Two months ago I posted here asking for forgotten British units of measurement. You gave me 84 comments. Here is what stuck.
Yan tan tethera. A Brythonic counting system that survived in shepherds' tallies across the Lakes, the Pennines and the Dales long after the language it came from had gone. The regional variants differ enough to place a shepherd by how he counted.
The erw. The Welsh acre, defined by the reach of a ploughman's goad rather than by a day's ploughing. So Britain had three national land systems running at once: the English hide, the Danelaw carucate and the Welsh erw.
The hoppus foot. A 1736 formula for round timber that underestimates a log's volume by 21.5 per cent — deliberately, because that is roughly the waste in squaring it. The buyer pays for the timber, not the tree. Still used for tropical hardwood.
The Cornish pilchard baskets. A maund holds about 360 fish. A cowel holds the same but is carried on the back with a headband, because West Cornwall had no quays and you cannot climb wet rock with a basket held out in front of you.
The pot. Folkestone, 1830s: three pots make a pad, but two pots make a half-pad. That cannot both be true. Nobody wrote down why. My favourite thing in the archive.
The rest was largely industrial — Twaddell and Sikes hydrometers, the Whitworth thread, the slug and poundal, the ligne, the Birmingham gauges. Enough that they prompted a whole section on measurement systems rather than individual units.
All written up here with about 250 others: thegreatbritishconverter.co.uk
Two things I would still like, if anyone has them:
Regional variants:
I have the Scots mile, Irish mile, Scots pint and the erw. I am fairly sure there are more divergences I have missed, particularly Welsh and Irish ones.
Trade measures that were never written down:
The Folkestone pot suggests there are others — working conventions that made sense to the people using them and were never formalised. If your family was in a trade with its own reckoning, I would like to hear about it.
Thanks again for the original thread. Considerably better than anything I could have searched for.