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Today is Bastille Day, and we celebrate by announcing the recent acquisition of a fascinating manuscript French Revolutionary calendar, or calendrier universel.

French Revolutionary calendar, 1804, French MS 147

French Revolutionary calendar, 1804, French MS 147

The revolutionary system was instituted in 1792, in order to eradicate all religious and royalist influences from the calendar. It was part of a larger endeavour to systematize units of measurement, including metrication and decimalization.

The Convention decreed that Year 1 of the Republic began on 22 September 1792, the day of the autumn equinox in Paris. Thereafter each year would contain twelve months of thirty days each (with provision for leap years).

Months were given new names based on the cycle of nature. Thus Brumaire, starting in late October, derived from the French brume (fog), while Messidor, starting on 19 or 20 June, took its name from the Latin word messis, (harvest).

Each month was divided into three décades or ‘weeks’ of ten days each. Décades proved unpopular, as workers had only one full day’s rest in ten, and were abandoned in April 1802 (Floréal an X). The entire calendar system was abolished by an act dated 22 Fructidor an XIII (9 September 1805), with effect from 1 January 1806, although it was briefly reinstated during the Paris Commune of 1871.

Our calendar (now French MS 147) measures 48 x 34 cms (metrication proved more successful than the Revolutionary calendar). It was evidently prepared in 1804 and was projected for use between 1804 and 1821. It may have been intended as a teaching aid in the classroom, or as a practical tool for converting dates between the French calendar and the Gregorian calendar used everywhere else in Europe.

For more information on the Revolutionary calendar, see the detailed Wikipedia entry.