Sq 7777
A Gallon is 1/9 of a firkin.
A firkin is a small beer cask, holding nine Imperial gallons (72 pints).
Two firkins make a kilderkin
Two kilderkins make a barrel
One-and-a-half barrels make a hogshead of 48 gallons (384 pints).
I hope this clears it up.
(I copied this from another site, and looking at it the maths doesn't add up! Not sure if a hogshead is 48 or 54 gallons)