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Metrication matters - Number 73 - 2009-06-10

Dear Subscriber,

Metrication matters is an on-line metrication newsletter for you:

  • if you are actively involved in a metrication upgrade,
  • if you are planning a metrication upgrade, or
  • if you have a general interst in the metrication process.

Help a friend if you know somebody else who can benefit from this newsletter, please forward this newsletter 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.

You can read all previous issues at /newsletter when you scroll to the bottom of the page. You will also find useful resources for your inevitable metrication upgrade from the Metrication matters web page at http://www.metrictionmatters.com.htm


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 Young, from the UK, wrote to say:

Hi Pat
I don't know if you are aware but manufacturers of beer are now selling pint cans of lager, but because here in the UK it is illegal to sell canned alcoholic drinks in imperial units they are labelling them 568 ml.
This country is rapidly going into reverse!
Best wishes. Keep up the good work.
Alan Young

Barbara Hall, from Skipton, wrote to say:

Hi Pat,
Only the first part of MM arrived. Not sure why.

I was able to supply Barbara with another copy of Metrication matters 72, so please let me know if this ever happens to you so I can investigate.

2 Editorial

NASA leads to the rear

It's sad to see when apparently sane and intelligent people do truly stupid things. This month I heard that NASA, the USA space agency, decided to go back to old American measures for a major space program, I didn't know whether to laugh at such stupidity, or to cry for the obvious implications for safety in space.

NASA already knows that old measures are not suitable for space travel. In 1999, they lost a complete space mission, the Mars Climate Orbiter, because some NASA people were working in metric units and one of their suppliers was working in feet, inches, pounds, and ounces. The spacecraft took almost a year to travel to Mars, and then it burnt up in the Martian atmosphere.

The loss of the Mars Climate Orbiter cost $327 million USD ($407 AUD) and achieved no scientific results it was a 100 % write-off. NASA now proposes to revert to old pre-metric measures for the Constellation Program that is planned to replace the Space Shuttle that currently takes astronauts to and from the International Space Station.

The decision made by NASA this week goes against NASA's measurement policy, and also against the policy of the USA federal government.

NASA policy says:

"Following the loss of the Mars Climate Orbiter, the NASA Office of Inspector General initiated a review of the Agency's use of the metric system. By law and policy, the metric system is the preferred system of measurement within NASA."

The USA federal government law is:

"This legislation amended the Metric Conversion Act of 1975 and designates the metric system as the Preferred system of weights and measures for United States trade and commerce."

As we know the Space Shuttles always had real live astronauts on board. This adds another level of risk to the NASA decision to use old pre-metric measuring words.

Not only is the spacecraft at risk, now the astronauts' lives are also in jeopardy.

But the situation is even more complex that this. The new NASA Constellation Program is intended to meet up at the International Space Station with Russian and European Space Agency spacecraft both of wnich design, build, and operate solely in metric units. The International Space Station is run cooperatively between the three space agencies.

Presumably, if NASA is managing operations on one day, all astronauts will measure and communicate in ounces and inches, and the next day, when the Europeans or the Russians are in control, they will all astronauts will have to use millimetres and grams.

However, all is not smooth sailing for NASA's change. Many members of the United States Metric Association (USMA) are actively opposed to the NASA decision. As an example, one writer to the USMA mail list, Jason Darfus, put it like this:

I am positively ashamed that this country continues to fumble and bumble along one step forward, two steps back when it comes to changing to the internationally recognized system of units we call the metric system! How much more inefficiency and loss of capital do we have to endure before my government decides to fulfil its responsibility to establish weights and measures, as specified in the Constitution (of 1787), and finally adopt the metric measurement system? The USA and two other third world countries are the only three that have yet to do this.

I would like to wish NASA well with their Constellation Program but history clearly does not favor their chances of success.

3 Oddities

In a discussion on the United States Metric Association (USMA) mail list Han Maenen of the Netherlands and Bill Hooper from Florida discussed the persistence of some old pre-metric measuring words in their separate languages (Dutch and English):

Han wrote:
In the Netherlands a folding measuring stick is called a 'duimstok', which is 'inch stick' in English. I have a wooden duimstok or inch stick with centimetres only on it. I just avoid measuring instruments with dual units like the plague.

Bill replied:
I frequently found students new to metric referring to the measuring sticks in my physics labs as "metre long yard sticks". I also had double metre sticks in my lab (200 cm long) and heard students call them "two-metre yard sticks". The phrase "yard stick" in my experience (20th century USA) has come to mean a wooden stick for measuring lengths, regardless of how long it is.

Han also noted:
Of course, the distance to Sixmilebridge near Limerick in Ireland is always given in km on road signs: 'Sixmilebridge 10 km'.
There is a small place in Ireland called Inch.

And Bill responded:
There is also a small town named Pound in the far western part of the US state of Virginia.

You can get in touch with the USMA mail list at: http://lamar.colostate.edu/~hillger/listserv.htm

4 Tips pointers and methods to make your measurements easier.

My wife, Wendy Pomroy, found this tip for cooking pasta in an Australian magazine.

Cooking pasta is easy if you use the 1000 10 100 rule.

You start with 1000 millilitres (1 litre) of water in a pot; you then add 10 grams of salt and bring the salted water to the boil; and finally you add 100 grams of pasta. Cook the pasta for 2 minutes less than it says on the pasta packet, and then test to see if it is 'al dente'. Strain from the water when the pasta is perfect!

Wendy also discovered this note in The Reach of a Chef by Michael Ruhlman:

... would be dropped into a specially built water bath kept at 51.5 degrees Celsius (about 125 degrees Fahrenheit); as in all Keller's kitchens, everything here is measured in metrics, a far more practical system for cooking).

Note: Thomas Keller is the chef and owner of two of the most highly regarded restaurants in the USA: the French Laundry in Yountville, Calif., and Per Se in New York. He has been hailed as one of the best chefs in the world.

To explore metric cooking further you can download, Metric cooking with confidence from /docs/MetricCookingWithConfidence.pdf

5 Signs of the times

Gradually, the international standard date format (ISO 8601) that is in the form yyyymmdd or yyyy-mm-dd is becoming more popular. I suspect that dates in the ISO 8601 format is favored as soon as people realise how useful this format is in any computer environment.

As an example, I store drafts of the Metrication matters newsletter (like this one for this month) as: mm-newsletter-2009-06 and I don't need to have the day on the end because the Metrication matters newsletter is sent on the 10th day of each month.

The ISO 8601 format also means that I can sort all of the back copies in date order by sorting any list either alphabetically or by date simply and easily.

You can see the full list of the previous Metrication matters newsletters in date order at the bottom of /newsletter.html

Stan Doore, from Washington DC, tells me that the ISO yyyymmdd date format has been used in US Government weather archive records since the 1800s when the Hollerith punched card was invented for storing weather observations. Stan later added this information:
On Sunday, a Fox News Channel clip from Prague television showed the date format of the clip as (yyyy.mm.dd) i.e. 2009.04.05
Isn't it interesting that others are moving to the ISO standard date format?
Stan Doore

John M. Steele commented:
The order yyyymmdd is used a lot with various separators in computers and digital media files as alphabetic sorting rules sort into data order.
In ISO8601, the only allowable separator in date format is a hyphen, or no separator, so, at best, they (Prague television) are using "mutant ISO8601."

6 Quotation

Never tell people how to do things. Tell them what to do and they will surprise you with their ingenuity.General George S. Patton (1885-1945)

7 Q&A


How are metric units used for the Global Positioning System (GPS)?


Firstly, the key principle behind the GPS is that light and other radiation always travels at the same constant speed called the 'speed of light'. Your GPS receiver uses the exact value for the speed of light, which is 299 792 458 metres per second.

Secondly, on a series of satellites in orbit around the Earth, each satellite has an extremely accurate synchronised atomic clock. Your GPS receiver finds your position on the Earth using the tiny time delays in the radio signals received from several of the GPS satellites to calculate where you are on the surface of the Earth.

As the accuracy of the GPS is within about 3 metres, it is using a time difference for the calculation of about 0.000 000 01 seconds (3 299 792 458 m/s) or about 10 nanoseconds.

Some GPS devices then use pre-metric conversion software to hide the metric units from the user by changing the metric units into one or other of the many old pre-metric measuring words.

8 Rule of thumb

The full capacity of human lungs varies from about 4 litres to about 6 litres, but when you breathe in and out you usually take in only 500 millilitres of air at a time. As most people breath about 16 times per minute you use about 8 litres of air per minute.

9 History

It is always a delight for me to read old measurement history. It's a bit like enjoying the Saturday 'Puzzle Page' in the newspaper where devious minds create dastardly puzzles.

This quotation from Wikipedia really stretched both of my remaining neurones:

The history of the modern troy grain can be traced back to a royal decree in 13th century England:

By consent of the whole Realm the King's Measure was made, so that an English Penny, which is called the Sterling, round without clipping, shall weigh Thirty-two Grains of Wheat dry in the midst of the Ear; Twenty-pence make an Ounce; and Twelve Ounces make a Pound. Henry III of England

Now here's the fun bit from Wikipedia:

The traditional reading of this text is that it refers to the troy pound, and that the reference to sterling pennies is purely symbolic. According to a more recent reading, however, the pound in question is the Tower pound, and it talks about the actual mass of real sterling pennies. The Tower pound, abolished in 1527, consisted of 12 ounces like the troy pound, but was 1⁄16 lighter. In any case, with both readings one needs to substitute 24 barley grains for the 32 wheat grains of the text, according to the general convention of a 4:3 equivalence, for it to make sense. The weight of the original sterling pennies was 22 troy grains, or 24 "Tower grains" if the Tower pound was divided in the same way as the troy pound.[6] Regardless of which pound this text originally referred to, a (troy) ounce still equals 2024 = 480(troy) grains, and a pound consists of 122024 = 5760 grains.

I suppose I could begin to understand some of this if I spent a few months studying this single paragraph, but I'm not sure why I would want to.

Now why (I wonder facetiously), do we only use milligrams, grams, and kilograms these days when history looks so interesting? You can read more of these historical measurement puzzles at http://en.wikipedia.org/wiki/Grain_(measure)

10 Hidden metric

Recently I heard of a pixel that was specified as being 100 micrometres along each side of a small square. However, this was soon quoted as being 254 dots per inch (dpi) on a popular computer web site. On checking this, I found that it is a very common practice to hide the original metric specifications, in micrometres, by using dpi to hide them. See http://www.google.com/search?q=2540.dpi


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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