20 Degrees C -- A Short History of the Standard Reference Temperature for Industrial Dimensional Measurements : A Reprint from the ¿Journal of Research of the NIST

One of the basic principles of dimensional metrology is that a part dimension changes with temperature because of thermal expansion. Since 1931 industrial lengths have been defined as the size at 20 degrees C. This paper discusses the variety of standard temperatures that were in use before that date, the efforts of C. E. Johansson to meet these variations, & the effort by the Nat. Bureau of Standards to bring the U.S. to the eventual world standard. Illustrations.Doiron, Ted is the author of '20 Degrees C -- A Short History of the Standard Reference Temperature for Industrial Dimensional Measurements : A Reprint from the ¿Journal of Research of the NIST', published 2007 under ISBN 9781422314685 and ISBN 1422314685.