Leonardo da Vinci designed an early anemometer to measure wind speed. The device used a hinged plate that moved with the force of the wind, allowing the observer to read the wind's strength from its position.
Leonardo included the design in his notebooks during the late fifteenth century. It was not a modern rotating-cup instrument; instead, it belonged to an earlier family of plate-based devices. Its importance lies in applying mechanical observation to atmospheric measurement.
An anemometer measures wind speed, while a wind vane shows wind direction. Leonardo also sketched other scientific instruments, including devices related to humidity and water movement, but those have different names and purposes. The design was a proposal rather than a widely manufactured instrument, so it is best understood as an early conceptual contribution to meteorology.