Its not that difficult to do it while in use, you just construct a parallel lock next to the existing ones that can remain in use.
It's even possible to upgrade a lock while in use, you just add new inlets and outlets for the new archimedes screw system, an unused archimedes screw or inlet/outlet is just a differently shaped boundary wall...
Even in 1881 all the necessary physics was already known, but I'm less surprised less informed people could rise to the top that easily back then.
I'm more surprised by the post-war 60's when physics and engineering became a lot more democratized, less elite...
It's even possible to upgrade a lock while in use, you just add new inlets and outlets for the new archimedes screw system, an unused archimedes screw or inlet/outlet is just a differently shaped boundary wall...
Even in 1881 all the necessary physics was already known, but I'm less surprised less informed people could rise to the top that easily back then.
I'm more surprised by the post-war 60's when physics and engineering became a lot more democratized, less elite...