French decimal clock from the time of the French Revolution

Decimal time is the representation of the time of day using units which are decimally related. This term is often used to refer specifically to French Revolutionary Time, which divides the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds, as opposed to the more familiar standard time, which divides the day into 24 hours, each hour into 60 minutes and each minute into 60 seconds. Image File history File links Horloge-republicaine1. ... Image File history File links Horloge-republicaine1. ... The French Revolution (1789–1815) was a period of political and social upheaval in the political history of France and Europe as a whole, during which the French governmental structure, previously an absolute monarchy with feudal privileges for the aristocracy and Catholic clergy, underwent radical change to forms based on... A pocket watch, a device used to tell time Look up time in Wiktionary, the free dictionary. ... Look up day in Wiktionary, the free dictionary. ... The decimal (base ten or occasionally denary) numeral system has ten as its base. ... Standard time is the result of synchronizing clocks in different geographical locations within a time zone to the same time rather than using the local meridian as in local mean time or solar time. ... The hour (symbol: h) is a unit of time. ... A minute is a unit of time equal to 1/60th of an hour and to 60 seconds. ... Look up second in Wiktionary, the free dictionary. ...

History

China

Main article: Ke (unit)

For its entire recorded history of two to three millennia, decimal time had been used in China alongside duodecimal time. The day was divided into both 100 parts called ke (Hanzi: 刻; Pinyin: kè) and into twelve double hours called shi (Traditional Chinese: 時辰; Simplified Chinese: 时辰; Pinyin: shíchen). To make ke compatible with shi, each ke was subdivided into 60 fen. Jesuits introduced Western time into China during the 17th century, at which time the day was redefined as having 96 ke (as well as 12 shi). Additionally, each month was divided into three periods of 10 days called xun (Hanzi: 旬; Pinyin: xún). xun are still used in formal documents. Ke (刻) is a traditional decimal time unit equalling 14. ... Ke (刻) is a traditional decimal time unit equalling 14. ... Japanese name Kanji: Kana: Korean name Hangul: Hanja: Vietnamese name Quoc Ngu: Hantu: A Chinese character (Simplified Chinese: ; Traditional Chinese: ; Pinyin: ) is a logogram used in writing Chinese, Japanese, sometimes Korean, and formerly Vietnamese. ... Pinyin, more formally called Hanyu Pinyin (Simplified Chinese: ; Traditional Chinese: ; Pinyin: ), is the most common variant of Standard Mandarin romanization system in use. ... Traditional Chinese characters refers to one of two standard sets of printed Chinese characters. ... This article does not cite any references or sources. ... Pinyin, more formally called Hanyu Pinyin (Simplified Chinese: ; Traditional Chinese: ; Pinyin: ), is the most common variant of Standard Mandarin romanization system in use. ... The Society of Jesus (Latin: Societas Iesu), commonly known as the Jesuits, is a Roman Catholic religious order. ... (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Japanese name Kanji: Kana: Korean name Hangul: Hanja: Vietnamese name Quoc Ngu: Hantu: A Chinese character (Simplified Chinese: ; Traditional Chinese: ; Pinyin: ) is a logogram used in writing Chinese, Japanese, sometimes Korean, and formerly Vietnamese. ... Pinyin, more formally called Hanyu Pinyin (Simplified Chinese: ; Traditional Chinese: ; Pinyin: ), is the most common variant of Standard Mandarin romanization system in use. ...

France

In more modern times, decimal time was introduced during the French Revolution in the decree of 5 October 1793: The French Revolution (1789–1815) was a period of political and social upheaval in the political history of France and Europe as a whole, during which the French governmental structure, previously an absolute monarchy with feudal privileges for the aristocracy and Catholic clergy, underwent radical change to forms based on... is the 278th day of the year (279th in leap years) in the Gregorian calendar. ... 1793 was a common year starting on Tuesday (see link for calendar). ...

XI. Le jour, de minuit à minuit, est divisé en dix parties, chaque partie en dix autres, ainsi de suite jusqu’à la plus petite portion commensurable de la durée.

XI. The day, from midnight to midnight, is divided into ten parts, each part into ten others, so on until the smallest measurable portion of duration.

These parts were named on 24 November 1793 (4 Frimaire of the Year II). The primary divisions were called hours, and they added: is the 328th day of the year (329th in leap years) in the Gregorian calendar. ... 1793 was a common year starting on Tuesday (see link for calendar). ...

La centième partie de l'heure est appelée minute décimale; la centième partie de la minute est appelée seconde décimale. (emphasis in original)

The hundredth part of the hour is called decimal minute; the hundredth part of the minute is called decimal second.

Thus, midnight was reckoned as 10 o'clock, noon as 5 o'clock, etc. Although clocks and watches were produced with faces showing both standard time with numbers 1-24 and decimal time with numbers 1-10, decimal time never caught on; it was not officially used until the beginning of the Republican year III, September 22, 1794, and was officially suspended April 7, 1795 (18 Germinal of the Year III), in the same law which introduced the original metric system. Thus, the metric system at first had no time unit, and later versions of the metric system used the second, equal to 1/86400 day, as the metric time unit. A platform clock at Kings Cross railway station in London A clock is an instrument for measuring and indicating the time. ... Russian Poljot Siberia model finished movement viewed through crystal back For other uses, see Watch (disambiguation). ... is the 265th day of the year (266th in leap years) in the Gregorian calendar. ... 1794 was a common year starting on Wednesday (see link for calendar). ... April 7 is the 97th day of the year in the Gregorian calendar (98th in leap years). ... 1795 was a common year starting on Thursday (see link for calendar). ... Look up si, Si, SI in Wiktionary, the free dictionary. ... Look up second in Wiktionary, the free dictionary. ... Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. ...

Decimal time was introduced as part of the French Republican Calendar, which, in addition to decimally dividing the day, divided the month into three décades of 10 days each, and was abolished at the end of 1805. The start of each year was determined according to which day the autumnal equinox occurred, in relation to true or apparent solar time at the Paris Observatory. Decimal time would also have been reckoned according to apparent solar time, depending on the location it was observed, as was already the practice generally for the setting of clocks. A French Revolutionary Calendar in the Historical Museum of Lausanne. ... Look up day in Wiktionary, the free dictionary. ... Look up Month in Wiktionary, the free dictionary. ... 1805 was a common year starting on Tuesday (see link for calendar). ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Illumination of Earth by Sun on the day of equinox The autumnal equinox (or fall equinox) marks the beginning of astronomical autumn. ... Solar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. ... This article does not cite any references or sources. ...

The French made another attempt at the decimalization of time in 1897, when the Commission de décimalisation du temps was created by the Bureau des Longitudes, with the mathematician Henri Poincaré as secretary. The commission proposed a compromise of retaining the 24-hour day, but dividing each hour into 100 decimal minutes, and each minute into 100 seconds. The plan did not gain acceptance and was abandoned in 1900. 1897 (MDCCCXCVII) was a common year starting on Friday (see link for calendar). ... The Bureau des Longitudes is a French scientific institution, founded by decree of June 25, 1795 and charged with the improvement of nautical navigation, standardisation of time-keeping, geodesy and astronomical observation. ... Jules TuPac Henri Poincaré (April 29, 1854 – July 17, 1912) (IPA: [][1]) was one of Frances greatest mathematicians and theoretical physicists, and a philosopher of science. ... Äž: For the film, see: 1900 (film). ...

Conversions

There are exactly 86,400 standard seconds (see SI for the current definition of the standard second) in a standard day, but in the French decimal time system there are 100,000 decimal seconds in the day, so the decimal second is shorter than its counterpart. Look up si, Si, SI in Wiktionary, the free dictionary. ...

Decimal to Standard

• One decimal second is 86,400/100,000 = 0.864 standard seconds.
• One decimal minute is 1,440/1,000 = 1.44 standard minutes, or 1 standard minute and 26.4 standard seconds.
• One decimal hour is 24/10 = 2.4 standard hours, or 2 standard hours and 24 standard minutes.

One hundredth of a day is 14 standard minutes 24 standard seconds, or approximately 15 minutes.

Standard to Decimal

• One standard second = 1.15740 decimal seconds
• One standard minute = 69.44 decimal seconds (or .69 decimal minutes)
• One standard hour = 4,166.67 decimal seconds (or 41 decimal minutes and 67 decimal seconds)

Fractional days

The most common use of decimal time of day is as fractional days used by scientists and computer programmers. Standard 24-hour time is converted into a fractional day simply by dividing the number of hours elapsed since midnight by 24 to make a decimal fraction. Thus, midnight is 0.0 day, noon is 0.5 d, etc., which can be added to any type of date, including: This article does not cite any references or sources. ... The NASA Columbia Supercomputer. ... A programmer or software developer is someone who programs computers, that is, one who writes computer software. ... The decimal (base ten or occasionally denary) numeral system has ten as its base. ...

• Gregorian dates: 2000 January 1.5
• ordinal dates: 00001.5
• Julian dates: 2451545.0
• Excel serial dates: 36526.5

As many decimal places may be used as required for precision, so 0.5 d = 0.500000 d. Fractional days are often reckoned in UTC or TT, although Julian Dates use Astronomical Time (TT+12h) and Microsoft Excel uses the local time zone of the computer. Using fractional days reduces the number of units in time calculations from four (days, hours, minutes, seconds) to just one (days). Fractional days are often used by astronomers to record observations, and were described in relation to the time of day by the 19th century astronomer John Herschel in his book, Outlines of Astronomy, as in these examples: The Gregorian calendar is the most widely used calendar in the world. ... ISO 8601 is an international standard for date and time representations issued by the International Organization for Standardization (ISO). ... The Julian day or Julian day number (JDN) is the integer number of days that have elapsed since the initial epoch defined as noon Universal Time (UT) Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That noon-to-noon day is counted as Julian day 0. ... This article or section does not adequately cite its references or sources. ... Coordinated Universal Time (UTC) is a high-precision atomic time standard. ... Terrestrial Time (TT) is the modern time standard for time on the surface of the Earth. ... This article or section does not adequately cite its references or sources. ... An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... John Herschel Sir John Frederick William Herschel (7 March 1792 – 11 May 1871) was an English mathematician and astronomer. ...

Between Greenwich noon of the 22d and 23d of March, 1829, the 1828th equinoctial year terminates, and the 1829th commences. This happens at 0^d·286003, or at 6^h 51^m 50^s·66 Greenwich Mean Time...For example, at 12^h 0^m 0^s Greenwich Mean Time, or 0^d·500000...

Greenwich is a town, now part of the south-eastern urban sprawl of London, England, on the south bank of the River Thames in the London Borough of Greenwich. ... (Redirected from 22 March) March 22 is the 81st day of the year in the Gregorian Calendar (82nd in Leap years). ... (Redirected from 23 March) March 23 is the 82nd day of the year in the Gregorian Calendar (83rd in Leap years). ... Johann Wolfgang von Goethe 1829 was a common year starting on Thursday (see link for calendar). ... Illumination of the Earth by the Sun on the day of equinox, (ignoring twilight). ... Time zones of Europe: Light colours indicate countries not observing summer time Greenwich Mean Time (Media:Example. ...

Swatch Internet Time

Main article: Swatch Internet Time

On October 23, 1998, the Swiss watchmaking company, Swatch, introduced a decimal time called Swatch Internet Time, which divides the day into 1000 .beats (each 86.4 s) counted from 000-999, with @000 being midnight and @500 being noon CET (UTC +1), as opposed to UTC. The company sells watches which display Internet Time. Internet Time has been criticized for using an origin different from Universal Time, misrepresenting CET as "Biel Mean Time", and for not providing for more precise units, although third-party applications have proposed "centibeats" (864 ms) and "millibeats" (86.4 ms). Swatch Internet Time is a concept introduced in 1998 and marketed by the Swatch corporation as an alternative, decimal measure of time. ... is the 296th day of the year (297th in leap years) in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... 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. ... Swatch Internet Time is a concept introduced in 1998 and marketed by the Swatch corporation as an alternative, decimal measure of time. ... Time zones of Europe: Light colours indicate countries that do not observe summer time Central European Time (CET) is one of the names of the time zone that is 1 hour ahead of Coordinated Universal Time. ... ... Universal Time (UT) is a timescale based on the rotation of the Earth. ...

Decimal times in fiction

Some science fiction authors use decimal time to reinforce the sense of "otherworldliness", notably Infocom's Planetfall and Stationfall games, which use "1 chronon = 1/10000 day" such that 0000 = midnight and 5000 = noon. Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar Zorkmid... Planetfall is a 1983 science fiction text adventure by Steve Meretzky of Infocom. ... Stationfall is an interactive fiction computer game written by Steve Meretzky and released by Infocom in 1987. ...

Isaac Asimov also uses and describes the use of Decimal time by the humans from the planet Solaria in his novel "The Naked Sun," in which he describes the Solarian hour as been divided into ten decads, each of which is divided into a hundred centads. Isaac Asimov (January 2?, 1920?[1] – April 6, 1992), IPA: , originally Исаак Озимов but now transcribed into Russian as Айзек Азимов) was a Russian-born American Jewish author and professor of biochemistry, a highly successful and exceptionally prolific writer best known for his works of science fiction and for his popular science books. ...

In the episode of The Simpsons, "They Saved Lisa's Brain," the members of Springfield's Mensa make changes to their town, including the implementation of using "metric time" to determine the time of day. Using "metric time" to indicate decimal time, Principal Skinner comments that the city's trains are not only are running on time, but they are running on metric time, while looking at an analog clock with numbers 1–10.^[1] Simpsons redirects here. ... They Saved Lisas Brain is the twenty-second episode of The Simpsons tenth season. ... Springfield is the fictional city in which the animated American sitcom The Simpsons is set. ... Mensa is the largest, oldest, and best-known high-IQ society in the world. ... This article does not cite any references or sources. ...

Other decimal times

Numerous individuals have proposed variations of decimal time, dividing the day into different numbers of units and subunits with different names. Most are based upon fractional days, so that one decimal time format may be easily converted into another, such that all the following are equivalent:

• 0.500 fractional day
• 5h 0m French decimal time
• @500 Swatch Internet Time
• 50.0 centidays
• 500 millidays
• 50.0% Percent Time
• 12:00 Standard Time

Some decimal time proposals are based upon alternate units of metric time. The difference between metric time and decimal time is that metric time defines units for measuring time interval, as measured with a stopwatch, and decimal time defines the time of day, as measured by a clock. Just as standard time uses the metric time unit of the second as its basis, proposed decimal time scales may use alternative metric units. Swatch Internet Time is a concept introduced in 1998 and marketed by the Swatch corporation as an alternative, decimal measure of time. ... Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. ... With regards to time, an interval is the duration between two events or occurrences of similar events. ... A stopwatch is a timepiece designed to measure the amount of time elapsed from a particular time when activated to when the piece is deactivated. ... A platform clock at Kings Cross railway station in London A clock is an instrument for measuring and indicating the time. ...

See also

• Decimal
• French Republican Calendar
• Hexadecimal time
• Metric time
• Stardate
• Unix time
• 24-hour clock

The decimal (base ten or occasionally denary) numeral system has ten as its base. ... A French Revolutionary Calendar in the Historical Museum of Lausanne. ... Hexadecimal time is the representation of the time of day as a hexadecimal number in the interval [0,1). ... Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... Unix time, or POSIX time, is a system for describing points in time: it is the number of seconds elapsed since midnight UTC on the morning of January 1, 1970, not counting leap seconds. ... 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. ...

External links

• Decimal Time
• Revolutionary Time
• Dials & Symbols of the French revolution. The Republican Calendar and Decimal time.

References

• National Convention of the French Republic (1793) LE CALENDRIER RÉPUBLICAIN Textes officiels Décrets Relatifs à l'établissement de l'Ère Républicaine published by Philippe Chapelin 2002
• Sizes, Inc. (2000) decimal time units Last revised February 27, 2004
• Herschel, John (1849) Outlines of Astronomy published by Gallica 1995
• Carrigan, Richard A., Jr. “Decimal Time.” American Scientist, (May-June 1978), 66(3): 305-313.