Museo Galileo
Virtual Museum
Gunner's rule
    • Setting:
      Room II
    • Maker:
      Hans Christoph Schissler
    • Place:
    • Date:
    • Materials:
    • Dimensions:
      length 180 mm
    • Inventory:
    • Gunner's rule (Inv. 2517)
    • Gunner's rule (Inv. 2517)

This rule, made by Hans Christoph Schissler, was used for military purposes (such as determining the calibers of stone and lead projectiles), land surveying, and time reckoning. Accordingly, there are a scale of weights for cannonballs, a linear measurement scale in Roman feet, a small magnetic compass in the leg joint, a viewer at the end of one leg, and a cross-arm with the scale of diurnal hours. A second cross-arm and plumb bob (missing) enabled the instrument to be used as a gunner's level for measuring inclinations and adjusting gun elevation. Brought to Florence from Germany by Prince Mattias de' Medici in the first half of the seventeenth century.