What did Leonardo da Vinci’s anemometer measure?

Leonardo da Vinci’s anemometer was designed to measure wind speed.

Leonardo drew the instrument while studying air movement and flight. Its design used a lightweight plate that could be pushed by moving air. The greater the wind’s force, the farther the plate moved, allowing the observer to estimate how fast the wind was blowing.

The device was not a modern electronic meter, and Leonardo did not have a standardized scale comparable to kilometers per hour. It was an early mechanical approach to an important problem in aviation and meteorology.

Leonardo’s wind studies were connected to his investigations of birds, wings, turbulence, and flying machines. His anemometer should not be confused with a wind vane, which shows wind direction rather than speed.