Scientific Instruments > Meteorology

18th Century Saussure Hair Hygrometer.

Item#: SMT482

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Brass hair hygrometer and mercury thermometer made in Switzerland according to Saussure. This important instrument was invented by Horace Benedict de Saussure (1740-1799), and published in his book: Essais sur l'Hygrom?trie. Ier. Essai. Description d'un nouvel Hygrometre comparable. Geneva: Barde, Manget, 1788. Cuvier regarded this book as one of the greatest contributions to science made in the 18th century. The effectiveness of hair hygrometer rests on the hygroscopic properties of organic substances in the hair, which lengthen as they absorb moisture. The change in length of the single human hair moves the pointer along the empirically calibrated scale. This hygrometer is functioning properly. However, it should be calibrated. Height of brass frame 30 cm.