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Testing of Measuring Tapes at the Bureau of Standards

Lewis Van Hagen Judson

出版	U.S. Government Printing Office, 1927
URL	http://books.google.com.hk/books?id=fRDpqSOd99wC&hl=&source=gbs_api
EBook	FULL_PUBLIC_DOMAIN

註釋

"The testing of the steel tapes used by the engineer and surveyor is done at the Bureau of Standards by comparison with a steel bench standard described in this paper. For the test of base-line tapes (usually made of invar with a length of 50 m) a much more elaborate apparatus is employed. This geodetic comparator is also described in detail. Results have shown that the length of 50 m invar base-line tapes can be determined with this apparatus to an accuracy such that the absolute errors of the certified result do not exceed 1 part in 1,000,000.