Belgium Long Case Clock, 1790

• 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.
• 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.
• Anchor Escapement - An anchor escapement is a type of mechanical escapement used in clocks and watches. It is a refinement of the older verge escapement, which was used in early mechanical timekeeping devices. The anchor escapement is characterised by the use of an anchor-shaped pallet that rocks back and forth, alternately locking and releasing the escape wheel. This action allows the movement of the watch or clock to be regulated, producing the characteristic tick-tock sound that is associated with mechanical timekeeping devices. The anchor escapement is generally more accurate and reliable than the verge escapement, and it is still used in many modern clocks and watches today.
• Hood - In longcase clocks, the hood is the wooden case that surrounds the works and dial, and includes the glass front, which is usually hinged, so the door can be opened to wind the clock or adjust the time. In 18th and 19th century longcase clocks the hood usually slides forward for removal, allowing access to the works.
• Oak - Native to Europe and England, oak has been used for joinery, furniture and building since the beginning of the medieval civilisation. It is a pale yellow in colour when freshly cut and darkens with age to a mid brown colour.
  
  Oak as a furniture timber was superceded by walnut in the 17th century, and in the 18th century by mahogany,
  
  Semi-fossilised bog oak is black in colour, and is found in peat bogs where the trees have fallen and been preserved from decay by the bog. It is used for jewellery and small carved trinkets.
  
  Pollard oak is taken from an oak that has been regularly pollarded, that is the upper branches have been removed at the top of the trunk, result that new branches would appear, and over time the top would become ball-like. . When harvested and sawn, the timber displays a continuous surface of knotty circles. The timber was scarce and expensive and was used in more expensive pieces of furniture in the Regency and Victorian periods.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.

This item has been included into following indexes:

• clocks, grandfather / longcase, period or age - 18th century, other 111
• clocks, grandfather / longcase, type - other 193