Why don’t we have a way of measuring time, metrically? E.g. 10 hours/day, 10 minutes/hour, etc.
Here’s France’s early attempt. It wasn’t very popular.
We kind of do, it’s based on the second. It is used for measuring time intervals rather than the time of day.
We do. The SI base unit of time is the second. Apply prefixes as needed.
Metric doesn’t mean decimal.
The basic problem with a fully-decimal system of time is that there are multiple natural cycles we’d like to include, with no particular relationship between them. No matter what you do, the number of days in a year is 365 plus change, and any useful calender is rather obligated to acknowledge both days and years as time units.
In SI (the System Internationale, the standard version of the Metric System), no effort is made to match any of those cycles. The metric second used to be defined as 1/86400 of the mean solar day, but the current standard for the second is based instead on the natural frequency of the cesium atom, which is much more stable. So it’s actually possible for the number of seconds in a day to vary.
To amplify on this a bit, the attempt to introduce decimal hours in 1793 is the bit of the French calendar reforms of the time that really crashed and burned. And while a couple of other explanations are sometimes nodded towards as contributing to this, it’s difficult to avoid the suspicion that this was overwhelmingly because of the sheer degree of prior investment in the existing system.
As the revolutionary government showed, it’s relatively easy to force through a change in the sequence of days and months. You simply issue a decree and make sure lots of calendars with the new days and months are printed. It’s not as if the existing calendars that people use a long useful life anyway - they’re the sort of item you buy afresh each new year anyway.
But clocks, that’s another matter. To enforce decimal hours you have to aim on trying to change every damn clockface in the republic. Every public clock, every clock in every house, every pocketwatch … Who pays for this? How do you encourage people to shift their clocks?
Now there were aspects of the new weights and measures that were also complicated to enforce - and highly unpopular. But the underlying motive there was as much standardisation as decimalisation. That argument didn’t apply with the clocks - there was already a universally agreed system in place across the country. Decimal hours just had an air of change for change’s sake. (Not that change for change’s sake couldn’t be a lethally powerful argument at the time.)
Decimal clocks were never manufactured on any scale even when they were (relatively briefly) mandated. The known examples are either prototypes, propaganda examples or gimmicks.
I hate hours:minutes:seconds and devised my own “millidays” system and actually had the conversion equivalents memorized to calculated to the nearest centiday/12-minute interval going in either direction. (Yes, I did have too much time on my hands).
h:m:s is as awkward as teaspoons cups and quarts, and I wish we had a decimal system instead. And not the scientific one based on seconds, but an everyday-use one based on a standard measure of a “day”.