Leonardo da Vinci sketched an odometer with a wheel to record distance traveled.
His design was based on counting repeated wheel rotations. As the cart moved, a mechanism could transfer motion from the wheel to a series of gears or compartments, allowing the device to register a measured distance. This is the same basic principle used by many later mechanical odometers.
Leonardo’s notebooks contain numerous studies of gears, wheels, and measuring instruments. An odometer would have been useful for surveying, mapping, road measurement, and military engineering. Accurate distance measurement was especially valuable when planning fortifications, canals, and transport routes.
Leonardo did not originate the general concept of an odometer. Ancient engineers, including those working in the Hellenistic and Roman worlds, had already used distance-measuring devices. His sketch is significant because it shows how Renaissance engineers revisited older mechanisms and refined them through detailed mechanical analysis.