Rare 1690 English Sun and Moon Pocket Watch by Baker

• Moon Dial - If we imagine life in the 17th century, the only source of ascertaining the time of day or night would have been the local church or municipal clock striking every quarter hour, and able to be heard by all in the village. In England, when longcase clocks became popular and more affordable in the late 17th century, the function of timekeeping and source of time was moved to within the home.
  
  An additional feature on some longcase clocks was to display the phases of the moon, that is the new moon, the full moon and the waning moon over the lunar 29 ½ day cycle. This information was important for farmers for working out cropping schedules; for travellers to know the amount of moonlight on a night they planned to travel; and for those who lived near the sea required knowledge of the tides.
  
  Where included, the moon dial is usually in the form of a disc incorporated into the main dial plate, usually in the arched top section. The lunar cycle starts with the new moon displaying, which is a dark night sky and no man-in-the-moon face being displayed, and then progresses to the full moon face showing on the 15th day of the lunar cycle, and back to no face displaying as the moon wanes. Most lunar dials are partially concealed on each side of their opening in the main dial plate by semi-circular "humps" that allow the painted face to emerge slowly just as the real moon goes out of and back into the earth's shadow.
  
  Nowadays, details of the lunar cycle is published in diaries, almanacs, and newspapers and although some modern longcase clocks are still manufactured with working moon dials, they are more for decoration than for use.
• 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  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.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.
• 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.
• Pique Work - A decorative technique used on jewellery and small decorative objects in which designs are created by inlaying small gold or silver studs and stips into tortoiseshell. The art reached its highest point in 17th- and 18th-century France, particularly for the decoration of small tortoiseshell articles such as combs, patch boxes, and snuffboxes.
• 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.
• Tortoiseshell - Tortoiseshell is a translucent material that comes from the horny carapace of a certain types of turtles, including the hawksbill turtle. It is often therefore mounted on a colour underground - often red - or inlaid with gold or silver thread, as seen in Boulle furniture.
  
  The texture and colour nuances of the material are extremely important. Heated tortoiseshell can easily be formed into various shapes. Like other natural materials, tortoiseshell becomes more beautiful with use. In a time before plastic, tortoiseshell was widely used for small objects such as combs and powder compacts.
  
  In 1973, the trade of tortoiseshell worldwide was banned under CITES (The Convention on International Trade in Endangered Species). Prior to importing or exporting items containing tortoiseshell a CITES permit must be obtained. Tortoiseshell items cannot be traded on Ebay.
  
  "Faux tortoiseshell", another case of man initiating nature, is made from old-style plastics such as celluloid and cellulos and is coloured with red, yellow and brown spots to imitate the genuine article. It is commonly used in glasses frames, musical instruments and costume jewellery.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• 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.

This item has been included into following indexes:

• clocks, material or decoration - tortoiseshell cased 105
• pocket watches, case type
  • open face, silver case 553
  • silver case 865