Leonardo da Vinci designed an anemometer, a device for measuring wind speed.
His version used a hinged plate that wind pushed upward. The height reached by the plate indicated the strength of the wind, with a graduated scale allowing the result to be read.
Leonardo developed the instrument while studying flight and atmospheric conditions. Wind direction and speed were essential to his ideas about flying machines, so a practical way to observe air movement had clear engineering value.
A modern anemometer often uses rotating cups, propellers, or ultrasonic sensors. Leonardo's design was different because it measured wind force through the movement of a plate. It is therefore an early meteorological instrument rather than a flight machine itself.