Bromsgrove Sterling Silver Pocket Watch, London 1770-1775

• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Sterling Silver - Sterling silver is a mixture of 92.5% pure silver and 7.5% of another metal, usually copper. Fine silver is 99.9% pure silver, and is relatively soft and the addition of the very small amount of copper gives the metal enough strength and hardness to be worked into jewellery, decorative and household objects.
• Pair Cased - A pair cased watch is one with a double case. The movement is encased, and for additional protection this is fitted into an outer case.
• 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  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.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:

• pocket watches, case type
  • open face, silver case 553
  • pair cased 156
  • silver case 865
  • silver, open face 200
• pocket watches, period - Georgian 258