it. Even this was unique as it was of timber, carried on bearers set in the wall. The waterway of the tunnel was just over 10 feet (3m) wide. With the towpath projecting 3 feet (lm) sufficient room was left for single line passage of boats. Although this would have been a fairly tight fit, the fact that the towpath projected from the wall allowed the full width to be filled with water, thus reducing the resistance to passing boats. Although the engineer of the Shrewsbury Canal, Josiah Clowes, designed the tunnel, the towpath was added at the suggestion of William Reynolds. The towpath did not unfortunately survive long, probably because of lack of maintenance, and was removed in 1819; just 22 years after the canal had opened. Boats were then `legged' through.
The Shrewsbury Canal was operated, until the Newport Branch opened, entirely by tub boats. Each boat was about 20 feet (6m) long and 6 feet 4 inches ( 1.9m) wide and carried about 8 tons. They were pulled in trains, a single horse pulling up to 140 tons. They continued to be used after this time, and in 1838 the canal company minute book records "when two trains of Boats shall have entered the Tunnel at the same time the party which shall have first passed the Centre of the Tunnel shall proceed and the other party shall return so as to allow the other to pass where both are laden but when one train is unladen such train shall turn back". As canal historian Charles Hadfield commented, "after a boatman had turned back a loaded train two or three times, his language must have been worth hearing"! It also makes one wonder how disputes had been resolved in the previous 40 years of operation - fisticuffs?
Both portals of the tunnel, although bricked up, can still be seen. The western portal is right beside the road to Preston and the western end can be approached along the canal from the Atcham - Uffington road at Berwick Wharf. The length of canal between the new A5 and the surviving bridge at Berwick Wharf, including the tunnel, is still owned by British Waterways and retains some water. BW make periodic inspections inside the tunnel which, apart from the ventilation shafts having been pushed in following the disposal the body of a tragic murder victim in the 1960's, is reported to be in good condition.
3. Shrewsbury Canal Guillotine Locks
The Shrewsbury Canal featured 11 locks. These were named Trench, Baker’s, Turnip, Hadley Park, Peaty, Shucks, Wheat Leasons (or Leasowes?), Britton, Wappenshall, Eyton and Eyton Lower. Can anyone throw light on the origins of some of those names?
The canal was built for the use of tub-boats, about 20 ft long and 6ft wide, which were pulled along in trains. The locks were each 81ft long and 6 ft 7 in wide, which meant that each would hold four tub-boats.
As can be seen in the photograph, these locks featured a guillotine gate at their lower end. The upper gate was of the usual swing type. However, it is not known if this is the original arrangement.
In 1797 Thomas Telford, who had then taken over as engineer of the canal, wrote that ‘the locks are so formed as to admit either one, three or four boats passing at a time, without the loss of any more water than what is just necessary…..This is accomplished by having gates that are drawn up and let down perpendicularly…. and each lock has three gates, one which divides the body of the lock’. Did this mean that each lock had three lifting gates, or that it had ordinary gates at each end and a lifting gate between them?
However, the mystery is that there is neither a record of the lifting gates having been moved to the lower ends nor have traces of intervening gates ever been evidenced at the locks themselves. It seems highly likely therefore that Telford was setting out his intention in his writings and that this arrangement never actually came about. It would indeed seem a logical arrangement to save water by varying the length of lock to suit the length of boats passing, but in practice the movement of a single tub-boat would probably be unusual.
Whatever the arrangement, in the original design the guillotine gate was counter-balanced by chains leading over wheels above the gate to a centre weight, a wooden box full of stones. However, starting in 1840 at Wheat Leasons the counterbalancing was altered so that a cast-iron weight sank in a well at the side of the lock as the gate was raised. All locks, other than Hadley Park, were finally converted to this pattern.
In the early 1830s, when the building of the Newport branch was under construction, the Shrewsbury Canal Company planned to widen all their locks and bridges to take the standard narrow boat that would in future have access from the national network. This it seems was going to prove to be too expensive and in the event only the two Eyton locks were converted along with the bridge openings between Wappenshall and Shrewsbury, but the design of the guillotine gate was retained. The locks and bridges between Wappenshall and Trench were not altered and especially narrow narrow boats were used on this section.
4. Trench Inclined Plane
When the Shrewsbury Canal was being planned the Company purchased part of the Wombridge Canal in order to give them direct access to the Donnington Wood and Shropshire Canals. However, the Shrewsbury Canal was 75 feet below the level of the Wombridge Canal and rather than a flight of locks, with the inevitable water supply problem, an inclined plane was planned to connect the two. This was not a new idea for there were several already operating in the area. Indeed the minute book of the Company of 6 July 1793 records that ‘an Engine similar to the one at Donnington Wood be erected at the Head of the intended Inclined Plane at Wombridge and that Mr. William Reynolds be requested to order the Engine from the Coalbrookdale Company’.
Basically the plane consisted of a double railway, 223 yards long, on which tub-boats were conveyed on large wooden carriages called “cradles”. To ensure that the boats remained in a horizontal position on the incline the wheels on the lower end of the cradle were larger. At the top side of the cradle there were two vertical posts between which a “bridle chain” was slung. The long rope which hauled the cradles was attached to bridle chains.
As most of the trade was coal, which was going down the plane (mostly wheat for the local mill went up), the cradles worked by counterbalance. At the lower end the rails went into the water so that the boats could easily be floated on and off the submerged cradle. The complication was at the top where the cradle had to negotiate a sill, without upsetting the boat.
The engine house was at the top of the incline, its roof extending out over the sill. Under this roof was a large drum onto which the rope which hauled the cradle, wound on and off. Behind the drum was a pair of wheels, or "sheaves", which the rope passed over and under before going on to the drum.
The rope drum was supported by three stone piers, the cradles passing into the docks of the top basin on either side of the centre pier. This pier housed the brake which controlled the speed of the cradle, and to this pier were attached two heavy “winding chains”. To both sides of each dock there were long pieces of wood, slightly tilted towards the water, which served as rails.
As the ascending cradle approached the sill the brake would be applied. A winding chain was then attached to the cradle and the engine really came in to play, hauling the cradle over the sill. At that point the main rope and bridle chains would fall slack, a third set of wheels on the side of the cradle would run along the wooden rails attached to the side of the dock, taking over support from the smaller wheels on the cradle. The winding chain would prevent the cradle going too far. One boat could then be floated off and another on. The process was then reversed with the winding chain being used to pull the boat over the sill before the cradle was stopped to allow it to be removed.
Modifications to the plane were carried out in the early 1840s. Edge rails set in chairs fastened to stone sleepers were used and a new engine of the Cornish type installed, also bought from the Coalbrookdale Company, at a cost of £400.Outliving even the Foxton inclined plane that had only opened in 1900, the Trench plane became the last inclined plane working in Britain. It finally closed on 31 August 1921.
Following on from the previous article on the Trench Inclined Plane, a couple of items have been received which add to the story. First, member Alex Bielecki has forwarded a copy of an article from the Journal of Industrial Archaeology (1965) which provides further information about the plane.
The article clarifies that the plane was used before the whole canal was opened. “At the end of August 1794, almost three years before the completion of the canal, Emanuel Galiere was appointed ‘to superintend the fire-engine at the inclined plane’. Amongst the earliest items to pass down the plane would be sections of the world's first cast-iron aqueduct, for erection on this canal at Longdon- on-Tern.”
As to the later modifications made to the plane, the article suggests that the timber sleepers may not after all have been replaced with stone ones, as “wooden sleepers were in use at the time the incline was abandoned”. Or were the stone ones found to be less effective and a reversion made to timber?
“At the same time a new rope was ordered for the incline from Duncan Rowett & Co. of Liverpool. Sixteen months later ‘Two patent wire ropes of 300 yards each and ½in. thick, from S. Newill & Co., Dundee’. A further rope was ordered in September 1842, 306 yards long and 1 in. thick”. Did they keep breaking?
These purchases and the installation of the new steam engine for £400 early in 1842 and two years later of an iron cradle costing £90, both ordered from the Coalbrookdale Co. were undoubtedly occasioned by the extra activity on the canal since the opening in the mid 1830’s of the Newport Branch.
The article also describes the state of the plane in 1965. “The heavy sandstone sill is still clearly visible, as are the docks which lead into the top basin. The latter are now cluttered with the masonry which formally supported the rope-sheaves. Along one of the dock walls one can just determine the position of one of the wooden rails. Only the foundations of the incline engine house remain. The top basin is all but filled with builder’s rubbish, and away round an old pit mound winds the dry bed of almost the last vestige of the old Wombridge Canal”.
And our President, Tom Manning, has sent a personal recollection:
“Many years ago before the Pumping Engine house above the basin at the top of Trench incline was demolished, I was having a look around when I noticed, close to where the emplacements for the boilers were, some weathered bits of wood sticking out of the ground. Each piece of wood had a short length of rusty chain attached to it. The penny dropped after a while and I realised I had stumbled upon a Tub-boat graveyard.” He adds “I have not been there since”.
Unfortunately Tom there is now no vestige of the plane apart from a street name. Unless anyone knows differently!
5. The Humber Arm
When the Birmingham & Liverpool Junction Canal was first considered the company looked to make a connection with the Shropshire canal network by building a branch from Cowley, near Gnosall, to the Donnington Wood Canal at Pave Lane. This would have been 7¾ miles long and level. However, this plan fell through and permission was obtained instead for the Newport Branch.
At the same time permission was granted for two branches from the Newport Branch. They were to be built to Edgmond and Lilleshall. The latter was to be executed by a canal with 7 locks or by tramroad. Neither of these branches were actually built but the purpose of the latter was later met by the Humber Arm.
The Humber Arm was opened in May 1844, more than 10 years after completion of the Newport Branch. It was about ¾ mile long and ran in a straight line from near the Dukes Drive Aqueduct to the Duke of Sutherland’s Lubstree wharf on Humber Lane. This gave the Lilleshall Company a more direct outlet to the national canal network than before and it carried out quantities of coal, pig iron, and fluxing limestone. Tramways linked the wharf with the company’s various works.
In 1870 the canal company, who were keen to divert traffic from the Trench Incline, agreed to lease Lubstree wharf from the 3rd Duke and pay a wharfage rate of ½d a ton. In order to carry, what was clearly a substantial trade, they diverted 30 boats from their fleet for the purpose. At the same time a standard-gauge railway line was built from the Lilleshall Company’s works to the wharf to replace the tramways.
By 1880 the arm was carrying only fluxing stone, despite the toll on iron ore having been reduced to try and promote trade. However, in a further attempt to promote the use of the arm the company agreed specially reduced rates for the Lilleshall Company for 300-400 tons a week of limestone and 100-150 tons of iron ore. They also hoped for an increased coal and pig-iron trade. This must have been a fairly successful move for a further siding was built and in 1891 and 1905 the lease on the wharf was renewed.
In 1922 however, the Duke of Sutherland decided to close Lubstree wharf and the railway line to Lilleshall. Thus the last traffic on the Humber Arm ceased, and along with many other of the Shropshire Union Canals the arm was legally abandoned by the L.M.S.R. Act of 1944.
6. Shrewsbury Canal Drawbridges
Between Wappenshall Junction and Shrewsbury there were 35 bridges to provide for roads and footpaths and to act as accommodation bridges to provide access between fields on farms. Of these bridges 13 were “movable” bridges, and all but one of these were drawbridges. They were all on the length between Wappenshall and Withington. (in which length there were only 6 fixed bridges); the remaining length to Shrewsbury having only fixed bridges.
In drawbridges a deck hinged to one abutment is suspended at the far end from horizontally pivoted balance beams which have to be pulled down by the use of a rope or chain to raise the bridge. The hinge was placed on the side of the canal away from the towpath so as to provide an unobstructed course for the towlines of the horse drawn boats.
The advantage to the canal company of building drawbridges was that it was a far cheaper alternative. With the bridge just above water level the construction work saved was considerable. Materials were not required to build up approach embankments where the canal was on essentially flat land, as in this part of Shropshire, and the span was reduced by dispensing with the need to span the towpath as well as waterway.
Not all the bridges were of the same design, as can be seen from the difference between the above photograph of a bridge (probably) near Withington and that at the top of this page of the bridge at Eyton.. The latter is very reminiscent of those to be found today on the Llangollen Canal with a quite substantial counterweight, whilst that above appears to be a much more rudimentary structure. With no cross member between the uprights it would also allow for agricultural wagons with a high load to cross.
7. Forton Aqueduct & Skew Bridge
At Forton, between Newport and Norbury Junction, are to be found two structures almost unrivalled on the rest of the canal network. The road from Forton to Meretown crosses both.
The first of these is the Skew Bridge. A skew bridge is one that has its arch set obliquely on its abutments instead of at right angles to them. Since the erection of courses of stone or brick to run obliquely to the walls of a bridge requires more skill and application than does a straightforward job, engineers often made all sorts of twists in roads as they approached bridges in their efforts to cross obstructions at right angles - hence the relative scarcity of skew bridges. In his book ‘Navigable waterways’ L.T.C.Rolt writes of “the necessity for crossing existing roads at oblique angles, … confronting engineers with an entirely novel structural problem”, and he cannot make up his mind as to the man who pioneered the skew bridge. Not only is the bridge at Forton a skewed bridge, but Telford saw fit to carry a brook directly underneath in a fine stone culvert. Last year Staffordshire County Council carried out strengthening work to the bridge, without any visible indication that anything has happened.
A few yards towards Norbury is an aqueduct which carries both road and canal over the River Meese. This aqueduct-bridge is, in the words of Staffordshire County Council “a Scheduled Ancient Monument, unique in Staffordshire, a most unusual structure in the country as a whole, and an important monument to the technology of the canal”. Unlike most canal aqueducts there is no narrowing of the canal at the crossing, which is particularly surprising because with the inclusion of the road the structure is of tremendous width.
Page last updated 13/02/2005
To comment on this site please contact: firstname.lastname@example.org