The Treaty of the Meter
The Convention of the Metre, often called the Treaty of the Meter in the United States, is a diplomatic treaty between 48 nations which gives authority to the Conférence Générale des Poids et Mesures (CGPM, General Conference on Weights and Measures), the Comité International des Poids et Mesures (CIPM, International Committee on Weights and Measures) and the Bureau International des Poids et Mesures (BIPM, International Bureau of Weights and Measures) to act in matters of world metrology, particularly concerning the demand for measurement standards of ever increasing accuracy, range and diversity, and the need to demonstrate equivalence between national measurement standards.
Representatives of 17 nations signed the Convention in Paris in 1875. In addition to establishing the BIPM and laying down the way in which the activities of the BIPM should be financed and managed, the Metre Convention established a permanent organizational structure for member governments to act in common accord on all matters relating to units of measurement. The Convention, modified slightly in 1921, remains the basis of all international agreement on units of measurement. There are now 48 Member States, including all the major industrialized countries.
The CGPM consists of delegates from all the Member States of the Meter Convention and currently meets every four years. The CIPM consists of 18 members, each belonging to a different Member State; it currently meets every year, usually in September at the BIPM. Suggested modifications to the SI are submitted to the CGPM by the CIPM for formal adoption. The CIPM may also on its own authority pass clarifying resolutions and recommendations regarding the SI (these resolutions and recommendations usually deal with matters of interpretation and usage).
To assist it in its broad spectrum of technical activities, the CIPM has set up a number of Consultative Committees ( Comités Consultatifs ). These committees provide the CIPM with information on matters that it refers to them for study and advice. Each Consultative Committee, the Chairman of which is normally a member of the CIPM, is composed of delegates from national metrology institutes such as NIST, specialized institutes, and other international organizations, as well as individual members. The Director of the NIST Physics Laboratory is the current U.S. delegate to the CGPM, the U.S. member, and Vice President of the CIPM. The current NIST delegate to the CCU, from the NIST Physics Laboratory, is also the Manager of its Fundamental Constants Data Center.
For information on the United States and the Metric System click here.