Leonardo da Vinci designed an anemometer, an instrument intended to indicate the strength of moving air.
His design used a vertical board or plate that could move in response to wind. A graduated scale allowed an observer to estimate how strongly the air was pushing the surface. Leonardo recorded the idea while studying flight, wind, and the behavior of air around flying machines.
An anemometer is not the same as a barometer. An anemometer measures wind speed or force, whereas a barometer measures atmospheric pressure. Leonardo’s device was comparatively simple and did not provide the precision of modern cup, vane, or sonic anemometers.
The instrument mattered because Leonardo understood that wind measurements were essential for studying birds and designing machines that might fly. His notebooks contain many observations of air currents, resistance, and the relationship between wind and motion. The historical device is therefore an early example of a scientific measuring instrument connected to aviation research.