The tun (Old English: tunne, Latin: tunellus, Medieval Latin: tunna) is an English unit of liquid volume (not weight), used for measuring wine,[1] oil or honey. Typically a large vat or vessel, most often holding 252 wine gallons, but occasionally other sizes (e.g. 256, 240 and 208 gallons) were also used.[2] The modern tun is about 954 litres.
The word tun is etymologically related to the word ton for the unit of mass, the mass of a tun of wine being approximately one long ton, which is 2240 pounds (1016 kg).
History
Originally, the tun was defined as 256 wine gallons;[nb 1] this is the basis for the name of the quarter of 64 corn gallons. At some time before the 15th century, it was reduced to 252 wine gallons, so as to be evenly divisible by other small integers, including seven.[nb 2]
He that ys a gawner owght to understonde there ys in a tunne lx systerns and every systern ys iiii galons be yt wyne or oylle.
He that is a gauger ought to understand that there is in a tunne 60 sesters, and every sester is 4 gallons, be it wine or oil.
—Untitled manuscript, consisting of a list of various customs duties, dated 15 July 1507[2][3][4]
With the adoption of the Queen Anne wine gallon of 231 cubic inches in 1706 the tun approximated the volume of a cylinder with both diameter and height of 42 inches.[nb 3] These were adopted as the standard US liquid gallon and tun.
When the imperial system was introduced in 1824 the tun was redefined in the UK and colonies as 210 imperial gallons. The imperial tun remained evenly divisible by small integers.[nb 4] There was also little change in the actual value of the tun.[nb 5]
Standard tuns of wine came to serve as a measure of a ship's capacity.[5]
^"Naval Architecture for All". United States Bureau of Transportation Statistics. Retrieved October 13, 2008.. "Historically, a very important and standard cargo for European sailing vessels was wine, stored and shipped in casks called tuns. These tuns of wine, because of their uniform size and their universal demand, became a standard by which a ship's capacity could be measured. A tun of wine weighed approximately 2,240 pounds, and occupied nearly 60 cubic feet." (Gillmer, Thomas (1975). Modern Ship Design. United States Naval Institute.) "Today the ship designers standard of weight is the long ton which is equal to 2,240 pounds."
