24 hour analog dial

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A Vostok 24-hour watch reading 09:54
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Shepherd Gate clock outside the Royal Greenwich Observatory
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The clock at Ottery St Mary, England, showing nearly noon, using the 12-hour time system on a 24-hour analog dial.


Clocks and watches with a 24-hour analog dial are marked with 24 numbers or hour marks around the edge. The hour hand makes 1 complete revolution, 360°, in a day. The more familiar 12-hour clock (and watch) dial shows 12 hours of the day at a time, and the hour hand makes two complete revolutions in a day. The 24-hour dial doesn't need to indicate a.m. or p.m.

24-hour analog clocks and watches are used today by pilots, scientists, and the military, and are sometimes preferred because of the unambiguous representation of a whole day at a time. Note that this definition refers to the use of a complete circular dial to represent a 24-hour day, not to the use of the numbers from 0 to 23 (or 1 to 24), the 24-hour clock system. Many medieval clocks — and even a few modern ones — use 12-hour numbering rather than 24, even though the "hour" hand makes a single revolution in a day.

History

The ancient Egyptians divided the day into 24 hours. There are diagrams of circles divided into 24 sections in the astronomical ceiling in the tomb of Senemut.

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sundial with 24-hour analog dial


Sundials use some or all of the 24 hour dial, because they measure the position of the sun in the sky. Sometimes, for artistic rather than practical reasons, all the 24 hour marks are shown.

Medieval clocks often used the 24-hour analog dial, influenced by the widespread example of the astrolabe. In Northern Europe, the Double-XII system was preferred: two sets of the Roman numerals I to XII were used, one on the left side for the night and morning hours, and another set on the right side of the dial to represent the afternoon and evening hours. In Italy, the numbers from 1 to 24 (I to XXIIII in Roman numerals) were used, leading to the widespread use of the 24 hour system in that country. On Italian clocks, though, the I was often shown at the right side of the dial, rather than the top. This probably reflects the influence of the Italian timekeeping system, which started counting the hours of the day at sunset or twilight.

In northern Europe, the Double XII system was gradually superseded during the 14th and 15th centuries by the single XII (12-hour system), leading to the widespread adoption of the 12-hour dial for popular use. The 24-hour analog dial continued to be used, but primarily by technicians, astronomers, scientists, and clockmakers. John Harrison, Thomas Tompion, and Mudge built a number of clocks with 24 hour analog dials, particularly when building astronomical and nautical instruments. The famous Big Ben clock in London has a 24 hour dial as part of the mechanism, although it is not visible from the outside.

In the 20th century, the 24 hour analog dial was adopted by radio amateurs, pilots, submariners, and for military use.

Today

24-hour analog watches and clocks are still being manufactured today, and are sought after by collectors and enthusiasts. A famous brand is the Glycine Airman watch. Other manufacturers who make 24-hour analog watches include Breitling, Raketa, Vostok, Fortis, Poljot, Swatch, and many others.




Glycine Airman

Swatch 24-hour watch


Design

The major variation in the design of 24-hour analog dials is the location of midnight and noon. Although always opposite each other, 180° apart, noon is sometimes at the top, sometimes at the bottom. A few rare variants place noon and midnight at the right and left sides. There is no ambiguity if the 24-hour numbering is used.

World time

A common use for the 24-hour analog method of representing time is for showing the way the time of day depends on one's location. A rotating globe, map, or disk can be used. Globes will often have a small disk at one of the poles that can be used for this.

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The World Time clock in Alexanderplatz, Berlin

In fiction

George Orwell uses the 12-hour and 24-hour dials to symbolize the old and new worlds in his novel Nineteen Eighty-Four. The 12-hour dial is a relic of pre-revolutionary society, used to represent the desirable past; the 24-hour dial and time system is the compulsory standard imposed by the Party, and represents both conformity and the undesirable nature of the new world. Orwell may not have been familiar with the long history of the 24-hour time system and dial in England, seeing it as a mainly continental convention.

Winston noticed that the furniture was still arranged as though the room were meant to be lived in. There was a strip of carpet on the floor, a picture or two on the walls, and a deep, slatternly arm-chair drawn up to the fireplace. An old-fashioned glass clock with a twelve-hour face was ticking away on the mantelpiece. Under the window, and occupying nearly a quarter of the room, was an enormous bed with the mattress still on it.


... In the fender was a battered tin oilstove, a saucepan, and two cups, provided by Mr Charrington. Winston lit the burner and set a pan of water to boil. He had brought an envelope full of Victory Coffee and some saccharine tablets. The clock’s hands said seventeen-twenty: it was nineteen-twenty really. She was coming at nineteen-thirty.


... With one hand in her pocket and a piece of bread and jam in the other, Julia wandered about the room, glancing indifferently at the bookcase, pointing out the best way of repairing the gateleg table, plumping herself down in the ragged arm-chair to see if it was comfortable, and examining the absurd twelve-hour clock with a sort of tolerant amusement.


The opening line is:

It was a bright cold day in April, and the clocks were striking thirteen.


In the 1927 film Metropolis, the opening scene shows both a 24-hour analog clock and a 10-hour analog clock, one above the other. Both are used to convey the impression of an alien and highly efficient society.

See also

References

  • Bruton, Eric. The History of Clocks and Watches. London: Black Cat, 1993.

External links

Circadian Locomotor Output Cycles Kaput, or Clock is a gene which encodes proteins regulating circadian rhythm. The CLOCK protein seems to affect both the persistence and length of the circadian cycle. CLOCK forms part of a basic-helix-loop-helix transcription factor.
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day (symbol: d) is a unit of time equivalent to 24 hours. It is not an SI unit but it is accepted for use with SI.[1] The SI unit of time is the second. The term comes from the Old English dæg.

Definitions

The day has several definitions.
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The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., from Latin, meaning "before mid day", or "before the middle of the day") and post meridiem (
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The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., from Latin, meaning "before mid day", or "before the middle of the day") and post meridiem (
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The 24-hour clock is a convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, numbered from 0 to 23. This system is the most commonly used time notation in the world today.
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Senemut / Senenmut
in hieroglyphs


Senemut (sometimes spelled Senmut, Senenmut or Senmout) was an 18th dynasty Ancient Egyptian architect and government official.
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sundial is a device that measures time by the position of the Sun. The most commonly seen designs, such as the 'ordinary' or standard garden sundial, cast a shadow on a flat surface marked with the hours of the day.
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astrolabe is a historical astronomical instrument used by classical astronomers, navigators, and astrologers. Its many uses included locating and predicting the positions of the Sun, Moon, planets and stars; determining local time given local longitude and vice-versa; surveying;
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Roman numerals is a numeral system originating in ancient Rome, adapted from Etruscan numerals. The system used in classical antiquity was slightly modified in the Middle Ages to produce the system we use today. It is based on certain letters which are given values as numerals.
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The hour (symbol: h, or occasionally hr; via Latin from Greek ὥρα "season, time span", ultimately cognate to English ) is a unit of time. It is not an SI unit but is accepted for use with the SI.
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John Harrison (March 24 1693 – March 24 1776) was an English clockmaker who revolutionised and extended the possibility of safe long distance sea travel in the Age of Sail by inventing a long-sought and critically-needed key piece in the problem of accurately establishing the
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Thomas Tompion (1639-1713) was an English master clockmaker and watchmaker known today as the father of English watchmaking.

Thomas Tompion was born around 1639 and was baptized July 25 1639 in Northill, Bedfordshire, England.
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Clock Tower is the world's largest four-faced, chiming turret clock. The structure is situated at the north-eastern end of the Houses of Parliament building in Westminster, London.
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London
Canary Wharf is the centre of London's modern office towers
London shown within England
Coordinates:
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Glycine is a Swiss watch manufacturer. Glycine became a noteworthy watch maker in the early 1950s for the introduction of their Airman model, a 24 hour watch favored by both military and commercial pilots. The Airman was worn by many U.S. Air Force pilots during the Vietnam War.
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Breitling is a brand of Swiss watches from the Canton of Jura. The watchmaker offers Certified Chronometers designed primarily for aviation use, though most frequently worn as high-end luxury watches.
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Vostok (Russian: Восток, meaning East) Watch Makers, Inc. produces mainly inexpensive, rugged military-style and diver's watches at its factory in Chistopol, Tatarstan, Russia.
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Fortis may refer to
  • Fortis (phonetics), a linguistic term
  • Fortis (finance), a financial services company, based in Belgium and the Netherlands
  • Fortis Inc.

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Poljot (Russian: "Полет", literally meaning "flight"), a brand of watches from Russia, originated in the USSR and was produced by the First Moscow Watch Factory.
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Swatch is a brand name for a line of wrist watches from the Swatch Group, a Swiss conglomerate with vertical control of the production of Swiss watches and related products. In 1982, Swatch was conceived and it was introduced on the market in Switzerland in March 1983.
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globe is a three-dimensional scale model of a spheroid celestial body such as a planet, star, or moon, in particular Earth, or, alternatively, a spherical representation of the sky with the stars (but without the Sun, Moon, or planets, because their positions vary relative to those
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Eric Arthur Blair

Pseudonym: George Orwell
Born: May 25 1903(1903--)
Motihari, Bihar, India
Died: January 21 1950 (aged 48)
London, United Kingdom
Occupation: Writer; author, journalist
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Nineteen Eighty-Four (1984)

British first edition cover
Author George Orwell
Country England
Language English
Genre(s) Dystopian, Political Novel
Publisher Secker and Warburg (London)
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Metropolis is a silent science fiction film created by the famed Austrian-German director Fritz Lang. It was produced in Germany in the Babelsberg Studios and released in 1927 during the height of the Weimar
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The 24-hour clock is a convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, numbered from 0 to 23. This system is the most commonly used time notation in the world today.
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24-hour watch is a wristwatch with an hour hand that completes a revolution every 24 hours. This type of watch is especially useful for airplane pilots, astronauts, members of the military, or anyone who uses a 24-hour clock.
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