Napoleon III Black Marble Clock with Bronze Urn

• 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.
• Art Nouveau Period - The Art Nouveau period was a cultural movement that emerged in the late 19th century, and was characterized by its emphasis on natural forms, flowing lines, and a decorative, ornamental style. Art Nouveau was a reaction against the ornate and heavily stylized designs of the previous era, and sought to create a new, more organic aesthetic.
  
  Art Nouveau was characterized by its use of sinuous, curving lines, as well as a focus on natural elements such as flowers, vines, and other organic shapes. Art Nouveau designers sought to create a total work of art, in which every element of a building or object was designed to be harmonious with the overall design.
  
  Some of the most iconic examples of Art Nouveau design include the Paris Metro entrances designed by Hector Guimard, the works of the artist Alphonse Mucha, and the architecture of Victor Horta in Brussels.
  
  The Art Nouveau period was at its peak between 1890 and 1910, but began to decline in popularity by the start of World War I. However, Art Nouveau remains an important influence on design and art to this day, and continues to be celebrated for its emphasis on natural forms and decorative style.
• 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.
• 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.
• 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.
• 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, material or decoration - marble or slate, black 345
• clocks, type - Art Nouveau 89