Leonardo da Vinci designed an anemoscope to show the direction of the wind.
An anemoscope is a wind-direction instrument, usually based on a vane or another indicator that turns with moving air. Leonardo’s drawings show his interest in creating a readable mechanical indication of wind direction, which would have been useful for studying flight, weather, and sailing conditions.
The name is easy to confuse with anemometer. An anemometer measures wind speed, while an anemoscope indicates wind direction. A simple weather vane performs the directional function, but Leonardo’s approach was part of his larger effort to observe and record natural forces mechanically.
Leonardo studied air as both a physical phenomenon and a possible support for flight. His notes examined birds, air resistance, currents, and the movement of wings. The anemoscope therefore belongs beside his aerodynamic investigations, even though it was not itself a flying machine. The surviving evidence concerns a design and observation instrument, not a documented mass-produced device.