Mendenhall Order - Knowledge

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metric standards because of their superior stability, and because they were better designed for carrying out precision comparisons. The Office found that the conversion tables in the 1866 law were satisfactory and used them to derive customary length and mass from the metric standards. The conversions were 1 yard =

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pound were presented to the United States". These were superior to the yard then in use, so one of them was adopted as the United States national standard yard. These yards were taken to England and re-compared with the imperial yard in 1876 and 1888. The pound provided by the United Kingdom agreed

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The imperial standard yard of 1855 was found to be unstable and shortening by measurable amounts. Also, the mint pound was found to be "likewise unfit for use". For several years before the Mendenhall order was actually issued, the Office of Weights and Measures was "practically forced" to use the

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In view of the probable success of this movement and of the certainty that such definitions would be built upon a metric foundation, it was deemed wise to have definite recognition of these national prototypes as the fundamental standards of reference in all metrological operations in which the

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Mendenhall ordered that the standards used for the most accurate length and mass comparison change from certain yard and pound objects to certain meter and kilogram objects, but did not require anyone outside of the Office of Weights and Measures to change from the customary units to the metric

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was passed by Congress and allowed, but did not require, the use of the metric system. Included in the law was a table of conversion factors between the traditional and metric units. The United States Coast Survey (which in 1878 became the U.S. Coast and Geodetic Survey) Office of Weights and

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Measures had on hand a number of metric standards, and selected the iron Committee Meter and the platinum Arago Kilogram to be the national standards for metric measurement. The standard yard and pound previously mentioned continued to be the standards for customary measurements.

99:, abbreviated BIPM after the French name. The BIPM made meter and kilogram standards for all the countries that signed the treaty; the two meters and two kilograms allocated to the United States arrived in 1890, and were adopted as national standards. 153:

The definitions of 1893 remained unchanged for 66 years, but increasing precision in measurements gradually made the differences in the standards in use in English-speaking countries important. By the

139:. Associated with the Congress would be a "Chamber of Delegates", officially organized for the purpose of coming to an international agreement on units of electrical quantities. As Mendenhall wrote, 75:

These were the fundamental standards for customary length and mass measurements in the United States, but the Office of Weights and Measures had other standards for metric measurements.

67:, and the British standards of length and mass were also destroyed. "When the new imperial standards to replace them were completed in 1855, two copies of the yard and one copy of the 157:

agreement of July 1, 1959, Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States agreed that 1 yard = 0.9144 meter and that 1 avoirdupois pound =

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with the United States mint pound, which remained the national standard according to Barbrow and Judson. Hockert claims the UK pound replaced the mint pound.

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marked a decision to change the fundamental standards of length and mass of the United States from the customary standards based on those of

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Mendenhall, T. C. (1893). "Fundamental Standards of Length and Mass". Reprinted in Barbrow, Louis E. and Judson, Lewis V. (1976).

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kilogram. Therefore, the Mendenhall order amounted to a formal announcement of a change that had already occurred in practice.

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Address to the National Conference on Weights and Measures to Commemorate Their 100th Meeting

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A series of conferences in France between 1870 and 1875 led to the signing of the

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1893 official standardization for metre-based systems of measurement in the USA

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Another motivation for the order was that later that year, in August 1893, an

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Weights and measures standards of the United States: A brief history

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Washington D.C.: Superintendent of Documents. pp. 28–29.

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Bulletin No. 26 – Fundamental Standards of Length and Mass

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