SI Unit: Second

This postage stamp features a closeup of a dual-scale decimal clock: 10 hours below and 12 hours on the upper face. The decimal hours had 100 decimal minutes, which had 100 decimal seconds.

The collection of scientific instruments at the Musée des Arts et Métiers (Paris, France) includes a few decimal clocks and pocketwatches.

When filming the kilogram and meter standards, I learned about decimal time from Dr. Lalande, who is a curator of scientific instruments at the Musée. His section includes some decimal clocks made in the 1790s.

Some of the timepieces show 10 hours and their subdivisions only; others also include duodecimal time markings. This is part of the 24-hour face of a clock.