Flamsteed Astronomy Society

The Bureau des Longitudes, Paris

— April 3, 2006

  The Bureau des Longitudes is a French scientific institution charged with the improvement of nautical navigation, geodesy and astronomical observation. The Bureau was established with authority over the Paris Observatory and all other astronomical establishments throughout France. It was charged with taking control of the seas away from the English and improving accuracy in measuring the longitudes of ships through astronomical observations and reliable clocks.

The Bureau now functions as an academy and still meets monthly to discuss topics related to astronomy. Regular publications fromm the Bureau include:


  *     Connaissance des temps, astronomical ephemerides, published annually since 1679;

*      Annuaire du Bureau des longitudes, almanac and calendar 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.


  The Bureau also convenes conferences on topics related to astronomy and geodesy, and publishes the proceedings.




  Over the years there have been changes to the remit of the Bureau, with revisions of the terms of reference in 1854, 1874, 1970 and as recently as 1998.


  In 1897, the Bureau des Longitudes established a commission to extend the metric system to the measurement of time. They planned to abolish the antiquated division of the day into hours, minutes, and seconds, and replace it by a division into tenths, thousandths, and hundred thousandths of a day. This was a revival of a dream that was in the minds of the creators of the metric system at the time of the French Revolution a hundred years earlier. Some members of the Bureau des Longitudes commission introduced a compromise 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.


  In January 1854 its mission was expanded with responsibility for producing various epheremides using its "Calculations Service" created in 1802, to organize several big scientific expeditions: geodetic measurements, observation of solar eclipses, observation of the transit of Venus, which were published in the Annals of the Bureau des Longitudes.  It participated in the foundation of several scientific organisations such as the International Office of Time (1919), the Group of Researches of Spatial Géodésie (1971) and the International  Earth Rotation Service (1988). 



Fondation du Bureau des Longitudes

Loi relative à la formation d'un Bureau des Longitudes

Règlement du Bureau des Longitudes



TITRE Ier - du Bureau des Longitudes et de ses Attributions

TITRE II - de l'Observatoire Impérial de Paris et de ses Attributions

TITRE III - de la Bibliothéque



TITRE Ier - des Attributions du Bureau des Longitudes

TITRE II - Composition du Bureau

TITRE III - des Services Intérieurs du Bureau des et de ses Réunions



Composition et Fontionnement du Bureau des Longitudes



Décret n° 98-446 du 2,juin 1998 modifiant le décret no 85-715 du L0 juillet 1985 relatif a l'Observatoire de Paris - NOR : MENS9800561 D


Regulations governing the Bureau des Longitudes

Documents available on the web site

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