The ancient Egyptians apparently used a decimal time system; we have been unable to find more information about it.
In China, a division of the day into 100 equal parts, called baike (百 刻), was introduced several centuries before the common era. This unit arose from the use of a water clock. A small hole allowed water to escape from the bottom of a jar and time was measured by noting marks on a stick floating vertically. The stick was marked in the same way as an ordinary ruler, into 10 cun each subdivided into 10 fen, making 100 divisions. These divisions acquired the name ke (刻), from the word for carve, because the marks were carved into the stick. (Westerners later translated ke as “quarter,” since the 14.4 minute ke was very close to the Western 15-minute quarter hour.)
Separate sticks were used for night and day, because a night, in particular, was divided into 5 watches regardless of its length. Pairs of sticks were prepared to match the changing lengths of day and night during a year. In the pair of sticks for the solstices, one stick would have 60 marks and the other 40, while in the pair of sticks for the equinoxes would each stick have 50 marks. By 130 bce, the timekeepers were continually adding ke to the day stick from the winter solstice to the summer solstice, and subtracting during the rest of the year. At first the pair of sticks was changed every 9 days, then every 7½ days. But the total number of ke on both sticks always equaled 100.
The government ceased official use of the 100-ke system in 1670, when it adopted Western 24-hour time, but the ke persisted in use until the late nineteenth century.
The 100-ke-in-a-day system co-existed for centuries with the 12-doublehours-in-a-day system. The two naturally coincide at only four times of day, and the various attempts made to reconcile them (for example, by making the number of ke 96, 108 or 120) never caught on.
The French Convention nationale voted in a decimal system on 5 October 1793, containing a 10-day week, a 10-hour day, a 100-minute hour, and a 100-second minute. Each hour was thus 144 ordinary minutes; each minute décimale was 1.44 minutes, and each seconde décimale was 0.864 seconds. The system was repealed on 31 December 1805.
Article 8 described the 10-day week:
Chaque mois est divisé en trois parties égales, de dix jours chacune, et qui sont appelées décades, distinguées entr'elles par première, seconde et troisième.
Each month is divided into three equal parts, of ten days each, which are called décades, distinguished as first, second and third.
Article 11 divided the day into decimal subdivisions:
Le jour, de minuit à minuit, est divisé en dix parties; chacque partie en dix autres, ainsi de suite jusqu'à la plus petite portion commensurable de la durée. Cet article ne sera de rigueur pour les actes publics qu'à compter du 1er du premiere mois de la troisième année de la république.
The day, from midnight to midnight, is divided into ten parts, each part into ten others, and so on in this manner down to the smallest possible division whose duration can be measured. This article is not to be enforced for public acts until the first of the first month of the third year of the republic.
Article 8 described the 10-day week, and named the days:
Chaque mois est divisé en trois parties égales, de dix jours chacune, qui sont appelées Décades. Les noms de jours de la décade sont: Primidi, Duodi, Tridi, Quartidi, Quintidi, Sextidi, Septidi, Octidi, Nonidi, Décadi.
Each month is divided into three equal parts, of ten days each, which are called Décades. The names of the days of the decade are: Primidi, Duodi, Tridi, Quartidi, Quintidi, Sextidi, Septidi, Octidi, Nonidi, Décadi (that is, they are in effect numbered).
Article 11 divided the day into decimal subdivisions, and named the parts:
Le jour, de minuit à minuit, est divisé en dix parties ou heures, chacque partie en dix autres, ainsi de suite jusqu'à la plus petite portion commensurable de la durée. La centième partie de l'heure est appelée minute décimale; le centième partie de la minute est appelée seconde décimale. Cet article ne sera de rigueur pour les actes publics, qu'à compter du 1er Vendémiaire, l'an trois de la République.
The day, from midnight to midnight, is divided into ten parts or hours, each part into ten others, and so on in this manner down to the smallest possible division whose duration can be measured. The hundredth part of an hour is called "minute décimale"; the hundredth part of the minute décimale is called the seconde décimale. This article is not to be enforced for public acts until the first of Vendémiaire in the third year of the Republic.
Article 22 suspended indefinitely the decimal division of the day and its parts.
La disposition de la loi du 4 frimaire an 2, qui rend obligatoire l'usage de la division décimale du jour et de ses parties, est suspendue indéfiniment.
The terms of the law of 4 frimaire year 2, which made use of the decimal division of the hour and its parts obligatory, are suspended indefinitely.
Don't miss the Wikipedia page on decimal time.
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Last revised: 27 February 2004.