Kilderkin

An 18-gallon cask volume representing exactly half of a standard beer barrel.

Eighteen gallons, or 144 pints, and exactly half a barrel. The kilderkin is the cask a country pub took when a firkin would run out too quickly and a barrel would go stale before it emptied, which makes it the most quietly practical vessel in the hierarchy. The name is a corruption of the Middle Dutch kindeken, a little child, arriving in English through the Low Countries beer trade along with a good deal of brewing vocabulary. The word appears in English customs records from the fifteenth century, and the size has scarcely changed since. Like the firkin above it and the pin below, the kilderkin exists because cask ale has a short life once broached: the whole ladder of sizes is a response to that one fact.