@cstross The UK has also been on the metric inch since like the 1930s. Saved our bacon in WWII because American-machined parts *weren't* a few thou per inch out.
Of course, in practice both the US and the UK had been on the metric inch for a while before then because the (I think Swedish) chap making the gauge blocks got fed up with having to maintain two product lines and split the difference between the two inches.
It's worse than that. The UK Arms industry (RSAF Enfield) used their own "Enfield Inch" standard from the 1850s for measurements under 2 inches, and the "Imperial Inch" (0.0004" larger) above that size. The "Metric Inch" was much later (1930) and 0.0000017" longer than the "Imperial Inch" or 0.000002" shorter than the US one. It caused problems with gun manufacture during WW2 in that US and UK parts weren't interchangeable. A more recent difficulty was the licensing of... 1/
...the Pattern 1853 Enfield Rifle to an American company for reproduction/reenactment purposes. The UK manufacturer supplied the drawings, dies, and various gauges, plus an original rifle as a pattern/test piece, and the US company set to work. They then complained that their parts would not interchange with the original rifle, despite precisely matching the drawings... "Are you using the Enfield Inch?" was the reply "We sent you a standard". "Er, what?" "Oh crap." ... 2/
...explanation followed: "There's a small wood box with sliding top and a gauge block inside it marked Enfield Inch; that's the unit used in all the drawings."
"Oh." they said, and retooled for the smaller "Inch".
Problem solved.
I remember being horrified by the "Bushel" and "Barrel" measures being different according to the item being measured - the old "Mathematical Tables" books had a reference section on the back page for some of them.
The old units linger on...
UK Beer is still sold in "Pints" - a somewhat arbitrary measure in some places - Shipping containers use the "TEU" (Twenty-Foot Equivalent Unit) for size, Steel drums are 200 litre, 55 (U.S) or 44 (UK) gallon capacity - and they're all the same size, and so on. At least we've ditched Apothecaries Measure and (nearly) everything except gold is measured in grams & kilograms these days. 4/last. 3:O))>
@cstross @Cadbury_Moose @tienelle
In what universe are you planning to substitute lead shot for popcorn in your cooking recipes?
@cstross @Cadbury_Moose @tienelle
Sorry, Charlie, but I don't know how you can possibly arrive at this conclusion about recipes if you cook regularly.
I cook and bake with US and non-US cookbooks, using both volume and metric weight measurements, and this is not how *either* of them work.
No recipe specifies 1 measuring cup of each ingredient, regardless what. That's as absurd as every recipe specifying 500 g of every ingredient. Either way you're not going to get cake or bread out of it.
@cstross @Cadbury_Moose @tienelle
We're entering the realm of complete absurdity now.
If you cook measuring in grams and ml, you *do* measure by volume as well as weight! What exactly do you think ml is a unit of?
It's not weight, except in the unique case of water at a specified temperature.
As I said, I *regularly* cook with recipes that specify grams (pro bakers commonly use it in specifying bread proportions.) There's no real difference in convenience between the two.