Historical context of the SI
Unit of mass (kilogram) |
Acronyms:
CGPM, CIPM, BIPM |
At the end of the
18th century, a kilogram was the mass of a cubic decimeter of water. In
1889, the 1st CGPM sanctioned the international prototype of the kilogram,
made of platinum-iridium, and declared: This prototype shall henceforth
be considered to be the unit of mass. The picture at the right shows
the platinum-iridium international prototype, as kept at the International
Bureau of Weights and Measures under conditions specified by the 1st CGPM
in 1889.
The
3d CGPM (1901), in a declaration intended to end the ambiguity in popular
usage concerning the word "weight," confirmed that:
The kilogram
is the unit of mass; it is equal to the mass of the international
prototype of the kilogram.
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SI Units
Background |