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Credit for canal engineers


Heartland

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Any search of what is written about canal engineers is often complicated by what has become accepted as opposed as to what actually was the truth. James Brindley and Thomas Telford frequently get much credit for achievements, where others contributed and deserve a certain recognition. John Duncombe is a case in point, whose contribution to the surveys of the Ellesmere Canal was considerable. He surveyed this canal before Jessop took charge and it was part of his survey that the aqueduct crossing at Pontcysyllyte was to be 125ft. 

 

Duncombe went onto to complete many more surveys for the Ellesmere Canal as plans for the route were altered. He left when his work was done, a year before the Pontcysyllte Aqueduct was opened. He then undertook work in Scotland surveying roads, but died in Inverness Goal, a sad end. 

  • Greenie 2
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I've always had an interest in the men who actually did the work. Lord So and So didn't build his great house, it was the builder.

Much is recorded in the railway age of men like Peto and Brassey, but there seems little about many of the canal contractors. These were the men that made it really happen.

Architect Thomas Harrison designed the Grosvenor Bridge over the River Dee in Chester, at the time the world's largest single span stone arch, but it took the skills and resources of James Trubshaw of Little Haywood in Staffordshire to actually build it and make it stay up.

 

James

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9 hours ago, JamesWoolcock said:

I've always had an interest in the men who actually did the work. Lord So and So didn't build his great house, it was the builder.

Much is recorded in the railway age of men like Peto and Brassey, but there seems little about many of the canal contractors. These were the men that made it really happen.

Architect Thomas Harrison designed the Grosvenor Bridge over the River Dee in Chester, at the time the world's largest single span stone arch, but it took the skills and resources of James Trubshaw of Little Haywood in Staffordshire to actually build it and make it stay up.

 

James

On some of his larger projects, Brassey was in partnership with William MacKenzie, with MacKenzie being the senior partner. He was trained in civil engineering by the L&LC Co, his father, Alexander, starting on the canal as a navvy c1790, and soon becoming their largest contractor. He had come down from Scotland with Robert Whitworth after the F&CC had been completed and Whitworth had taken charge of building the L&LC.

One of the most important groups of canal engineers came from the Halifax/Bradford area. Thomas Steers worked on the plans for the C&HN circa 1740, and his plans were used later by John Smeaton. They seem to have encouraged local millwrights and surveyors to go into canal engineering, with John Longbothom being one. He was the original L&LC engineer. Joseph Priestley, the L&LC's manager also came from the area, and he was one of the Smeatonians who met in London to discuss canal matters. John Sutcliffe was another local man who worked on canals, and who was very critical of some of the other early engineers, such as Rennie. Perhaps the most important was Robert Whitworth, who was a surveyor from the Calder Valley. After Brindley took over the C&HN, Whitworth almost immediately became Brindley's righthand man and did most of the subsequent surveying on Brindley's projects. To have taken over so quickly suggests that he was already well versed in the technology needed for canal building. There are a number of other important canal engineers from the area.

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William MacKenzie, had a long engineering pedigree, he was associated with the construction of the Deep Cutting, BCN, at Smethwick where a long cutting , 18ft below  and beside the earalier cutting of 1788-1791 was done 1826-1829.

 

The link between navigable canals mill streams is a subject that deserves further research. Water powered mills evolved over time with the overshot, iron wheel being a culmination of design as this gave the optimum power ratio. The requirement for making stream, or leats, from a weir to a mill pool or directly onto the wheel could result in cuts up to and over a mile long being made to the mill in order to obtain the required height. Those who engineered those mill streams over at least eight hundred years, created a legacy of waterway construction techniques that were adapted by the navigable waterway builders.

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19 hours ago, Heartland said:

but died in Inverness Goal, a sad end. 

Yes, if only the full-backs had done their job properly...

1 hour ago, Heartland said:

Water powered mills evolved over time with the overshot, iron wheel being a culmination of design as this gave the optimum power ratio.

Though I'm not an avid student of watermills I have always liked them, and have noticed that they come in overshot, undershot and in-between (midshot?) varieties. Why is the overshot wheel the most effcient?

Edited by Athy
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3 hours ago, Athy said:

Yes, if only the full-backs had done their job properly...

Though I'm not an avid student of watermills I have always liked them, and have noticed that they come in overshot, undershot and in-between (midshot?) varieties. Why is the overshot wheel the most effcient?

The middle one tends to be the best, and is called a high breast wheel. Overshot wheels rely upon the weight of the water in the bucket, and are best suited to smaller streams and rivers. Undershot wheels rely upon the flow of water, so tend to be on larger, slower flowing rivers. The breast shot wheel uses both static and kinetic energy, so tend to be more efficient. Smeaton was the first to try to work out relative efficiencies, and there are details of his experiments in his books, which you can download from Google Books. They have a lot of canal information in them as well.

  • Greenie 1
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"Breastshot", that's the word which had slipped my memory. Thank you, have a greeno.

So, Heartland reckons that the overshot wheel was the most efficient, while Pluto plumps for the breastshot. Any votes for the undershot (which I would have imagined would be efficient as long as the stream kept flowing strongly)?

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  • 2 weeks later...

Overshot or breast shot, that is the question- one that is complicated through the understanding of potential and kinetic energy- as well as the fact did the mill engineers have that grasp of understanding the mathematics behind what was best. I believe the study is called  Hydrodynamics, where water flow is calculated to decide the optimum type of wheel.  Overshot wheels gave the best performance when water supply was limited, as was often the case. Breast Shot wheels became more popular in the 19th century as a water dynamics became better understood. In the context of the original thread as mill streams were being built over long distances, the water supply would have been somewhat limited, hence my observations. However with medium to good supplies of water the breast shot could be the best. With fast flowing rivers the undershot was quite capable for the mill task.

 

It would be interesting to find how many breast shot wheels relied on carried to the wheel by a long mill stream

Edited by Heartland
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  • 2 months later...

Where expenditure was involved, it would seem that some of the early canal projects required the opinions of other engineers to confirm or suggest alterations. James Brindley was involved with surveying canals in Staffordshire and Derbyshire between 1758 and 1759 that was to form the basis of the eastern Trent & Mersey Canal route later. Yet John Smeaton was also requested to check these proposals that led to a revision of 1761. Whilst Brindley and Smeaton had different backgrounds, they clearly had a natural ability for choosing suitable solutions.

 

Brindley may well have the ability to view a situation and carry out the practical aspects, but being self taught in writing, lacked the skills of putting his thoughts with a clarity that was required for publishing ideas and concepts. He was fortunately ably assisted by others in this regard. With Smeaton his education was different having a father who was an attorney. Like Brindley he had a practical ability, but having the advantage of a better education, it seems, was able to inform a wider audience of concepts and ideas.

 

I suspect Smeatons report of 1761 on the navigation from the Potteries to Wilden was a catalyst for progressing that important work and enabled Brindley to pursue it with vigour. 

 

John Duncombe also had his work checked by William Jessop, then a respected engineer, who was engaged in a variety of projects. The engineering challenges required to put Duncombe's plan into execution were vast and in the end never finished. The line to Shrewsbury, the long tunnels and the canal to the Dee were all casualities of delay and escalating costs. Survey after survey was made before the route of today was made and opened.

Edited by Heartland
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