Leonardo da Vinci designed an anemoscope, an instrument for showing the direction of the wind.
An anemoscope differs from an anemometer, which measures wind speed. Leonardo’s design belonged to his investigations of air movement and flight. By indicating the direction from which air was moving, such an instrument could help an observer study weather conditions and assess the behavior of flying machines.
Renaissance engineers had practical reasons to monitor wind. Wind affected sailing, artillery, ventilation, and attempts to imitate bird flight. Leonardo’s notebooks contain several instruments and diagrams concerned with atmospheric motion, including devices related to measuring or displaying wind.
A weather vane is a familiar form of direction indicator, but “anemoscope” is the more specific historical term for the instrument associated with Leonardo’s design. The name comes from Greek roots referring to wind and observation.