The Locks, Broadwaters & Iron Trunk Aqueduct

View from Cosgrove Lock towards the Broadwaters and the Iron Trunk Aqueduet
The Broadwaters

Repairing the Iron Trunk

Looking back from the Iron Trunk Aqueduct towards Cosgrove with the Broadwaters in the right

Posted to Mr. J. Feil 15 Oakmead Rd, Balham, S.W. February 10th 1909
Text on the postcard: This shows the "Broadwater" on the right hand side. It sometimes flows right into the river Ouse which is underneath the "Iron Trunk". The river separates Northants from Bucks. You will notice "Cosgrove Lodge" Mr. B's [Branson's] House on the right hand side and as you know our house is just behind it. You can also see the locks and lock house at the side of the canal. The "Towing path" is terribly rough and used to cut the tyres of my bike when I rode along here to the shop. I often used to ride over the "Trunk" to save the trouble of getting off my bike. I have left off doing it though now as I once had rather a bad accident I escaped but damaged the bike rather badly. This is of course looking towards C. [Cosgrove]

The Iron Trunk Aqueduct

Initially, nine locks were used in a temporary arrangement to lower and raise the canal for the crossing of the River Great Ouse at Wolverton at the river's water level. In 1799 William Jessop designed a three arch masonry aqueduct and embankment to cross the river and replace the locks.

The original plan had been to take the canal across the Ouse at river level, using two four lock flights to descend into and ascend out of the Ouse Valley.  This scheme would have slowed canal traffic and wasted water, besides leaving the canal vulnerable to river flooding.  In 1800 Barnes suggested, as an alternative, carrying the canal cross the Ouse Valley on a high embankment using an aqueduct to bridge the river. 

This proposal was accepted, but as the embankment and aqueduct were expected to take two years to complete, a temporary locking system was installed to permit traffic to cross the Great Ouse valley while the embankment and aqueduct were being built. 

All was not well with the Navigators’ workforce. During construction of the Wolverton Embankment on the Grand Junction Canal, a demand for higher wages met with this directive from the Board to the site engineer . . . .

“ . . . . to discharge at all risqué these offenders, and to use his utmost endeavours to bring them to Justice, and to call on the Magistracy and Yeomanry of this County to repress and punish all acts of Outrage and Violence and an illegal conspiracy or combination for increase of wages.”

GJCC Minute Book, 5 May, 1801

The work was put out to tender, and in December 1802, a contract was let to a consortium headed by Thomas Harrison of Wolverton.  Work on the embankment and on the three-arched brick and stone aqueduct, to Jessop’s design, commenced in August 1803 and was opened to traffic on 25th August, 1805.  However, in January 1806, a section of the embankment failed; this was repaired, the failure being attributed to poor workmanship by the contractor, who disputed this claim and submitted an account of additions of his own.  In 1807, Benjamin Bevan, of Leighton Buzzard and Henry Provis were assigned to examine the contractor’s claims.  By this time Jessop’s aqueduct was showing signs of failure and in February 1808 it collapsed, severing the canal.  Fortunately the locking system across the Great Ouse valley was still in place and was used to bypass the failed aqueduct. 

As a temporary solution, Provis designed a wooden trough to bridge the Great Ouse, Bevan being given the task of designing a permanent replacement.  Telford’s cast iron trough aqueduct at Pontcysyllte had by now proved itself, and Bevan adopted this construction for his structure, although the Ouse aqueduct troughs had to be substantially larger and stronger than at Pontcysyllte due the Grand Junction Canal’s greater width.  The iron units were cast at the Ketley foundry at Coalbrookdale, transported to Cosgrove by canal and assembled and erected on site.  During its long life, Bevan’s iron aqueduct has experienced only two stoppages for maintenance, in 1921 and in 1986.

An artist’s impression of the Cosgrove Embankment under construction, showing Jessop’s aqueduct and the original scheme for crossing the valley.

Contemporary sources tell the story below:

“GRAND JUNCTION CANAL.―We are happy to announce the completion of nearly all the great works which are going on upon this important and extensive line of navigation. On Monday morning last, the stupendous embankment between Wolverton and Cosgrove, near Stony-Stratford, was opened for the use of the trade. By this great work nine locks by its side, four down and five up, are avoided, and one level sheet of water is now formed, from Stoke Bruerne to some miles south of Fenny Stratford (this overlooks the lock at Cosgrove), as well as on the Buckingham branch, extending to within a mile of that town. The embankment seems to possess great stability.

The branch and iron railway, that is to connect the Grand Junction Canal with the New River at the town of Northampton, as also with the Leicestershire and Northampton Union Canal, are proceeding rapidly, and their completion may be expected about the end of next month.”

The Morning Post, 30 August 1805

Others were not quite so confident:

“All the works of that extensive and complicated undertaking, the Grand Junction Canal, are now completed.  The stupendous embankment that had been raised between the villages of Wolverton and Cosgrove, near the market town of Stony Stratford, has been lately opened for the use of trade and internal navigation. . . . The arches erected under this embankment, to create a passage for the river Ouse, which arches were believed and reported to be in a sinking state soon after the central arches were struck, are at present considered as sufficiently firm, and the embankment is thought to possess all imaginable strength and durability.”

The Universal Magazine of Knowledge and Pleasure, July-Dec, 1805

Reference to the “arches were believed and reported to be in a sinking state” refers to the three arches of a brick-built aqueduct, designed by Jessop, which carried the embankment over the Great Ouse.  When the timber shoring was removed the aqueduct began to show signs of failure . . . .

“After its erection Mr. Bevan, the engineer, of Leighton Buzzard, being called upon, gave it as his opinion, it would not stand twelve months; his prediction was verified, for in less than six months after its construction, the materials were so indifferent, that a continued leak of the aqueduct was observable.”

A Tour of the Grand Junction Canal in 1819, John Hassell (1819)

The embankment had experienced slippage in 1806, shortly after its opening.  This was repaired, to be followed in February 1808 by failure of the aqueduct:

“On Friday morning last the inhabitants of this town were thrown into the utmost consternation, by information which arrived from Wolverton, that the large embankment for carrying the new line of the Grand Junction Canal across our valley, about a mile below this town, had fallen in; and that the river Ouse was so dammed up thereby, that this town must shortly be intirely inundated to a great depth.  I hastened to the spot, where my fears were very much allayed, by finding that one of these arches, which had been propped up underneath with timber, soon after the centres were removed, was still standing; and that this one arch, owing to there being no flood in the river, was able to carry off the water of the river as fast as it came down.  On examining the other two arches, I found that about 22 yards in length of the middle part of each had fallen in, and blocked up the arches, laying the canal above in complete ruins, emptying it as far as the nearest stop-gate on each side, and exposing the remains of 500 quarters of coke and cinders which the contractors had lain in the arches.  The ends of each of the broken arches were found standing in a crippled state.  Most fortunately for the Public, as well as the Company, the old line of the canal and locks across the valley are still remaining, and in sufficient repair, immediately to convey the barges, and prevent interruption to trade: but the loss of £400 per month, which I am told has of late been the amount of extra tonnage received by the Company for goods passing over this embankment, will be lost to them during the period of re-building the arches and repairing the canal over them.”

Jackson’s Oxford Journal, 27th February, 1808

With the locks in place the canal opened for traffic in the autumn of 1800. Work started on the aqueduct two years later. The contractor, interestingly enough, was Thomas Harrison himself. Harrison was not without previous experience in canal ventures although he had nor been involved in any completed projects. He was not an entirely disinterested party in the coming of the canal to Wolverton . Harrison was inclined to spread his investments widely but he was not an investor (as far as we know) in the Grand Junction Canal, but it was as a building contractor that he won the contract for the construction of the aqueduct over the River Ouse. Today we might detect a whiff of conflict of interest, but the Trustees did not seem to notice, or at least not record any objections and had full confidence in Harrison in such matters. The Canal Company must have been of like mind because they did award him the contract. The aqueduct was built with three arches to support a wooden trunk which was lined with clay to prevent leaks - which it failed to do. The design was flawed. Boats began to use it in August 1805 but it was probably a perilous structure from the start. A few months later part of the embankment slipped. Repairs were effected but the Company Architect was not satisfied. Arguments about who was at fault went back and forth between Harrison and the Canal Company until February 1808 when the aqueduct spectacularly crashed overnight.

The lockkeeper at Cosgrove, a Mr Cherry, was the first to notice the disaster at 1 1 pm that night and had the presence of mind to close the gates at his end and send out the alarm. Most Wolverton houses were high enough above the valley to be unaffected, but there was great consternation at the mills and at Stony Stratford about the prospect of flooding. Farmers also became anxious about their livestock in the meadows. That this happened in the middle of the night only aggravated the anxiety, but when daylight came, although the valley was in flood, it was no worse than a normal winter’s flood and apparently livestock losses were minimal. In three days the water level subsided and even though an enormous quantity of earth had slipped into the river there was still an unblocked channel for the river course..

from "Manno's Manor "- Bryan Dunleavy

A subsequent investigation attributed the aqueduct’s failure, not to deficiency in Jessop’s design, but to poor workmanship on the part of the contractor.  The legal dispute with the contractor that followed was settled in the Company’s favour, with damages being awarded for loss of trade and the cost of the replacement. 

Today, the Great Ouse is bridged by Benjamin Bevan’s iron trunk aqueduct of 1811:

“The new aqueduct bridge of the Grand Junction Canal, over the Ouse River, below the town of Stoney Stratford at Wolverton, which has been for some time in preparation, of cast iron, in lieu of that of brick, which fell down in 1808, was on 22nd January, at one o’clock, opened for the passage of boats, the “Empress”, belonging to Mr. Pickford, and his “Queen Charlotte”, being the first of 30 which passed this first metal aqueduct that has been constructed anywhere in the South of England. ― The whole length of the iron-work is 101 feet; it is wide enough for two boats to pass each other, and has a towing path of iron attached to it; it is firm and tight in every part.  Mr. Benjamin Bevan, the Engineer who designed it, and about twenty persons only besides the boatmen were present, no announcement having been made of its completion.  The opening of this Aqueduct and the passage of trade over the embankment, will, it is expected, add full £500 per month to the revenues of the Company.”

The Tradesman Vol. VI., Jan - June, 1811

Canal boat going over the Iron Trunk
Horse drawn boat going over the Iron Trunk

Cosgrove Skating on the Broadwaters 1929 & 1933

Wolverton Express 22nd February, 1929

Skating in North Buckinghamshire

Skaters had a glorious weekend on Saturday and Sunday last, and the centre of activity so far as this district was concerned was the broad waters at Cosgrove, where on Saturday afternoon and all day on Sunday there were four or five hundred people on the large expanse of ice, whilst on the bank there were more than that number of spectators.  Sliding was as much in evidence has actual skating, and old and young alike delighted in the pleasures of the sport.

On Sunday afternoon, it was noticeable that one Wolverton old age pensioner, who had attained his three score years and ten had donned his skates and demonstrated that he had not lost any of the skill that he evidently developed in his younger days.  Very few skaters were on the Buckingham Arm from Cosgrove to Old Stratford on Sunday.  A few of the more venturesome skaters found water in some parts and except for a drenching, suffered no worse harm.

Wolverton Express 3rd February, 1933

North Bucks Enjoys the Ice

Four happy, yet all too short, days, was a lot of local skaters to enjoy the pleasures of the ice. During the whole of last week the thermometer stood at about, or below, freezing point, and the keen east and north east winds help to freeze every sheet of water in the neighbourhood, including the Grand Union Canal and River Ouse. Skaters in the Wolverton district had their first “try out” on the ice on Wednesday, when quite a number of people had an enjoyable afternoon of pleasure on the pond at the Old Wolverton Manor Farm. On Thursday and the three subsequent days, the Broad Waters at Cosgrove was the centre of attraction, and each day crowds of skaters practised their art on this extensive sheet of water in skating and ice sports. There is no doubt that the Broad Waters provided one of the best sheets of ice that had been in the neighbourhood for many years, and a remark of a skater that “it looks too good to skate upon” was very true. From the heights of the canal bank the ice was so clear as to make people wonder whether there was ice actually there at all, but any fears of the skaters in this direction were rapidly dispelled for the “Broads” were literally crowded, especially on Saturday and Sunday. Local football clubs on Saturday bemoaned the fact of poor support, but many of the usual frequenters of the football grounds were intent upon enjoying the pleasure of the ice before a thaw set in.

On Sunday the “Broads” were visited by thousands of people, the majority although not being themselves skaters, finding enjoyment in the pleasures of others. Especially in the afternoon, when the weather was so favourable for walking, the canal footpath between Old Wolverton and Cosgrove was so crowded with a continuing stream of people that it much resembled a promenade at some favoured seaside resort in the summer months.

Fortunately ice accidents were few. One Wolverton lady, Mrs. Walton, of Windsor Street, had the misfortune to fall on the Broad Waters on Thursday and fractured her arm. This was the most serious of the accidents reported, others being quite minor affairs.

The thaw began on Sunday. A steadily changing barometer prepared the way for it. Sunday night brought rain which, falling on the frozen earth, made the transport and travel conditions early on Monday most difficult. Railwaymen living several miles from their work suffered from the fact that the omnibuses in which they usually travel were unable to climb the gradients of the road and that morning the men were forced to walk to their work, with the result that there were many late arrivals in Wolverton. One omnibus skidded the whole width of the road near the Railway Works, and another mounted the pavement, whilst one bus was unable to climb even the slight gradient near the Science and Art institute.

A modern day view of boats going over the Iron Trunk