Museo Galileo
Virtual Museum
Circle-dividing engine
    • Setting:
      Room X
    • Inventor:
      Michel-Ferdinand d'Albert d'Ailly, Duc de Chaulnes
    • Maker:
    • Place:
    • Date:
    • Materials:
      wood, brass, marble
    • Dimensions:
      1610x1170x1250 mm
    • Inventory:
      586, 3244
    • Circle-dividing engine (Inv. 586, 3244)

This dividing engine, built in the workshop of the Museo di Fisica e Storia Naturale, was used to mark scale divisions on arcs of circles (of astronomical and nautical instruments, for example). Some features resemble those of the engine designed by the Duc de Chaulnes.

The engine is mounted on a heavy marble slab resting on an elegant eighteenth-century table. It consists of a large brass disk with a toothed rim and a mechanical system for guiding and adjusting the motion of a tracing burin. A handle with a graduated quadrant serves to rotate a worm screw that meshes with the rim of the disk, on which the scale to be divided was fastened. Each turn of the handle translated into a minuscule rotation of the disk. Two micrometric microscopes (of which one is now missing) served to check the positioning of the divisions etched by the burin.