Onyx Clock with Seagull and Wave Design by E. Guy

• 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.
• Onyx - Onyx is a form of agate, used from antiquity and popular again in the 1920s and 30s. European onyx is generally green, but can be many other colours, and can contain bands of black and/or white.
  
  This multicoloured stone is widely used for table tops, lamp bases and in jewellery. Some types of onyx are also used for cameos of which the upper white layer is cut away to reveal the colour beneath.
• Art Deco Period - The Art Deco period was a cultural movement that emerged in the 1920s and 1930s, and was characterized by its emphasis on modernism, luxury, and elegance. The name "Art Deco" comes from the Exposition Internationale des Arts Décoratifs et Industriels Modernes, a large exhibition held in Paris in 1925 that showcased the latest trends in decorative arts.
  
  Art Deco was a reaction against the ornate and elaborate styles of the previous era, and reflected a new modern sensibility. It was characterized by streamlined, geometric shapes, bright colours, and the use of new materials such as chrome, glass, and Bakelite. Art Deco designers sought to create a sense of luxury and sophistication, often incorporating expensive materials such as ivory, marble, and rare woods.
  
  Art Deco had a significant impact on a wide range of artistic fields, including architecture, fashion, graphic design, and interior design. Some of the most iconic examples of Art Deco architecture include the Empire State Building in New York City, the Hoover Building in London, and the Palais de Chaillot in Paris.
  
  The Art Deco period came to an end in the 1940s, as World War II and changing cultural trends led to a shift in artistic styles. However, Art Deco remains an important influence on design and art, and continues to be celebrated for its modernist sensibility and glamorous aesthetic.

This item has been included into following indexes:

• clocks, material or decoration
  • marble and slate, Art Deco 71
  • marble or slate 430
  • onyx 30