Grave (unit)
The grave was the original name of the kilogram, in an early version of the metric system between 1793 and 1795.
The modern kilogram has its origins in the pre-French Revolution days of France. Louis XVI created a Consultative Commission for Units to devise a new decimal-based system of measurement. This royal commission, which included such aristocrats as Antoine Lavoisier, founded the very beginnings of the “metric system”, which later evolved into the contemporary International System of Units (SI).
In 1793 a new, decimal series of weights was introduced by the French Revolutionary government. The series of weights (milligravet, centigravet, decigravet, gravet, centigrave, decigrave, grave, centibar, decibar, bar ) contained three root unit names without a prefix: gravet, grave, and bar. Of these, the grave was the central unit with a definition. It was the weight of one cubic decimeter of pure water at the melting temperature of ice.
In 1795, the three root unit names were replaced by a single new name: the gram. The new gram was equal to the old gravet. Four new prefixes were added to cover the same range of weights as in 1793 (milligram, centigram, decigram, gram, decagram, hectogram, kilogram, myriagram).
The regulation of trade and commerce required a “practical realisation”: a single-piece, metallic reference standard. The kilogram was more convenient as a standard than the gram. A brass cylinder was made that served as the prototype of the provisional kilogram.
