Happy New Year to all our readers.
In this article, the Editor explains the reason for the absence of new posts on MV in recent weeks. This leads to a discussion of a issue that few of us, perhaps, have encountered.
The Editor writes:
“During late November and early December, I was assisting one of my sons with the renovation of a row of cottages that he had recently acquired in the French Alps. He was keen to take his family there over the Christmas break, but there was much work that needed to be done to make this possible.
From 1967 to 1975 I had been working in the construction industry while its switch from imperial to metric was taking place. A decision had been made early in the changeover to work with units in multiples of 1000: mm, m and km; mL, litres and cubic metres; g, kg and tonnes; N, kN and MN, and so on. No ccs, cL or hectograms. This had a number of advantages for construction including a reduced risk of confusion and the avoidance of the need to add units to dimensions on drawings.
However, my son who attended school in the 1980s had grown up with a “whatever works for you” version of the metric system, and centimetres definitely worked for him.
Readers may remember the “Metric Sense” campaign led by Anne Attlee in the 1980’s and 1990’s, which also encouraged the use of the units that people were comfortable with. This was an attempt to overcome some of the hostility to the metric changeover that had become apparent in the early 1980s. In particular “Metric Sense” advocated the use of centimetres in replacement of inches, a metric unit taking the place of an imperial unit of similar magnitude.
How would this play out when the DIY duo went to work?
Initially, it appeared that UK construction had done the right thing 50 years earlier:
“Dad, I need a length of boarding 180 long.”
“Don’t you mean 1800?”
“No, 180 centimetres.”
And so on. It took us a while to get used to each other’s thinking, and we wondered how the French managed. The local DIY store provided some clues (and a breathtaking view from its car park – British DIY enthusiasts are allowed to be envious). 
Here are some shelf labels in the store:
This shows recommended supply pipe sizes for various appliances: bath, basin, wc, etc.
So it seems the French go in for “metric sense” too. Which reminds me of an incident early in the 1970s. I was then working in the London office of Arups on the design of Centre Beaubourg, later renamed Centre Pompidou, in Paris. The UK had been one of the first countries in the world to adopt SI. French engineers visiting the London offices said they had no difficulty with our use of millimetres, but they were really struggling with kN for force and N/sq mm for stress. But that is another story.
And the Alpine DIY project? Significant progress: a new concrete ground floor, provision of a hot water system, bath, flushing wc, new staircase, rewiring (by a French contractor) and upgraded insulation. Plus massive snowfalls. I am told the holiday was a great success.”
Metric Views 
During my 5 years in France I only ever encountered the use of cm for linear measures, as a result that is much what I use now. However, unlike those imperial things, I have no problems mixed ‘units’ of mm, cm, or m. As far as I am concerned they are all the same units. This in turn comes from electronics where multipliers are (or were in the day) part of just about every hour of every day (pico, nano, micro … kilo, mega, Giga).
Once the concrete has set and its time to move on to finishes even you may be astonished at how easy things are when everything is measured and priced in square metres (m²). Everything that is from paint through wall coverings, tiles, wood panelling, carpet et al. Just measure the wall, floor or ceiling and compare prices is a trice from the paint tin to the mahogany panelling, its all the same units, wonderful!
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It’s interesting to note how “per square metre” is written – “LE M2” on the shelf label for the tiles (Dalles). All capitals, and with the “2” on the same line as the letters and not as a superscript. Strictly speaking, this is completely wrong, as most metric users probably know. The letter “m” for metre should be lower case and the “2” should be a superscript. But in wholly metric countries, usage does not always follow the strict rules of SI. It is also common to see “kgs” or even “KGS” instead of the correct “kg”. The upside is, there is no danger of confusion as everyone is using the same metric system and these examples are really just “poetic licence” (though I know it annoys some people, including myself sometimes).
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@ Jake 2018-01-15 at 15:17
This is sloppy usage. The problem arises when the context is not so obvious, obscure or even downright unfathomable.
Examples, forgive me if some are a bit technical, milli v Mega, bits v Bytes, metre v mile, GB v GiB, just a few that come to mind, particularly when some correctly used (GiB), few actually know that is the correct term most of the time.
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Jake,
I’ve brought this point up on a number of metric based forums, that the incorrect usage of unit symbols is directly related to the poor teaching of SI units world wide. This is something the BIPM really needs to address. There needs to be a common plan on teaching SI to young students. That is to teach them that the unit symbols only have one form and all others are wrong, in the same way that each word has only one correct spelling. Emphasis on spelling has resulted in almost 100 % universal correct spelling in all writings and documents. The same emphasis needs to be applied to SI symbols.
In addition, the teaching of SI needs to encompass a more expanded use of SI units. In reference to BrianAC’s post, SI should not be treated as just a competitor to imperial, but a familiarity with all prefixes needs to be ingrained. Using centimetres as if they were inches, metres as if they were yards, kilometres as if they were miles is not the way it should be. Everyone should be as familiar with nanometres, micrometres, gigametres, terametres, yottametres, etc as they are with kilometres. The same with all other units.
The metre is the base unit, the prefixes don’t create new units, they just scale the base unit. That is the way it needs to be taught and that is the way it will be used.
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@Daniel Jackson: 2018-01-19 at 13:50
Very well put, I totally agree with a possible proviso that extended multipliers would be used only by a few people (maybe those scientists people talk about as if they were a different species).
The 7 basic SI units at least should be taught with, and as part of basic arithmetic. Back in the day we were taught Roman nomenclature (M,X,L,V,I) so I can’t see it being too difficult to teach SI instead.
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BrianAC and Daniel Jackson:
I agree with you both, but in everyday, general usage in the metric country where I live, I normally do not see much more than the basics, nothing scaled up or down. I’m talking markets and supermarkets, petrol stations, the things an ordinary member of the public sees every day, rather than someone using metric in the workplace. I know those usages are wrong, but my point was they do not lead to misunderstanding.
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@Jake:
It’s probably less to do with ‘poetic licence’ and more that the computer software which churns out the shelf labels from the stock database does not make it easy to generate the correct symbols or the workers are not trained to use it properly. Give them keyboards with ‘²’, ‘³’, ‘×’, ‘°’, ‘µ’, ‘Ω’ and non-breaking-[thin-]space keys and typefaces with lower-case letters and symbols and this should become a non-issue. Same for till receipts, invoices, inventories, etc. and Metric Views comments (‘the Planck constant h is 6.626 070 040 × 10⁻³⁴ J·s’)!
Incidentally, there are UN/ international shipping standards which use upper-case Latin alphabet mnemonics only for metric units—so they can be communicated by telex, etc. So (IIRC) ‘KGS’, ‘CM’, ‘MTR’, ‘SQM’, etc. might well validly appear on bulk packages at the DIY store!
@Daniel Jackson:
I confess to not knowing the more extreme prefixes, despite being one of the fortunate ones not hindered by exposure to imperial at school. We were taught metric in a multi-disciplinary, incremental fashion from about 5 years old. Dr. Metric has told us why everything must be centimetres at that stage (eye development). First with colour-coded wooden blocks, then wooden rules, transparent (plastic!) containers of various shapes to be filled with water, milli- and kilo- prefixes for litres and grams, wooden metre sticks & wheels, etc. It was probably only by 14 years old that we were habitually using prefixes between pico- and tera-, most of those in electronics as BrianAC says. From the age of 8 we were given increasingly extended tables of prefixes, but only learned the ones in the middle through regular use and looked up the others as required. In science, it was scientific notation exclusively from 11 years onwards and use of prefixes discouraged altogether! BIPM could make its SI brochure available in more [unofficial?] languages and just recommend teachers (and students) worldwide to actually use it directly, tailoring their lessons to the local culture themselves.
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