The modern SI system defines the second as the base unit of time, and forms multiples and submultiples with metric prefixes such as kiloseconds and milliseconds.
In 1790, French diplomat Charles Maurice de Talleyrand-Périgord proposed that the fundamental unit of length for the metric system should be the length of a pendulum with a one-second period, measured at sea level on the 45th parallel (50 grades in the new angular measures), thus basing the metric system on the value of the second.
The commission rejected the seconds-pendulum definition of the metre the following year because the second of time was an arbitrary period equal to 1/86,400 day, rather than a decimal fraction of a natural unit.
In January, 1791, Jean-Charles de Borda commissioned Louis Berthoud to manufacture a decimal chronometer displaying these units.
[6] The final system, as introduced in 1795, included units for length, area, dry volume, liquid capacity, weight or mass, and currency, but not time.
In the 19th century, Joseph Charles François de Rey-Pailhade endorsed Lagrange’s proposal of using centijours, but abbreviated cé, and divided into 10 decicés, 100 centicés, 1,000 millicés,[8] and 10,000 dimicés.
In 1897, the Commission de décimalisation du temps was created by the French Bureau of Longitude, with the mathematician Henri Poincaré as secretary.