SJ5242 : Grindley Brook top staircase lock 1 Llangollen Canal
near to Grindley Brook, Shropshire, Great Britain
In a staircase the upper gate of one lock is also the lower gate of the one above it. Operating a staircase is very different from operating a flight. It can be more useful to think of a staircase as a single lock with intermediate levels. As there is no intermediate pound, a chamber can only be filled by emptying the one above, or emptied by filling the one below; thus the whole staircase has to be full of water (except for the bottom chamber) before a boat starts to ascend, or empty (except for the top chamber) before a boat starts to descend. In an apparent staircase the chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting. Examples of real staircases are Bingley and Grindley Brook. Examples of apparent staircase locks are Foxton Locks and Watford Locks on the Leicester Branch of the Grand Union.
The Llangollen canal is an arm of the Shropshire Union canal that runs from Hurleston Junction to Llangollen with a wide variety of scenery along its course. Its total length is 46 miles, but the last 1½ miles from Llangollen to Llantisilio is unnavigable by any boats over about 10' length.
The canal's vital statistics for craft are:
Length 72 '
Draught 2'3" (Hurleston to Pontcysyllte) 2' (P. to Llangollen)
These are the maximum dimensions for any craft, based on the minimum dimensions of locks & bridges.
There are a total of 21 locks on the canal, but only two between Llangollen and Whitchurch (a distance of about 31 miles). One of the most notable things about the canal is the strong flow especially in the "narrows" near Llangollen and in the tunnels near Chirk. About 12 million gallons of water passes down this canal from the River Dee to the Shropshire Union every day.
The most famous feature of this canal is the superb feat of engineering that is the 200-year-old Pontcysyllte Aqueduct rising 126' above the River Dee and running for over 335 yds - for more information on this see the numerous photos for squares SJ2742 and SJ2741
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- Grid Square
- SJ5242, 43 images (more nearby)
- Jo Turner (find more nearby)
- Image classification?
First in 5 Years (TPoint) ?
- Date Taken
- Monday, 13 June, 1994 (more nearby)
- Sunday, 4 November, 2012
- Geographical Context
- Subject Location
OSGB36: SJ 5236 4286 [10m precision]
WGS84: 52:58.8573N 2:42.6597W
- Photographer Location
- OSGB36: SJ 5237 4288
- View Direction
- South-southwest (about 202 degrees)
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