Museo Galileo
Virtual Museum
Plate electrical machine
    • Setting:
      Room XI
    • Maker:
    • Date:
      early 19th cent.
    • Materials:
      boxwood, brass, glass
    • Dimensions:
      total height 1900 mm; table 1300x1050 mm; glass disk diameter 1000 mm, thickness 5,5 mm
    • Inventory:
      Dep. LV, Torino
    • Plate electrical machine (Dep. LV, Torino)
    • Plate electrical machine (Dep. LV, Torino)

Frictional electrical machine with glass disk rubbed by four cushions with large taffeta flaps. These prevent the charges on the glass from dissipating into the air. The cross-piece of the frame supports a Volta pistol in the shape of a brass urn. The prime conductor consists of two brass tubes with spherical ends connected by a cross-tube fitted with an electrode, resting on glass supports; they terminate in jaw-collectors to facilitate the transfer of the charge at both sides of the glass disk. Positive charge is taken from the prime conductor, while negative charge is taken from the hook at the top of the machine. The signature plate is lost. In nineteenth-century manuals of electricity, this pattern is generally called the "Ramsden type," after the English maker Jesse Ramsden. In fact, it is a typical French design.