# Leonardo Bridge

 Is the bridge stable when pushing downwards? Is the bridge stable when pushing from the side? Can you build a longer or shorter bridge?
Maths

Leonardo da Vinci devised this bridge in the 15th century while working as a military engineer in Milan.
Designed to help marching armies cross rivers, the bridge works by interlacing the sticks which holds them in place. The bridge can be constructed quickly, with no tools or fasteners, and was ideal for temporary use.

Downward weight actually makes the bridge more stable, but the bridge is very unstable against sideways force. In da Vinci’s original design, notches could be cut into the timber to make the bridge more stable.

History

In the 1480s the area of Milan was at war. So young Leonardo da Vinci wrote to Duke Sforza asking for a job as an engineer, writing:

“In case of a siege, I know how to dry up the water of the moats and how to construct an infinite number of bridges, covered ways, scaling ladders, and other machines for this type of enterprise.”

Da Vinci worked as a military engineer in Milan for the next 17 years, designing all kinds of bridges, catapults, tanks, submarines and flying machines.

People
 Leonardo da Vinci 1442 – 1519 Da Vinci was an Italian artist, engineer, inventor and mathematician. Possibly most famous for painting the Mona Lisa and other art works, da Vinci worked for 17 years as a military engineer. Here he invented machines of war including catapults, tanks, submarines, and flying machines. Da Vinci also designed several types of bridges, including the self-supporting bridge that could be constructed quickly with little skill or tools.
Applications

The original use of Leonardo’s bridge was as a temporary structure, that could be built quickly and with little skill or tools.

The bridge is sometimes built today for exhibitions, like this one from Stuttgart, Germany celebrating traditional carpentry. Here, a 10m bridge is constructed in ten minutes.
This bridge is strong enough to drive across.

Maths at Home

Leonardo’s bridge is easy to construct at home. Here are some instructions of how to make a Leonardo bridge using lollipop (popsicle) sticks.