Leonardo da Vinci is credited with improving the anemometer, a wind-measuring instrument, using a hinged plate.
An anemometer measures wind speed. Leonardo's version used a plate that could move in response to the wind. The angle or position of the plate provided an indication of how strongly the air was moving. This approach made the instrument useful for observing wind without needing the rotating cups found on many later anemometers.
Leonardo studied air movement as part of his investigations into flight, weather, and fluid motion. His notebooks contain observations and mechanical proposals rather than a single standardized instrument that became universally adopted. The hinged-plate concept is nevertheless associated with his efforts to quantify wind strength.
The word is sometimes confused with instruments that measure wind direction. A wind vane indicates direction, while an anemometer measures speed. Modern anemometers commonly use rotating cups, propellers, or ultrasonic sensors, but the underlying purpose remains the same.