Leonardo da Vinci designed an anemometer, an instrument for measuring wind speed.
His sketch shows a vertical device with a plate that is pushed by moving air. As the wind increases, the plate rises along a graduated scale, allowing an observer to estimate the wind's force. Leonardo's version was intended to help study atmospheric conditions and the performance of flying machines.
An anemometer is not a barometer, which measures atmospheric pressure, nor a wind vane, which indicates direction. Modern cup and propeller anemometers measure wind speed by converting rotation into a reading, while ultrasonic instruments use sound waves. Leonardo's mechanism was much simpler and relied on the movement of a physical plate.
The invention reflects Leonardo's habit of combining observation with engineering. He investigated air resistance, bird flight, clouds, and storms, and his weather instruments were part of that broader study. The surviving drawing is an early example of an instrument designed to turn an invisible natural force into a measurable quantity.