1407. Da Vinci

You're probably wondering what Leonardo da Vinci has to do with the Chesapeake and Ohio Canal.
We mostly know Leonardo as a great painter. We think of the Mona Lisa, the Last Supper or the Ginevra de Benci which you can see in the National Gallery in Washington, D.C.
But Leonardo was interested in a lot of things like anatomy, aeronautics, mechanics and engineering.
In 1485, he was looking for a job, so he wrote to the Duke of Milan, saying," I can construct  light, strong and portable bridges...I can demolish every fortress whose foundation is not laid in stone...I can make armored wagons carrying artillery...in time of peace, I believe I can give you complete satisfaction in conducting water from one place to another." He also said he could do a little painting.
Before Leonardo, canals used something called a portcullis gate, kind of a big castle gate, that you could raise and lower in the water. Not the best design.
Leonardo came up with the idea for mitered lock gates that would point upstream. The water pressure would hold the gates in place. Furthermore, at the bottom of the gate would be a butterfly paddle that you could open or close to regulate the water level in the lift lock. When the water pressure equalized on both sides of the gate, it would be easy to swing it open.
Leonardo's design spurred canal building in Europe, and it is the basis for all canal lift locks from the Erie to the Panama Canal.