French 8-Day Slate Mantle Clock with Bell Strike

• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Barrel (in a Clock) - In a clock or watch, the barrel is a cylindrical component that stores the energy from the mainspring. As the mainspring is wound, it stores energy in the barrel. As the clock or watch runs, the energy is gradually released from the barrel, turning the clock's gears and keeping the time.
  
  The barrel is typically located near the centre of the movement (the mechanism that powers the clock) and is connected to the center wheel, which drives the rest of the gears. The barrel typically has teeth on its outer surface that mesh with the gears in the movement, allowing it to transmit energy to the rest of the clock. Some barrels are designed to be wound by hand, while others are automatically wound by the motion of the wearer's arm.
• 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.

This item has been included into following indexes:

• clocks, material or decoration
  • marble or slate, black 342
  • slate 344