--- metadata: title: 'Resolutions of the CGPM: 18th meeting' date: '1987-10-15' source: BIPM - Pavillon de Breteuil url: https://www.bipm.org/en/CGPM/db/18 resolutions: - dates: - '1987-10-15' title: Third verification of the national prototypes of the kilogram identifier: 1 url: https://www.bipm.org/en/CGPM/db/18/1/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=97 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: recalling / further recalling date_effective: '1987-10-15' message: recalling and confirming cgpm-resolution:en/15/3[Resolution 3 of the 15th Conférence Générale des Poids et Mesures], - type: having / having regard date_effective: '1987-10-15' message: having asked the advice of the Comité International des Poids et Mesures and having approved its decision to proceed with a comparison of the international Prototype of the kilogram with its designated copies ("témoins") and with the working-standard prototypes of the Bureau International des Poids et Mesures, - type: considering date_effective: '1987-10-15' message: considering that the Bureau International des Poids et Mesures will then be in a position to organize a general comparison of the national prototypes, a comparison which should begin in the period 1989-1990, actions: - type: recommends date_effective: '1987-10-15' message: recommends that the laboratories concerned prepare to send to the Bureau International des Poids et Mesures their national prototypes of the kilogram in platinum-iridium for a general comparison of these prototypes. - dates: - '1987-10-15' title: Study of the surface condition of mass standards identifier: 2 url: https://www.bipm.org/en/CGPM/db/18/2/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=98 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: considering date_effective: '1987-10-15' message: considering that long-term stability is one of the essential characteristics of mass standards, - type: considering date_effective: '1987-10-15' message: considering that improvements in balances now allow variations in mass of only a few micrograms in a kilogram to be observed, - type: considering date_effective: '1987-10-15' message: considering that variations of this order have been observed and have been attributed to surface effects due in particular to atmospheric agents, - type: considering date_effective: '1987-10-15' message: considering that present methods of cleaning the surfaces of mass standards may have unsuspected effects, - type: considering date_effective: '1987-10-15' message: considering that a wide range of methods now exist for the study of the surfaces of alloys used in mass standards, - type: considering date_effective: '1987-10-15' message: considering that important results have already been obtained using these methods for the study of the surface contamination of mass standards, actions: - type: recommends date_effective: '1987-10-15' message: recommends that laboratories apply the wide range of techniques now available for the study of surface composition and behaviour to platinum/10% iridium and other alloys used in mass standards. - dates: - '1987-10-15' title: Assumption of responsibility for International Atomic Time identifier: 3 url: https://www.bipm.org/en/CGPM/db/18/3/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=98 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: considering date_effective: '1987-10-15' message: considering the importance of measurements of time and in particular of the International Atomic Time scale, which has already been the subject of cgpm-resolution:en/14/2[Resolution 2] of the 14th Conférence Générale des Poids et Mesures and of cgpm-resolution:en/15/4[Resolutions 4] cgpm-resolution:en/15/5[and 5] of the 15th Conférence Générale, - type: having / having regard date_effective: '1987-10-15' message: having taken note of the resolutions adopted by the international Unions concerned - International Astronomical Union, International Union of Geodesy and Geophysics and International Union of Radio Science, actions: - type: thanks / expresses-appreciation date_effective: '1987-10-15' message: pays tribute to the Bureau International de l'Heure and to its host organization, the Paris Observatory, for creating International Atomic Time and for the quality of the work carried out in order to establish it and diffuse it, - type: approves date_effective: '1987-10-15' message: approves the decisions of the Comité International which resulted in assumption by the Bureau International des Poids et Mesures of responsibility for establishing and diffusing International Atomic Time and - type: recommends date_effective: '1987-10-15' message: recommends the national institutions concerned to pursue with the Bureau International des Poids et Mesures their collaboration for establishing and improving International Atomic Time. - dates: - '1987-10-15' title: Time comparisons using satellite links identifier: 4 url: https://www.bipm.org/en/CGPM/db/18/4/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=99 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: considering date_effective: '1987-10-15' message: considering that high-precision timing is rapidly becoming an essential part of modern telecommunications, - type: considering date_effective: '1987-10-15' message: considering that two-way satellite links allow international time comparisons at very high precision, - type: considering date_effective: '1987-10-15' message: considering that it appears possible to exchange pseudo-random-noise timing signals simultaneously but without interference with other uses of the channel, - type: considering date_effective: '1987-10-15' message: considering that such pseudo-random-noise techniques also allow high-precision ranging, actions: - type: recommends date_effective: '1987-10-15' message: recommends that the responsible national and international bodies support experiments over telecommunications satellite links for the study of synchronization techniques by means of pseudo-random-noise modulation within the framework of the international timing programs as part of the generation of International Atomic Time. - dates: - '1987-10-15' title: Study of perturbing effects in the realization of the second identifier: 5 url: https://www.bipm.org/en/CGPM/db/18/5/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=99 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: recalling / further recalling date_effective: '1987-10-15' message: |- recalls that the definition of the second as it results from the decisions of the 13th Conférence Générale des Poids et Mesures implies that the caesium atom used as reference is at rest and unperturbed, this implies in particular that, in its practical realization, measurements must be corrected for the velocity of the caesium atoms with respect to the clock reference frame, for magnetic and electric interactions, spin exchange and other possible perturbations, and, in order to implement the necessary corrections, actions: - type: recommends date_effective: '1987-10-15' message: recommends that theoretical studies of all perturbing effects be developed - type: recommends date_effective: '1987-10-15' message: recommends that experiments in order to identify these effects, to verify their theoretical interpretation and to evaluate the uncertainty of the corresponding corrections be actively pursued. - dates: - '1987-10-15' title: Forthcoming adjustment to the representations of the volt and of the ohm identifier: 6 url: https://www.bipm.org/en/CGPM/db/18/6/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=100 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures, considerations: - type: considering date_effective: '1987-10-15' message: considering that world-wide uniformity and long-term stability of national representations of the electrical units are of major importance for science, commerce and industry from both the technical and economic points of view, - type: considering date_effective: '1987-10-15' message: considering that many national laboratories use the Josephson effect and are beginning to use the quantum Hall effect to maintain, respectively, representations of the volt and of the ohm, as these offer the best guarantees of long-term stability, - type: considering date_effective: '1987-10-15' message: considering that because of the importance of coherence among the units of measurement of the various physical quantities the values adopted for these representations must be as closely as possible in agreement with the SI, - type: considering date_effective: '1987-10-15' message: considering that the results of recent and current experiment will permit the establishment of an acceptable value, sufficiently compatible with the SI, for the coefficient which relates each of these effects to the corresponding electrical unit, actions: - type: invites / further invites date_effective: '1987-10-15' message: "*invites* the laboratories whose work can contribute to the establishment of the quotient voltage/frequency in the case of the Josephson effect and of the quotient voltage/current for the quantum Hall effect to vigorously pursue these efforts and to communicate their results without delay to the Comité International des Poids et Mesures, and" - type: instructs date_effective: '1987-10-15' message: instructs the Comité International des Poids et Mesures to recommend, as soon as it considers it possible, a value for each of these quotients together with a date for them to be put into practice simultaneously in all countries; these values should be announced at least one year in advance and would be adopted on 1 January 1990. - dates: - '1987-10-15' title: Development of a new international temperature scale identifier: 7 url: https://www.bipm.org/en/CGPM/db/18/7/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=101 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: considering date_effective: '1987-10-15' message: considering that world-wide uniformity and long-term stability of temperature measurements are of major importance for science, commerce and industry from both the technical and economic points of view, - type: considering date_effective: '1987-10-15' message: considering that the value of a temperature on the practical scale must correspond closely to the value of the thermodynamic temperature in the SI, - type: considering date_effective: '1987-10-15' message: considering that the 15th Conférence Générale des Poids et Mesures, taking cognizance of the differences that have been demonstrated between values of temperature on the International Practical Temperature Scale of 1968 (IPTS-68) and the corresponding values of thermodynamic temperature, has instructed the Comité International des Poids et Mesures to establish a new, substantially more accurate scale, - type: considering date_effective: '1987-10-15' message: considering that it will be possible to propose in 1989 a new scale for which any remaining departures from thermodynamic temperature will be inconsequential for many years to come, actions: - type: invites / further invites date_effective: '1987-10-15' message: invites the Comité International des Poids et Mesures and the national laboratories to complete the development of this new temperature scale and to fix a date for putting it into practice simultaneously in all countries; the values of the differences between this new scale and the IPTS-68 should be announced at least one year before the adoption of the new scale which could take place on January 1st 1990. - dates: - '1987-10-15' title: Apportionment of contributions identifier: 8 url: https://www.bipm.org/en/CGPM/db/18/8/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=101 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures considerations: - type: considering date_effective: '1987-10-15' message: considering that, after each Conférence Générale des Poids et Mesures (CGPM), taking account of those states which have joined the Convention du Mètre since the preceding CGPM should result in a reduction of the assessment percentages for all the other states, actions: - type: decides date_effective: '1987-10-15' message: decides that a corresponding reduction factor will be uniformly applied to all the assessment percentages, including the maximum and minimum percentages defined in Article 20 of the Rules Appended to the Convention du Mètre and modified by the 11th and 16th CGPM. - dates: - '1987-10-15' title: Funding of the BIPM identifier: 9 url: https://www.bipm.org/en/CGPM/db/18/9/ reference: https://www.bipm.org/utils/common/pdf/CGPM/CGPM18.pdf#page=102 approvals: - type: affirmative degree: unanimous message: The 18th Conférence Générale des Poids et Mesures, considerations: - type: considering date_effective: '1987-10-15' message: considering the importance of the work carried out by the Bureau International des Poids et Mesures (BIPM) and of the services that it provides to all countries, - type: considering date_effective: '1987-10-15' message: considering the necessity of furnishing the BIPM minimum resources to avoid endangering the pursuit of these activities and - type: considering date_effective: '1987-10-15' message: considering the difficulty of foreseeing, in the present economic circumstances, the minimal financial means that would permit the BIPM to fulfil its mission of world centre of scientific metrology, actions: - type: decides date_effective: '1987-10-15' message: |- decides that the fixed part of the annual funding of the BIPM will be increased in such a way that the sum of the fixed part and the supplementary part (defined in Article 6 (1921) of the Rules Appended to the Convention du Mètre of 1875) be, for the States subscribing to the Convention at the time of the 18th Conférence Générale des Poids et Mesures, raised to 17 960 000 francs-or in 1989 + 18 858 000 francs-or in 1990 + 19 801 000 francs-or in 1991 + 20 791 000 francs-or in 1992.