Leonardo da Vinci improved an anemometer for studying wind and flight.
An anemometer measures wind speed or, in some designs, wind force. Leonardo’s version used a plate that moved in response to the wind, with a scale intended to indicate the strength of the airflow. He included the instrument among his investigations of birds, air currents, and flying machines.
Leonardo did not invent the general idea of measuring wind. Earlier devices had been used to judge wind force, and later anemometers developed into rotating-cup, propeller, and pressure-based instruments. His contribution was a thoughtful Renaissance design that made wind measurement more systematic and useful for his aeronautical studies.
The instrument is sometimes confused with a wind vane. A wind vane shows direction, while an anemometer measures speed or force. Leonardo’s interest in both airflow and flight explains why the device appears alongside his studies of wings and gliding, but the anemometer itself was a measuring instrument, not a flying machine.