Metrication matters - Number 6 - 2003-11-10
Contents
1 Feedback - notes and comments from readers 2 Editorial 3 Oddities - measurements from around the world 4 Tips - pointers and methods to make your measurements easier. 5 Signs of the times 6 Quotations 7 Q&A - readers' questions and answers 8 Rule of thumb 9 History 10 Hidden metric
1 Feedback
Alan Cortie wrote to say: 'I am an ex-South African Mechanical engineer living and working in the USA. Since I grew up with, and used the Metric system exclusively during my professional career, you can only imagine how frustrated I have become having to start using WOMBAT (Ways of Measuring Badly in America Today - Ed.) ... However, I have been pestering everybody to start thinking in hard metric terms, a least for our export business ... I also insist that export drawings be dimensioned in metric only, and formatted for A series paper. A lot of complaints, but then you get the odd little compliment: "There are a lot fewer fasteners sizes to worry about ... we can cut inventory". Alan concluded by saying, 'I guess the USA needs a few more 'Metric Evangelists'.
David Shatto was kind enough to say, 'Pat, I've been reading your writing for a couple months now, and think it is very good. You have a humorous way of making metrication seem important to an ordinary person'.
2 Editorial
Some methods produce a smooth and rapid transition from old measures to metric; and others don't. One of the most successful ways to slow down metrication is to use 'soft conversions'. Soft conversions are used when the size of the measure remains the same while the name of the measure changes. As an example, think of the Imperial pint. In the UK, the government decided that an imperial pint (568.261 mL) would be rounded down to 568 mL; this is a 'soft conversion'. In Australia, the government decided that the same imperial pint would be rounded up to 600 mL; this is known as a 'hard conversion', and I have no idea why the words 'soft' and 'hard' were chosen. The net result of these actions was that Australia changed to metric volumes for shopping and for cooking with a smooth and rapid transition, and the UK is still struggling to make the same change after almost forty years of effort.
3 Oddities
In 1942, two nuclear physicists, C. P. Baker and H. G. Holloway, decided that, compared to hitting a sub-atomic particle, hitting a whole atomic nucleus was 'like hitting the side of a barn'. The name 'barn' has been used as jargon in nuclear physics for a small unit of area ever since. Another jargon word for a small area is a 'shed', which is roughly half the size of a 'barn' (ha ha – tee hee – very droll!). Had they used a metric unit such as square femtometres, the rest of us might have had a chance of checking a reference book to see what they were talking about.
4 Tips
Some years ago, I was talking to a group at the office of a publisher in the USA. We were checking a page that contained both text, and diagrams. As my original work was on an A4 page, I informed the group that I would enlarge the page so that we could all see the detail clearly. The group did not know what I was talking about, and I did not know that I was about to have a problem. The photocopier I tried to use for the enlargement had its two trays loaded with USA letter size and USA legal size papers making my planned enlargement, by doubling, impossible. I had assumed that the two trays would be loaded with A4 and A3 so that enlargements and reductions by doubles and halves could be readily done. I was completely unaware that the USA is now the only country in the world that does not readily have this simple technique available in every office with a photocopier.
5 Signs of the times
There are 10 kinds of people in the world – those that understand binary numbers and those who don't.
6 Quotation
'There indeed is one, and only one, metric system, (properly SI, Système International) - always the latest revision of the international standard that describes it. For engineers worldwide, the standard is ISO 1000 ... 'The standard describes a universal, international language of measurement. 'Essentially, all units created in modern times are metric in every country of the world, including the United States. The evolution is coordinated by an international committee in which the United States has participated since 1875.' Stan Jakuba, 'Mechanical Engineering USA' 2001 January.
7 Q&A
Q How will pilots know how high they are using metric measures?
A Pilots already know how to use air pressure to estimate their height, and they know that this is fairly accurate up to about 8500 metres. Almost all planes fly lower than 8500 metres; only international jumbo jets, military aircraft, and space shuttles fly higher. Before a pilot takes off, they check the air pressure with their control tower and calibrate their altimeter using this pressure. Since air pressure decreases regularly as they get higher – at about 12 pascals of pressure for each metre of height – a pilot can readily estimate height by watching the falling pressure gauge. Using the metric measure, of 12 pascals per metre (12 Pa/m), you can also readily change it – using metric prefixes – to 12 kilopascals per kilometre (12 kPa/km).
Q Can you recommend some good metric web sites?
A Point your search engine to one of these:
Bureau International des Poids et Mesures (BIPM) This is the official home of the International System of Units http://www.bipm.fr/
Metric Methods http://www.metricmethods.com/
SI Navigator http://metric1.org/
United Kingdom Metric Association http://www.ukma.org.uk/
USMA - US Metric Association http://lamar.colostate.edu/~hillger/
8 Rule of thumb
Anchoring your boat: – Allow 10 m of anchor line for each metre of depth you expect. If the water is 3 m deep, you will need 30 m of anchor line.
9 History
Accidents of history can have profound effects on the history of nations. In 1802, when William Lambton was about to begin his survey of India, the only measuring chain that he could readily obtain consisted of 40 links, each two feet and six inches long (~ 750 mm). However Lambton held the view that he 'would much have preferred that based on the decimal metre and its derivatives as already calculated by the French' (The Great Arc, John Keay, Harper Collins 2000). This meant that the whole of India was originally surveyed in feet and decimal feet, and this possibly influenced the Indian government decision to delay metrication until 1957.
10 Hidden metric
Running, walking and jogging shoes are designed, cut out, and constructed wholly in millimetres with a precision to the nearest tenth of a millimetre. This metric information is then hidden and the shoes are described to potential customers in 'size numbers'. For those who have not studied shoe sizes, a size number in shoes is the approximate length of a barley grain, and this has been the length of a 'shoe size' since the time of the Magna Carta in 1215.
Cheers,
Pat Naughtin Geelong, Australia
Pat Naughtin is a writer, speaker, editor, and publisher. Pat has written several books and he has edited and published many others. For example, Pat was the lead writer of a chapter of a chemical engineering encyclopedia, and recently he edited the measurement section for the Australian Government 'Style manual: for writers, editors and printers'. Pat has been recognised by the United States Metric Association as a Lifetime Certified Advanced Metrication Specialist.
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