John Frewen-Lord recalls several recent examples of difficulties with measurement and asks if common measuring devices actually inhibit using the metric system.

It is said that constant exposure to the metric system (and its associated measuring devices) will gradually make us ever more comfortable in using the metric system on a day-to-day basis. But is this true?

When it comes to measuring devices, most of us have used the simple metric ruler, whether in school or at home. It is invariably easy to understand – a simple clear scale graduated in millimetres, with the 10-mm graduations marked off in some fashion. But does that simplicity and clarity apply to all the common of measuring devices we use or otherwise encounter in our (adult) daily lives? Not necessarily.

Some devices make it downright difficult to understand how to read them, while others actually invite you to not bother to measure in metric units at all, which no doubt pleases the metric sceptics in our society, but does nothing that actually benefits the country. Compounding all this is the fact that many people have a less than adequate understanding of the metric system itself, in spite of it being exclusively taught in schools for the last 40 years.

I noticed this recently when I went down to my local post office to post a parcel. I had already weighed it on my electronic kitchen scales, which displayed a reading of 482 g. Armed with this knowledge, I suggested to the lady behind the counter that we could see how accurate my kitchen scales were compared with the post office ones. “Probably not,” she replied. “Our scales measure only in kilograms.” Quite how she copes with grams and kilograms in her private life will remain a mystery.

More serious in terms of being able to measure in metric units was when a flying tree branch in a recent wind storm broke one of the windows of a nearby house. The tenant is a young man in his late 20s, who would have been educated at school entirely in metric. On being asked to assess the damage to the window, I phoned a window repair company, who asked me the size (in millimetres) of the sealed double-glazed unit in the hope that it might be a standard stock item. As I tried to manipulate the steel tape measure while still holding my phone, the tenant offered to measure the window. He gave me the dimensions in inches. I asked him for the dimensions in millimetres.

His response was that he didn’t actually know how to read a standard dual-marked steel tape in metric units – he could only do it in inches. And when you look at the typical steel tape available in the UK, perhaps his difficulty is partly understandable. For a start, and has been mentioned many times elsewhere both in the UK and in the USA, dual-marked steel tapes, which are the only type easily available, invariably have the imperial scale uppermost, which is the edge most people measure against. This applies even when the tape is labelled on its case in metres only (as many are, especially those intended for the building trade).

That in itself makes measuring off in metric units more difficult than it need be, but what makes things even more complicated is the number of different ways that metric units are displayed on various different tapes. My favourite tape is a surveyor’s 30-m metric-only tape that I bought in Germany. It is marked off in millimetres (not centimetres) in 10-mm increments. Thus a measurement of 2163 mm would be measured or read off by going to the 2100 mark (in red, with the ‘2’ a larger size), then moving to the next 60 marking (in black), leaving you to just count off the final 3 millimetres. It is very easy to read the right dimension, in millimetres, with no chance of error.

But the other steel tapes I have are much more confusing. They are all dual-marked, with the lower metric side using a variety of formats (centimetres only, separate metres and centimetres, but never just millimetres). No wonder people find it easier to use the upper imperial part of the tape. (Interestingly, I have an old wooden folding rule dating from the 1930s, given to me by my late uncle who was an engineer, and which, like my surveyor’s tape, is marked in just millimetres on the metric side, making it just as easy to read. Unusually the other side is marked off in decimal-feet.)

Other measuring devices might well also inhibit a true understanding of how to measure in metric units. The late Pat Naughtin extensively documented how dual tapes, thermometers, and so on retarded metric learning. While it is easy to buy a Celsius-only thermometer (my local garden centre sells nothing but), that seems to be about all. My electronic kitchen scales can be switched between imperial and metric, while my electronic bathroom scales can show three readings – kg, pounds, and the dreaded stones (and arrived originally set to stones, meaning that anyone wanting to use something else had to then find the switch and change the setting). Even my car can be switched between metric and imperial for nearly all its computerised functions (and arrived set to imperial, except for the climate control and outside temperature displays, which are Celsius-only, no doubt reflecting the fact that the British public really do appear to have embraced metric temperatures).

It seems to me that there is a decision on the part of manufacturers of measuring devices to make using metric measurements as difficult as possible, thus prolonging the unnecessary use of imperial in our mostly metric world. Can all this be changed? Technically of course, yes – manufacturers could easily make metric scales and markings much easier (and the default), as well as giving us a choice as to whether we want metric-only devices or dual-marked ones (after all, we have a choice in most other things we can buy). In practice, however, for some reason, such choice in measuring devices seems non-existent, and will probably stay that way unless either the British public starts demanding metric-only (or at least metric-friendly) measuring devices across the board (not very likely), or the government mandates some proper metric-only standards at the consumer level (even less likely). All part of our Very British Mess.

Editor’s note: Details of metric supplies, including measuring tapes, can be found at the UKMA web site: http://www.ukma.org.uk/metric-supplies

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