2780: Jack and Gill: of Liquid Jul 31, 2024

In SI units, there are certain standards by which measurements’ names are converted or not, so 100 grams technically converts to 1 hectogram, but you will never see this, and you would be more likely to hear 100,000 milligrams or 0.1 kilograms. This is also officially done in US customary units and unofficially in the imperial system.

For instance, ½ a cup* is almost always denoted as such, but may be referred to as a gill, particularly in measuring liquids like alcoholic drinks especially. Despite its orthographic similarity to ‘gill’ as in “of a fish”, it is pronounced /d͡ʒɪl/, extra proof of which is that ½ of a gill is a jack. You might assume that this was formed as a pun based on the nursery rhyme, but it was the other way around; the poetic words are in reference to King Charles I lowering the volume of a jack in 1625 in order to collect more on taxes, which then by definition made gill smaller, or in other words come tumbling after. The earliest, 17th century versions of the rhyme indeed use the spelling of ‘Gill’ and not ‘Jill’ as most would write it today.

*Very technically, a gill is ¼ of a pint, as pints are the basis of the system, but this is equal to ½ a cup.