The Standard-Cell Comparator, a Specialized Potentiometer (Classic Reprint)

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Excerpt from The Standard-Cell Comparator, a Specialized PotentiometerIn recent years, however, the movement for the revision of the values of the electrical units has accentuated the demand for high precision and reliability in the intercomparison of primary standards. For example, it is desirable that the absolute measurements of current now under way in several national laboratories shall give results agreeing to 1 part in when reduced to a common basis. To do this, it is desirable that each laboratory should know the values of its resistance standards and standard cells, in terms of its inter national ohm and volt, to 1 part in This in turn means that it would be desirable to hold down fortuitous errors in the comparison of its working coils and cells with those representing its units to one or two units in the next decimal place, that is, to 1 or 2 parts in The extension of the accuracy of a class of measurements by an additional decimal place requires recourse to refinements and precautions previously regarded as uncalled for.This paper describes a special potentiometer which is used in the standard-cell laboratory of the Bureau of Standards. In its design and construction all available precautions and refinements have been utilized in order that it shall meet the exacting requirements of the new era in the history of the electrical units.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.