Worried

[Colin WhittakerParticipant @colinwhittaker20544]

Primary school I think was Imperial. Secondary school up to 16 was Metric. The sixth form was back in Imperial. Then University in Metric. Then the Oilfield in American Imperial before almost immediately the Oil Company decided to go Metric.

So now I am pretty well ambidextrous.

Pressure testing in kPa still makes me nervous and measuring reservoir volumes in acre feet is just dumb. I can remember my weight in university in stones and pounds but today I know it only in kgs.

And I almost beat the university challenge student to. "What was the price on the Mad Hatter's hat in decimal currency?"

Colin

[Peter G. ShawParticipant @peterg-shaw75338]

Well now, as someone in their mid-70's I went to school from 1948 to 1959 and was taught imperial measurements, weights & currency (£sd), and therefore I should be totally at home with imperial. However, I always struggled with converting up and down between the various units, inches to feet to yards to miles, ounces to pounds to stones to hundred weights to tons, pennies to shillings to pounds (sterling) etc. Things like adding 3/32 to 1/4 were, and still are, fraught with errors and mistakes.

Decimal conversion for money, apart from an initial hiccup or three, is so much simpler and easier to use. And so, when metric became all the rage in the 1970's, I deliberately set about making a set of kitchen cabinets wholly in metric, and since then have worked in metric as much as possible, so much so that in some respects I now think in metric. Frankly, it's so much easier that I fail to understand how anyone could ever want to use imperial.

Of course, there are some things that haven't yet changed, eg body weights, but even here I'm slowly beginning to think in kgs. Body height I haven't yet conquered, and I still use mpg and my spreadsheet for car fuel consumption automatically converts from litres to gallons before telling me that my car does 38.7mpg. Distances on signs – when you can find them, that is – are still in miles or yards, but even so, I now think in metres rather than yards. Incidently, sometime ago, I think I saw something that implied that distance measurements for roads and paths in the UK had to be in either imperial only, or both imperial and metric simultaneously, with metric only being illegal. Anyone remember this, or know anything about it?

An anecdote. Recently I went to a local cafe and had a cup of coffee, price £2.60. I went to pay with a £20 note. The young woman behind the bar brought out the calculator, so I went "That's £18, no £17.40 in change." Her calculator agreed! A few days later I went to my elder grand-daughter's house. She is 12 yrs, 9 months and in top set in everything at school. I said to her, "If a pay for a cup of coffee costing £2.60 with a £20 note, how much change should I receive?" The answer came back immediately, no hesitation, no thinking time, "£17.40". I then told her the story, finishing up with "And that's why you are in top set at school".

In respect of centimetres, I don't use them if I can avoid them. Unfortunately, they have become so ingrained into common parlance now that it's almost impossible to avoid their use, so reluctantly, I do sometimes use them, usually as a conversion from millimetres.

Peter G. Shaw

[Neil WyattModerator @neilwyatt]

Posted by Andrew Johnston on 26/09/2019 11:45:36:

Posted by Paul M on 26/09/2019 09:25:05:

I remember at infant school we had to recite our times tables every day, and had mental arithmetic tests every Friday afternoon. A good grounding in my opinion.

Not in mine! At primary school we had a chart on the wall covering all pupils with coloured stars for each table recited. I was always at the bottom, and never did complete up to 12 times table. My argument was that recitation didn't equal understanding, which was more important. Of course I was also bone idle and stroppy. Amazing really that I are an engineer.

I just worked then out as I went along by adding the numbers. They never had the wits to ask us random pairs of numbers.

Mu mum said as long as you remember 7×8=56 you won't be caught out.

[Neil WyattModerator @neilwyatt]

Posted by Paul M on 26/09/2019 09:25:05:

To sum up this country, in my town you can find direction signs for pedestrians that make me laugh. Any distance less than a mile is in metres and any distance above a mile is in miles.

There's a section of no overtaking road near Swadlincote where for about a mile the distances to the end of the zone are given in yards – to a precision of one yard. For exampel, say '1027 yards'.

I would like to know if they put in the poles and then measured the distances or vice versa.

Neil

[BazyleParticipant @bazyle]

I certainly appreciate that when I think 5×4 the answer 20 is just there in my head without effort but it's the "1&8" that amuses me is still there too.

Who remembers the 17/6 (seventeen & sixpenny) note? If you do don't let on for a day or two so the youngsters have time to ask grandpa.

Are there any countries left with a non-decimal currency? I think the part of Africa I was in went decimal before the UK but somewhere I still have the odd coin with a hole in the middle.

[Nick Clarke 3Participant @nickclarke3]

Posted by Neil Wyatt on 26/09/2019 17:17:50:

Posted by Paul M on 26/09/2019 09:25:05:

To sum up this country, in my town you can find direction signs for pedestrians that make me laugh. Any distance less than a mile is in metres and any distance above a mile is in miles.

There's a section of no overtaking road near Swadlincote where for about a mile the distances to the end of the zone are given in yards – to a precision of one yard. For exampel, say '1027 yards'.

I would like to know if they put in the poles and then measured the distances or vice versa.

Neil

Or didn't bother measuring it at all on the assumption no one else would either?

[Nick Clarke 3Participant @nickclarke3]

One useful conversion is 750W is approximately 1HP – as older machinery is equipped with fractional horsepower motors while the smaller new stuff is measured in Watts.

[Nick Clarke 3Participant @nickclarke3]

Posted by bill ellis on 26/09/2019 11:35:13:

Same with a persons weight, I can visualise 14st but 89Kg is not as easy.

I can't ever visualise me being either14st or 89kg again

[MichaelRParticipant @michaelr]

What bothered me when we went decimal I lost a 140 pence from my pound sterling, or did I ?, !!

Mike.

[Nick Clarke 3Participant @nickclarke3]

Posted by MichaelR on 26/09/2019 19:09:32:

What bothered me when we went decimal I lost a 140 pence from my pound sterling, or did I ?, !!

Mike.

On decimal day morning, just after opening time I went into a pub (not quite legally, I have to admit) bought a bottle of Guinness for the sake of spending my first decimal money. After a lot of '2.4 pence is a penny' and 'a shilling is 5p' and 'there are a hundred p in a pound' sort of discussions between the two bar staff I was given my change from a pound note.

Counting it up a bit later for the novelty value of seeing the decimal coins I found I had more than a pound in change ………..!

[HOWARDTParticipant @howardt]

I went from imperial in mechanical engineering at college in my third year to another college for my fourth year which was metric. Somehow I still managed to be one of six out of twenty that passed at then end of year and was offered a place at university, but had to turn it down. Throughout my working life I had no problem working in either units.

[blowlampParticipant @blowlamp]

I like the metric system, but I don't get the way that is often used nowadays of describing an object as (say) 8 times smaller than something – whats wrong with it being 1/8th the size? Seems to me that you've got to be a mental gymnast to work that one out… Think like it's 8 times bigger but then reverse big into small.

[Jon LawesParticipant @jonlawes51698]

What a miserable bunch. Light a candle rather than cursing the darkness.

I don't know how many hoops to a rood or chains to a gill, but then I also don't have rickets or TB, so swings and roundabouts.

[Michael GilliganParticipant @michaelgilligan61133]

 < deleted >

Edited By Michael Gilligan on 26/09/2019 22:12:15

[Nigel Graham 2Participant @nigelgraham2]

I'm fairly sure the (anonymous??) Greta & The Good of the ISO loftily allow the Bar when measuring a useful pressure, instead of their mathematically-neat Pascal (even kilos of 'em).

The Pascal is useless! You need 100 000 of them just for 1Bar (14.7psi). It is too small for real pressures as in tyres, boilers and hydraulics and geology. Yet is too big for acoustics, in which sound pressures are measured in µPa and decibels (dB, not linear units on their own, like pints and feet, but logarithms of ratios of the linear unit, here the µPa, to a base level)

To give a handle on that, the 0dB reference-level for sound pressures in air = 20µPa, which is the faintest a fully-healthy human ear can hear. It is a staggeringly tiny 10^(-11) or 1 / 1 00 000 000 000, Bar. Marine sonar's reference-level (or 0dB) = just 11Pa.

Our maximum – and it will harm your ears – is often quoted as 120dB, which is 1 000 000 times that pressure so is a crushing 20 Pascals.

(Cor!. Been retired three years now from working for a sonar manufacturer, and can still remember [ALT + 0181] to type the micro symbol!)

++

Others mention perches. They went out of use long ago, but Network Rail seems still to use Miles and Chains (22 yards) for distances..

+++

The Statute Mile is still the only legal unit for road miles in the UK, so really, short distances ought be in Yards, not metres.

+++

I used to contribute to a branch of Wikipedia called Answers (dot.com). Now frozen, it was a large, classified Q&A site with all manner of topics, including the sciences and mathematics.

I soon twigged most of the questions on the latter's section on mensuration were almost certainly from American school-children wanting others to do their homework for them, on US Imp / Metric conversions. There were some adults with real-life problems too, like swimming-pool disinfectant dosing volumes: I think some had bought chemicals with metric units on the instructions.

Sadly for them, though darkly amusing for me, there was a small coterie of regular correspondents who'd really tie the poor blighters up in knots. To, say, "How many kilometers [sic] in 40 miles?" these characters would invoke Algebra needlessly and Dimensional Analysis both needlessly and wrongly, convert via inches and cms… and sometimes their own arithmetic was incorrect! Oh, and its 64. (An easy mental-arithmetic one, with that number, at 50 times 8/5.)

I would reply saying it does not involve Dimensional Analysis or even Algebra, just a multiplier you can easily find in a book or on-line! I'd also point out it's "~tres" not "-ters", on these French words.

++

Why though do car manufacturers delight in quoting engine powers in kiloPoules (1000-hens??) and luggage space in litres (travelling aquarium, rather than long enough for a 7.25"g 9F?) ?

'

To think I learnt, or at least was taught, Compound Multiplication… I think I could still work out how to calculate the price of 3cwt 2qrs of coal at £4 10s 6d a ton! As long as draught ale comes in pints, we'll be right!

[Paul LousickParticipant @paullousick59116]

When I started work as a mechanical engineer draftsman (originally draughtsman, sorry draftperson), we used imperial units and a year later had to learn everything im metric. No problem I thought, 1/2" in metric is 0.5 inches. Wrong !

The metric measurement which I dislike is litres / 100 km instead of the old mpg for petrol consumption because 100 is not a base unit and the equivalent metric unit should be km / litre.

Paul

[Nigel Graham 2Participant @nigelgraham2]

Oops. First sentence should read "… Great and The Good of ISO…"

I blame the slip on hearing too much of Her Nibs from Sweden on the radio news..

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Mike Poole on 26/09/2019 13:09:25:

Is anyone actually interested in buying fuel in litres? I still think in miles per gallon and so do my cars, litres per 100km does not seem to be of any interest to anyone in the UK.

Mike

Hi Mike, so what's stopping anyone thinking in miles per litre. My car does about 11 miles per litre, i.e. when I buy fuel I only have the choice of buying in litres but my speedo thing only registers miles, 600 miles divided by 55 litres = about 11 miles per litre, simple.

Regards Nick.

P.S. Oh! and my car doesn't complain that it has to burn litres and drives for miles, just flashes a fuel pump icon when the equation is in danger of reaching zero miles per anything.

 

Edited By Nicholas Farr on 27/09/2019 00:29:06

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Paul Lousick on 26/09/2019 23:32:33:

[ … ]

The metric measurement which I dislike is litres / 100 km instead of the old mpg for petrol consumption because 100 is not a base unit and the equivalent metric unit should be km / litre.

.

I’m pretty sure that fuel consumption should actually be measured in litres per km

or, of course, gallons per mile

… the inverse seems perverse.

MichaelG.

Edited By Michael Gilligan on 27/09/2019 00:32:53

[HopperParticipant @hopper]

And far be it from you to be perverse of course!

[Brian GParticipant @briang]

I suspect MPG and km/100l became established because every performance number for cars obeys the "bigger is better" principle which doesn't require explanation or understanding.

Brian

[Michael GilliganParticipant @michaelgilligan61133]

Sorry, Brian … I think you missed my point

It was about which way up the ratio should be expressed.

There is a good clue in the expression “fuel consumption”

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Pedant Alert!

Only amateurs and Jeremy Clarkson take MPG seriously because it's grossly unscientific. First the heat value of fuel depends on its density rather than volume – this makes heavy fuels like diesel look excessively better than petrol and LPG. Secondly MPG is only meaningful if the engines being compared are moving the same weight over the same journey at the same speed. Even measuring MPG on the same car is dubious: Traffic Jam, cruising at 56mpg on flat empty motorway, and racing over the Alps produce different results.

The grown-ups measure performance using a basket of measures, also imperfect but less so:

The preferred measure of engine goodness is CO₂ in grams per km measured under controlled conditions. Other emissions are equally important. CO, Hydrocarbons, Nitrous Oxides and Particulates are all measured in mg/km. Ideally these should be zero.

Unlike children, grown-ups are liable to be dishonest about measurements that cost them money. They cheat, lie and obfuscate. Remember Volkswagen…

Dave

 

Edited By SillyOldDuffer on 27/09/2019 09:20:11

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 27/09/2019 09:17:52:

[ … ]

Even measuring MPG on the same car is dubious: Traffic Jam, cruising at 56mpg on flat empty motorway, and racing over the Alps produce different results.

[ … ]

.

Which are displayed convincingly [and reasonably accurately] on my dashboard display.

Analogue reading of “instantaneous” mpg

Digital reading of ‘cumulative’ mpg since last reset

Digital reading of “estimated distance available if you continue driving as you have been in the last few minutes”

MichaelG.

[CirclipParticipant @circlip]

Ahh, yes, BUT, now we have a new boy on the block. Thanks to the auto cut off feature of most (All?) new cars to boost the MPG/km/ltr figures what price the forecourt calculators? Yet another complication, "This hybrid does 124MPG" ??????? by what parameter?

Regards Ian.

[Author]

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