French Boulle Mantel Clock with Cherub and Sunburst Bob

• Pendulum - The pendulum was discovered around 1602 by Galileo Galilei, and was adopted for time keeping by the Dutch mathematician and natural philosopher, Christiaan Huygens, who excelled in astronomy, physics, and horology.
  
  The pendulum comprises a metal rod usually of brass or steel with a metal disk, known as a bob, at the end. The movement of the pendulum is driven by weights or a spring, and as a pendulum swings in a regular arc, it was found accuracy could be controlled to within a few seconds a week.
  
  Timekeeping can be adjusted by changing the height of the bob on the rod, making the pendulum either swing slower or faster.
  
  The disadvantage of the pendulum was that changes in temperature also changed the length of the pendulum, interfering with the accuracy of the clock, and so in the 18th century two types of mercurial pendulums were invented which countered the movement in the steel rod.
  
  The pendulum was the world's most accurate timekeeping technology until the invention of the quartz clock, regulated by a quartz crystal, in 1927.
• Boulle - Boulle work is the name given to tortoiseshell and metal inlay using brass and sometimes silver, found on furniture and smaller wooden objects. It originated in Italy but was developed by Frenchman Andre Charles Boulle (1642 - 1732) under Louis XIV.
  
  Boulle was appointed Royal Cainet Maker to Louis XIV and designed furniture and clockcases for the monarch.
  
  In preparation, the tortoiseshell and metal were cut together following a design, using a fine fret saw.
  
  In the application of the Boulle, the carcase of piece of furniture was covered with the tortoiseshell which in turn was inlaid with the matched designs in metal, which in turn was elaborately engraved.
  
  The use of Boulle work furniture continued mainly in France until the 19th century.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Gilding - Gilding is a method of ornamentation whereby a thin sheet of gold metal is applied to items made of wood, leather, ceramics, glass and silver for decorative purposes.
  
  For furniture including mirrors, the sheet of gold is usually applied over a coating of gesso. Gesso is a mixture of plaster of Paris and gypsum mixed with water and then applied to the carved wooden frames of mirrors and picture frames as a base for applying the gold leaf. After numerous coats of gesso have been applied, allowed to dry and then sanded a coat of "bole", a usually red coloured mixture of clay and glue is brushed on and allowed to dry, after which the gold leaf is applied. Over time parts of the gilding will rub off so the base colour can be seen. In water gilding, this was generally a blue colour, while in oil gilding, the under layer was often yellow. In Victorian times, gilders frequently used red as a pigment beneath the gold leaf.
  
  Metal was often gilded by a process known as fire gilding. Gold mixed with mercury was applied and heated, causing the mercury to evaporate, the long-term effect of which was to kill or disable the craftsman or woman from mercury poisoning. The pursuit of beauty has claimed many victims, not the least of which were the artists who made those pieces so highly sought after today.
• Ormolu - Ormolu was popular with French craftsmen in the 18th and 19th century for ornamental fittings for furniture, clocks and other decorative items. True ormolu is gilt bronze, that is bronze that has been coated with gold using a mercury amalgam. Due to the health risks associated with using mercury, this method of creating ormolu was discontinued in France in the 1830s. A substitute was developed consisting of about 75% copper and 25% zinc, however it was inferior to the bronze version. It was often lacquered to prevent it tarnishing.
• Tortoiseshell - Tortoiseshell is a translucent material that comes from the horny carapace of a certain types of turtles, including the hawksbill turtle. It is often therefore mounted on a colour underground - often red - or inlaid with gold or silver thread, as seen in Boulle furniture.
  
  The texture and colour nuances of the material are extremely important. Heated tortoiseshell can easily be formed into various shapes. Like other natural materials, tortoiseshell becomes more beautiful with use. In a time before plastic, tortoiseshell was widely used for small objects such as combs and powder compacts.
  
  In 1973, the trade of tortoiseshell worldwide was banned under CITES (The Convention on International Trade in Endangered Species). Prior to importing or exporting items containing tortoiseshell a CITES permit must be obtained. Tortoiseshell items cannot be traded on Ebay.
  
  "Faux tortoiseshell", another case of man initiating nature, is made from old-style plastics such as celluloid and cellulos and is coloured with red, yellow and brown spots to imitate the genuine article. It is commonly used in glasses frames, musical instruments and costume jewellery.

This item has been included into following indexes:

• clocks, mantle & shelf, material or style
  • gilded 58
  • gilt metal / ormolu 548
• clocks, mantle & shelf, period or origin
  • French 762
  • Victorian 494
• clocks, material or decoration
  • Boulle 97
  • tortoiseshell cased 106