Canals

[Hopkirk]

When our ancestors dug the canals, how did they line them to stop all the water leaking away?

[Fitzer]

In general they are lined with clay, with brick linings in locks and the like.

[Hopkirk]

Thanks, Fitzer.

Mind you, I would have thought that even clay would let quite a lot through.

[Peter Pedant]

Clay

No clay is pretty resistant to water - -

famous story of Lord - Derwentwater ? Bridgewater in the Lords taking clay in and some water and showing their lordships....

you needed an act of parliament to build a canal - presumably thro someone elses land - so the earliest would be the Bridgewater Canal act around 1762.

Canals also have plugs - someone dredged out a cartwheel coverd with fabric and when all the water in the canal leaked away, a yokel said
arr that be a plug, that be, and now you're let all the water out ! arr

[Fitzer]

it's called puddling and is apparently completely watertight http://en.m.wikipedia.org/wiki/Puddling_(engineering)

[Mosaic]

Peter P, the tale you half-relate was that James Brindley, engineer, took clay into what we would call a 'presentation' to his sponsor, Francis Egerton Duke of Bridgewater, and demo'd how it would work. Up to that point there had been a discontinuity of technological development from the times of Roman stone-built aqueducts, a good millennium-plus before. Egerton had seen Roman aqueducts during his Grand Tour, so had an idea that Brindley's scheme would work. And it did.

Canal linings were not any old clay but puddled clay ie stomped down to remove all the air spaces.

[Mosaic]

Doubt very much the plug idea PP. The early contour-following canals avoided locks, so had inbuilt safety points where 'stop planks' would be inserted if there were problems.
If a canal looked like overfilling there were escape channels inbuilt.

But no plugs.

[Hopkirk]

Yes, nice story about the plug, but I can't believe it.

Since you can't open a lock gate until the water levels are virtually the same, I don't think you would have the strength to pull the plug out.

[sandyRoe]

At the time it was said an Irishman did this

As a side note, in 1978 a maintenance team was dredging the bottom of the canal to remove rubbish. Later that day, they were told that a large whirlpool had formed and the canal was quickly losing water. It turned out, one of the first things removed from the canal was a large plug that had been installed to allow the canal to drain in an emergency.[12]

[sandyRoe]

http://en.wikipedia.org/wiki/Chesterfield_Canal

[Peter Pedant]

Oh dammit all, I always was a b++lsh+++......and people can tell you know...

As a side note, in 1978 a maintenance team was dredging the bottom of the canal to remove rubbish. Later that day, they were told that a large whirlpool had formed and the canal was quickly losing water. It turned out, one of the first things removed from the canal was a large plug that had been installed to allow the canal to drain in an emergency.[12]

http://en.wikipedia.org/wiki/Chesterfield_Canal

last sentence in Restoration

I remember when it happened. I hadnt realised it was 1978

[woofgang]

when I was looking at building my first garden pond in the 70's puddling clay was one of the suggested methods.

[Hopkirk]

Fair enough. Good story.

[Peter Pedant]

//Since you can't open a lock gate until the water levels are virtually the same, I don't think you would have the strength to pull the plug out//

This is a a calc you do in Physics at school - the pressure (force) on a lock gate is astronomical - is it a ton for one inch difference ?
where as on the now westablished cartwheel it would be the depth of the canal ( 3- 4 ' ) times the area of the wheel - er in appropriate units.

must've done this years before 1978 as I am stuck in imperial measure.


I can tell you we zummerzet levellers never understood how canals worked, as they are all drainage canals darn there and what IS the point of lining with puddled clay as it will keep the water OUT ?

ho hum

[Hopkirk]

I bet it was more than a cartwheel with a bit of fabric though. That would never hold.

[Peter Pedant]

O god whilst we are at it:
House of Lords story:

http://books.google.co.uk/books?id=Y7c2rVtmyPcC&pg=PA26&;lpg=PA26&dq=canals+clay+watertight+house+of+lords&source=bl&ots=uHHdDRurXO&;sig=-VtfLbhmxX-b5ebAwSwX5uhEoCY&hl=en&sa=X&ei=KArpU4moNcam0QXdkICgAg&ved=0CCAQ6AEwAA#v=onepage&q=canals%20clay%20watertight%20house%20of%20lords&f=false


1762 I am glad to say - but ..... I wasnt there

that one was from my history master 1966 yes in the Zu,,erset levels and I am sure he wouldnt get that wrong

[jourdain2]

Haven't read the other answers (am on a quick scan) but they used to puddle clay to line them.