The French Revolution’s Decimal Time (1793–1805)

During the Revolution, France tried to remake time itself along rational, scientific, decimal lines — just as they did with weights and measures (leading to the metric system).

They introduced:

10 hours in a day

100 minutes per hour

100 seconds per minute

→ So, 1 decimal hour = 2 hours 24 minutes in our system.

They even minted decimal clocks and watches.

❓ Why didn’t it last?

Human habits were too strong

People had been living with 12/24-hour time for thousands of years.

Religious rhythms (church bells, prayer times) and social routines (mealtimes, markets) were all based on 12/24.

Inconvenient fractions

The 12-hour division is practical because 12 splits neatly into halves, quarters, and thirds.

10 splits only into halves and fifths — far less useful in daily division of labour, meals, and navigation.

No international adoption

Unlike metric weights and measures (which were globally useful), decimal time clashed with the rest of the world, which stayed with 24 hours.

Trade, travel, and diplomacy became harder, not easier.

Practical resistance

Clockmakers, merchants, and ordinary people disliked the complexity of dual systems.

In 1805, Napoleon quietly dropped decimal time (but kept the metric system, which stuck).

🚂 Why 12/24 survived

Deep roots in astronomy and natural cycles.

Divisibility of 12 is superior to 10 for fractions.

A balance of cultural tradition and mathematical convenience.

💡 So: we almost ended up with 10-hour days — but humans revolted against Revolutionary rationalism when it clashed with their lived experience. Metric length and weight were intuitive and practical; decimal time was not.