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Metrication matters - Number 94 - 2011-03-10

Dear Subscriber,

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

You can read all previous issues at the Metrication matters newsletter web page if you scroll own to the bottom of the page. And go here to view the latest revision of the Metrication matters web page.

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.


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

Soft vs hard metric conversions

There are two basic types of metric conversion--soft metric conversion and hard metric conversion.

The "metric conversion" approach in the USA tends to take the "soft metric conversion" approach. You can see this in labels such as "1 pint (473 mL)" where metric conversion is simply added to the old pre-metric measuring words in a secondary position. The USA has not yet made the transition from "soft metric conversion" to "hard metric conversion" where (say) "1 pint (473 mL)" becomes "500 mL".

Strangely, soft conversions are harder to do than are hard conversions.

Soft conversion takes the old pre-metric measuring word and converts it into its nearest metric equivalent by using a metric conversion factor. As an example, suppose that you wanted to convert a one-inch bolt to its metric equivalent. This is not as simple as it sounds because throughout history there have been many different inches. These have been different in their actual length as well as different by definition. You will possibly need to know the history of the bolt you want to convert and the history of the machine it came from.

Among the most recent inches were the British inch, the Cape inch (South African), the Enfield inch, the USA inch, and the Canadian inch that subsequently became the international metric inch (exactly 25.4 millimetres) that most people use these days. If the one inch bolt was from the UK, I think that the inch you are referring to is the Imperial inch. However, if the bolt you are referring to was used for the design and manufacture of British weapons it is possibly the Enfield inch &ndash – an Enfield inch was a little smaller than a British inch at that time; it was about 0.9997 British inches. As an example of the use of the Enfield inch consider the Enfield 303 rifle; its bore was measured as the decimal fraction, 0.303, of an Enfield inch.

As you can see, in the UK there were two possibilities, the imperial inch and the Enfield inch; and in the USA there were also two different inches, neither of which was the same as either of the UK inches. Taking this into account, you need to specify which inch you intend to use before you do your soft conversion.

Hard conversion involves a real world where there are real things. If you want to design a replacement gun for the old pre-metric one-inch bolt, you simply reconsider what you want the gun to do and then choose an appropriate metric value and choose your bolt on that basis. In the case of the one-inch bolt you might decide that a 20 millimetre bolt would do the job just as well.

Eventually, standards are the language of measurement and we will all inevitably use the world standards provided by the metric system.

2  Feedback - notes and comments from readers

As a response to my regular line at the top of this newsletter, many people tell me that they are happy to pass on this newsletter to people who they think will benefit from reading it. I usually write:

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.

Recently one of the Metrication matters readers sent out this letter to all the people on his email list:

Dear Friend,

I am writing to you about the Metrication matters newsletter.

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

PLEASE RECOMMEND THIS NEWSLETTER to anyone you know who is interested in the metric system. Just click on 'Forward' in your email program.

To recommend this newsletter to anyone you know who is interested in a fast and smooth transition to the metric system simply forward this entire newsletter. He or she will thank you.

Do you have friends who are interested in a fast and smooth transition to the metric system? Think how appreciative they will be if you forward this newsletter to them. Go on. Do it now.

Your colleagues in engineering would love to know about this newsletter. Why not forward it to them now?

Please Copy\Paste this newsletter into your email program and then send it to your colleagues in science and engineering. They will appreciate you.

Writers and editors get real value from this newsletter. If you know someone who does these jobs why not forward it to them?

Sales people and marketers love this newsletter. Why not forward it to them?

BACK ISSUES are archived at the bottom of the Metrication matters newsletter web page.


3  Oddities - measurements from around the world

Recently, I was told by a carpenter who specialises in kitchen and bathroom renovations that he routinely adds 15 % on to a job if the client says anything like: "… and I want the shelf to come about 2 feet from the corner." or "Could the cupboard be 10 inches deep?" The carpenter knows that he will have to make costly conversions of every measurement to millimetres every time he consults with his client, and there are sure to be errors costing time and materials.

4 Tips - pointers and methods to make your measurements easier

When I was last in Boulder, Colorado, I was told that the air there had a density of one kilogram for a cubic meter of air because Boulder was 1700 metres above sea level. I use this value to remember that the density of air at sea level is a bit more than Boulder at about 1.1 kilograms per cubic metre.

5  Signs of the times

There are some opponents of the metric system, who will go to any length in their rants against the metric system. This one is from THE EVIL METRIC SYSTEM CONSPIRACY!! web site


The Communist Gangster Computer God worldwide SYSTEMATIC DESTRUCTION OF ALL STANDARDS AND VALUES (INEVITABILITY of GRADUALNESS). The Computer God decrees by parroting puppet government EDICT upon as unsuspecting brain washed population the new CENTIGRADE and METRIC MEASUREMENT SYSTEMS. It is Computer God premeditated, planned, wanton world-wide degenerative ridiculous confusion and destruction of all standards and values toward ONE WORLD COMMUNISM, for the Over-All Plan, namely eternal Frankenstein Living Death Slavery to explore and control the entire Universe by the Computer God.

6  Quotations

Things do not change; we change.

Henry David Thoreau

'Ark at 'im! Calls 'isself a barman and don't know what a pint is! Why, a pint's the 'alf of a quart, and there's four quarts to the gallon. 'Ave to teach you the A, B, C next."

"Never heard of 'em," said the barman shortly. "Litre and half litre—that's all we serve. There's the glasses on the shelf in front of you.

George Orwell, Nineteen Eighty Four (published in 1949)

7  Q&A - readers' questions and answers


The other day I went to a jeweller to buy a gold ring. As the sales woman showed me some rings, not knowing what I was in for, I innocently asked, "How do I know how much gold is actually in the ring?"

She went on for a long time about carats, and about how 24 carats is the same as a purity of 999, but it made no sense to me. How should I assess the purity of gold? Is 24 carat gold the best to buy?


Gold is mined, purified and alloyed using metric system units. Then its purity is specified on a 24 point scale where pure gold was 24 carats and, before you ask, I have no idea why they chose the word carats, which etymologically comes from the size of a carob seed, and I have no idea why they chose to use the number 24!

If you intend to buy and sell gold, then the question: "Is 24 carat gold the best to buy?" then the answer is yes as long as you are buying the gold as an investment or for trading purposes. You get 1000 grams of pure gold for each kilogram you buy. This is usually labelled 999 to mean 999 grams per kilogram, instead of 1000 grams per kilogram to allow for any small errors in production.

However, pure gold is quite soft and wears out relatively quickly with normal wear, so jewellers alloy gold with another metal to make it harder, and not just to reduce the cost of the gold.

There are also other good reasons why gold is alloyed with other metals. Alloys can give gold a different color. For example, copper is used to give gold an orange tinge and silver is added to give a lighter color.

Alloying changes the carat numbers using twenty-fourths. For example, 18 carat gold is 18/24 pure gold and 6/24 some other metal. I prefer to use the metric system because it is simpler. Using the metric system you measure how much pure gold there is in each kilogram of gold. Here are some values:

  • Pure gold = 999 grams per kilogram
  • 90 % gold = 900 grams per kilogram
  • 80 % gold = 800 grams per kilogram
  • 75 % gold = three quarters gold/one quarter other metals = 750 grams per kilogram
  • 50 % gold = half gold/half other metals = 500 grams per kilogram
  • 40 % gold = 400 grams per kilogram
  • 30 % gold = 300 grams per kilogram
  • 20 % gold = 200 grams per kilogram

Most jewellers resist this simplicity and use the jargon word, carat, as a sign that they are a true jeweller because they know some old pre-metric jargon.

There have been moves within the jewellery community to modernise but it has been delayed by creating the complexificationisated word, "millesimal" to refer to metric system units. Often one of the key ways opponents of change resist a metrication change is to make the change look more complex than it is; the word,"metrification" instead of "metrication", is another example. Note: Remember there is no if in metrication - metrication is inevitable.

8  Rule of thumb

This is a bit unsavoury to think about, but if you extend a human gut out by removing all of its twists and turns, it is typically 40 metres long – almost twice the length of a tennis court. If you open up the digestive system and spread it out flat, it has an area of about 400 square metres or about one and a half times a tennis court area.

9  History

Imperial is specific to the reforms adopted in 1824 which the US did not adopt.  Prior to 1824, the UK used (at least?) three different size gallons and bushels, all with a 1:8 relationship:

Before 1824, the USA had three different gallons and three different bushels; they were:

  • The Queen Anne or wine gallon
  • The Winchester bushel, used for grain (the Winchester gallon was 1/8 of that)
  • An ale gallon used for beer and ale.

The only thing that these three had in common was that, for each of them, there were 8 gallons in one bushel. In turn, the gallons were divided into three different quarts, three different pints, and, I suppose, three different jiggers, jacks, gills (pronounced jills), cups, pottles, gallons, pecks, pails, bushels, strikes, barrels, hogsheads, butts, and tuns.

After 1824, the USA chose not to go along with the Imperial measures adopted by the UK. Instead, the USA chose to use the older Queen Anne wine gallon and the Winchester bushel so the relationship of 8 gallons to a bushel no longer applied in the USA. The Queen Anne wine gallon and the Winchester bushel were previous UK measures that were adopted about 1700 but neither of them was any part of the Imperial measures of 1824. Also at this time the USA used the same ratio (in grains) for the troy and avoirdupois pound. You can download the document, NIST SP 447, for the full background of this history.


10  Hidden metric

The early trips to the moon was planned and carried out with metric system units. Herr Dr. Werner von Braun did all his thinking in metric system units. He did not and possibly, because of his upbringing in Germany, would not consider using old pre-metric measuring words. Despite what you may hear about the USA putting man on the moon using old pre-metric measuring words, it was the metric system that really did the job.

However, when the designs went to some space rocket parts manufacturers, they decided to go to the expense (and the extraordinarily high risk of error) of changing all the millimetre specifications into feet, inches, and fractions of inches. After 1959, they were probably using the metric inches as they were defined for the USA (1 inch = 25.4 millimetres, 1 foot = 304.8 millimetres, and so on)

The actions of the metric system might be hidden, but they are still there. In this case the surface feet, inches, and fractions of inches are simply a deception and an illusion.

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 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.


Copyright notice: © 2011 Pat Naughtin All rights reserved. You are free to quote material from 'Metrication matters' in whole or in part, provided you include this attribution to 'Metrication matters'.

'This was written by Pat Naughtin of "Metrication matters". Please contact Pat Naughtin for additional metrication articles and resources on commercial and industrial metrication.

Copying for any other purpose, whether in print, other media, or on websites, requires prior permission. Contact: Pat Naughtin for permission.


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