Pendulum from the time recorder, by the British Time Recorder Co. Ltd, London, England, 1940-1970

Record summary

Held and catalogued by Science Museum Group, London (object number 2004-173/3), this is a pendulum - timepiece by British Time Recorder Company Limited, made in London, Greater London, England, United Kingdom, London, dated 1905. The Atlas places it in the Golden Age of Mechanical Watchmaking period (1900 – 1945) of its Movements & Components collection. The record is illustrated with 1 photograph.

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

Pendulums, balances and balance springs

The oscillator determines a timekeeper's rate. Galileo observed the near-isochronism of the pendulum; Huygens applied it to clocks in 1656 and the balance spring to watches in 1675. Temperature changes alter pendulum length and balance-spring elasticity, so eighteenth- and nineteenth-century makers devised compensation: Graham's mercury pendulum, Harrison's gridiron, bimetallic split balances for chronometers and watches, and Charles-Édouard Guillaume's invar and elinvar alloys (Nobel Prize in Physics, 1920).

Balance springs evolved from flat spirals to Breguet's overcoil (1795) and helical springs for chronometers; twentieth-century alloys (Nivarox) and twenty-first-century silicon springs largely solved temperature and magnetism problems.

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.

Read next:Balance spring (hairspring)Anchor (recoil) escapement