Horace Bénédict de Saussure devised the first hair-tension hygrometer in 1783, but Leonardo da Vinci invented a version of the hygrometer as early as the late 1400s. Francesco Folli designed the first practical hygrometer in 1664, and John Frederic Daniell built the first dew-point hygrometer in 1820.
- Guillaume Amontons invented a type of hygrometer that was similar to a three-liquid barometer in 1687.
- James Hutton developed the first psychrometer in the late 1700s.
- Johann Heinrich Lambert first coined the name “hygrometer” in 1774.
- Robert Hooke, prolific inventor of the universal joint, balance spring and a prototype respirator, made improvements to hygrometers and barometers.
The above image shows a hygrometer from “A Text-book on Chemistry”. Which was published by John William Draper in 1861. This hygrometer by John Frederic Daniell (1790-1845) was intended to determine the dew point. The image and a description of this hygrometer can be found on page 52. The book is freely available at Google Books.
