Grave (mass)
From Wikipedia, the free encyclopedia
French king Louis XVI created a Consultative Commission for Units to create a new decimal system of measurement. This royal commission, which included such aristocrats as Lavoisier, founded the very beginnings of the "decimal metric system", which later evolved into the contemporary SI. The original goal of this royal commission was to create a unit of mass that would be known as "grave" and symbolized G. This mass unit, whose name is derived from the word "gravity," was used early, since 1793. It would be defined as the mass of a cubic decimeter of water at the freezing point. The definition of grave originally was to be represented by an artifact mass standard. A milligrave (mG), alternatively called "gramme", was to be 1/1000 of a grave, and a kilograve (kG), alternatively called tonne, was to be 1000 graves.
However, the new system did not come into effect until after the French Revolution, when the new revolutionary government captured the idea of the metric system, but introduced some significant alterations. Since many mass measurements of that time concerned masses smaller than one grave, French scientists, fearing that a grave would be too big for every-day use, decided in cooperation with Republican government that the unit of mass should be the "gramme". Because a one-gramme standard was hard to use, and too small for establishing, especially to make a defining prototype of it, it was further decided that the original definition of the one-grave prototype should be kept under a different name, the kilogram, following a prefix system. This was introduced in 1795, and thus in turn the definition prototype began to be known as the "kilogram of the archives". Because of these developments, since 1875, the unit of mass is known as the "kilogram", redefined by a new platinum-iridium prototype whose mass was strictly the same as the mass of the "kilogram of the archives". In this way, the original name "grave" was finally rejected, and the name "kilogram" was adopted instead for the base unit of the SI.
The decision of the Republican government had been mainly politically motivated, because name "grave" was at that time considered politically incorrect and resembled the aristocratic title of the Markgrave, an alternative name for the title of Count that, like other nobility titles, was not compatible with the notion of égalité. Because of this history, SI now uses a somewhat inconsistent base unit with its name including a kilo prefix.
