I received a Christmas present of a useful airtight plastic food container, “perfect for food storage and organizing your pantry.” I looked at the information on its label about the quantities it would hold: 4.2 qt/134.4 oz. I immediately felt irritated that it was not an exact quantity in litres. What is wrong with the metric quantities we are now used to? I had sized it up with my eyeballs and reckoned it would hold about four litres.
Why is this firm not using metric? Is this yet another example of the “patriotic” retreat from all things European? I googled comparable products online, and found this Chester retailer advertising a container of similar size as containing 3.5 litres. I googled the name of the manufacturer of my new container – Gourmet – and found that they are in fact based in New York. So, they are using the non-metric measurements still in use in USA.
A little nostalgia after lunch
Being at the stage of post-prandial immobility from Christmas food, I then spent an hour or so checking up on these old measures, which were drilled into us at English primary school:
Liquids: 20 ounces (fl. oz) = 1 pint, 2 pints = 1 quart, 4 quarts = 1 gallon. We knew what these looked like as milk came in pint bottles, and watering cans contained gallons.
Weights: 16 ounces (oz) = 1 pound (lb); 14 pounds = 1 stone; 2 stones = 1 quarter; 4 quarters =1 hundredweight (cwt) 20 hundredweight = 1 ton (=2240 lb). (ton not to be confused with tonne, the metric measure of 1000kg).
In childhood, I learned what ounces of butter look like, and pounds of apples. Our own weights were measured in stones by the nurse with scales. I never got a grip on what a ton looked like, though I recall my brother used it for lorry-loads and railway trucks. I think our household used to buy coal by the cwt. A sack of coal weighed 16 stone = 2 cwt.
Twelve is divisible by 2, 3, 4 and 6
From this little trip into the past, one learns that our ancestors mostly shunned measures on the base of 10 (metric) and liked measures that divide easily by four. Didn’t they ever count with five digits of the hand? Actually, it is possible to count in 12s on the four fingers if you count all the segments of each finger of one hand (three segments x four fingers = 12).
Mathematicians are rather keen on the merits of base 12 counting. Having factors both four and three makes divisions much easier. 10/3 = 3.333, an awkward quantity, whereas 12/3=4, or 12/4=3. Where we do use a base 12 for counting, for instance 12 months of the year, it is easier to work the quarters (3 months). Eggs are more neatly packed in half dozens than in the long box of 10.
Historically it is known that different cultures have used different bases: Jews counted time in seven days; Mayans used base 20 and Babylonians base 60. The Egyptians used base 12, which is perhaps why units connected with time and astronomy (months, hours, degrees in a circle (360)) are base 12. But most of the world has now adopted base 10 with all the convenience of decimals, a system which could in practice be applied to any other base, depending how many beads you put on the string of the abacus before you move a bead on string two.
The metric system, using base 10, came to be adopted because of the scientific leadership of France at the time of growing trade and scientific research when standardising measurement was of growing importance. The British also tried to standardise at the same time by using the “Imperial” measures across all their colonies and trade, the measures quoted above that I was taught in school.
Let’s all go metric
The UK actually switched to metric in 1965, eight years before joining the EU. From then on for the next two decades at least, it was easy to purchase kitchenware, rulers, or measuring tape that always gave both the old imperial measures as well as the metric. More recently, it is more common just to find one’s purchase is only metric. Hence my surprise at my non-metric Christmas present.
But the further complication, which I only discovered by tapping in the numbers and trying to use the internet for conversions, is that the difference between “imperial” and American measures is often not made obvious by the websites. The symbols are the same.
I googled the labelled quantities of my container: 4.2 qts = 3.9751 litres. But 134.4 oz = 3.81871718 litres. So not equivalent. But the label says 4.2 qt/134.4 oz. Maybe, I sniffed, these manufacturers don’t consider kitchen measures need to be accurate in their litres equivalents. If I type in 4.2 quarts in ounces, I get 134.4 us fluid oz (as on the label); so this is correct according to US measurements. So, my confusion was because Google was not indicating whether its calculations were in British Imperial or US Customary. I didn’t even know there was a difference. I didn’t learn this in school.
The Encyclopædia Britannica site states:
A British Imperial quart is equal to 1.13 liters (or 40 fluid ounces) whereas a quart in US Customary system is 0.941 (32 fluid ounces). A gallon in imperial system is 160 fluid ounces while US is 128 fluid ounces.
How much does one cup of sugar weigh?
One reason why I was patiently exploring this on Christmas Day is because in my festive cooking I had been flummoxed by the variation in measurements used in recipes I had attempted from the internet. Most of the cheesecake recipes I looked up (from BBC Food, Mary Berry, Jane’s Patisserie etc.) used grams, but then suddenly I would flip through to one that needed cups (do I have a set of American measuring cups?) and required a baking tin measurement of 9 inches diameter.
I do like standardised metric measurement for my cooking kit and for my web searches. Just a pity about the French forcing us all to use base 10 instead of base 12.