Leonardo da Vinci’s air-measuring device was an anemometer.
An anemometer measures wind speed or, more broadly, the movement of air. Leonardo designed a plate-style anemometer in the late 15th century. As wind pushed a hinged plate, the position of the plate could be read against a graduated scale, giving an indication of wind strength.
The instrument was useful for his studies of flight and airflow. Leonardo examined birds, wind, and the resistance of air while developing flying-machine concepts. His device did not measure wind speed with the accuracy of modern cup, vane, or electronic anemometers, but it represented a practical attempt to turn air movement into a visible measurement.
An anemometer is not the same as a barometer. A barometer measures atmospheric pressure, while an anemometer measures wind speed or airflow. Leonardo’s work demonstrates how his invention studies combined observation, mechanical design, and the measurement of natural forces.