■ Practical system of units (CR, 80)* Resolution 6 In accordance with the wish expressed by the 9th Conférence Générale des Poids et Mesures (CGPM) in its Resolution 6 concerning the establishment of a practical system of units of measurement for international use, the 10th CGPM decides to adopt as base units of the system, the following units: length meter mass kilogram time second electric current ampere thermodynamic temperature degree Kelvin luminous intensity candela CIPM, 1956 ■ Definition of the unit of time (second) (PV, 25 , 77)* Resolution 1 In virtue of the powers invested in it by Resolution 5 of the 10th Conférence Générale des Poids et Mesures, the Comité International des Poids et Mesures, considering 1. that the 9th General Assembly of the International Astronomical Union (Dublin, 1955) declared itself in favour of linking the second to the tropical year, 2. that, according to the decisions of the 8th General Assembly of the International Astronomical Union (Rome, 1952), the second of ephemeris time (ET) is the fraction 496 986 408 813 276 960 12 × 10 − 9 of the tropical year for 1900 January 0 at 12 h ET, decides * The unit name “degree kelvin” was changed to “kelvin” in 1967 by the 13th CGPM (Resolution 3, see p. 62). * This definition was abrogated in 1967 by the 13th CGPM (Resolution 1, see p. 62).
Appendix 1 • 57 “The second is the fraction 1/31 556 925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.” ■ Système International d’Unités (PV, 25 , 83) Resolution 3 The Comité International des Poids et Mesures, considering • the task entrusted to it by Resolution 6 of the 9th Conférence Générale des Poids et Mesures (CGPM) concerning the establishment of a practical system of units of measurement suitable for adoption by all countries adhering to the Meter Convention, • the documents received from twenty-one countries in reply to the enquiry requested by the 9th CGPM, • Resolution 6 of the 10th CGPM, fixing the base units of the system to be established, recommends 1. that the name “Système International d’Unités” be given to the system founded on the base units adopted by the 10th CGPM, viz.: [This is followed by the list of the six base units with their symbols, reproduced in Resolution 12 of the 11th CGPM (1960)]. 2. that the units listed in the table below be used, without excluding others which might be added later: [This is followed by the table of units reproduced in paragraph 4 of Resolution 12 of the 11th CGPM (1960)]. 11th CGPM, 1960 ■ Definition of the meter (CR, 85)* Resolution 6 The 11th Conférence Générale des Poids et Mesures (CGPM), considering • that the international Prototype does not define the meter with an accuracy adequate for the present needs of metrology, • that it is moreover desirable to adopt a natural and indestructible standard, decides 1. The meter is the length equal to 1 650 763.73 wavelengths in vacuum of the radiation corresponding to the transition between the levels 2p 10 and 5d 5 of the krypton 86 atom.
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