MEASUREMENT SYSTEM

any of the systems used in the process of associating numbers with physical quantities and phenomena. The concept of weights and measures, though it has come in modern times to include temperature, luminosity, pressure, and electric current, once consisted of only four basic measurements: mass (weight), volume (liquid or grain measure), distance, and area. The last three are, of course, closely related. Basic to the whole idea of weights and measures are the concepts of uniformity, units, and standards. Uniformity, the essence of any system of weights and measures, requires accurate, reliable standards of mass and length and agreed-on units. A unit is the name of a quantity, such as kilogram or pound; a standard is the physical embodiment of a unit, such as the platinum-iridium cylinder kept by the International Bureau of Weights and Measures at Paris as the standard kilogram. Two types of measurement systems are distinguished historically: an evolutionary system, such as the British Imperial, which grew more or less haphazardly out of custom, and a planned system, such as the present-day International System of Units (SI; Systme Internationale d'Units), in universal use by the world's scientific community and by most nations. This article surveys the development of some of the world's major measurement systems and their distinctive characteristics. Additional reading The understanding and development of systems of physical measurements, from early elementary to sophisticated modern ones, are discussed in A.E. Berriman, Historical Metrology: A New Analysis of the Archaeological and the Historical Evidence Relating to Weights and Measures (1953, reprinted 1969); B.D. Ellis, Basic Concepts of Measurement (1966); Bruno Kisch, Scales and Weights: A Historical Outline (1965); Keith Ellis, Man and Measurement (1973); H. Arthur Klein, The World of Measurements: Masterpieces, Mysteries, and Muddles of Metrology (1974; reissued 1988 as The Science of Measurement: A Historical Survey); Owen Bishop, Yardsticks of the Universe (1984); O.A.W. Dilke, Mathematics and Measurement (1987); and Witold Kula, Measures and Men (1986; originally published in Polish, 1970).Advance toward modern systems of measurement is traced in Arthur E. Kennelly, Vestiges of Pre-Metric Weights and Measures Persisting in Metric-System Europe, 19261927 (1928); Landmarks in Metrology1983 (1983), a collection of papers written in the third quarter of the 20th century and published in connection with an international conference on the subject; Rexmond C. Cochrane, Measures for Progress: A History of the National Bureau of Standards (1966, reprinted 1976), emphasizing the extent of NBS involvement in 20th-century scientific progress; C. Douglas Woodward, BSIThe Story of Standards (1972), on the work of the British Standards Institution; Lal C. Verman, Standardization, a New Discipline (1973); and E.L. Dellow, Measuring and Testing in Science and Technology (1970).Development and maintenance of the U.S. customary system in particular are discussed in Ralph W. Smith, The Federal Basis for Weights and Measures: A Historical Review of Federal Legislative Effort, Statutes, and Administrative Action in the Field of Weights and Measures in the United States (1958); L.J. Chisholm, Units of Weight and Measure: International (Metric) and U.S. Customary (1967, reprinted 1974), especially interesting for its tables of conversion equivalents; and Lewis V. Judson, Weights and Measures Standards of the United States: A Brief History (1976).Useful reference information, in dictionary or table form, is compiled in Stephen Dresner, Units of Measurement: An Encyclopaedic Dictionary of Units, Both Scientific and Popular, and the Quantities They Measure (1971); John L. Feirer, SI Metric Handbook (1977); H.g. Jerrard and D.B. McNeill, A Dictionary of Scientific Units: Including Dimensionless Numbers and Scales, 5th ed. (1986); J.V. Drazil, Quantities and Units of Measurement: A Dictionary and Handbook (1983); and The World Measurement Guide: Editorial Information Compiled by The Economist, 4th rev. ed. (1980).Current research and development in the field is reported in such periodicals as M & C: Measurements & Control (bimonthly, U.S.); Measurement and Control (monthly, Great Britain); Measurement Science & Technology (monthly); and Measurement: Journal of the International Measurement Confederation (quarterly). Lawrence James Chisholm The Editors of the Encyclopdia Britannica