What Leonardo da Vinci instrument measured wind direction and strength?

Leonardo da Vinci’s instrument for measuring wind direction and strength was an anemometer.

Leonardo designed an early anemometer in the late fifteenth century. Its moving indicator responded to the wind, giving an observer a way to judge both the direction of airflow and its relative force. The instrument was useful to Leonardo’s studies of flight, because wind conditions strongly affect the performance of wings and gliding machines.

The word anemometer comes from Anemoi, the Greek personifications of the winds. Modern anemometers often use rotating cups, propellers, or ultrasonic sensors, while modern weather stations may measure wind speed and direction electronically.

Leonardo’s device should not be confused with a barometer, which measures atmospheric pressure, or a hygrometer, which measures humidity. His instrument did not provide the precise digital wind-speed readings used by meteorologists today, but it belongs to the early history of systematic wind measurement.