Kingsford

Ah, yes, I see. I completely misread the post; happens to the best of us.😅

Another quick question, do we know where south of the two locks the outlet is for the water that goes over the bywash/overflow/waste weir?

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That's what I kind of figured, and I figure that during regular operations that the doors on the T&M lock were probably left opened most of the time. Also, since it could be operated in either direction, does that mean the southernmost and northern most gates in this chamber sat on a sill so they are both "upper" gates? What of the area in between the two locks? BTW, any current examples of canal junctions like this which still operate where either side is higher? Would love to see some profile drawings like Pluto just posted to be better able to visualize their workings. Someone's got to be able to mock up a profile of the Hall Green lock chamber in Paint, or something, and it'd be a nice reference document for future questions. Honestly, I'd message someone about this so as not to clutter the thread, but it says I need 10 posts to do this.

Thanks, everyone, for helping me understand what was - and wasn't - unusual about this particular lock. BTW, what are some scenarios in which the T&M would have been higher than the Macclesfield? Just regular weather events, leakages, etc? David, from an old drawing I've seen, the T&M's north/south or up/down lock gates were just single gates and didn't "point" in either direction. The only pointed set of gates seems to have been the northern gates of the Macclesfield stop lock.

Right, I understand the basic purpose, and that would exmplain why the T&M manuevered to have the new Macclesfield install a stop gate, but doesn't explain the reason for then building their own stop backed right up to it, except for obvious redundancy in case something happened to the Macclesfield stop gate. And, maybe, the explanation it's just that simple (redundancy). But, as has been discussed, this was a very unusual setup. We're talking two chambers with four sets of doors in which both locks could act as lift locks; in fact, it seems arguable that that was their primary function. Typically, these canal junctions would only have two doors, correct? I think the other thing is that when we're talking about a "lock" we're usually talking a pound enclosed by two sets of doors to provide a rise/fall, whereas a "stop lock" is just a gate, right?

Sorry to bump what is such an old post, but I've had questions about Hall Green that I still haven't quite fully found a good answer to. Some of the confusion may be how terms are being/have been used (is the "stop lock" the water in between either of the gates, or just the "down" gate on either lock?). But, just to describe the setup in the overly-long chamber from north to south you had a set of pointed gates, then a single gate, then a small gap in between, then another single gate, and then another single gate at the entrance to the T&M side? Did I get that correct? From the various pieces I've read on this, it seems that the purpose was originally to keep the Macclesfield slightly higher to 'protect' the T&M Hall Green branch. And, if that was the case, the Macclesfield lock really just functioned as a lift lock. Anyone have any of the original documentation organizing the development of the canal? The Macclesfield website seems to at least imply that any lock where the two met was simply to prevent water loss from the T&M. But then you see mentions all over that "either canal could be higher." This seems to skip right over in time the explanation for the development and purpose of the T&M lock. But we know that it was needed for one reason or the other, so I guess them both functioning as lift locks would make sense. To end, a boat traveling "down" the from the Macclesfield would be locked down into the Macclesfield lock, and then in the chamber the three other gates would simply be opened - after they paid their toll to T&M - to allow passage? Is it that simple? Would kind of like to see someone make a little diagram describing how this setup worked.