Date and Hour


Distances, volumes, masses had been decimalized. But...

there still were twenty-four hours in a day and sixty minutes in an hour, right angle was still equal to ninety degrees, water still boiled at eighty degrees (Reaumur) or two hundred and twelve degrees (Fahrenheit). This looked somewhat messy, was it possible to let the nice structure of the decimal metric system be polluted by these weird measures?


Centesimal degree and grade were developed

The Weight and Measures Committee decided in 1794 that "the thermometric degree will be the hundredth part of the distance between the freezing mark and the boiling water one". The centesimal - or centigrade - degree was born. But almost secretly: never a law nor a decree made its use compulsory...


How long had been the circle divided in 360 degrees? Since the Babylonians, 18 centuries before Christ? Since the 4th century BC, when Chinese people divided the circle in as many parts as (almost) days in the year? It had been a long time anyway that the right angle had 90 degrees. Not a big gap between 90 and 100, and by its decree of 1st August 1793 the Convention took the plunge: the angle degree was replaced by the grade or decimal degree, equal to 0.9 sexagesimal degree.


as well as the Republican time and calendar.

Year was divided in twelve months of 28 to 31 days, there were seven days in a week, 24 (or two times 12) hours in a day, 60 minutes in an hour, 60 seconds in a minute. This worked well - it still does - but looked quite reminiscent of the traditional religion; this was not tolerable to the proponents of a Republic which, albeit not yet laic, only trusted its Supreme Being. Also these ratios seven, twelve, sixty, looked untidy compared to the neat decimal order. Why not thus build a brand new calendar, truly republican, and of course, decimal? To be sure, even with the Revolution impetus, it was not possible to alter the only two elements of time linked to astronomic constants, i.e. the year - duration of the earth revolution around the sun - nor the day - duration of the earth revolution around its axis. But there was full freedom for the others, all conventionally fixed: starting date of the era, month, week, hour, minute.


Not a great success for decimal time

Realistic, the Convention, through Prieur de la Côte d'Or, acknowledges that decimalization of day and hour would only bring "a troublesome confusion in most usual actions with no proportionate advantages". Therefore "use of decimal division of day and its parts is indefinitely postponed" by the law of 18 Germinal year III. Quite ironic: one will recall that this law is the one which established the metric system...


just some more for the decimal calendar

The Republican calendar has been certainly better accepted by the populace, possibly attracted by the poetic names of months and the tempting allegoric drawings used to popularize them. Indeed from 1793 on all official documents and a number of private writings are dated according to the new system. But the Republican calendar suffered from being... republican. This was not really acceptable for an Emperor: on 22 Fructidor year XIII (9th September 1805) Napoleon signs the senatus-consult repealing the use of the Republican calendar and restating the Gregorian calendar by 1st January 1806. Of course political reasons could not be invoked to justify such a renunciation, and the senatus-consult was based on a report from Laplace. Since 1795 Laplace was fostering a reconsideration of the Republican calendar, to correct an error, pointed out by Delambre, on leap-years: three five-year franciades were necessary per century... The reconsideration was postponed by the insurrection of 1st Prairial year III - that sent Romme to the Guillotine - but was a good excuse in 1805.

The Republican calendar thus lived for 12 years, plus a 18 day-resurrection during the Commune of 1871. Since then it is shelved as a curiosity, together with the thelemic, Bahà'i, Zoroastre, druidic, pataphysic, proleptic and many other calendars. Somewhat regrettable: after all, we still are in a Republic!




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