Abstract
WE have received a copy of a report on the progress of the metric system which was presented by Dr. Guillaume at the meeting of the fifth general conference on weights and measures held in Paris in October last. A previous report by Dr. Guillaume on the same subject was reviewed in these columns in 1908 (April 30). In the first part of the present work the author deals with the question of standards of measure and weight. As regards the use of vitreous quartz or silica for the construction of standards of length he points out that recent investigations tend to show that this material is unsuitable for the purpose, owing to inconstancy of length. A his-toriqal account is then given of the attempts made at the international bureau to find an appropriate material for the construction of standards of length for use in the laboratory, where the question of cost prohibits the employment of iridio-platinum. These efforts led to the important series of investigations with respect to the metro-logical properties of the alloys of nickel and steel, and to the discovery by Dr. Guillaume of the alloy of minimum expansion, now well known as “invar.” The feeble expansion of invar would render this alloy an ideal material for standards of precision were it not for its tendency to instability. In spite of this drawback, however, its use for secondary standards deserves careful consideration in cases where an accuracy of one part in a million is sufficient.
Article PDF
References
Les r cents Progrs du Systme m trique. By Ch. Ed. Guillaume . Pp. 118. (Paris: Gauthier-Villars, 1913.) Price 5 francs.
Rights and permissions
About this article
Cite this article
Recent Progress of the Metric System . Nature 93, 483 (1914). https://doi.org/10.1038/093483a0
Issue Date:
DOI: https://doi.org/10.1038/093483a0