I knew it would have that effect. I'm certainly not advocating centimeters ONLY. As an engineer, I fully agree that all professional societies advocate the use of millimeters only on engineering drawings (to at least 99.999 m), and that only they are used in industrial manufacturing. (I disagree that the approach avoids the need for decimal fractions; in automotive, many dimensions are to 0.1 mm and some to 0.01 mm). Also, what little I know about Federal construction guidelines (the only metric construction in the US) says they use millimeters in plans.
However, I think both need to be taught. For measuring people, clothing, plants and animals, snow, etc., millimeter resolution is often excessive, and the practice has been to work to the centimeter. I would probably agree that the centimeter should NEVER be used with a fraction, vulgar or decimal. If an integer centimeter isn't good enough, then centimeters aren't good enough, use millimeters. Alternatively, I could probably live with no centimeters if the rule of 1000 allowed numbers down to 0.01 m, where the number was limited to two decimal precision. (it's not really a rule anyway, only a guideline) I don't think the choice makes or breaks metrication (lack of political will is COMPLETELY effective, however) or that the US particularly tried to adopt the centimeter. All metricated industries use the millimeter internally, they may use the centimeter in promotional material, and a few other fields use the centimeter. ________________________________ From: Stephen Humphreys <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Sun, January 31, 2010 4:48:38 PM Subject: [USMA:46534] Re: Centimeters vs inches Well you *DID* ask for it John! ;-) ________________________________ From: [email protected] To: [email protected] Subject: [USMA:46533] Re: Centimeters vs inches Date: Mon, 1 Feb 2010 08:02:07 +1100 On 2010/01/31, at 23:14 , John M. Steele wrote: Pat will love this story: >http://www.newschief.com/article/20100131/NEWS/1315040/1009/LIVING?p=1&tc=pg > >Wife measures in inches at home, and in centimeters in store. Great line, "I >just thought they were small inches." > >It ends questioning why we use the ruler of the ruler we overthrew in 1776 and >advocates the US going metric. Dear John, Great story and well told. However I would like to point out something about my attitude to centimetres. Some years ago I observed that metrication transitions using centimetres went much more slowly than metrication transitions using millimetres. Transitions using millimetres were smooth, rapid, and complete while transitions using centimetres were (and are still) slow, partial, and so riddled with bitter fighting that they seem to be endless. This puzzled me because I simply didn't understand why this should be so, and in particular why the difference should be so dramatic. As examples, the Australian building and construction industries chose to use millimetres for their metrication transition and they were all done with the process in about two years; the textile industries chose to use centimetres and they are still struggling with their metrication transition after 40 years with no clear end in sight. These were personal observations as I worked in both of these industries. Sadly, very sadly, our primary (elementary) and high school teachers in Australia also chose to use the centimetre based approach. We now have the situation where children leave school to (say) begin a construction job and they have to begin to learn about how to plan, cut, fix, and estimate using millimetres. I overheard a discussion between an old carpenter and his new trainee when the youngster reported a measurement in centimetres; the old man scornfully commented, 'What's that cm thing, we call cm a "curtain measure" around here, and we don't ever use them.' I have long been an admirer of the policy of the Australian building industry for its simplicity and for its clarity. The Australian Building and Construction Advisory Committee policy was: The metric units for linear measurement in building and construction will be the metre (m)and the millimetre (mm), with the kilometre (km)being used where required. This will apply to all sectors of the industry, and the centimetre (cm)shall not be used. … the centimetreshould not be used in any calculation and it should never be written down. *Standards Association of Australia 'Metric Handbook, Metric Conversion in Building and Construction 1972 With these words the Australian Building and Construction Advisory Committee effectively banished centimetres from the building trades in Australia, with the result that metric conversion in these trades was smooth, rapid, and completed in about two years. Most other trades followed their example, and subsequently followed their successful metrication program. Broadly speaking, about 85 % of Australians work in millimetre based activities; about 10 % use centimetres; and the remaining 5 % rarely measure at all. About that time, I decided to investigate this issue and sought the support of the knowledgeable people who subscribe to the USMA maillist – the long paper in the form of a discussion at http://www.metricationmatters.com/docs/centimetresORmillimetres.pdf is the result of this consultation process. During the years that I have been watching the differences between centimetre metrication transitions and millimetre metrication transitions I have formed various views as to why there are such notable differences. As an example, my first idea, which I have now rejected, was that centimetres were chosen by occupations traditionally taken by women and that millimetres were chosen in traditional men's activities. Currently I think that the choice of millimetres has profound advantages over centimetres because it favors the almost exclusive use of whole numbers within a work environment – there are no vulgar or common fractions and there are no decimal fractions on any building sites in Australia because all dimensions are in millimetres. This is also true for building sites in India, New Zealand, and South Africa. My goal at the present time is to try to inform people who have not yet made their choice as to whether to use centimetres or millimetres to choose the better approach of using millimetres. I believe that the failure of the metrication process in the USA in the 1970s can largely be traced to the choice of centimetres because the process worked so slowly that the participants considered that, after a few years of trying, the entire process had failed. The truth is that the centimetre based metrication transition started in the 1970s will now continue until metrication is completed – this is inevitable once the process has begun – but it will be slow, it will be costly, and it will be painful. So far, like centimetre based metrication in Australia, it has taken 40 years and there is no clear end in sight. It's hard to predict how long a centimetre based transition might take, but it is probably reasonable, as a best guess, to suggest 200 years as a working figure. The alternative is to choose millimetres and have done with the whole metrication transition process by about 2012. As a 'Rule of Thumb' you could think of 2 years for a metrication transition using millimetres and 200 years for a metrication transition using centimetres. Cheers, Pat Naughtin Author of the ebook, Metrication Leaders Guide, that you can obtain from http://metricationmatters.com/MetricationLeadersGuideInfo.html PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/ to subscribe. ________________________________ Not got a Hotmail account? Sign-up now - Free
