Leonardo da Vinci sketched an anemometer to measure wind speed.
His design used a vertical board or plate that moved in response to wind. A graduated scale could then indicate the wind’s strength. The instrument is commonly associated with Leonardo’s studies of flight and atmospheric movement, because understanding wind was essential to his investigations of birds and possible flying machines.
An anemometer is specifically a wind-speed instrument. It is different from a wind vane, which shows direction, and from a barometer, which measures air pressure. Modern cup, propeller, sonic, and laser anemometers use more advanced methods, but they serve the same broad purpose.
Leonardo’s sketch is important less as a modern precision instrument than as evidence of his experimental approach. He tried to make invisible air motion observable through a controlled mechanical response and a scale that could be read.