19 August 2005

Since learning about it in Mrs. Clarke’s third-grade class (back in 1978), I’ve been a fan of the metric system, though I rarely use it. As Americans, we’re surrounded by archaic units of measure — we’re immersed in them. At the box factory, I deal in inches and fractions-of-inches all day long. (We also deal with a base-sixteen world here. I can convert sixteenths nearly as easily as tenths.)

For me, one of the most confusing aspects of the metric system has been temperature. I understand that to convert fahrenheit to celsius, one subtracts thirty-two and multiplies by nine-fifths. Or five-ninths. Or whatever. I understand this intellectually, but for some reason, the whole procedure is so semantically complex that I’ve never bothered.

In a recent AskMetafilter thread on the metric system, somebody restated the problem in a way that suddenly made sense to me: don’t think “nine-fifths”, think “1.8”. Yes, I know these are identical terms, and I should have done my own conversion long ago. But I never have. Now, after learning to use “1.8”, the whole fahrenheit-celsius conversion thing is a piece of cake. It was instantaneously clear. Everything clicks.

0 degrees celsius is 32 degrees fahrenheit (cold)
10 degrees celsius is 50 degrees fahrenheit (cool)
20 degrees celsius is 68 degrees fahrenheit (room temperature)
30 degrees celsius is 86 degrees fahrenheit (warm)
40 degrees celsius is 104 degrees fahrenheit (hot)

Now I can add temperature to my metric arsenal. (Ironically, it interests me less to know that I way 86 kilograms in metric than to know that I weigh 13-1/2 stone in whatever antiquated British system uses that for a measure. I’ve always thought that stoneweight was fun!)

For sheer complexity, I don’t know of anything more confusing than the British monetary system before decimalizaton.

OLD MONEY                                 NEW MONEY (after 1971)
� (libra)    = pound                      �  = pound
s (solidus)  = shilling                   
d (denarius) = penny/pence                p = [new] penny/pence (pee)
�1,3/6 = 1 pound, 3 shillings, 6 pence    �1.50 = 1 pound, 50 pence
OLD COIN/NOTE                   VALUE       NEW COINS
farthing                        1/4 d
halfpenny (ha'penny)            1/2 d
penny (copper)                    1 d
..............................................1/2 p (discontinued)
twopence (tuppence)               2 d
   -a silver coin, pre-1643, and a copper coin from the reign of 
    George III (1738-1820).
................................................1 p
threepence (thruppence)           3 d
groat 1351-1662                   4 d
fourpence 1836-1856               4 d
................................................2 p
sixpence (tanner)                 6 d
   -note this is not the same as the tenner, a 10-shilling note.
shilling (bob)                   12 d...........5 p
florin                            2 s..........10 p
half crown                        2/6
crown                             5 s 
   -a commemorative coin, rather than common currency.
half-sovereign/half-pound        10 s..........50 p
   -the half-sovereign and sovereign coins were gold and worth 
    far more than the equivalent notes, at least in the 20th century. 
sovereign/pound (quid)           20 s...........�1 coin & note = 100 p
   -the modern 50p and �1 coins are not gold.
guinea                           21 s     equiv �1.05 
   -the guinea has not been minted since 1813, but professional 
    fees and prices for luxury items are still quoted in guineas.

For even more info, check out the wikipedia article. (Last night, Andrew and I had a conversation about determining the value of various monetary sums mentioned in Patrick O’Brian and Jane Austen novels. This page has some info on the subject (look to the bottom).)


On 19 August 2005 (12:31 PM),
Lynn said:

One of the things we struggle with here at work is trying to convert liters, cubic inches and horsepower. No formula ever seems to work well.

On 19 August 2005 (04:49 PM),
Denise said:

Who gives a hoot about this? Where are my rabbits????

Ok – just kidding. I worked with China all the time in my NOW OLD job (as of this minute) and the conversions drove me crazy on a regular basis!

Why can’t we just conform?

On 19 August 2005 (07:19 PM),
Andrew Parker said:

Ah, third grade. When our country was optimistic enough to imagine that the US would adpot “SI” by 1992. *That* makes it seem like a long time ago, eh?

Google now does most conversions you’re likely to need, which is cool.

On 20 August 2005 (07:36 AM),
dowingba said:

Your little celsius conversion method doesn’t exactly work properly. Using your formula, -40 fehrenheit is -129.6 celsius; when in fact they should both be -40.

On 20 August 2005 (03:22 PM),
Mom said:

An easier conversion method from Celsius to Fahrenheit — one suggested by my Aussie friends — is to double the Celsius temperature and add 15. The result isn’t quite as accurate as the Metafilter method but is easy to do in my head (which isn’t real mathematical). I find myself having to convert Fahrentheit into Celsius quite often for my Canadian, Australian, and English friends. We are indeed in the minority in the world.

On 26 August 2005 (10:05 AM),
Jeff said:


I think you mis-multiplied somewhere… you need to add 32 to make the conversion work-out properly:

1.8 x -40 = -72 + 32 = -40


1.8 x 10 = 18 + 32 = 50
1.8 x 20 = 36 + 32 = 68, and so on…

I missed this entry, as I was in Canada when it was written. The plains of the Peace Country (Alberta) can have quite a temperature variation… one day it was 27, the next it was 7, and then it literally froze the day after that. Then it was back up to 28 by the next day… pretty crazy.

I would suggest the following Centigrade conversion scale for those living in northern Alberta:

10 degrees celsius is 50 degrees fahrenheit (warm)
20 degrees celsius is 68 degrees fahrenheit (hot)
30 degrees celsius is 86 degrees fahrenheit (scorching hot)
40 degrees celsius is 104 degrees fahrenheit (surface of the sun)

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