I think it speaks for itself; some of these are now historical.
Just remember how hard it is to say millimeter and kilometer, before proceeding:
|barleycorn||⅓ inch, the length of The Standard Barleycorn1|
|inch||3 barleycorns (yup)|
|link||7.92 inches (0.66 ft)|
|foot||12 inches, feet that fit size 14 shoes|
|rod||¼ chain, 16½ feet|
|chain||22 yards, 100 links (792 in)|
|furlong||220 yards, 10 chains|
|mile||80 chains, 5,280 feet|
You can’t make this stuff up. Well, it seems like you can. It seems like somebody did, slowly, via committee.
A subset of these became standardized as the Imperial Units, which included Just 8 Convenient Units for describing length (bolded above). It cut down on about half the nonsense, but it’s still kinda crazy why we need so many units when we have place value numerals & SI prefixes for orders of magnitude.
But like the quote the future is here, it’s just not evenly distributed, most of these units are dead to most of us, who understand only feet & inches (probably to measure ourselves), yards (because of football), and miles (because of cars).
Let’s just use metric
I doubt there actually was such a thing. But it would be funny to imagine a single kernel, under glass, under glass. But seriously, the barleycorn was the base unit ↩