almost invariably the point of the V is in the center of the river
Ted, I have two guesses: 1.) Perhaps the opening wasn't in the center of the river then (in other words, the river moved, over the centuries); 2.)if it was deliberately built in the center, I bet it has something to do with the current helping to "encourage" the fish to move through.
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tsuwm, I haven't had time to look through old threads, though I'm sure there've been new words I have known and loved. So the only one I can think of is pie-poudre/powder.
I still have a thing for hemidemisemiquaver--it just makes me smile!