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metrication matters - Number 84 - 2010-05-10

Metrication matters is an on-line metrication newsletter for those actively involved, and for those with an interest in metrication matters. We assume as we write the Metrication matters newsletter that our readers are Metrication leaders in their communities.

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Dear Subscriber,


1 Editorial 2 Feedback - notes and comments from readers 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 Editorial

To understand how things change can provide very powerful tools when you are planning a metrication upgrade. Chip and Dan Heath have released a new book about how things change – it is called:

'Switch: How to Change Things When Change Is Hard'.

In the Wall Street Journal the Heath's book is reviewed in an article entitled, 'Old Habits Die Hard', see http://online.wsj.com/article/SB10001424052748703315004575073452332633146.html?mod=WSJ_LifeStyle_Lifestyle_5

The author of the review is Christopher F. Chabris a psychology professor at Union College in Schenectady, N.Y. who writes:

The Heath brothers think that the sciences of human behavior can provide us with tools for making changes in our lives—tools that are more effective than "willpower," "leadership" and other easier-said-than-done solutions. The authors explain a couple of fundamental principles of psychology and distill from them concise recommendations for bringing about change. They convey their ideas primarily through stories about people, companies and organizations that have successfully undertaken major realignments, sometimes in the face of long odds.
The first psychological principle that "Switch" exploits is the fact that our brains do not contain a single, general-purpose decision-making unit. Instead, we have two systems: one that is rational, analytical and slow to act; and another that is emotional, impulsive and prone to form and follow habits.
The other major psychological principle at work in "Switch" is the idea that, more than we suspect, outside influences control our actions. All the good intentions and native intelligence in the world can be defeated if the setting is not right. But small changes to one's environment can have a big effect.

I highly recommend 'Switch: How to Change Things When Change Is Hard' to you as a valuable resource to help formulate your thinking about the metrication upgrades where you are involved. I also recommend a previous book by Chip and Dan Heath called 'Made to Stick: Why Some Ideas Survive and Others Die' as very relevant to metrication planning and implementation. This second book has been summarised like this:

Mark Twain once observed, “A lie can get halfway around the world before the truth can even get its boots on.” His observation rings true: Urban legends, conspiracy theories, and bogus public-health scares circulate effortlessly. Meanwhile, people with important ideas–business people, teachers, politicians, journalists, and others–struggle to make their ideas “stick.” Why do some ideas thrive while others die? And how do we improve the chances of worthy ideas? In Made to Stick, accomplished educators and idea collectors Chip and Dan Heath tackle head-on these vexing questions. Inside, the brothers Heath reveal the anatomy of ideas that stick and explain ways to make ideas stickier, such as applying the “human scale principle,” using the “Velcro Theory of Memory,” and creating “curiosity gaps.” In this indispensable guide, we discover that sticky messages of all kinds–from the infamous “kidney theft ring” hoax to a coach’s lessons on sportsmanship to a vision for a new product at Sony–draw their power from the same six traits. Made to Stick is a book that will transform the way you communicate ideas. It’s a fast-paced tour of success stories (and failures)–the Nobel Prize-winning scientist who drank a glass of bacteria to prove a point about stomach ulcers; the charities who make use of “the Mother Teresa Effect”; the elementary-school teacher whose simulation actually prevented racial prejudice. Provocative, eye-opening, and often surprisingly funny, Made to Stick shows us the vital principles of winning ideas–and tells us how we can apply these rules to making our own messages stick.

2 Feedback

In the early morning hours of April 14, I was interviewed on radio for the Australian Broadcasting Commission (ABC). This was broadcast all over Australia to all states and territories. We did it as a live interview so that we could receive talk-back. You can access the interview here: http://www.abc.net.au/overnights/stories/s2880252.htm?site=melbourne

The following day I received many comments including this one from a primary school teacher. The teacher's text is in bold italics and I have interspersed some remarks.

On 2010-04-14, at 12:19 , G Sproats wrote:


Last night (or rather, early this morning on ABC Local Radio with Trevor Chappell) I listened to your talk and enjoyed it.

Dear Grant,

Thank you for your kind remark.

One comment you made that particularly interested me was on body measurements; viz. that your elbow to fingertip was 50 cm.

No, I used the length 500 millimetres from elbow to fingertip (Historically this has been called a 'cubit'). I very, very, rarely use the metric system unit, centimetre, even though I know that it is a legitimate part of the International System of Units (SI). I have only used centimetres to estimate the volume of three things in the last 40 years: froth on a head of beer, the volume of a small fish tank, and the size of a stool of sheep faeces when I was researching digestion!

I avoid centimetres because I have observed, after 40 years of studying the metrication process, that using centimetres simply slows down the whole process of changing from old pre-metric measuring words to the modern metric system dramatically. This is possibly largely due to the fact that choosing millimetres means you never have to use fractions – any kind of fractions become obsolete – this includes decimal fractions and also common or vulgar fractions. See the article at /docs/centimetresORmillimetres.pdf for extensive discussion of this issue. I would be delighted if you could add any further thoughts that I could include in this discussion – your thoughts would be included under the teacher-librarian classification. I would be especially delighted if you could point me to any example where a metrication transition to the metric system using centimetres has been simple, smooth, economical, and above all, FAST!

I’ve made an analysis of the various occupations in Australia, and the length units they prefer to use. From 117 occupations listed by the Australian Bureau of Statistics, the results are as follows:

millimetre users – 96 occupations

Aircraft maintenance engineer (avionics), aircraft maintenance engineer (mechanical), aircraft maintenance engineer (structures), automotive electrician, binder and finisher, blacksmith, boat builder and repairer, bricklayer, broadcast transmitter operator, business machine mechanic, cabinetmaker, cable jointer, carpenter, carpenter and joiner, communications linesperson, computing support technician, dental technician, draftsperson, drainer, electrical engineering technician, electrical power line tradesperson, electrician (special class), electronic engineering technician, electronic equipment tradesperson, electronic instrument tradesperson (special class), electroplater, engraver, farrier, fibrous plasterer, fitter, flat glass tradesperson, floor finisher, furniture finisher, furniture upholsterer, gasfitter, gem cuter and polisher, general communications tradesperson, general electrician, general electronic instrument tradesperson, general fabrication engineering tradesperson, general gardener, general mechanical engineering tradesperson, general plumber, glass blower, graphic pre-press tradesperson, greenkeeper, gunsmith, jeweller, joiner, landscape gardener, leather goods maker, lift mechanic, locksmith, mechanical engineering technician, mechanical services and air conditioning plumber, medical grade shoemaker, metal casting tradesperson, metal fabricator (boilermaker), metal machinist (first class), metal polisher, motor mechanic, optical mechanic, painter and decorator, panel beater, patternmaker-grader (clothing), piano maker, piano tuner, precision instrument maker and repairer, pressure welder, printing machinist, refrigeration and air conditioning mechanic, roof plumber, roof slater and tiler, saw maker and repairer, screen printer, sheet metal worker (first class), shipwright, shoemaker, sign writer, small offset printer, solid plasterer, stonemason, surveyor, textile, clothing or footwear mechanic, toolmaker, upholsterers and bedding tradespersons, tree surgeon, vehicle body maker, vehicle painter, vehicle trimmer, wall and floor tiler, watch and clock maker and repairer, welder (first class), wood tradesperson, and wood turner.

centimetre and inch users – 12 occupations

Apparel cutter, baker, canvas goods maker, chef, cook, dressmaker, general clothing tradesperson, nursery person, pastry cook, picture framer, sail maker, and tailor.

7 occupations where length measures are relatively unimportant

Butcher, buttermaker or cheesemaker, confectioner, ladies hairdresser, smallgoods maker, men's hairdresser, and meat tradespersons.

Summary of occupations

96 occupations use millimetres 83.5 %

12 occupations use a more or less random collection of centimetres, feet, inches, yards and other old pre-metric measuring words 10.4 %

7 occupations use length measures but they are relatively unimportant 6.1 %

Given that more than 80 % of trades, crafts, and professions prefer millimetres, it seems to me that there is a very high probability that your students will use millimetres predominantly during their working lives. I have been involved in many training programs where Australian students, after leaving school, are using millimetres for the first time in their lives. One of our main tasks is to un-teach all the centimetres stuff taught by teachers in schools. Recently, I heard a senior trades person berate a junior apprentice for measuring in centimetres; he said "centimetres – don't you know that c - m stands for 'children's measures' and we don't use them on any of our jobs – next time tell me in millimetres."

I also consider that it’s best to keep it simple, and to only teach the four prefixes: micro, milli, kilo, and mega in primary schools. The other 16 metric prefixes need only be learned by senior students who are studying sciences, especially subjects like astronomy and physics.

You might also notice that nobody regularly uses decimetres, decametres or hectometres in Australia at all. Except for the non-preferred centimetre, the prefixes centi, deci, deca, and hecto are essentially not used in Australian daily activities in any trade, craft, or profession and maybe they shouldn't be taught in any detail – simply make mention of their existence. In the rare cases where these prefixes are used, and these are rapidly becoming rarer, these odd prefixes can soon be learnt. Certainly students shouldn't be bothered with converting to or from them.

I have seen 200 plumbers change to the metric system in a single day using millimetres. I also regularly observe metrication attempts that have lasted for 100 years or more using centimetres. A classic example is the Kodak company who changed completely to millimetres for photographic negative materials in 1904 and are still struggling with their phonographic paper division in 2010. And this comes at an enormous cost to the company – probably about 10 % of turnover every year since 1904 – and to the nation of the USA as a whole – see /docs/CostOfNonMetrication.pdf

As a Primary school teacher (Carinya Christian School, Tamworth) I am keen to know of more facts about our bodies. I have taught my class information like:

Our foot fits from wrist to elbow.

This is too variable and of no immediate use to the student as it is of no obvious practical use.

Try these 'handy' measurements:

  • width of little fingernail (mine is 10 mm)

  • width of all fingers (mine are 20 mm except for my little finger; it is 15 mm)

  • width of hand across the knuckles (mine is 100 mm)

  • hand span from thumb tip to little finger tip (mine is 240 mm)

  • length of 'cubit' from elbow to tip of long finger (as you know, mine is 500 mm so when I put my two longest fingers touching at their tips, then my elbows spread apart are 1000 millimetres or 1 metre)

Have students measure the length of their own shoes in millimetres then use this information to estimate unknown lengths you have marked out on the floor of a classroom or outside. Repeat this using the student's own normal walking pace – you can do this by direct measurement or by counting how many steps a student needs to cover a known distance (say) 2000 millimetres inside or 10 000 millimetres outside and then finding their own pace length in millimetres by division (Notice how easy this is when there are no fractions to consider!).

Our nose fits from thumb to tip of forefinger (when they are pressed side-by-side)

When do you ever use your nose for measuring – forget it!

Left shoulder to fingers (curled in 90 degrees) on right hand of outstretched arm = 1m

Make sure that students know that this varies widely from person to person and from time to time even for people who are fully grown.

Arm span = height (although I heard your disclaimer on that one!)

Put this as a theory to your class and ask them to check it out using the height and arm span of their own bodies – use a whiteboard for arm stretching measurements. Also do this first thing in the morning and last thing in the afternoon – most people lose height through the course of each day as their inter-as their vertebral discs become compressed – variations up to 38 millimetres during a day have been measured.

A final one I've learnt years ago but cannot remember exactly is that the circumference of our upper thigh = our head? Or from knee to hip = head circumference?? Do you have any more interesting facts like these to do with measurement/ratios on our bodies?

Read the passage from Gulliver's Travels where the good people of Lilliput make a set of clothes for (the giant - to them) Gulliver. I don't know if you have read Gulliver's Travels' recently, but there is a delightful description of how the Lilliputians made a shirt and suit for Gulliver requiring only the measure around his thumb — the rest of the dimensions needed for the design and making of the clothes were then calculated from that single measurement. You might like to explore this by having students measure around their thumb in millimetres, then doubling this to see how it fits around their wrist. Next double the wrist measurement to get the neck size (also the distance around the leg just above the knee) and then doubling this to get the waist measurement. Notice how doing this in millimetres avoids all fractions. Along the way you might notice that from elbow to wrist is about a hand-span, and that from hip to knee is about 2 hand-spans as is the distance from your knee to your ankle. Other observations might be that the distance from shoulder to shoulder is close to the length of your cubit (for me this is 500 mm).

The kids love being able to put mathematical reasoning into use - especially if it involves their bodies!

Use something like face paint to mark where a metre comes to on their bodies (on me it is at the point of my hip bone)

Please let me know via this email, plus any additional facts and figures that I can share with my class (Year 4).

A little later the teacher responded with this short email:


Thank you so much for your rapid response. I am here at school preparing my program for Maths in term 2 and will eagerly use many of the applications that you have suggested. I will try to let you know (for your information) how my class goes and any exciting new developments we discover.

Again, thanks.


PS I usually only speak in mm when talking about anything to do with lengths around my workshop at home (which the tradesmen and hardware shop assistants are glad of me doing!) So sorry that I slipped into using the dreaded 'children's measure'. I'll see that I emphasise the importance of using mm above cm to the class.

When I wrote to Grant to ask his permission to use his name in this article and to ask when children moved to 'joined up writing' as I thought that this might be a good time to make a transition from 'cm' to 'mm' (that is from 'children's measures' to 'mature measures'). Grant replied:


Thanks for your enquiry re. permission to use my name. My answer is that of course you may use it. I work for Carinya Christian School -Tamworth.

Per your second question, children are required to move to "joined up writing"in Year 4 (the Year I am currently teaching.) I agree that this would be a good time to emphasise the use of millimetres as standard unit for all measurements (still noting, though, the other possible units such as centimetres, metres and kilometres.) We are not using decametres at all.

Thanks again.

Grant Sproats

You can access the interview that started this correspondence on ABC radio here: http://www.abc.net.au/overnights/stories/s2880252.htm?site=melbourne but don't leave it for too long as they usually only leave podcasts on their web page for a few weeks.

3 Oddities

A quote from the UK that I found at http://ourstory.com/thread.html?t=456900 reads:

According to the 1988 Weights and Measures (Intoxicating Liquor) Order, serving draught beer and cider in litres is illegal.

I find this exceedingly odd given that the metric system was invented in the UK. See /who-invented-the-metric-system.html

4 Tips – pointers and methods to make your measurements easier.

Making a jelly as a dessert seems simple enough so who would have thought that it is beset with non-existent international standards. When one of Australia's leading cooking writers, Stephanie Alexander, wanted to prepare some sweets she was soon in trouble. She wrote:

This is where the plot thickens (excuse the pun!) and we must get our heads around the concept of "bloom". Bloom is the measure of the gelling power of gelatine. The weight of the sheet is NOT the measure of its gelling power. Just because one leaf weighs 5g and another weighs 1.6g, one cannot assume that the heavier sheet will set the same amount of liquid three times more solidly than the lighter leaf.

And this was before she became angry. Later she added:

The reality seem to be that different firms import different grades, sometimes because their clients are used to a particular kind, sometimes to simplify distribution, or for less discernible reasons. All acknowledge that there is no central marketing body, no information to help the layman and no standard conversion between different grades of leaf gelatine or between leaf gelatine and powder. (Manufacturers of leaf gelatine are, of course, not that interested in advising customers how to convert recipes that use leaf gelatine to powdered gelatine.)

One person I consulted told me she had always used one heaped half-teaspoon per leaf.

This works well if using a Dr Oetker sheet, or a Gelita Gold sheet, but does not work if using Titanium. Silver, meanwhile, sets to the same strength as Titanium, even though both the weight of the sheet and the bloom values are different.

Confused? Of course you are! The confusion is an unacknowledged nightmare for food writers and their readers.

You can read the complete article at http://www.theage.com.au/articles/2004/04/19/1082326141351.html

5 Signs of the times

Metric signs were fitted to the I-19 highway in Arizona in the 1970s and they're still there but they are being threatened with replacement. See http://lamar.colostate.edu/~hillger/signs/i-19-tucson.html

6 Quotation

If we are to achieve results never before accomplished, we must expect to employ methods never before attempted.

Francis Bacon

7 Q&A


How do you choose the best thickness of card when you are getting business cards printed? When I went to a printer they chatted to me about poundage and pointage – I have to admit that I didn't understand a word they were saying.


In the metric system card, in fact all kinds of paper, are measured using the metric system unit, grams per square metre. The international symbol for this is g/m2. Personally I prefer to use at least 250 g/m2 if the card is coated with a clear lamination on one side or 300 g/m2 if the card is coated on both sides.

8 Rule of thumb

An old brewer's rule of thumb suggested that a brewer could find the right temperature to 'pitch' the yeast by placing his thumb in the 'wort' as it was cooling after being boiled. When the brewer could comfortably keep his thumb in the wort it was time for the yeast to be added. However, modern theory suggests that this might be a little too high – when I brewed beer I waited until the temperature went below 24 °C – and I knew this because I used a thermometer.

9 History

A pascal of pressure is equal to one newton of force applied to one square metre of surface. The pascal was named after Blaise Pascal (1623-1662) who was the first person to measure differences in altitude with a barometer. The 14th Conference Générale de Poids et Mesures (CGPM) officially adopted the name pascal for the SI unit, newton per square metre, in 1971.

10 Hidden metric

A friend in the USA wrote to tell me about an exchange he had in a supermarket:

Standing next in line to us was a youngish woman with her teenage daughter. We exchanged a little repartee and I made some comment about metric quantities. She told me she didn't "understand metrics."

I wrote back to my friend to say:

This is a woman who has just driven to the supermarket in a car that was designed and manufactured completely in metric units. She is holding a (say) leather purse that was tanned using solely metric units for its tanning (e.g. moles of tannage); she is probably holding a plastic carry bag that was evaluated in its quality control to the nearest micrometre; her clothing was designed from fibres that were also evaluated using micrometres; at birth her daughter's body mass was determined in grams in case she needed any emergency treatments that would be administered in milligrams or micrograms of pharmaceuticals; all the money in her purse was made from minerals that were mined (in tonnes and kilograms), treated with chemicals (in kilograms and moles), and alloyed and minted to tolerances of micrograms and micrometres.

Without metric measures, this women would be standing at the deli counter without any money, she would have no purse and no carry bag; she and her daughter would be naked; and they would have to walk home!

Pat Naughtin

Geelong Australia

Pat Naughtin is a writer, speaker, editor, and publisher. Pat has written several books and has edited and published many others. For example, Pat has written 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.

Pat is the author of the e-book, Metrication Leaders Guide, that you can obtain from /MetricationLeadersGuideInfo.html

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Dear Pat

First let me congratulate you on the wonderful wealth of information in “Metrication Leaders Guide”. I have been able to find valuable information on metrication in it. My country SAINT LUCIA in the West Indies, is going metric and I am the Coordinator of the St. Lucia Metrication Secretariat. ...

Thank you for sharing that wealth of information that you gathered over your years of experience dealing with metrication. Your book is invaluable!

Judy Rene

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