Wednesday, October 09, 2013

Decimalisation

I just followed a recipe which called for 2 cups of flour, 2 ounces of butter, 1/2 cup cheese, 1 pinch of something, 1/4 cup cream, 1/4 cup some other liquid. Cut butter into flour using two knives (what? I'll just cut it and rub it as usual), add other stuff...and then drop the dough on a greased cookie sheet in one ounce portions.

But I don't know how much the dough weighs! We've just used a combination of the weirdest measures known to man. And if I did calculate the weight it would probably be in pounds/feet or kilowatts or Imperial Gallons. The US weights and measures system is a complete mess.

Wikipedia gives the "cup" style table. 

Liquid volume
Most common measures shown in italic font
Exact conversions in bold font
UnitDivisionsSI Equivalent
minim (min)~1 drop or 0.95 grain of water61.611519921875 μL
US fluid dram (fl dr)60 min3.6966911953125 mL
teaspoon (tsp)80 min4.92892159375 mL
tablespoon (Tbsp)3 tsp or 4 fl dr14.78676478125 mL
US fluid ounce (fl oz)2 Tbsp or 1.0408 oz av of water29.5735295625 mL
US shot (jig)3 Tbsp44.36029434375 mL
US gill (gi)4 fl oz118.29411825 mL
US cup (cp)2 gi or 8 fl oz236.5882365 mL
1 (liquid) US pint (pt)2 cp or 16.65 oz av of water473.176473 mL
1 (liquid) US quart (qt)2 pt0.946352946 L
1 (liquid) US gallon (gal)4 qt or 231 cu in3.785411784 L
1 (liquid) barrel (bbl)31.5 gal or 12 hogshead119.240471196 L
1 oil barrel (bbl)42 gal or 23 hogshead158.987294928 L
hogshead63 gal or 8.421875 cu ft
or 524.7 lb of water
238.480942392 L
The "cooking" table has another set of them.

Most of the rest of the world gets along with things that work in multiples of ten, and are based on each other so that calculations are much easier. It's not surprising that the Mars Climate Orbiter crashed
due to ground based computer software which produced output in non-SI units of pound-seconds (lbf×s) instead of the metric units of newton-seconds (N×s) specified in the contract between NASA and Lockheed.
Pound-seconds? In an interplanetary vehicle. I think it's really time to get with the SI program. Bite the bullet, USA.

England did, officially going from the arcane LSD monetary system (20 shillings in a pound, 12 pennies in a shilling, 21 shillings in a guinea, 2.5 shillings in a half crown) to a nice clean 100 pence in a pound.



It wasn't easy.



Since then, I gather from remarks British people make, that the rest of the SI system has more or less arrived (kilograms, liters etc.) with the traditional hold-out of the "mile" (which is 80 chains, or 8 furlongs, or 5280 feet or 1760 yards).

Mind you, a country which has to teach its kids how many drams in a hogshead instead of how many milliliters in a liter might explain the education gap in my last post.

Edited: typo


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