In the course of my wanderings, I found a lock. Not a padlock -- a canal lock. At a place called the Narrows.
Now, I've seen locks on canals before. I've watched some modern ones operate, lifting great big freighters up what looked like a couple of stories. Impressive, to say the least.
But this lock -- while far smaller -- was impressive, as well. Maximum length was maybe 75 feet, and the rise only about a yard. But what impressed me was that the thing was built in 1830-something, and was still operating with the original technology. (OK, not entirely. The lockmaster used a modern-ish bullhorn to speak to the boat captains, but that was the only upgrade I noticed.)
The lock gates had long levers on them; they could be opened or closed by cranking a chain around a couple of pulleys (mechanical advantage of the lever arm multiplied by mechanical advantage of the crank arm). The small doors which allowed water to flow into (or out of) the lock area were lifted by similar chain/crank arrangements. The bridge across which I drove (single lane, admittedly) swung out of the way -- it was mounted at its center on some sort of planetary gearing, powered from above by hand. The whole operation was handled (and I do mean handled) by three people, one of whom seemed not in the best of health.
In the half-hour or so that I watched, the lock passed seven boats in one direction and four in the other, while allowing road traffic to cross the bridge for at least 20 minutes. That's a pretty good level of efficiency, given no major upgrades (technical refurbishment, I'm sure) in about 175 years.
If it ain't broke, don't fix it.