Leonardo da Vinci designed an odometer with a wheel and counter to record distance traveled.
His design used a cart whose wheel turned as the cart moved. A gear mechanism transferred the wheel's rotation to a counting system, allowing the device to register distance. The drawing is associated with Leonardo's studies of mechanical motion and surveying.
An odometer does not directly measure speed or time. It measures accumulated distance, traditionally by counting wheel rotations and multiplying by the wheel's circumference. Leonardo's proposal applied that principle to a portable mechanical instrument.
The design is sometimes described as an early form of a modern vehicle odometer, but it was intended as a distance-measuring cart rather than an electronic dashboard instrument. Similar wheel-based measuring devices were useful to engineers, mapmakers, and military surveyors.