Museo Galileo
Virtual Museum
Saussure hair hygrometer
    • Setting:
      Room XIV
    • Inventor:
      Horace-Bénédict de Saussure
    • Maker:
      Jaques Paul [attr.]
    • Place:
    • Date:
      late 18th cent.
    • Materials:
      brass, silvered copper
    • Dimensions:
      width 98 mm, height 325 mm
    • Inventory:
    • Saussure hair hygrometer (Inv. 2033)

Instrument identical to the hygrometer described by Horace-Bénédict de Saussure c. 1780. It consists of a brass frame on which is stretched a bundle of hair (originally, a single hair was called for) secured by small jaws and passing over a pulley with a pointer. A counterweight, connected to the pulley, kept the bundle taut. The hair, which functions as a hygroscopic substance, varies in length with air humidity. The changes can be read on a semicircular silvered scale registering the positions of the pointer. This instrument, attributed to the maker Jaques Paul, is similar to item inv. 3708.