#### llondel

##### HE

Little things like knowing that an acre was originally a chain wide and a furrow long (furlong). Then knowing that there are ten chains to a furlong and that a chain is 22 yards, the length of a cricket pitch.

Also the confusing array of volumetric units, where it turns out that fluid ounces in the UK and US are not the same, and the fact that in the US there are 16 fluid ounces to a pint, whereas in the UK there are 20. We both have the same number of pints to the gallon, which is why US gallons are smaller than proper imperial ones.