Some historical questions

[Catrin]

While we were away on the Thames Ring I began to wonder about the paint scheme for lock gates. I don't imagine that lock gates were originally painted, and now (on BW at least) they are all in the same black and white scheme - with slight differences for broad and narrow locks. I have to admit that I don't know if there are regional differences to these schemes. So, question 1 - when did this black and white paint scheme develop - and were there earlier versions of the paint scheme?

 

Question 2 - how on earth did the canal engineers manage to build tunnels through almost a couple of miles of hillside working from inside a series of vertical air shafts. I know that Braunston has a number of 'wiggles' but you can see one end from the other. How did they know exactly which direction to strike out from at the bottom of a shaft? How did they know how far down they were? (You can tell I'm not a civil engineer!)

 

Question 3 - how did they keep the air breathable at the bottom of the air shafts - especially in the sections of tunnel striking out from these? Pumps of some kind I'm sure - but is there anyone out there who can give more information?

 

Throwing this out to the historical experts.

Cheers

Cath

[Keeping Up]

Re number 2: they would suspend a plank or similar from another plank, with two lengths of string (one at each end). The plank at the bottom of the shaft would lie parallel to the plank at the top. They would aim the top plank at a suitable landmark (eg Braunston Church) and as well as lining up the row of shafts on that direction, would also dig undergorund in the direction the plank pointed.

 

Presumably one of the navvies in Braunston had a knot in one of his lengths of string, hence the slightly wrong direction

[dor]

Many lock beams on the Shropshire Union (e.g. the Audlem flight) are painted grey and white. Rumour has it that someone ordered the wrong paint and they had to use it up somewhere ...

[Catrin]

Re number 2: they would suspend a plank or similar from another plank, with two lengths of string (one at each end). The plank at the bottom of the shaft would lie parallel to the plank at the top. They would aim the top plank at a suitable landmark (eg Braunston Church) and as well as lining up the row of shafts on that direction, would also dig undergorund in the direction the plank pointed.

 

Presumably one of the navvies in Braunston had a knot in one of his lengths of string, hence the slightly wrong direction

Cheers, Allan, I guessed it must be something like this, but I'm still astounded that they managed to get anything like as accurate as they did in the circumstances. They would only have to be a couple of degrees off to make quite a big difference.

Cheers

Cath

[Derek R.]

Mostly fact, with a little calculated guesswork:

 

The whole of Blisworth tunnel was lined up from the tower of St. Mary's Church at Stoke Bruerne from where the entire line can be viewed. As the point of view from that tower was the highest point above the line of the tunnel, a telescope and theodolite would then be used to ascertain the various heights above water level. All this would have been plotted onto a longitudinal cross section drawing, and once chosen, the various sites for digging vertical shafts would have begun - 19 for Blisworth. Once at datum level for the tunnel floor, horizontal excavation began using possibly the 'planks', and a length of hose pipe with glass tubes at each end and a mark to keep 'level'. The tube would have sufficient water in it, so that when both ends were held vertically - any distance apart - the water would show at the mark when both glasses were at equal levels - a long flexible spirit level in fact. The problem with a plank might be it's limited length before bending under its own weight. With a water tube, the distance apart was only governed by the length of the pipe. Its accuracy was greater.

 

As regards supplying fresh air; I have not read of any apparatus that was actually used, but if necessary a bellows pump may have been manned either at surface level, or once gained, tunnel level. Other than that, it would be by natural convection.

 

Why black and white? A smart appearance shows pride and efficiency, black and white stand out - 'look at me, I'm an engineering feature!' Or if black tar paint was used for preservation, you wouldn't want that soiling your clothes when opening gates - so along came white. Don't know really, just some ideas. And if someone had ordered a big batch of wrong colour, quite likely to use it to get a job done than cart it all back.

 

Derek

[Nightwatch]

There was a good programme on sky/cable or what ever called Industrial Revelations with the chap from the Fast Show.

A superb series. In one he demostrated how this was done. I have no reason to doubt his word. Can't really put into words how this was done but it was interesting. An early style of surveying which in part is the same today.

 

Willing to be shot down if I am talking rubbish.

[jake_crew]

There was a good programme on sky/cable or what ever called Industrial Revelations with the chap from the Fast Show.

 

His name was, and probably still is, Mark Williams.

 

 

 

 

Ack-ack guns stood down to level 5.

[Keeping Up]

There was a good programme on sky/cable or what ever called Industrial Revelations with the chap from the Fast Show.

A superb series. In one he demostrated how this was done. I have no reason to doubt his word. Can't really put into words how this was done but it was interesting. An early style of surveying which in part is the same today.

 

Willing to be shot down if I am talking rubbish.

That's Mark Williams. He knows a lot about the canals, after he toured with Mikron for many years. He was excellent acting with them - and a great guy to share a few beers with after the shows.

[Catrin]

Thanks to everyone with their suggestions - we don't have sky/cable so I never saw this series, and a search on YouTube has not come up with anything relevant. A pity, it sounds interesting - I always think that one of the interesting things about industrial archaeology (and history/ archaeology generally) is how they managed to do these things.

 

Once at datum level for the tunnel floor, horizontal excavation began using possibly the 'planks', and a length of hose pipe with glass tubes at each end and a mark to keep 'level'. The tube would have sufficient water in it, so that when both ends were held vertically - any distance apart - the water would show at the mark when both glasses were at equal levels - a long flexible spirit level in fact. The problem with a plank might be it's limited length before bending under its own weight. With a water tube, the distance apart was only governed by the length of the pipe. Its accuracy was greater.

 

As regards supplying fresh air; I have not read of any apparatus that was actually used, but if necessary a bellows pump may have been manned either at surface level, or once gained, tunnel level. Other than that, it would be by natural convection.

 

Why black and white? A smart appearance shows pride and efficiency, black and white stand out - 'look at me, I'm an engineering feature!' Or if black tar paint was used for preservation, you wouldn't want that soiling your clothes when opening gates - so along came white. Don't know really, just some ideas. And if someone had ordered a big batch of wrong colour, quite likely to use it to get a job done than cart it all back.

 

Derek

Cheers Derek, I like the idea of the extra long spirit level, and it makes sense about the black tar paint used as a preservative, but with white bits to stop you soiling your clothes.

 

I'd be quite surprised if they didn't have some kind of pump to keep the air viable in the bottom of the pits - they must have been very deep, and would be unlikely to have much natural convection before the canal tunnel had been developed. A quick look at the map suggests that they must have been up to about 30 metres deep. I can remember reading about a very deep prehistoric pit somewhere in Southern England, which during excavation required constant fresh air pumped into it because the air became foul very quickly. Unfortunately, I no longer own the book I read about it in, and I can't quickly turn something up on the Internet. I cannot remember anything about the dimensions of this pit, but I do remember it was very deep (it may have been much deeper, and far narrower), and there was no immediately obvious purpose to the pit - I think they decided it was 'religious'. Clearly there is no problem with air supply through the canal tunnel now, but I have always assumed that they needed something while digging the ventilation shafts. I suppose that once some of the shafts were connected together they could have used the mining idea of lighting fires under some of the shafts to create a through draft.

Cheers

Cath

[Derek R.]

30 what?

143ft is the greatest from surface to tunnel, that's the second vent in from the Blisworth end.

Dinosaurs rule OK.

 

Derek

[ChrisPy]

until the introduction of GPS, modern survey techniques were only a development of traditional methods.

the accuracy of the Channel tunnel shows what could be done.

 

now we don't need surveyors. just a Garmin for 60quid.

[alan_fincher]

Worth a read, for anybody interested.....

 

http://www.blisworth.org.uk/images/Tunnel%...unnel-Story.htm

[LEO]

now we don't need surveyors. just a Garmin for 60quid.

 

Thank the Lord I retired before GPS came in if that's the case.

 

Leo

[furnessvale]

until the introduction of GPS, modern survey techniques were only a development of traditional methods.

the accuracy of the Channel tunnel shows what could be done.

 

now we don't need surveyors. just a Garmin for 60quid.

 

How does that work 143ft down in Blisworth tunnel? :-)

 

Geoge ex nb Alton retired

[andywatson]

Re number 2: they would suspend a plank or similar from another plank, with two lengths of string (one at each end). The plank at the bottom of the shaft would lie parallel to the plank at the top. They would aim the top plank at a suitable landmark (eg Braunston Church) and as well as lining up the row of shafts on that direction, would also dig undergorund in the direction the plank pointed.

 

Presumably one of the navvies in Braunston had a knot in one of his lengths of string, hence the slightly wrong direction

 

Mine surveying practice for establishing direction was to hang a couple of heavy weights on wires set as far apart as possible within the diameter of the shaft. The azimuth at surface would be accurately transferred down the shaft.

 

After 2 of the vertical shafts had been connected a wire supended into each shaft could be used to refine the azimuth measurement.

[Hairy-Neil]

I've heard it said the white ends on the balance beams came about through a combination of wartime nght working requirements and air raid precations.

[tony collins]

That's Mark Williams. He knows a lot about the canals, after he toured with Mikron for many years. He was excellent acting with them - and a great guy to share a few beers with after the shows.

Anthony Burton was technical advisor on those programmes and he was making tv shows about national heritage matters (including canals) when Mark Williams was in nappies. I like the way MW does the shows and he undoubtedly has a great deal of knowledge of the subject. BTW What is the Fast Show? Is it a spin off of Top Gear? ( when Top gear was a motoring programme of course)

 

Tony.

[Guest User]

While we were away on the Thames Ring I began to wonder about the paint scheme for lock gates. I don't imagine that lock gates were originally painted, and now (on BW at least) they are all in the same black and white scheme - with slight differences for broad and narrow locks. I have to admit that I don't know if there are regional differences to these schemes. So, question 1 - when did this black and white paint scheme develop - and were there earlier versions of the paint scheme?

Yes I'd heard too that the black and white was because it stands out at night, and its visible at a distance, mind you I've noticed there's currently one or two new gates on the southern GU that have been left unpainted, seems a shame, hope its not the start of a trend ?

[gazza]

http://www.youtube.com/watch?v=zGBTrCZObyA

 

top 90's sketch comedy show

[alan_fincher]

BTW What is the Fast Show? Is it a spin off of Top Gear? ( when Top gear was a motoring programme of course)

I understood it was a spin off of Water World, but hosted by Phylis.

[Catrin]

30 what?

143ft is the greatest from surface to tunnel, that's the second vent in from the Blisworth end.

Dinosaurs rule OK.

 

Derek

 

Sorry, I'm a teacher, I'm not allowed work in £sd any more! I couldn't find anything quickly about the depth of the tunnel quickly, so I guesstimated from a map - quite a bit more than 30 metres, then.

 

I like the idea of the white ends of the balance beams as being visible at night.

[Guest User]

30 what?

143ft is the greatest from surface to tunnel, that's the second vent in from the Blisworth end.

Dinosaurs rule OK.

 

Derek

143 ft = 42.9 metres

[tony collins]

http://www.youtube.com/watch?v=zGBTrCZObyA

 

top 90's sketch comedy show

Having watched the clip, I'm glad I missed it!

[stewey]

There was a good programme on sky/cable or what ever called Industrial Revelations with the chap from the Fast Show.

A superb series. In one he demostrated how this was done. I have no reason to doubt his word. Can't really put into words how this was done but it was interesting. An early style of surveying which in part is the same today.

 

Willing to be shot down if I am talking rubbish.

You can see an extract from his programme, called Industrial Revelations: Canal Building Problems (the Harecastle Tunnel) on the HowStuffWorks website here:

http://videos.howstuffworks.com/discovery/...blems-video.htm

 

There are numerous other video extracts from his series available on this website.

 

Stewey

 

[alan_fincher]

mind you I've noticed there's currently one or two new gates on the southern GU that have been left unpainted, seems a shame, hope its not the start of a trend ?

This is absolutely standard practice hereabouts.

 

New beams often remain unpainted for several years.

 

Personally I don't agree though about the appearance thing - I think some of the newly installed gates and beams look superb "in the raw". The standard of craftsmanship looks so much better before being smothered in tar in my view.

 

Particularly impressive are cases like Hunton Bridge where both ends have been re-gated at the same time - something I never recall seeing before on the lower reaches of the GU.

 

The tragedy though, is top gate renewals that have gone back to omitting the gate paddles - a very retrograde step after a spell where gate paddles generally were included, (albeit with those horrible "baffles" that massively slowed the flow).