Leonardo da Vinci improved a hygrometer, an instrument for measuring humidity in the air.
His design used a balance to compare the weight of a moisture-absorbing material with a reference object. As the material absorbed water from the air, its weight changed, allowing humidity to be estimated. This was an early attempt to turn atmospheric moisture into a measurable quantity.
A hygrometer is different from a barometer, which measures air pressure, and an anemometer, which measures wind speed. Leonardo’s work belongs to the broader Renaissance effort to quantify natural phenomena through instruments and experiments.
Modern hygrometers use electronic sensors, chilled mirrors, or other precise methods. Leonardo’s version was comparatively simple and did not provide the accuracy of modern instruments, but it helped establish the principle that changes in moisture could be measured systematically.