†
The SI is, of course, a living system which evolves, and which reflects current best
measurement practice. This 8th edition therefore contains a number of changes since
the previous edition. As before, it lists the definitions of all the base units, and all the
Resolutions and Recommendations of the CGPM and the
Comité International des
Poids et Mesures
, the CIPM (known in English as the International Committee for
Weights and Measures), relating to the International System of Units. Formal
reference to CGPM and CIPM decisions are to be found in the successive volumes
of the
Comptes Rendus
of the CGPM (CR) and the
Procès-Verbaux
of the CIPM
(PV); many of these are also listed in
Metrologia
. To simplify practical use of the
system, the text provides explanations of these decisions, and the first chapter
provides a general introduction to establishing a system of units and to the SI in
particular. The definitions and the practical realizations of all the units are also
considered in the context of general relativity. A brief discussion of units associated
with biological quantities has been introduced for the first time.
Appendix 1 reproduces, in chronological order, all the decisions (Resolutions,
Recommendations, Declarations) promulgated since 1889 by the CGPM and the
CIPM on units of measurement and the International System of Units.
Appendix 2 exists only in the electronic version, which is available at
/.
It
outlines
the
practical
realization of some important units, consistent with the definitions given in the
principal text, which metrological laboratories can make to realize physical units and
to calibrate material standards and measuring instruments of the highest quality. This
†
Editors’ note: The 9th CGPM in 1948 initiated the study that led to the formal establishment of
the SI by the 11th CGPM in 1960.