Ancient Rome: The Odometer Of Vitruv

What Was the Odometer of Vitruvius

The Odometer of Vitruvius was a narrow wagon frame with a large 4 foot in diameter chariot wheel attached. This was done in a way that would remind you of a modern wheelbarrow. It was very important for the invention to work the wheel was a specific diameter.  A pebble fell into a container after every revolution of the wheel which was manually moved along by hand. As the wagon moved along the chariot wheel would turn 400 times for every Roman mile.

Every time the wheel completed a rotation a pin on the wagon engaged a cogwheel that had 400 teeth. Meaning the chariot wheel would turn one complete revolution per mile. The complete rotation would engage a different gear with holes so that pebbles that were located on it could fall into a container.  Each time a pebble dropped a certain measured distance was being marked. The total miles covered could be counted by counting the number of pebbles. In other words, the first known odometer was born.

Background On The Odometer

Vitruvius, who served as an engineer and architect for the Romans is usually credited for the invention of the odometer. There might have been other Odometers before Vitruv, but only his' design survived. His invention was thought to happen roughly around 23 BC. But we don't know for certain his design actually worked.

Leonardo da Vinci once attempted to create the odometer based on Vitruvius s design, but he was unable to get it to work. But engineer Andre Sleeswyk takes a shot at it in 1981 replacing da Vinci's square-toothed gear designs with the three-way pointing teeth of the Antikythera system. With the slight adjustment, Andre was able to get his model to work.

How did Vitruvius' Wagon Odometer Work?

If you pull Vitruvius' wagon, the wheel, as you could imagine, rotates. A finger is mounted on one wheel. This finger rotates a gear (grey) on each turn. This gear should have 400 cleats. One of those cleats is extended. This extension rotates another gear (blue), which lies horizontally.

This horizontal gear is only rotated once per mile because the big wheel rotates slowly.
There are about 25 holes in the horizontal gear. In it are small stones. When the wheel turns, one stone will fall into a pot.

If you want to count the miles you went on one day, you just have to count how many stones are in that pot. The number of stones equals the miles you went.

Odometer of Archimedes

Vitruvius created an odometer for calculation of distance around  23 BC. But Archimedes of Syracuse may possibly have been the original creator of the original device. It is said Archimedes created his odometer during the First Punic War which occurred from 264 BC to 241 BC. 

Who Was Marcus Vitruvius Pollio

Marcus Vitruvius Pollio was a Roman widely known as Vitruvius. He was is most well known for the set of ten books on architecture he wrote sometime during the 1st century BC called De architectura. In addition to being an author, he also was an architect, military, and civil engineer for the Romans as well. 

His concepts for the ideal portion of the architecture and the human body were a huge influence on the great Leonardo da Vinci. In fact, it was the inspiration the Leonardos very famous painting titled Vitruvian Man. The painting even included notes based on Vitruviu's work. 

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