That time France tried to make decimal time something

Deepak Gupta
Deepak Gupta January 17, 2022
Updated 2022/01/17 at 3:42 PM

Although Marie Antoinette was pressured to care, the French Revolution of 1789 was aimed at more than simply overthrowing the monarchy. The revolutionaries sought to free the nation from its past, specifically from the clutches of the Catholic Church, and point France towards a more glorious and prosperous future. They did so, in part, by radically transforming their measures of the passage of time.

Throughout the 18th century, most French people were Catholic, as that was the only religion allowed to be practiced openly in the country, and since the repeal of the in 1685. As such, the nation traditionally adhered to the 12-month Gregorian calendar – itself based on even older sexagesimal (6-unit) divisible systems, adapted from the Babylonians and Egyptians – while French clocks cycled every 60 minutes and seconds.

But if there was little reason to continue using the established chronology system beyond tradition, the revolutionaries thought, why not transmute it into a more rational and scientifically supported method, just as the revolution itself sought to bring stability and new order to French society. as a whole? And what better system to interpose than the decimal, which already governed the nation’s weights and measures. Thus, while he was not busy abolishing the privileges of the First and Second Estates, eliminating the church’s power to levy taxes or just , France’s neophyte post-revolution government began to reform the kingdom’s calendars and clocks.

The concept of decimal time, in which a day is divided into multiples of 10, was first suggested more than thirty years earlier, when French mathematician Jean le Rond d’Alembert, in 1754, “It would be very desirable that all divisions, for example the livre, the sou, the toise, the day, the hour, etc. from tens to tens. Such a division would result in much easier and more convenient calculations, and would be far preferable to the arbitrary division of the livre into twenty sous, the sou into twelve deniers, the day into twenty-four hours, the hour into sixty minutes, etc. .”

On the eve of the Revolution, a year divided into 12 months of 30 days each, their names inspired by the harvests and the prevailing climate in Paris during their occurrences. That there are 365 days in a year is an immutable fact dictated by the Earth’s motion around our local star. So 12 months of 30 days each resulted in 5 days (6 in a leap year!) these, the revolutionaries reserved for national holidays.

Each week was divided into 10 days, every day was divided into 10 equal hours, which were divided into 100 minutes, with each minute divided into 100 seconds (approximately 1.5 times longer than conventional minutes) and each second divided into 1000 ” tiers”. Individual layers can also be divided into 1,000 even smaller units, called “quatierces”. Implementing tierces would also lead to the creation of a new unit of length, called the “half-handbreadth”, which is the distance that the twilight zone travels along the equator along a tier, and equal to one billionth of the circumference of the tier. planet – about 4 centimeters.

The decimal hour was formally adopted by , “The day, from midnight to midnight, is divided into ten parts, each part into ten others, and so on down to the smallest measurable portion of the duration.” As such, midnight would be indicated as 00:00, while noon would be 5:00.

A clock with decimal and conventional demarcations

Public domain

At midnight of the autumnal equinox on September 22 of that year, France’s Gregorian calendar inaugurated the 1st Year Vendémiaire II of the French Republican calendar. From then on, every new year would begin at midnight of the autumnal equinox, as noted by the Paris Observatory.

“The new calendar was based on two principles”, a 2017 exhibition at the International Museum of Watches, , noticed. “That the republican year must coincide with the movement of the planets, and that it must measure time more accurately and symmetrically, applying the decimal system whenever possible. Non-religious, he advocated a rational approach and honored the seasons and work in the fields.”

The main advantage of a decimal time system is that since the base used to divide time is the same used to represent it, the entire time representation can be treated as a single string.

On the one hand, this system offered the clear advantage that both the number base used to define time and the number base used to divide it are the same number. For example, fast, how many seconds are there in three hours? The answer, most people go Google, is 10,800 – 60 seconds/minute x 60 minutes/hour x 3 hours. In decimal time, you simply get 30,000 — 3 hours x 10,000 seconds/hour.

However, due to an oversight in its logical design due to gaps in astronomical knowledge, the republican calendar struggled to properly accommodate leap years. “The period of four years, after which it is usually necessary to add a day, is called the Franciade in memory of the revolution which, after four years of effort, brought France to republican government, . “The fourth year of Franciade is called Sextile.”

The problem is that leap years, if we’re counting new years at midnight on the autumnal equinox in Paris, don’t happen consistently every four years. By the measure of the equinox, the first leap year of the republican calendar would have to occur in the year III, while the leaps in the 15th and 20th years would happen half a decade apart.

There were also more practical problems with switching the nation’s chronology to an entirely new system, such as the fact that people already had perfectly good watches that they would have to replace, decimal time would remain in effect. It was also extremely unpopular with the working class who would only get one day of rest in 10 using the Republican calendar (plus half a day on the fifth) instead of the Gregorian one day in seven, not to mention the ten-day week wreaked havoc. in the traditional Sunday religious services, since Sunday would cease to exist.

Overall, the idea simply failed to capture public support – despite decrees requiring the creation of decimal-based clocks – and was officially suspended on April 7, 1795. The French then took a quick look at metric time, which also measured the passage of time in factors of ten, but based its progression on conventional seconds (also known as 1/86400 of a day). Of course, all these efforts were moot when Napoleon declared himself emperor in 1804, made peace with the Vatican, and reinstituted the Gregorian calendar, thus relegating the republican calendar and decimal time to the dustbin of history. The lesson here being, unless , don’t try to fix what isn’t broken yet, especially when doing so might net you a trip to the guillotine.

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