Silver cased verge watch with date indicator

Record summary

Held and catalogued by British Museum (object number 1958,1201.2336), this is a calendar watch by Thomas Fenn, made in London (England) (New Exchange), dated 1660–1670. The Atlas places it in the Early Modern Horology period (1600 – 1750) of its Pocket Watches collection. Materials and techniques recorded by the source: wood, leather, brass, silver. Recorded dimensions: Diameter: 49.50 millimetres (inner case) Diameter: 57 millimetres (outer box). The record is illustrated with 3 photographs.

Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.

Catalogue description

Atlas type guide

Calendar, moon-phase and perpetual calendar watches

Calendar complications range from a simple date to the perpetual calendar, which automatically allows for months of different lengths and leap years until 2100. Pocket watches with perpetual calendars were made in the eighteenth and nineteenth centuries; Patek Philippe made the first perpetual calendar wristwatch in 1925, and series production followed in 1941. The annual calendar (Patek Philippe, 1996) needs correction only once a year.

Moon-phase displays use a disc with two moons and 59 teeth advanced daily, approximating the 29.5-day lunation; more precise trains reduce the error to one day in over a century.

General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.