Leonardo’s Lock
Model of Leonardo’s Lock Gate, Château du Clos Lucé
Search online for Leonardo’s inventions and up pop the usual suspects: Helicopter, parachute, tank, diving suit et al but hardly ever the one which actually worked in his own life time as opposed to hundreds of years in the future.
His ground breaking mitre lock*, a momentous advance in canal technology, one of his finest achievements has continued in use for over five hundred years virtually unchanged.
In 1498 Ludovico Sforza** duke of Milan, appointed Leonardo State Engineer responsible for rivers and canals. Legend has it that Leonardo had no staying power. Not so. He held this very important Post for over twenty years.
Milan’s canals were as important as those were to Venice and Amsterdam. They connected the city to rivers and ultimately to the sea which meant that Milan became an affluent trade destination.
When Ludovico asked Leonardo to improve the navigability of the canal system by connecting the Naviglio and Martesana canals to Milan’s internal waterways, he created six new locks, one was for the San Marco canal.
He came up with a pair of gates each hinged on opposite walls. Made with vertical planks with horizontal and diagonal braces, iron sheathing for the joints, a brick floor underneath the gates and a recess in the walls into which each gate folded.
When closed, the gates form a V-shape pointing upstream. Two forty-five degree angles meet each other. When the incoming water hits them, it forces the two mitres into each other which results in a self-sealing gate.
Model of Leonardo’s Lock Gate, Château du Clos Lucé
Leonardo also introduced a small sluice gate at the bottom of the gates. Opened from above with a rope and pulley it allowed water in the lock to start emptying before the big gates could be fully opened.
Nearly all modern lock gates follow Leonardo’s principle. They can be seen on the Suez and Panama Canals and the mighty Mississippi. Unbelievably, the one place you will not see them is in Milan. If you hare foot it there to see the Master’s innovation you will be in for a shock. A sad old wannabe Lock at the end of the Via San Marco is one of the few remnants of the once impressive canal system. Now filled in and paved over, all you will find is modern buildings.
In the superb Go To Leonardo Exhibitions at Château Clos Lucé, the Master’s beloved old home, many of his jaw dropping inventions are stars of the show. His Canal Mitre Lock Gate is not one of them but now that we can’t see it in Milan, you never know, perhaps one day we will see it on one of Clos Lucé’s rivers.
* Device for raising and lowering boats and ships between stretches of water of different levels. Sluices are opened and closed in the doors which allow water to either fill or empty the canal lock. As water is replenished from high, a channel carries water past the lock into the lower pound.
** It was Ludovico who commissioned Leonardo to paint The Last Supper in the refectory of Santa Maria delle Grazie convent in Milan.
Post by Pamela, photography by Mark.
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