Primary Standards

Standards of physical measurement, a scattered assortment of artificially defined constants that has been a familiar source of commercial and conversational frustration, were in their beginnings invented for reasons of local convenience and have had essentially only one other thing in common: they cannot be reproduced independently. The uniformity requirements of industrial practice which called for the standardizing of many things, measurement among them, led inevitably in many countries to the establishing of great national laboratories equipped to reach ever finer and more accurate means of measurement. Elaborate procedures were developed to insure that standards remain the same from one time to another, and in the case of the prototype meter and kilogram preserved at Sèvres, France, for instance, as well as with duplicates in the possession of other nations, great care amounting to the most elegant incubator treatment has been exercised to avoid even the most minor variations which might be induced by changes in temperature or other external conditions.

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