UKMA’s Chairman received the following critical letter from a thoughtful correspondent (a student or teacher of physics). As it is better argued than most efforts from defenders of imperial measures, it was thought that it was worth publishing (slightly edited to conceal his identity) – together with Robin’s reply.
This was the original letter:
Dear Robin,
Fundamentally, there is no reason to adopt any one unit over another, by virtue of the definitions, e.g. the metre is determined by the ratio of 1/(speed of light in m/s) – it could equally be defined in feet (speed of light feet/s). The choice is ultimately for consistency in scientific publications and engineering (and international trading), but there is no reason not to keep it in existence for everyday usage for a number of reasons (and in the same way most foreign people speak English as a second language, but still have their own mother tongue – thus exposed to 2 different ways of thinking). Indeed some of the arguments against imperial actually suggest the very reason why imperial should not be scrapped, but perhaps, with the exception of the Farenheit scale, be re-introduced! Metric units are not even rigidly adhered to in physics, where we revert to units that most conveniently relate to the scales of observation, for example energy in units of eV (the electron-volt) when talking about atomic energy structure, mass in terms of “atomic mass unit” for atoms, or “solar masses” in astronomy (yes there was the classic metric-imperial mistake at NASA on the Mars orbiter, which could have been avoided with a standard international unit, but that is not the argument here).
1) As your site mentions, many people use imperial units in describing length and height: it is precisely because the very origin of imperial units of length – derived from everyday objects – that it is so much more intuitive to use. What’s easier – describing somebody’s height in feet and inches, or in m / cm?
2) Numeracy skills in this country are at an all time low – now why could that be? Imperial measures, by virtue of not being very simple to use, force people to think about numbers and fractions. All units are ratios in one form or another, thus by maintaining the presence of fractions in the notation, we are reinforcing the fundamental nature of measurement; that what quantity you are specifying is not really an absolute number, but a ratio with respect to some pre-defined unit – the basis of which is arbitrary (and on this point, the foot is clearly an easier unit to estimate without a ruler than a metre). The specific ratios also being arbitrary – yes 10 makes it easier, but is no more correct than divisions of a foot by 12, 24 (half an inch) 48 (quarter of an inch) 96 (eigth of an inch) and so on (and here we can see the nice power of 2 relationship) – it is purely convenience, a convenience which encourages laziness in thinking and loses sight of the fundamentals, and consequently a severe dumbing down in science at schools, so that now the only bit of real maths a pupil is given, in the advanced GCSE science questions, is the “equation” for speed, which they are actually given – something which even when I did GCSEs in the 1980’s was expected to be known by heart even by the 2nd year, and was certainly not worthy of “advanced GCSE” status. What next – decimalise the byte?
3) Base 12 is more flexible than base 10, as with 16 ounces in a pound 12 is divisible by 1,2,3,4,6.
10 is divisible by 1,2,5.
5ths are less useful than 4ths and 3rds. And mathematically, base 12 is much nicer than base 10, you are less likely to end up with recurring reciprocals like 3.33333~ if wanting to divide a given length of something into an integer number of sections.
I think that to say everyday measurements in this country are in a muddle is slightly misleading – most of us know what these units mean, having grown up with both – it is only pedantism over having a consistent set of units, where in everyday situations this is not so important. The only circumstance where I can think that the imperial system is a muddle is in the vagueness of plumbing fittings, where for e.g. thread fitting diametres are not actually based on the thread diameters, but on the inner-section of pipe that might pass through them. Ultimately, I feel let down by this country and our declining education system for not having taught both imperial and metric units, irrespective of the need to have one international standard.
Cheers
[name withheld]
—————————————————————————————————————-
and this was the reply:
Dear zxzxzxzx
Thank you for your comments, which I read with interest. I am not able to reply in full detail but would make one or two brief points.
As you say, because the Government started the metrication process in 1965 and then lost its nerve and has effectively abandoned the whole project, we are now in a situation where both the metric system and imperial units are in widespread use. The problem with this is that most people do not have a secure grasp of either system – let alone both. This does create genuine problems of incomprehension, conversion errors, mistakes and accidents – and in some cases actual costs of having to run both systems – one for internal transactions and another for the public interface. Take a look at our blog article http://www.metricviews.org.uk/2007/10/15/whats-wrong-2-systems/ for further comment. (You are welcome to contribute yourself).
It is quite untrue that imperial units are “intuitive” or natural. How long is your foot? What I think you mean is that imperial units are familiar – just as it is “natural” to speak English. People brought up in metric countries do not think imperial units are “intuitive”. See also blog article http://www.metricviews.org.uk/2007/10/28/imperial-units-natural/ which includes comments from a German and a Dane on this point.
The argument about the advantages of base 12 are academic rather than practical. There is no prospect of converting the world’s counting system from decimal to duodecimal, and it is obviously sensible that the measurement system should be aligned as far as possible with the counting system. In any case imperial units are mostly not to base 12: 16 oz in 1 lb, 14 lbs in a stone, 8 stones in a cwt, 8 pints in a gallon, 3 ft in a yard, 1760 yds in a mile, 43 560 sq ft in an acre. How would you divide a lb or a mile by 3?
The evidence on numeracy skills is patchy, and even if it were true that numeracy skills have declined, this would be more likely to be due to other factors such as flaws in the national curriculum, poor maths teaching and the prevalence of pocket calculators and computers and the general dumbing down of mental processes – e.g. “satnavs” replacing map-reading and navigation skills.
UKMA’s proposals are not particularly draconian. Indeed, they are the method by which Australia, New Zealand and many other countries successfully made the change. Unfortunately, UK governments have adopted policies that are the opposite of those proved to be successful – which is why we are in the present muddle.
At least I think we can agree that successive UK governments have let us down.
Best wishes
Robin Paice
Spare a thought for the publishers of Christmas catalogues. If you were in their position, would you:
use only metric, and risk putting off those who will only think imperial, or
use only imperial, and risk confusing those who have become used to the simplicity of metric, or
use both metric and imperial, increase your costs, run the risk of making errors in conversion, and find your catalogue looks rather messy, or
avoid units altogether (quite an achievement – well done Tesco!) and leave potential customers guessing just how big, for example, the stealth kettle on p.68 or the Cookie Monster on p.91 might be?
Fortunately, it is only in the UK and Canada that you would have this problem. But unfortunately you are likely to face it again next year and for several years to come.
I can’t think of a more obvious example of why metric is more intuitive than imperial than measuring your own height. Most people probably don’t even realise the unconscious calculations that they perform every time that they measure in imperial.
Using an imperial tape measure, you can’t just read your height in feet and inches, you have to read the value in inches, then divide by 12 to give the feet, then subtract this multiple of 12 from the first value to give the inches. If you want accuracy greater than to the nearest whole inch, you then have to know how to express the number of inch subdivisions as a fraction. Different tape measures will have different subdivision units. If the subdivisons are sixteenths of an inch, then the number of sixteenths have to be divided by 2 repeatedly until 2 will no longer divide without a remainder. That, or you need to know how to count in sixteenths – 1/16, 1/8, 3/16, 1/4, 5/16, 3/8, etc.
Measuring in metric is literally childsplay in comparison, just read the value in centimetres from the tape.
The writer of the original letter made a valid point when he said that the metric system does not readily lend itself to repeated division by 2 or 3. However there is an underlying problem with any measuring system (an indeed with any new system): a number of compromises need to be made to accommodate those existing practises that are not being reformed.One of the existing practices that had to be accommodated when the metric system was first designed was the decimal counting system – our civilisation does not use a duodecimal or hexadecimal system. This meant that to incorporate all the benefits of the metric system and also to accommodate easy repeated division by 2 or 3 the designers of the metric system would have to change the system of counting to a duodecimal or hexadecimal based system. Clearly, if such a revolutionary step had been proposed as part of the introduction of the metric system, the system would never have got off the ground.
I’m not sure why you’ve published this letter – it makes all the tired old excuses we’ve heard before, none of which has any merit.
It worries me that this person may be teaching my children physics at school. They clearly have no understanding of measurement; don’t understand the purpose of arithmetic; and don’t know the difference between a measurement system and a language. They show their ignorance by asking why it’s preferable to use one unit rather to two to describe a person’s height. I would have thought that the answer is obvious. We’ve answered all these points already, can we just move on please?
Unfortunately Imperial units are still used in schools. Many students have rulers that are also marked in inches. In mathematics calculations are done involving conversions: Imperial to Metric and from Metric to Imperial.
Staffroom noticeboards sometimes have congratulatory messages announcing new births with the weight in Pounds and Ounces.
Newsletters to Parents may also include Imperial units.
I wonder is there any school in the UK that considers itself ‘pure metric’, giving students 100% exposure to only metric units while they are at school?
If the government decided to adopt full metrication including road signage, this will help support the teaching of subjects, such as Geography, Maths, and Physics.
Philip Bladon http://www.simetricmatters.com
There is nothing more nonsensical then for someone to claim to have been an SI supporter then have “seen the light” and now see a purpose in imperial. This type of claim is meant to persuade the non-committed from going over to the SI side by pretending to have once been a supporter and seeing the folly of his/her ways.
The very use of the term draconian in the first sentence tells a different story. This is one of the favourite buzzwords of the opposition.
The other clue to this person’s true nature is the claim that imperial is base 12 and metric is not. This is yet another of the points imperialists dwell on. Yet, someone truly informed knows this is far from the truth.
Measurement systems do not form part of any number base. Number bases are strictly means of utilizing a quantity of symbols to represent numbers. In base 10 (decimal) we use 10 distinct symbols to represent numbers. In base 12 (dozenal) there are 12 symbols. Base 2 (binary) uses only two symbols.
What this person calls bases are in fact nothing more then conversion factors. All imperial and all metric are presently part of base 10 numeration.
What ever set of numbers are used as divisors have nothing to do with the system and everything to do with users’ choice. It is a falsity that SI is 10 based, when it is in fact base 10 harmonized. There is nothing 10 about SI other then the relationships between the base units and the prefixes. All units are based on a 1:1 relationship with each other.
The use of numbers used is not determined by SI but by the user. In the construction industry the use of 100 mm module is the norm. This means sizes like 100, 200, 300, 400, 600, 1200, 2400, 3600, 4800, etc. mm can be found. Thus the use of both rounded metric numbers and those that can be easily divisible by 12 or its sub-multiples.
The author is claiming that SI can only be used correctly if numbers that are in the 1,2,5 and 10 series are used. Yet nothing in the BIPM rules makes such a claim.
I disagree with the author’s assertion that “most of us know what these [non-metric] units mean”. This is plainly not true. Even some of the more common units in use are not well understood.
Many, if not most, people do not know how big an acre is, whether 800 yards is more or less than 1/2 mile, how many pounds there are in a stone, how long a furlong is, how many feet are in a mile, how big a 10 rod allotment is, how big a 12-yard skip is (clue: it’s not 12 yards long!), what a sign on a railway bridge showing “4m 20c” means (clue: it’s nothing to do with bridge heights), whether a 100 bhp engine is more powerful than a 100 kW one, whether a 10,000 BTU air-conditioner is better than one rated at 2 kW, whether £1.99 per pound is better value than £4.25 per kg, how many US gallons are in an imperial gallon, how it can be 20 degrees one day and then 90 degrees the next, … The list is endless.
The fact that the continued use of poorly understood non-metric units for trade and transport purposes can cause confusion, opportunities for hoodwinking customers, and even danger on our roads is all too obvious.
I agree with Peter. Although I’m 40 I still do not properly know what most non-metric units mean although I can approximate in most cases. I only ever make mistakes when I have to convert from one system to another though – back in the 80’s I managed to buy carpet that was too short and too wide because I’d measured in metric and was forced to convert “on the fly” in the shop so will now only do metric since it saves me money!
Unfortunately there are some places I cannot do this – ok, so I can approximate 1 yard to 1 metre for distances on the roads but when it comes to feet and inches… my car is 1999mm wide and 1684mm high and that’s all I know. I could convert this to imperial myself but what if I make a mistake? I’ve also seen dual metric/imperial signs where there is a difference between the measurements so what if the people putting up the signs have also made a mistake? This in itself is in my mind a good reason we should not mix units.
The correspondent wrote:
“What’s easier – describing somebody’s height in feet and inches, or in m / cm?”
In metric there are a number of choices, the preferred one depending on circumstance:
e.g.
1.73 m
1 m 73
173 cm
1730 mm
Despite the number of variants no arithmetic is required. In two cases single whole numbers only are used.
I would argue that the second form is only ever used because of the habits inherited the from non-metric unit conventions where progressively larger quantities are expressed in larger units but with the remainder in smaller units where precision requires it. As those smaller units are related to larger ones by non-decimal factors the decimal point cannot be used and so two separate numbers are required, as well as a certain amount of conscious arithmetic. Ok feet and inches aren’t too bad in this respect but what about stones and pounds – how many people know their 14 times table?
There is a reason that marketing uses terms like horsepower and BTU. They have no meaning to most people but can be used to give the impression the person buying the product is getting a lot of something. 10 000 BTU sounds like a lot more the 2.5 or 3 kW. Even if expressed as 3000 W, that doesn’t sound as impressive as 10 000.
The same with horse power. A 100 HP motor sounds more powerful then 75 kW. A person is expected to image that the 100 HP is like a team of 100 horses doing the work. That sounds more impressive then the imagery of the power of 750 – 100 W light bulbs.
Pricing per pound is made to sound cheaper then pricing per kilogram. However, pricing per 100 g can be made to sound cheaper then pricing per pound. There is an advantage to the shop to price in pounds and display the amount vended in grams. The shop can push a bit more product.
When the consumer asks for a pound and they see the scale is going over a pound, they can always yell STOP. When it is in grams they have to depend on the sales clerk to stop at the amount asked for (if in pounds). In this case, they will be much more over then if the customer yells stop. The clerk will always ask if the over amount is OK, to which the customer usually responds positively. The customer is aware the cost to him/her will be more then the unit price on the sign, but they accept it as normal when two units are used in the market.
The moral of the story is that whatever methods work best to increase the sale of products by the shop will be employed. Dual pricing can also be used to justify price increases as there is a cost in both material and labour to mark everything twice. The shop will feel the consumer is willing to pay the extra price (possibly slightly inflated then what it costs to provide the supplemental unit pricing) just to see obsolete units and justify charging more for the privilege. Of course the shopper is never told they are paying more to have pricing added in imperial.
I’m somewhat suprised by the venom from certain contributors.
Is it official metrication policy to be nasty to those who prefer imperial in the hope that they’ll “see the light”?
I think that many that will read this, who are undecided or don’t hold a strong opinion, will warm closer to the imperial ’side’