John wrote "For the UK, there is more history and more obsolete units (but how many REALLY care about those old conversions)".
Most Brits are not aware of all the obsolete measurements that we have. I often hear - "Give him an inch and he will take a mile", or as some newspaper headlines have put it "Give him an inch and he will take 1.609 kilometres". The real saying was "Give him an inch and he will take an ell" - an ell, which ceased to be legal for trade in 1824, being 45 inches. _____ From: [email protected] [mailto:[email protected]] On Behalf Of John M. Steele Sent: 30 November 2009 13:15 To: U.S. Metric Association Subject: [USMA:46214] Re: content inch pound meter gram In snipping your remarks to the minimum, I have damaged your color coding. Sorry. The Otis approach is interesting. Given the usual "feelings" associated with color, I am surprised they didn't reverse red and blue. The point of a succesful metric conversion is that inch-pound design has no future. New inch-pound work should be red to raise a flag. (NASA should consider this.) On historical values of conversion factors, I would suggest that these changes are mostly very minor, and mostly of interest to metrology students. No need to teach to everybody. Historical precision was worse than modern precision and these differences (for the most part) would never matter in everyday life or modern interpretation of it. Even the much discussed International vs. Survey foot is only a difference of two parts per million, and can't matter in results having five or fewer significant digits (which is 99+% percent of all practical work). (If you go back to a Roman foot, the difference is a little bigger). Even in surveying, the Survey foot doesn't really matter in local surveying, only geodetic surveying, or in the State Plane coordinate system where millions of feet of false origin offset are added to basic data, introducing an error of 2 feet per million feet of false origin. The area where it does matter, and it is more cultural than historical is volume. The US has retained an obsolete gallon, and an obsolete bushel based on a second gallon rather than adopt the Imperial gallon. Except for that, there is no redefinition that is significant enough to teach anything but the modern value in the US or Australia, because no (essential) change has occurred within our history. For the UK, there is more history and more obsolete units (but how many REALLY care about those old conversions). --- On Sun, 11/29/09, Pat Naughtin <[email protected]> wrote: From: Pat Naughtin <[email protected]> Subject: [USMA:46213] Re: content inch pound meter gram To: "U.S. Metric Association" <[email protected]> Date: Sunday, November 29, 2009, 8:24 PM . I am a fan of the Otis Elevators approach where they identify all jobs as old or as new; they then identify each job as whether it is a new design and construction or a repair job to an existing elevator. Obviously the words, old-new, new-new, and new-old were immediately confusing so they used color codes: red and blue for existing foot-pound equipment and green and gold for new metric equipment. They then had four possibilities so that all work could have a color code: Red = repair of existing equipment in feet and pounds Blue = new work to be done in feet and pounds Green = new work to be done in metric Gold = repair of existing metric equipment in metric Obviously the company were planning for a transition period that might last 100 or more years (elevators are long-lasting) but most importantly nobody has to do any measurement conversions - in any direction. . . . . Agreed, keeping in mind that the current definition of an inch, a foot, and a pound are just that - current - they have changed over the years so any historical documents need to know the historical timing and the historical place where the old pre-metric measuring words came from.
