Ebonised Daniel Quare Bracket Clock, 18th Century

• Chapter Ring - A separate metal plate on the face of a clock, on which the numerals for the hours and sometimes parts of the hours, are displayed, usually wheel shaped and sitting on top of the dial plate. The chapter ring is often a feature of the clock and can be silvered or enamelled to stand as a contrast to its background. The hours are usually shown in Roman numerals, although in the late 19th and earlt 20th century, Arabic numerals became fashionable.
• 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.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Fusee - The fusee movement was used in clocks and pocket watches from the mid 17th century. The fusee is a cone shaped drum within the works that is linked to the barrel of the spring, usually by a length of chain.
  
  As the mainspring loses its tension over time, the cone shaped barrel compensates for this by increasing the tension, by pulling the mainspring tighter, thus ensuring the time remains constant.
  
  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.
  
  The fusee continued to be used in marine chronometers until the 1970s.
• Spandrel - An architectural term that in horology refers to the triangular ornamental decoration in the corners of of the dial plate. The spandrels are usually of cast brass and may be additonally chased and engraved. On painted dial clocks the spandrels are also usually painted.
• Verge Escapement - A verge escapement is an early mechanical escapement used in clocks and other timekeeping devices. It is an early form of the escapement mechanism, which is used to regulate the movement of the hands of a clock or watch. The verge escapement consists of a vertical shaft called the verge, which is mounted on the clock's main plate. Attached to the verge are two pallets, which engage with the teeth of the escape wheel. As the escape wheel turns, the pallets alternately lock and release it, allowing the movement of the clock to be regulated. The verge escapement was widely used in early mechanical clocks, but it was eventually replaced by the more accurate and reliable anchor escapement.
• Back Plate - On many types of clocks, the movement operates between two plates, usually made of brass, one at the back, and the other at the front, which forms a mount for the dial.
  
  On English bracket, mantle and table clocks the backplate was often visible through a glass door or panel from the late 17th century, and could be profusely engraved with scrolling decorations, flowers, foliage, birds, and figures. The engraving could also include the maker?s name.
  
  The amount of engraving reduced and became simpler as the 18th century progressed, and by 1800, had been reduced to a border, often with the maker's name in the centre. By the early 1800s all decoration had ceased, and only the maker's name was added, and by the Victorian era, most bracket, mantle and table clocks had no engraving.
• Bob Pendulum - A bob pendulum consists of a brass or steel rod with a disc shaped metal weight at the end. The most common use of a bob pendulum is in a grandfather clock where it oscillates to keep the time. The length of the rod and the weight of the bob are the key parameters for determining the period of oscillation, and the timekeeping of the clock can be accelerated or slowed by altering the height of the bob.

This item has been included into following indexes:

• clocks, type - bracket 335
• Quare, Daniel (England) - clocks, maker or retailer 2