One of our regular contributors, John Frewen-Lord, observes that the beauty and value of the built-in simplicity and coherence of the metric system is not being learned by the UK population despite forty years of teaching.

He writes:

“This is a subject that I and others have touched upon before in past posts on Metric Views, but it seems that it perhaps needs revisiting in light of the recent YouGov survey commissioned by the UKMA. The survey showed conclusively that the British public prefers to still keep using what is a rather cumbersome and clumsy collection of disjointed measuring units, eschewing the simple and rather well integrated metric system that is not only easily available, but is what a majority of the UK population has been taught (if not actually learned) during their school days.

People keep saying that the metric system is for scientists, engineers and other specialist applications, but is not suited to everyday use. That is so wrong. One anti-metric website even states that the metric system is for bureaucrats. Considering that 95% of the world’s population uses only (or at least primarily) the metric system for every part of their lives, that makes for rather a lot of bureaucrats! Obviously that statement is simply ridiculous. The metric system is, to use its well-known tagline, ‘for all people, for all time’ (Condorcet, 1791). So why does a majority of the British public not use it, when it is so obviously much easier to use, even for ‘everyday’ calculations?

In fact, there are many occasions when, faced with a measuring problem, I find that use of the metric system really provides the only easily achieved solution – imperial simply just doesn’t ‘cut it’. The following are just a few of these problems that I have encountered that show just how simple using the metric system is in our everyday world (apologies if these sound a bit like school exam questions, but they genuinely are real problems that use of the metric system helped me to easily solve).

When our previous house was being rented, the estate agent needed to measure how much heating oil was in the tank. He ‘dipped’ it by inserting a long measuring stick into the tank, and reading the oil depth mark. He noted the depth in inches, which, considering he was a chartered surveyor, rather surprised me. He then proceeded to phone his office with the depth and tank diameter, where they had ‘conversion tables’ that would give him the number of litres in the tank. Before he had even got through to his office, I had worked it out on my mobile phone calculator. [The depth, measured as 19-3/4 inches, I converted to a rounded 50 cm. The tank was 1.96 m in diameter, as per its manufacturer’s label. Using the formula Pi x r² x h, the calculation was 3.142 x 98 x 98 x 50 ÷ 1000 = 1509 litres. Or 3.142 x 0.98 x 0.98 x 0.5 x 1000 – it comes to the same thing.] A colleague who walks as a hobby mentioned that it takes him 23 minutes to walk from his house to the railway station. He knew that he walks at between 3-1/2 and 4 mph, and said that ‘one day’ he must work out exactly how far the railway station is. I immediately told him it was around 2.3 km. He picked up on the relationship between 23 minutes and 2.3 km, but was intrigued as to how they were connected like that. After I told him, we now have at least one person who has switched to SI, at least for his walking activities. Considering that less than half the YouGov respondents did not know how many yards there were in a mile, it is perhaps not surprising that people find it very difficult to do this kind of calculation in imperial units. [Using an average of say 3.7 mph, this converts to 6 km/h. Dividing by 60 gives us 100 m/min – a very useful and easily used value when calculating walking times and distances.] Similarly when driving. Anti-metric types say that imperial has that wonderful relationship of 60 mph equalling a mile a minute, and that metric doesn’t have that. Actually, it does, and better. At lower speeds over shorter distances (say a mix of urban and two-lane rural roads), we tend to measure our journey times in minutes. A good average speed for this type of journey is 60 km/h, or 1 km/min. A journey of 20 km can therefore be expected to take 20 minutes (obviously it could be very different from that). Conversely, over long distances, we tend to measure our journey times in hours. Assuming primarily motorway/dual carriageway driving, we can probably average 100 km/h. A journey of 300 km can therefore be expected to take 3 hours. My other half could not find a measuring cup to measure out 150 mL of water needed for a recipe (she does cook in metric). I came to the rescue by taking a regular cup, placing it on the electronic kitchen scales, then zeroed the scales, and poured in water until the scales read 150 g. Until that moment, she had not realised the one-to-one relationship between litres and kilograms. Likewise when our local shopping centre hosted a blood donor clinic, a young lady who was obviously a nurse of some kind accosted me and asked whether I wanted to give a pint of blood. I said that that I didn’t do pints, but might be persuaded to give half a litre. No problem, she said, and then asked if I knew what percentage of my body’s fluid content half a litre was. After a few seconds calculating in my head, I said a little over 1%, with which she concurred. She said that most people think it’s much more than that, assuming they even know that the human body is about 60% water by weight (can vary quite a bit). Considering that it is all but impossible to relate stones and pounds to pints, no wonder people have no idea how little a ‘pint’ of blood is as part of their body fluid content. [I weigh 66 kg. 60% of that is 40 kg, which means I have around 40 L of body fluid within me. 0.5 L is 1.25% of that.] Our heating system is getting old, and is not very efficient. I was pricing out the running costs of a new system, and calculated that a set of new radiators probably could give out around 12 kW of heat output on maximum heat (it’s a large old house). Our gas is priced at 5.5p/kW.h, meaning that it would cost £0.66/h to heat the house on maximum heat at 100% efficiency. I now could compare a new boiler at 97% efficiency with our old one, which the plumber has said is probably no better than 70%. (Annoyingly, new radiators are still often rated in BTUs, which is less than helpful.)

So why do we still cling to yards and miles, to stones and pounds, to pints and BTUs, and all the other weird and disconnected units of imperial measure, which make the sorts of problem solving and price comparisons noted above all but impossible? An informed public is a valuable safeguard against getting ‘ripped off’ by manufacturers, retailers and contractors alike, as well as enabling us to make correct decisions in many aspects of our lives. Yet continuing to use imperial measures, with their extreme difficulty in making meaningful comparisons, all but guarantees a public that cannot be properly informed. I guess we get what we deserve.”

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