hygrometer
An instrument for measuring the degree of moisture suspended in the air and predict changes in the weather. Leonardo da Vinci created a simple set of scales with cotton on one end and a non-absorbent substance, such as wax. When humidity is in the air it is absorbed by the cotton that becomes heavier than the wax, tipping the scale. (Kremer, 2025) Photo from The Henry Ford Dearborn, Michigan, 2025.