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.