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The Bureau des Longitudes is a French
France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
 scientific institution, founded by decree of June 25 1795 and charged with the improvement of nautical navigation
Navigation

Navigation is the process of reading, and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks....
, standardisation of time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
-keeping, geodesy
Geodesy

Geodesy , also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space....
 and astronomical observation. During the 19th century, it was responsible for synchronizing
Clock signal

In electronics and especially Synchronous logic digital circuits, a clock signal is a Signalling used to coordinate the actions of two or more Electronic circuit....
 clocks across the world. It was headed during this time by François Arago
François Arago

Fran?ois Jean Dominique Arago was a France Northern Catalonia mathematician, physicist, astronomer and politician....
 and Henri Poincaré
Henri Poincaré

Jules Henri Poincar? was a French mathematician and theoretical physicist, and a philosophy of science. Poincar? is often described as a polymath, and in mathematics as The Last Universalist, since he excelled in all fields of the discipline as it existed during his lifetime....
. The Bureau now functions as an academy
Academy

An academy is an institution of higher learning, research, or honorary membership.The name traces back to Plato's school of philosophy, founded approximately 385 BC at Akademia, a sanctuary of Athena, the goddess of wisdom, north of Ancient Athens, Greece....
 and still meets monthly to discuss topics related to astronomy
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
.

The Bureau was founded by the National Convention
National Convention

During the French Revolution, the National Convention or Convention, in France, comprised the constitutional and legislative Deliberative assembly which sat from 20 September 1792 to 26 October 1795 ....
 after it heard a report drawn up jointly by the Committee of Navy, the Committee of Finances and the Committee of State education.






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The Bureau des Longitudes is a French
France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
 scientific institution, founded by decree of June 25 1795 and charged with the improvement of nautical navigation
Navigation

Navigation is the process of reading, and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks....
, standardisation of time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
-keeping, geodesy
Geodesy

Geodesy , also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space....
 and astronomical observation. During the 19th century, it was responsible for synchronizing
Clock signal

In electronics and especially Synchronous logic digital circuits, a clock signal is a Signalling used to coordinate the actions of two or more Electronic circuit....
 clocks across the world. It was headed during this time by François Arago
François Arago

Fran?ois Jean Dominique Arago was a France Northern Catalonia mathematician, physicist, astronomer and politician....
 and Henri Poincaré
Henri Poincaré

Jules Henri Poincar? was a French mathematician and theoretical physicist, and a philosophy of science. Poincar? is often described as a polymath, and in mathematics as The Last Universalist, since he excelled in all fields of the discipline as it existed during his lifetime....
. The Bureau now functions as an academy
Academy

An academy is an institution of higher learning, research, or honorary membership.The name traces back to Plato's school of philosophy, founded approximately 385 BC at Akademia, a sanctuary of Athena, the goddess of wisdom, north of Ancient Athens, Greece....
 and still meets monthly to discuss topics related to astronomy
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
.

The Bureau was founded by the National Convention
National Convention

During the French Revolution, the National Convention or Convention, in France, comprised the constitutional and legislative Deliberative assembly which sat from 20 September 1792 to 26 October 1795 ....
 after it heard a report drawn up jointly by the Committee of Navy, the Committee of Finances and the Committee of State education. Henri Grégoire
Henri Grégoire

Henri Gr?goire was a France Roman Catholic priest, Civil Constitution of the Clergy of Blois and a French Revolutionary leader....
 had brought to the attention of the National Convention France's failing maritime power and the naval mastery of England
England

native_name =|conventional_long_name = England|common_name = England|image_flag = Flag of England.svg|image_coat = England COA.svg|symbol_type = Royal Coat of Arms...
, proposing that improvements in navigation would lay the foundations for a renaissance in naval strength. As a result, the Bureau was established with authority over the Paris Observatory
Paris Observatory

The Paris Observatory is the foremost astronomy observatory of France, and one of the largest astronomical centers in the world....
 and all other astronomical establishments throughout France. The Bureau was charged with taking control of the seas away from the English
England

native_name =|conventional_long_name = England|common_name = England|image_flag = Flag of England.svg|image_coat = England COA.svg|symbol_type = Royal Coat of Arms...
 and improving accuracy when tracking the longitudes of ships through astronomical observations and reliable clocks.

The ten original members of its founding board were:

  • Geometers:
    • Joseph-Louis Lagrange;
    • Pierre-Simon Laplace
      Pierre-Simon Laplace

      Pierre-Simon, marquis de Laplace was a France mathematician and astronomer whose work was pivotal to the development of astronomy and statistics....
      ;
  • Astronomers:
    • Joseph Jérôme Lefrançais de Lalande;
    • Pierre Méchain
      Pierre Méchain

      Pierre Fran?ois Andr? M?chain was a France astronomer and surveying who, with Charles Messier, was a major contributor to the early study of deep sky objects and comets....
      ;
    • Jean Baptiste Joseph Delambre
      Jean Baptiste Joseph Delambre

      Jean Baptiste Joseph, chevalier Delambre was a France mathematician and astronomer.After a childhood fever, he suffered from very sensitive eyes, and believed that he would soon go blind....
      ;
    • Dominique, comte de Cassini
      Dominique, comte de Cassini

      This article is about the French astronomer. For his Italian-born great-grandfather, see Giovanni Domenico Cassini.Jean-Dominique, comte de Cassini was a France astronomer, son of C?sar-Fran?ois Cassini de Thury....
      ;
  • Jean-Charles de Borda
    Jean-Charles de Borda

    Jean-Charles, chevalier de Borda , was a France mathematician, physicist, political scientist, and sailor.Born in the city of Dax, Landes, in 1756 Borda wrote M?moire sur le mouvement des projectiles, a product of his work as a military engineer....
    , who carried out work related to the mechanics
    Mechanics

    Mechanics is the branch of physics concerned with the behaviour of physical body when subjected to forces or Displacement , and the subsequent effect of the bodies on their environment....
     of fluid
    Fluid

    A fluid is defined as a substance that continually deforms under an applied shear stress. All liquids and all gases are fluids. Fluids are a subset of the Phase and include liquids, gas, Plasma physics and, to some extent, plasticity ....
    s and precursor of Carnot
    Lazare Carnot

    File:Lazare Nicolas Marguerite Carnot00.jpgLazare Nicolas Marguerite, Comte Carnot , the Organizer of Victory in the French Revolutionary Wars, was a France politician, engineer, and mathematician....
     because of his insights on thermodynamics
    Thermodynamics

    In physics, thermodynamics is the study of the conversion of heat energy into different forms of energy ; different energy conversions into heat energy; and its relation to macroscopic variables such as temperature, pressure, and volume....
    ;
  • Jean-Nicolas Buache, geographer
    Geographer

    A geographer is a scientist whose area of study is geography, the study of Earth's physical natural environment and human habitat .Though geographers are historically known as people who make maps, map making is actually the field of study of cartography, a subset of geography....
    ;
  • Louis Antoine de Bougainville
    Louis Antoine de Bougainville

    Louis-Antoine, comte de Bougainville was a French admiral and explorer....
    , celebrated navigator
    Navigator

    A navigator is the person onboard a ship or aircraft responsible for its navigation. The navigator's primary responsibility is to be aware of ship or aircraft position at all times....
    ; and
  • Noël Simon Caroché, manufacturer of telescopes.


By a decree of January 30 1854, the Bureau's mission was extended to embrace geodesy, time standardisation and astronomical measurements. This decree granted independence to the Paris Observatory
Paris Observatory

The Paris Observatory is the foremost astronomy observatory of France, and one of the largest astronomical centers in the world....
, separating it from the Bureau, and focused the efforts of the Bureau on time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
 and astronomy
Astronomy

Astronomy is the science of Astronomical object and Phenomenon that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the physical cosmology....
. The Bureau was successful at setting a universal time in Paris via air pulses sent through pneumatic tubes. It later worked to synchronize time across the French colonial empire by determining the length of time for a signal to make a round trip to and from a French colony
Colony

In politics and in history, a colony is a Territory under the immediate political control of a state. For colonies in antiquity, city-states would often found their own colonies....
.

The French Bureau of Longitude established a commission in the year 1897 to extend the metric system
Si

Si, si, or SI may refer to :...
 to the measurement of time
Time

Time is a component of the measurement used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects....
. They planned to abolish the antiquated division of the day into hour
Hour

The hour is a unit of time. It is not an SI unit but is Non-SI units accepted for use with SI....
s, minute
Minute

A minute is a unit of measurement of time or of angle.The minute is a Unit of measurement of time equal to 1/60th of an hour or 60 seconds. In the Coordinated Universal Time time scale, a minute occasionally has 59 or 61 seconds; see leap second....
s, and second
Second

The second , sometimes abbreviated sec., is the name of a units of measurement of time, and is the International System of Units SI base unit of time....
s, and replace it by a division into tenths, thousandths, and hundred thousandths of a day
Day

A day is a units of measurement of time equivalent to approximately 24 hours. It is not an International System of Units unit but it is accepted for use with SI....
. This was a revival of a dream
Dream

Dreams are sequence s, sounds and feelings experienced while sleeping, strongly associated with rapid eye movement sleep. The contents and biological purposes of dreams are not fully understood, though they have been a topic of speculation and interest throughout recorded history....
 that was in the minds of the creators of the metric system at the time of the French Revolution
French Revolution

The French Revolution was a period of political and social upheaval and radical change in the history of France, during which the French governmental structure, previously an absolute monarchy with feudalism for the aristocracy and Roman Catholic Church clergy, underwent radical change to forms based on Age of Enlightenment principles of cit...
 a hundred years earlier. Some members of the Bureau of Longitude commission introduced a compromise
Compromise

In arguments, compromise is a concept of finding agreement through communication, through a mutual acceptance of terms?often involving variations from an original Objective or desire....
 proposal, retaining the old-fashioned hour as the basic unit of time and dividing it into hundredths and ten thousandths. Poincaré served as secretary of the commission and took its work very seriously, writing several of its reports. He was a fervent believer in a universal metric system. But he lost the battle. The rest of the world outside France gave no support to the commission's proposals, and the French government was not prepared to go it alone. After three years of hard work, the commission was dissolved in 1900.

Since 1970, the board has been constituted with 13 members, 3 nominated by the Académie des Sciences. Since 1998, practical work has been carried out by the Institut de mécanique céleste et de calcul des éphémérides.

Publications

  • Connaissance des temps, astronomical ephemerides, published annually since 1679;
  • Annuaire du Bureau des longitudes, almanac
    Almanac

    An almanac is an annual publication containing tabular information in a particular field or fields often arranged according to the calendar. Astronomy data and various statistics are also found in almanacs, such as the times of the rising and setting of the sun and moon, eclipses, hours of full tide, stated festivals of church es, terms of...
     and calendar
    Calendar

    A calendar is a system of organize days for a social, religious, commercial or administrative purpose. This organization is done by giving names to periods of time ? typically days, weeks, months and years....
     for public and civil use, published annually since 1795;
  • Éphémérides nautiques, (from 1889) for marine navigation;
  • Éphémérides aéronautiques, (from 1938) for civil and military aerial navigation.


External links

  • Institut de Mecanique Celeste et de Calcul des Ephemerides - This institute hosts ephemeris calculations formerly hosted by the BDL.