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Buiding Britain's Canals


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13 hours ago, David Schweizer said:

Which makes his statement even more inaccurate, as there are 29 continuous locks at Tardebigge.

 

 

It’s all a bit arbitrary though isn’t it? You can cut the statistics in various ways and in any case the only ‘continuous’ locks are those in staircases. Caen Hill and Tardebigge have discrete locks that are consecutive.

 

A flight was only really defined by the way the canal company managed the locks. Some individual locks are not considered part of a flight with those in near proximity whereas other’s are, hence distance isn’t the defining factor. Tardebigge is recognised as a flight of 30 locks yet it’s bottom lock is closer to Stoke’s top lock than it’s top own lock is to it’s second top lock - hence you’ve described it as 29 continuous locks. You’ve made your own rules up for what constitutes a flight, but that’s all anyone ever does. It’s just that some are more obvious than others.

 

At least we’re agreed the statement was inaccurate, it wasn’t necessarily incorrect though.

 

JP

Edited by Captain Pegg
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On 08/10/2019 at 21:14, Alan de Enfield said:

Amazing how the viaduct had to be built strong enough to take the weight of the water + the weight of two boats + the weight of their cargo.

 

And I thought a boat displaced its weight of water - just shows how wrong you can be !!

By the way

The structure you refer to, which is for navigation by boats, is an "aqueduct" .

A "viaduct" carries a road , which may be a railway . The term 'road' is applicable to a railway as well as a highway.

 

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Strictly, an aqueduct is a watercourse constructed to convey water, which can include ditch, bridge, tunnel, pipe etc. In that sense, the whole of the Llangollen Canal might be considered an aqueduct as to conveys water from the Horseshoe Falls to the Shopshire Union and Hurleston Reservoir. When I visited the Pont Du Gard aqueduct in France, it was explained that the Romans considered the entire watercourse an aqueduct, not just the bridge. 

 

Our definition of aqueduct tends to mean any bridge carrying a watercourse regardless of the number of spans. It would perhaps make sense to define multi-span aqueducts as a specific type of viaduct but it seems the word viaduct was only derived from aqueduct around the time of the building of the railways. 

 

 

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1 hour ago, MartynG said:

By the way

The structure you refer to, which is for navigation by boats, is an "aqueduct" .

A "viaduct" carries a road , which may be a railway . The term 'road' is applicable to a railway as well as a highway.

 

Why do the terms have to be mutually exclusive? No reason it can’t be both. It carries water making it an aqueduct; and it carries a transport route making it a viaduct. Does ‘via’ refer to a specific mode of transport - or two - rather than just a route? I’d have thought not.

 

More importantly though we all knew what was meant by the word Alan used.

 

JP

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1 hour ago, stegra said:

Strictly, an aqueduct is a watercourse constructed to convey water, which can include ditch, bridge, tunnel, pipe etc. In that sense, the whole of the Llangollen Canal might be considered an aqueduct as to conveys water from the Horseshoe Falls to the Shopshire Union and Hurleston Reservoir. When I visited the Pont Du Gard aqueduct in France, it was explained that the Romans considered the entire watercourse an aqueduct, not just the bridge. 

 

Our definition of aqueduct tends to mean any bridge carrying a watercourse regardless of the number of spans. It would perhaps make sense to define multi-span aqueducts as a specific type of viaduct but it seems the word viaduct was only derived from aqueduct around the time of the building of the railways. 

 

 

 Avoncliffe aquduct, is also technically a viaduct as well as an aqueduct, as it carries a road wide enough to transport a horse and cart on one side, and an equally wide road on the other side which used to carry a tramway from the underground Westwood stone quarry.

 

 

Edited by David Schweizer
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On 12/10/2019 at 11:20, David Schweizer said:

 Avoncliffe aquduct, is also technically a viaduct as well as an aqueduct, as it carries a road wide enough to transport a horse and cart on one side, and an equally wide road on the other side which used to carry a tramway from the underground Westwood stone quarry.

 

 

And nearby Dundas aqueduct carries a private road serving the nearby cottage.

Quite unnerving as your'e chugging across to have a Range Rover coming towards you only just fitting the available space.

 

Steve

 

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On 08/10/2019 at 21:14, Alan de Enfield said:

Amazing how the viaduct had to be built strong enough to take the weight of the water + the weight of two boats + the weight of their cargo.

 

And I thought a boat displaced its weight of water - just shows how wrong you can be !!

I don't think it does, does it? If I remember my physics, it displaces the volume of the submerged bit, not the weight. That's how old Archy of bath fame got the volume of the crown, he could then check that volume against the equivalent of gold and lead, and the weight differences told him what the sparkly thing was made of. I think. 

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2 hours ago, Arthur Marshall said:

I don't think it does, does it? If I remember my physics, it displaces the volume of the submerged bit, not the weight. That's how old Archy of bath fame got the volume of the crown, he could then check that volume against the equivalent of gold and lead, and the weight differences told him what the sparkly thing was made of. I think. 

 

A body will displace it's own weight, (mass?), of water, (a liquid?), but, if it doesnt have the volume to displace its' own weight, it will sink. 

 

Here:

 

https://physics.weber.edu/carroll/archimedes/principle.htm

 

 

  • If the weight of the water displaced is less than the weight of the object, the object will sink
     

  • Otherwise the object will float, with the weight of the water displaced equal to the weight of the object.

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3 hours ago, Arthur Marshall said:

I don't think it does, does it? If I remember my physics, it displaces the volume of the submerged bit, not the weight. That's how old Archy of bath fame got the volume of the crown, he could then check that volume against the equivalent of gold and lead, and the weight differences told him what the sparkly thing was made of. I think. 

You’ve simply rearranged the equation, Arthur. It would of course be difficult to displace anything other than the volume of the submerged bit. What’s important is the factor that determines how much of a vessel is submerged, and that’s the weight (and it really is the weight and not the mass in this case).

 

For a fully submerged object the volume of the vessel is key - but the same physics still applies - since that is directly the volume of water it displaces. Should a vessel carrying a heavy cargo sink on an aqueduct designed only to carry the weight of water it can hold there could be trouble. I wasn’t being entirely flippant with my earlier comment. It’s not unforeseeable.

 

JP

 

Edited by Captain Pegg
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38 minutes ago, Captain Pegg said:

Well Custard was a particularly thick cat.

Custard was a thick general too. He once had a aquaduct filled with a non newtonian fluid, as part of a bet. 

 

The bet was, he could run the length of the aquaduct without sinking. Rumour has it, he got half way across, stopped to tie his shoe laces and sunk to the bottom. We  have come to know this as custards last stand.

 

I am discustard this forum is sinking so low. 

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