2002-07-31 In Great Britain the National Physical Laboratory made comparisons of the Imperial Standard Yard to the International Meter, which yielded differing values for the inch over the years. The 1922 value of 25.399956 mm per inch by was arbitrarily selected for use in calibrating the most precise measuring devices.
Could one assume correctly that the UKIP and the BWMA would not recognise the 25.4 mm definition, but continue to recognise the value of the inch based on the Imperial Standard Yard? Has anyone who has received information from their sources ever received a definitive answer from them on how they define the inch? John ----- Original Message ----- From: "Hillger, Don" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Wednesday, 2002-07-31 11:08 Subject: [USMA:21453] Re: Inch See: http://lamar.colostate.edu/~hillger/dykt.htm#inch -----Original Message----- From: Markus Kuhn [mailto:[EMAIL PROTECTED]] Sent: Wednesday, 2002 July 31 09:00 To: U.S. Metric Association Subject: [USMA:21452] Re: Inch Jim McCracken wrote on 2002-07-31 13:45 UTC: > The inch was not set at 25.4 millimeters centuries ago, but in the > 1950s. Was setting the inch to 25.6 mm or 25.0 mm seriously discussed as an option at this or at any earlier opportunity? Is the rationale for the choice of 25.4 mm for the inch documented somewhere in more details, as well as the history of previous definitions for the inch? When was the inch defined in the US for the first time with an accuracy of better then 0.1 mm? the practice of length measurement with a relative error below 1% surely must predate the 1950s significantly ... even centuries ... Markus -- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
