Flash clock

An archive of the clock from an old version of this site. Original page.  

Lavoisier

Antoine-Laurent de Lavoisier, in a convocation letter to the members of the Commission for weights and measurements, for October 13, 1793, (22 vendémiaire an II) expressed himself in terms of the new regulations: “We remind you, dear citizen, that the Commission for weights and measurements shall meet, from now on, on the 2nd and 5th and 8th of each decade, at 7 decimal hours exactly (4 hours 48 minutes in the afternoon in the old style).”

An interesting use of decimal time. Note that he gave an exact decimal time, then translated that into “old style,” rather than the other way around. He also refers to the décade, rather than the week. Meetings are to be held every third day with a three-day weekend. 

This was when decimal time and the calendar were first introduced. He died in prison shortly after that, in the unfortunate snuffing of a leading light of science, another victim of the times. 

Current stardates

Captain’s log, stardate 78862.1.  

Amongst the date and time formats I’ve supported on this site is the current stardate. But since there is no consensus or single version that is accepted, I’ve gone back and forth with which to use. Initially, I used Modified Julian Dates, but then I started using TrekGuide’s formula, as that was consistent with when TNG, DS9, and Voyager episodes aired, but those episodes haven’t aired for decades. 

Other decimal times

We tend to think of decimal time as a division of the day, but there are other bases, too. 

 Many companies use decimal time for payroll or hourly billing, with hours as the base, divided into hundredths. So 6:30 PM is written as 18.50. Punch clocks like this are common. 

 Astronomers sometimes divide years into decimals such as 2023.789. 

Computers often use Unix time, which counts seconds, sometimes divided into milliseconds and microseconds, like 1699042927.711. 

 So there is already a whole world of decimal time already in use!

International Astronomical Union

The International Astronomical Union (IAU) has been using decimal time in its telegraphed circulars for over a century. Following the recommendations of the IAU, the dates of observations, or of astronomical events, should be written in the order of year, month, day, so that in principle it can be appended by the decimal fraction of a day. An example decimal time would be 2023 Nov. 3.1234 UT, where .1234 is the time of day represented as a fraction. All times are Universal Time (GMT). This fraction is identical to MJD, but with a Gregorian calendar date. 

 For an actual example, see IAU circular

History

You may wonder, what did decimal time actually look like in history? I’ve read thousands of records from the Revolution and can tell you. See here for actual examples.

Web clock

I just noticed that the HTML5 clock on this page shows Comic Sans on Windows PC instead of cursive. I think I have now fixed that. I also added some drop shadows to make it look more 3D. There is also now a little hand for day of the week (décade) which is also indicated by text, (Decadi, Primidi, etc.) Let me know what you think. There is a larger version here. 

It’s blue, white, and red to match the tricolour flag, with a Phrygian cap to celebrate the French Revolution. It’s written in HTML5 and JavaScript. I made my first decimal clock in AT-BASIC over 40 years ago. That one was more…basic. I used to have Java clocks ⏰ 🕰️ on my old website, but this one’s better.