Diana Mystery Clock with Blue Enamel Spherical Globe

• 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.
• 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.
• 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.
• Bronze - An alloy of copper and tin, traditionally in the proportions of about 9 parts of copper to 1 part of tin.
  
  The discovery of bronze in Western Asia in the 4th century enabled people to create metal objects which were superior to those previoulsy possible because of its strength and hardness, and it has been used throughout the world for weapons, coins, tools, statuary and other decorative items.
  
  It is very fluid in a molten state, and its hardness, strength when set, and non-corrosive properties makes it most suitable for casting sculpture.

This item has been included into following indexes:

• clocks, type - mystery 80