1860 Parkinson & Frodsham Mahogany Marine Chronometer

• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Circa - A Latin term meaning 'about', often used in the antique trade to give an approximate date for the piece, usually considered to be five years on either side of the circa year. Thus, circa 1900 means the piece was made about 1900, probably between 1895 and 1905. The expression is sometimes abbreviated to c.1900.
• Tier - One or more under-shelves of a table or cabinet.
• Maintaining Power - A horological term to describe a subsidiary driving force such as a spring or additional weight in a clock, which keeps the movement going while the mainspring is being rewound.
• Mahogany - Mahogany is a dense, close grained red-coloured timber from the West Indies and Central America. It was first imported into Europe in the the early 18th century and its use continued through the 19th century. It was popular for furniture making because of its strength, the wide boards available, the distinctive grain on some boards, termed flame mahogany and the rich warm colour of the timber when it was polished.. The "flame" was produced where a limb grew out from the trunk of the tree, and this timber was usually sliced into veneers for feature panels on doors, backs and cornices.
  
  Some terms used to describe mahogany relate to the country from which it originally came, such as "Cuban" mahogany, "Honduras" mahogany etc. However unless the wood has been tested the names assigned are more a selling feature, rather than a true indication of the timber's origin.
• 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  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.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:

• chronometers and deck watches - marine 84
• Frodsham, Charles (London) - clocks and watches 28