A black marble mantle clock with Marly horse figure, later 19th century, with maker's mark of Japy Freres to mechanism, of architectural style with an extended cornice, an engraved and gilt, decorated case enclosing a black marble dial with Roman numerals set within a cast bezel, the base of shaped and extended form, surmounted by a spelter, Marly horse after the 18th century original by Guillaume Cousteau, with key, and pendulum, height 30.31 in., width 20.08 in., depth 8.27 in.
- 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.
- 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.
- Spelter - Spelter was the name given to an alloy of zinc and brass or copper used in the 19th century for statuary and lighting. It is a brittle bluish-white metal. It was used as a cheap replacement for bronze, but being brittle easily breaks and can't be repaired. When finished it can often be mistaken for bronze, but if discreet a scratch on the base displays shows a greyish colour, the metal is spelter, if a golden colour the metal is most likely bronze.
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