Today I learned that the miter lock - the V-shaped pair of gates that control water levels in a marine environment – was invented in the 1490s by Leonardo da Vinci.
I've seen working locks many times, from the mighty Soo Locks with their capacity to move 1000- foot freighters from lake to lake via immense 250-ton gates, all the way down to tiny DIY wooden portcullis canal locks in the countryside.
I visited the Ballard Locks by land, and chatted with the operators, passing yachters, and a...