Leonardo da Vinci's machine concept for measuring wind speed was an anemometer.
An anemometer measures wind speed, and Leonardo designed a simple visual form in which wind deflected a plate attached to a graduated scale. The stronger the wind, the farther the plate would move. By reading its position, an observer could estimate the wind's force or speed.
Leonardo's interest in wind measurement was closely connected with his studies of flight, air currents, and weather. Reliable measurements could help an investigator compare conditions and understand how moving air affects wings and other surfaces. His design did not use the rotating cups found on many modern anemometers.
The device is sometimes confused with a barometer, but a barometer measures atmospheric pressure. A hygrometer measures humidity, while an altimeter measures altitude. Leonardo's anemometer was a proposed scientific instrument, not evidence that he possessed a modern standardized system of meteorological measurement.