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Metrication matters - Number 56 - 2008-01-10

Dear Subscriber,

I hope this email arrives when you are well, in good spirits, and that you feel that you are moving inevitably toward your complete upgrade to the metric system, in all aspects of your life.

Metrication matters is an on-line metrication newsletter for those actively involved, and for those with an interest in metrication matters.

Help a friend – if you know somebody else who can benefit from this newsletter, please forward it to them and suggest that they subscribe. If a friend passed on this newsletter to you, please check the details of the free subscription at the end.


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 – notes and comments from readers

Elizabeth Gentry from the Metric Program at NIST wrote to pass on some information about John Wilkins, the first person in the world to suggest a measuring system based on a 'universal measure'.

You can find references to John Wilkins at: http://www.buffalo.edu/news/9057 and at: http://english.montrealplus.ca/arts_entertainment/vegetable_rites_birds_in_the_moon/1081512

You can also see the full text of John Wilkins measurement system (with my translation from 17th Century English) at: http://www.metricationmatters.com/articles.html where you can choose either the:

John Wilkins translation full version or John Wilkins translation shorter version

Be aware that the full version is a large document that will take some time to download and that the shorter version only includes my translation. I suggest that you use the shorter version if a large download is a problem for you.

Bruce M. Herbertson III from Erwin in Tennessee wrote to say:

I love your newsletter and it has been very helpful in helping me educate those around me. Further more I like to print up copies of it and pass it out to my co-workers. They like to tease me a little but they are also of the mindset that it is ok to learn something new. Though as you and I know metric is nothing new.

As Bruce is working in the retail trade I was able to send him this reference to a customer service video that is doing the rounds in professional speaking circles. It is http://www.stservicemovie.com and although it takes a little while to load, be patient. It’s worth it.

2 Editorial

From 2008 January 1, goods vehicles and buses will have new speed limits on UK motorways. The speed limits in future will be 90 km/h and 100 km/h. Part of the reason for this change is that goods vehicles and buses that travel internationally are being required to have speed limiters fitted that conform to European standards.

This means that the UK current motorway speed limits of 60 mph (96 km/h) and 70 mph (113 km/h) for goods vehicles and buses will effectively be superseded.

But there is no change intended for other road users such as cars, motorbikes, and small vans. UK roads will now have two sets of speed limits on the same roads and at the same time.

When I want to reflect on how not to carry out a metrication program and to do it as badly as possible, I only need to seek guidance from the experience of the UK.

3 Oddities – measurements from around the world

Body mass index

Around 1840, Adolphe Quatelet developed the idea of a Body Mass Index (BMI) in an attempt to relate body mass and height of European people. In some places it is still called the Quatelet Index. Quatelet's BMI can be useful to let you know how your body mass compares with the average after allowing for your height.

BMI isn't as useful (without modification) for Asian people, children, short adults or highly muscular people, such as athletes, who can have a high BMI without being overweight.

Quatelet defined 'body mass index (BMI)' as mass in kilograms divided by your height squared; your BMI is then expressed in kilograms per square metre (kg/m2.

BMI values of 19 kg/m2 to 25 kg/m2 are considered normal, values outside this range — both lower and higher — can mean an increased risk of various diseases especially heart disease.

Here are some approximate BMI values.

Adults BMI kg/m2
Underweight Less than 19
Normal 19 – 25
Overweight 25 – 30
Obese More than 30

For better data you might refer to World Health Organisation (WHO) and Center for Disease Control (CDC) data about BMI from pages like http://www.halls.md/body-mass-index/overweight.htm

To work out your own body mass index (BMI) use bathroom scales to find your mass in kilograms and a metre stick or a tape to find your height in metres. Then use a calculator to enter:

Your body mass (kg) ÷ your height (m) ÷ your height (m) = your BMI (kg/m2)

That's not a misprint; you need to enter your height twice because this will then calculate your BMI in kilograms per square metre (kg/m2).

Now compare your BMI with some other notable people.

The heaviest woman ever recorded was Carol Yager (1960/1994) who is estimated to have reached a body mass of 725 kilograms. As her height was 1.7 metres this gave her a BMI of 250 kg/m2.

725 kilograms ÷ 1.7 metres ÷ 1.7 metres = 250.8 kg/m2

Robert Pershing Wadlow (1918/1940) is commonly believed to have been the tallest person ever. He was 2.72 metres tall and his body mass was 199 kilograms. This gave him a BMI of 27 kg/m2:

199 kilograms ÷ 2.72 metres ÷ 2.72 metres = 26.9 kg/m2

So Robert Pershing Wadlow was slightly overweight.

In contrast, the shortest person ever, Gul Mohammed (1957/1997), had a body mass of only 17 kilograms and he grew to a height of 0.57 metres. His BMI calculation is:

17 kg ÷ 0.57 m ÷ 0.57 m = 52.3 kg/m2

Gul Mohammed would be classified as grossly obese with his BMI of 52 kg/m2 even though his body mass was only 17 kilograms. However, it is more likely that Gul Mohammed would have been assessed on a children's BMI scale.

The women chosen as Playmates in Playboy magazine are taller than average at 1.68 metres and much lighter than average at 52 kilograms. This gives then an average BMI of 18.4 kg/m2 so they are unhealthily underweight.

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

This tip works pretty well in Australia, New Zealand, South Africa, the UK and the USA but I'm not sure about how it goes in Asia or South America.

Knowing that the average height of a male is about 1.75 metres and of a female is 1.65 metres you can quickly scan across the heights of the people at a party to find individuals who are of average height. You then estimate everyone else's height using their average height and by knowing that the width of a male fist is reasonably close to 100 millimetres or 0.1 metres. By the way, it is quite difficult to estimate people's height to much greater precision than about 50 millimetres; so if you are having a height guessing competition its best to restrict estimates in metres and to two decimal places that end with either a 0 or a 5.

5 Signs of the times

The fast trains between Brussels, London, and Paris have been upgraded to run at 300 kilometres per hour but lest those naughty kilometres catch on in the UK, the company that runs the trains, Eurostar, is actively promoting the new train's top speed as 186 mph!

6 Quotations

Usually when people are sad, they don't do anything. They just cry over their condition. But when they get angry, they bring about a change.
Malcolm X (1925/1965)

When great changes occur in history, when great principles are involved, as a rule the majority are wrong. The minority are right.
Eugene Victor Debs (1855/1926)

7 Q&A – readers' questions and answers

A word that seems to pop up frequently in discussions about the metric system is deprecated. What does deprecated mean?

The International System of Units (SI) has gone through a continuous improvement process since the Englishman, John Wilkins, first suggested it in 1668. For example the French improvements of the 1790s added the word metre (instead of Wilkins' universal measure) and the Dutchman, Van Swinden, developed the metric prefixes that are now at the heart of the metric system.

When new ideas have been added sometimes they have replaced old words or ideas; new things are included to replace old things. To preserve backward compatibility, the old ones are still accepted for a time. In an attempt to encourage users to adopt the new standards, the old features are deprecated, and this essentially means that although you can use the old feature, the recommendation is that you don't. For example, Ångstrom units were accepted for a time before the use of nanometres became more common.

8 Rule of thumb

Australia is a dry continent that often experiences prolonged droughts. After 10 years of drought here in Geelong we have quite severe water restrictions on when we can use garden hoses. Currently we are allowed to water our gardens with a hand-held hose for one hour on Tuesday and for another hour on Saturday.

This means that most of us recycle 'grey water' from our bathrooms, kitchens, and laundries using buckets. When we had one of our one-hour hose use sessions, I timed how long it took to fill a 10 litre bucket with our garden hose — it took one minute. Now I know that if I water a square metre of garden bed for one minute, I will use 10 litres of water and the soil will get the equivalent of 10 millimetres of rainfall. I also know that this means that when I run the hose for the full hour available I will use 600 litres of water on my garden.

9 History

Thomas Jefferson seems to have played a key role in the development of the metric system in France, especially with respect to its decimal nature, while he was ambassador there from 1785 to 1789.

As Jefferson was a professional surveyor before going into politics he had practical experience in the use of the chain invented by Edmund Gunter (1581/1626). Gunter's Chain was based on Simon Stevin's decimal arithmetic (published in 1585) in that it had 100 links to facilitate the use of decimal arithmetic in making relatively complex trigonometric calculations for triangulation studies in land surveying.

Thomas Jefferson and George Washington had already agreed on a decimal currency for the USA and both were keen promoters of decimal ideas. George Washington had also been a surveyor before he entered politics. In promoting their decimal ideas both in the USA and in France, Jefferson and Washington were most ably supported by Benjamin Franklin.

To see these events in their historical context go to: http://www.metricationmatters.com/docs/MetricationTimeline.pdf and search for Franklin, Gunter, Jefferson, or Washington.

10 Hidden metric

A friend was playing with his Tom-Tom global positioning system (GPS) that he had set to using metric measures in England. He wrote:

One thing that becomes blatantly clear though is that there is more metric on our roads than meets the eye. We all know about the 'yards' signs, which are really 'metres' in disguise, but I've noticed quite often that signs for 1/3 mile and 2/3 mile are often placed at 500 m and 1000 m intervals.


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.

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