Leonardo da Vinci designed an anemometer to measure wind speed and indicate wind direction.
His version used a lightweight plate that moved in response to airflow. A graduated scale allowed an observer to estimate the strength of the wind, while the arrangement could also reveal its direction. The design is usually dated to the late 15th century and is associated with Leonardo’s interest in flight and atmospheric conditions.
An anemometer is not a barometer: a barometer measures air pressure. It is also different from a modern cup anemometer, whose rotating cups provide a direct indication of wind speed. Leonardo’s device was an early observational instrument rather than a modern electronic meter. The invention is especially relevant to his studies of birds, air currents, and the practical conditions needed for flying machines.