Museo Galileo
Virtual Museum
Viviani's rope hygrometer
    • Setting:
      Room IX
    • Inventor:
      Vincenzo Viviani
    • Maker:
      Vincenzo Viviani [attr.]
    • Place:
    • Date:
      second half 17th cent. (oldest part)
    • Materials:
      wood, brass
    • Dimensions:
      length 2560 mm, height 675 mm
    • Inventory:
    • Viviani's rope hygrometer (Inv. 799)

Hygrometer attributed to Vincenzo Viviani, fully resembling the model invented by Santorio Santorio. On a wooden board, to be hung on a wall, a horizontally stretched rope of twisted gut is used as hygroscopic substance, weighted at the center by a boxwood ball. The changes in air humidity cause the gut to lengthen or shorten, modifying the ball's vertical position. This is measured by means of a graduated brass plate attached to the board. The brass plate is probably the only original part.