Clocks · Speaking clock announcer module
MkIII speaking clock announcer module by General Post Office
- Maker / attribution
- General Post Office (maker)
- Date
- c. 1955
- Historical period
- Modern Mechanical Horology (1945 – 1969)
- Country of origin
- Unrecorded in source
- Object type
- Speaking clock announcer module
- Dimensions
- Overall: 740 x 515 x 250 mm
- Holding institution
- Royal Museums Greenwich
- Accession / object no.
- ZBA4264
- Credit line
- British Telecommunications plc. Reproduced with kind permission of BT Archives.
- Catalogue title (original)
- MkIII speaking clock announcer module (English)
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Record summary
Held and catalogued by Royal Museums Greenwich (object number ZBA4264), this is a speaking clock announcer module by General Post Office, dated c. 1955. The Atlas places it in the Modern Mechanical Horology period (1945 – 1969) of its Clocks collection. Recorded dimensions: Overall: 740 x 515 x 250 mm. 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
Catalogue description — Royal Museums Greenwich
This is an announcer module from the Mark III speaking clock, developed by the Post Office Engineering Research Station at Dollis Hill, London in the 1950s to replace the older Mark I device, used since 1936. The Mark II was never used in the UK, instead being developed for use in Australia. The Mark I machine used glass disks to hold the voice recordings. This Mark III version used a neoprene jacket over a rotating metal drum to contain magnetically-held recordings of the voice. Millions of Britons have dialled 'TIM', the ‘speaking clock’ that the General Post Office introduced in 1936. A nationwide search chose Ethel Cain as the first voice for the service. She was succeeded by Pat Simmons and then by Brian Cobby, the current voice of the ‘Accurist Speaking Clock’. Presented by Connected Earth, BT's heritage programme
Historical context
Modern Mechanical Horology (1945 – 1969)
Tool watches for divers, pilots and astronauts; electric watches anticipate the electronic age.
Post-war clocks combined new materials and industrial design: plastic and metal cases, battery-powered transistor movements from the late 1950s, and design classics by George Nelson, Max Bill and others. The first caesium atomic clock (1955) moved the definition of time from astronomy to physics.
Read the period in the timelineMore clocks from this periodEarlier: Golden Age of Mechanical Watchmaking
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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