Clocks · Atomic clock
Electric clock by Efratom GmbH, Germany, 1960-1996
- Maker / attribution
- Efratom GmbH (maker)
- Date
- 1960-1996
- Historical period
- Quartz Revolution (1969 – 1990)
- Country of origin
- Germany
- Place
- Munich, Munich
- Object type
- Atomic clock
- Dimensions
- overall: 116 mm x 100 mm x 100 mm,
- Holding institution
- Science Museum Group, London
- Accession / object no.
- 2022-1409
- Catalogue title (original)
- Atomic Oscillator Clock
Record summary
Held and catalogued by Science Museum Group, London (object number 2022-1409), this is an atomic clock by Efratom GmbH, made in Munich, Munich, Germany, dated 1960-1996. The Atlas places it in the Quartz Revolution period (1969 – 1990) of its Clocks collection. Recorded dimensions: overall: 116 mm x 100 mm x 100 mm. The record is illustrated with 4 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
Science Museum Group description
The success of the Global Positioning System (usually known by its acronym, GPS) depends on each of the constellation of satellites being able to calculate its exact position. To do this, each relies on very high precision timepieces. The first iteration of the GPS system used timepieces which were developed from the Efratom Model FRK, and this particular item was given to the GPS system's chief engineer upon his retiring from Efratom in 1996.
Historical context
Quartz Revolution (1969 – 1990)
Seiko's Astron begins mass quartz timekeeping; traditional industries contract sharply.
Quartz movements and digital displays made accurate clocks cheap and ubiquitous after the early 1970s. LED and LCD clocks, clock radios and radio-controlled clocks appeared, while traditional mechanical clockmaking contracted sharply in Germany, France and Britain.
Read the period in the timelineMore clocks from this periodEarlier: Modern Mechanical Horology
Atlas type guide
Quartz, atomic and electronic time standards
In 1927 Warren Marrison and J. W. Horton at Bell Telephone Laboratories built the first quartz clock, which used the piezoelectric vibration of a quartz crystal as its oscillator. Quartz clocks replaced pendulum regulators in observatories in the 1930s and 1940s and revealed irregularities in the Earth's rotation. In 1955 Louis Essen and Jack Parry at the National Physical Laboratory in Britain operated the first practical caesium atomic clock; in 1967 the SI second was redefined in terms of the caesium-133 transition.
Atomic and quartz standards are distributed by radio time signals, telephone 'speaking clocks', and today by satellite navigation and network time protocols. Objects in this group — oscillators, frequency dividers, receivers, master clocks — document the transition from mechanical to electronic timekeeping.
What to look for
- Laboratory racks, oscillator ovens and frequency counters rather than dials.
- Makers' labels from national laboratories, observatories or telecom companies.
- Indications of frequency (e.g. 100 kHz, 9,192,631,770 Hz for caesium).
Dating clues
- Quartz observatory clocks: from about 1930.
- Caesium standards: from 1955.
- Radio-controlled consumer clocks: from the 1980s.
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:The Quartz Revolution era
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