French Silver Open Face Pocket Watch by Berthoud Paris

• Engine Turned - Engine turning is a decorative technique used on metal surfaces to create intricate curving or geometric pattern. The process involves cutting a series of lines into the surface of the metal using a rose engine or decoration lathe which rotates the metal as it cuts, allowing the operator to create a repeating pattern that covers the entire surface. The resulting surface has a shimmering, reflective quality that is often described as "engine turned." Where an engine turned item has been enamelled, the term used to describe the decoration is usually guilloche.
  
  Engine turning was originally developed to decorate metal objects such as firearms, scientific instruments, and other metal objects that required precise and elegant design.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Bezel - On a clock or watch, the bezel is the metal frame into which the watch or clock glass is fitted. In clocks, the bezel may include a hinge and a flange, in effect a door to the face of the clock. In jewellery the bezel is a band of metal with a projecting lip that holds the gemstone in its setting.
• Fusee - The fusee movement was used in clocks and pocket watches from the mid 17th century. The fusee is a cone shaped drum within the works that is linked to the barrel of the spring, usually by a length of chain.
  
  As the mainspring loses its tension over time, the cone shaped barrel compensates for this by increasing the tension, by pulling the mainspring tighter, thus ensuring the time remains constant.
  
  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.
  
  The fusee continued to be used in marine chronometers until the 1970s.

This item has been included into following indexes:

• Berthoud, Paul-Francois (French 1870-1939) - sculptor 6
• pocket watches, case type
  • open face, silver case 570
  • silver case 905
  • silver, open face 204