French decimal time
How to read it
The day, from midnight to midnight, is cut into ten hours. Each hour holds one hundred minutes, and each minute one hundred seconds, so a day has 100,000 decimal seconds.
Midnight is 0:00:00 and noon is 5:00:00. A decimal hour is 2.4 ordinary hours, a decimal minute is 86.4 ordinary seconds, and a decimal second is 0.864 of an ordinary one, so the last figure ticks a little faster than you expect.
Where it came from
Jean-Charles de Borda proposed the scheme in November 1792, and the decree of 5 October 1793 set it in law, dividing the day “into ten parts or hours”.1 It became mandatory for public records on 22 September 1794 and was suspended on 7 April 1795, barely six months later.1
It never fully went away at once: some towns, Marseille and Toulouse among them, kept using it for a while, and two clock faces at the Tuileries showed decimal hours until at least 1801.1
Sources
- Decimal time (Wikipedia, CC BY-SA 4.0)