Leonardo Da Vinci’s Canal Lock is his longest standing most successful invention. Centuries later, the miter lock is still used in most canals and waterways around the world including Panama Canal.
It replaced the old Portullis Lock which was basically a door placed directly across the canal. Da Vinci’s is 2 gates placed together at a 45 degree, and it sealed tighter when the water pushed against it. It is also easier to open and close, and back in the day when they were manual, it made the job much easier.
The simple design was leaps and bounds ahead of its time, like most things Leonardo Da Vinci invented.
Another tick off my 40-before-40 list.