Metrication matters - Number 59 - 2008-04-10
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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 metric1 Feedback
Bill Hooper PhD, from Virginia, went to no end of trouble to test my NaughtinDEX rule for estimating your body mass. Bill drew up a comparative Excel table of heights and body masses from 1.55 metres to 2.20 metres and from 60 kilograms to 110 kilograms. Bill then wrote to say:
Pat,
Attached is a table of BMI values for various heights and masses. I created it to see if your trick of dropping the hundreds from you height (in m) and removing the decimal point would actually lead to a desired mass value consistent with some selected "good" BMI.
YOUR METHOD WORKS! I chose to look for the values of BMI that were closest to 25, which is the official cutoff point between normal and overweight. (I still will quibble that this is not the "ideal" BMI. It would be more appropriate to call it the maximum normal BMI. The body masses obtained from it would then not be "ideal body mass" but would be maximum "normal" mass; "normal" meaning that anything higher would be overweight.)
Anyway, look at the values closest to 25 in my table; I've marked them in color, but if the color does not come through, you can shade them in yourself. It seems to be coincidence, but it does appear that for almost every one, your empirical rule seems to work.
Look at one line, the one for 1.80 m. Drop the "1" from this value (leaving ".80" and also drop the decimal point to get "80". Reading across the table to the colored box that shows "24.69" (the closest value to 25), you can see that the mass at the top of that column is indeed "80".
This works for all the heights between 1.65 m and 1.95 m. It goes a little bit off for heights of 1.60 m and less. For 1.55 m heights, for example, your rule would lead to a mass of 55 kg (drop the "1" and the decimal point to get "55") when the mass calculated would be 60 kg. Thus, your rule would tell a 1.55 m person that he/she should be at 55 kg or less to be not overweight, when in fact he/she could be as much as 60 kg and still not be overweight.
For heights of 2.00 m and above, your rule would need to be modified but it is simple to do. Surely you can't just "eliminate the "2" in the "2.00" because you would get an answer of zero! However, if you modify your rule by stating that you reduce the whole number part by 1 (so 2.00 becomes 1.00) and then drop the decimal point, you get "100". The colored column across from the 2.00 m value is under the column headed "100! Voila! Your rule still works. (And the modified version also continues to work for heights below 2.00 m, too.)
Summarizing, your rule begins breaking down for heights of about 1.60 m and below, and it needs to be modified for heights of 2.00 m and above. Otherwise, it does work.
BUT, calculating your BMI (using metres and kilograms) and simply learning that 25 is the cutoff point between "normal" and "overweight" still seems easier to me.
Bill Hooper
1810 mm tall
I will leave it to you to decide what Bill Hooper's ideal body mass should be using the information below his signature. You can then decide which is easier.
2 Editorial
Often we become so focused on the details of the metric system that we forget that the objective is to change people's mindsets from their current position of using many old pre-metric measures in a sort of jumble to the simplicity of the metric system especially in its form as the International System of Units (SI). However, this often means that we don't concentrate on the change process that is necessary to bring this about. To overcome this deficit might I suggest that you read some of the leading thinkers on the change process itself. My preferred references in this area are Jeannie Duck's, The Change Monster and John Kotter's Leading Change. Go to the bottom of .htm for details of how you can obtain these references.
3 Oddities
This item comes from World Wide Words, a weekly newsletter written by Michael Quinion in the UK.
I SAY TWADDLE, YOU SAY TWADDELL ... My research skills escaped me last week in trying to discover something about degrees Twaddle. Crawford MacKeand and Joe Cunningham tell me that the inventor of the scale was William Twaddell, an instrument maker of Glasgow in the early nineteenth century. The National Museum of Scotland's Web site (http://wwwords.org?TWHY) has a picture of a set of six of his graded hydrometers. He made them to estimate the specific gravity of various liquids (the NMS caption specifically mentions spirit proofing, which presumably means the famous Glasgow whisky), though his scale was later used in many other industries. The Dictionary of National Biography doesn't mention him, though the scale named after him has an entry in the Oxford English Dictionary. He is so little known that at least one maker currently sells hydrometers engraved with the "Twaddle" scale. The many people who spell the name wrong may be forgiven, however, since all three citations for the OED's entry, dated between 1853 and 1873, spell it "Twaddle", as do most of the earlier ones that I've now found. In 1825, The Repertory of Patent Inventions said of the device, "It was first constructed by a poor tippling glass-blower in Glasgow, whose name was Twaddle. Hence it is called Twaddle's hydrometer." Might it be that William Twaddell's obscurity lies in part in his imbibing too much of the product he was testing?
You can join the World Wide Words mail list at: http://www.worldwidewords.org/maillist/index.htm
4 Tips
With the metric system it is possible to choose from the metric prefixes in such a way that all of the values you use each day can be whole numbers. You and your staff can operate completely without reference to vulgar or common fractions and without decimal fractions. For a full report on how to do this go to /articles then scroll to the bottom to find the article, Whole number rule for the metric system.
5 Signs of the times
Howard Ressel, from New York, bought an imported bottle of water from that came from Italy. The label had to be modified to suit the law in the USA. Howard reports:
The size is 50 cl 16.90 fl oz (font the same) and the serving size is given as 8 Fl oz (240 ml). At least they say it comes from a mountain that is 1935 meters high.
6 Quotation
I think that I have used this quotation before but I am reusing it to point out that Lord Kelvin mistakenly held the belief that the metric system was French when, in fact, it had initially been developed by the English Bishop, John Wilkins, in 1668 (See several John Wilkins articles at: /articles they are near the top). Lord Kelvin was speaking to an audience in the USA.
You, in this country, are subjected to the British insularity in weights and measures; you use the foot and inch and yard. I am obligated to use that system, but I apologize to you for doing so because it is so inconvenient, and I hope all Americans will do everything in their power to introduce the French metrical system ... I look upon our English system as a wickedly brain destroying piece of bondage under which we suffer. The reason why we continue to use it is the imaginary difficulty of making a change, and nothing else; but I do not think in America that any such difficulty should stand in the way of adopting so splendidly useful a reform.
From a lecture by Lord Kelvin in Philadelphia, 1884
7 Q&A
Question:
Does the metric system play any part in discussions about the greenhouse effect, global warming, and climate change?
Answer:
It constantly amazes me how important measuring issues are to everything we do. Some time ago I was reading some Australian energy consumption statistics when I came across this summary:
... Non-renewable fuels used to generate electricity include black coal (53,576 kt), brown coal (65,075 kt), and natural gas (291,372 TJ). Hydro-electricity was the main renewable source of electricity, and in 2001-02, 15,567 GWh of hydro-electricity were produced ...
From 'Detailed Energy Statistics, Australia' Australian Bureau of Statistics' (ABS) web page.
I found that the choices of measuring units made by the ABS make it very difficult for me to compare energy from oil, with energy from black or brown coal, with hydroelectric energy, or with energy from petroleum. This diversity of measuring units fails to communicate effectively with either the public or with politicians when they need to consider energy issues.
Fortunately, there is an immediate solution to this communication problem and that is contained within the single (SI) metric unit, joule. As an example of its use, consider the Australian energy use figures, quoted above, lightly edited, sensibly rounded, and expressed in petajoules (PJ):
... Non-renewable fuels used to generate electricity include 1600 PJ from black coal, 1000 PJ from brown coal, and 290 PJ from natural gas. Hydro-electricity was the main renewable source of electricity, and in 2001-02, 56 PJ of hydro-electricity were produced
How can any citizen concerned about global warming begin to comprehend the various jargons incorporated in the ABS statistics? More importantly, how can national and world leaders sensibly discuss energy issues when the language of energy measurement is made so unnecessarily complex?
To reinforce this point here is the same ABS energy data in a table format.
Energy source Diverse measures (SI) metric units
PJ = petajoulesBlack coal 53,576 kt 1600 PJ Brown coal 65,075 kt 1000 PJ Natural gas 291,372 TJ 290 PJ Hydro-electricity 15,567 GWh 56 PJ
Expressing energy in joules, whenever energy information is provided, means that conversions are no longer necessary, and all forms of energy are immediately comparable. You don't have to memorise, look up, or calculate with conversion factors because there aren't any.
This measurement muddle is even worse in the USA where they have yet to widely adopt the modern metric system more formally known as the International System of Units (SI). In the USA, there are some people still using things like:
toe's (for tons of oil equivalent measured in one or other of the British thermal units) MMBtu/Mcf (for million million British Thermal Units per million cubic feet)
and using conversion factors like
1 short ton per cubic yard = 0.0330687831 long tons per cubic foot. I wish the USA well with their inevitable metrication transition, but if anyone tells you that the USA will take a leadership role in the measurement components of the global warming discussion anytime soon — 'tell 'em they're dreamin'!
I believe that we need to understand the issues behind peak oil and global warming better than this, and so do our legislators and elected politicians. For a full treatment of this issue see my submission to the Australian Garnaut Climate Change Review at: http://www.garnautreview.org.au/CA25734E0016A131/pages/submissions-general-submissions
8 Rule of thumb
If you wish to lead a temperature transition is a hospital, you might place posters with these rules of thumb:
Temperature Condition 37 °C Normal body temperature 38 °C Low fever 39 °C High fever 40 °C Dangerously high fever
Seek emergency medical
treatment immediately!9 History
Han Maenen, from the Netherlands, helped me put together this group of factoids.
- the metric system took 50 years before it reached 50 million users (from about 1790 to 1840).
- radio took 38 years before it reached 50 million users.
- computers took 16 years to reach 50 million users
- the internet took 4 years to reach 50 million users.
The metric system now has almost 7 000 000 000 users as everyone on Earth, including all citizens of the USA, uses the metric system every day either directly or indirectly.
10 Hidden metric
Michael Payne, from Virginia, reports that the Plakolite company makes their acrylic sheets in all millimetre sizes and then labels them in decimal fractions of inches. Michael writes:
I bought some listed as 0,08'' on the label, nothing else yet it's 2 mm thick almost exactly. I have no doubt it's all metric converted to decimal inches.
See: http://www.plaskolite.com/runtosize.htm for details.
Cheers,
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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