Scottish gallon

In Scotland, a unit of liquid capacity, as a survival in the 19th century following the introduction of the imperial gallon in 1826, about 13.552 liters (about 2.9835 imperial gallons).

David I's Assize


The Assize of 1426

Item the bol sal contene in breid xxix inche within the burdis and abufe xxviij inche and a half evin oure thort, ande in depnes ix inche. The furlote sal contene twa galonis ande a pynte ande ilk pynt sal contene be wecht of cleir watter of Tay xlj unce, that is for to say ij pundis and ix unce troyis. Swa weyis the galone xx punde and viij unce; swa weyis the furlote xlj pundis. Ande the bol contenande four furlotis weyis viijxx and iiij pundis.† The old boll frist maid be King Dauid contenit a sextarn, the saxtarn contenit xij galonis of the auld mete, ande ilk galone weyit ten pundis trois and foure unce of diverse watteris. Swa weyit the boll vjxx iij pundis. Sua this new bol new maid weyis mar than the auld boll be xlj lib', quhilkis makis twa galounis and a half. And a chopyn of the auld mete ande of the new mete now ordanit ix pyntis and thre muchekynis.

Item, the boll shall contain in breadth twenty-nine inches within the boards, and above twenty-eight inches and a half, in a straight line from side to side, and nine inches in depth. The firlot shall contain two gallons and a pint, and each pint shall contain by weight of clear Tay water, forty-one ounces, that is to say two pounds and nine ounces Troy.

confirming that the troy pound being used has 16 ounces (41 = 2 ×16, + 9), which is explicitly stated in an earlier section of the document, not reproduced here.

So the gallon weighs twenty pounds and eight ounces; so the firlot weighs forty-one pounds.

Thus the gallon contains (20×16, + 8 = 328 ounces which, taking the Scottish troy ounce of 1427 at 480 grains¹ each of 0.06479 grams, suggests a capacity of about 10.2 liters.

And the boll containing four firlots weighs 164 pounds. The old boll first made by King David [I] contained a sextern, the sextern contained twelve gallons of the old measure, and each gallon weighed ten pounds Troy and four ounces of various waters. 

The old gallon (David I's) weighed "ten pundis trois and foure unce of diverse watteris", (164 ounces of a mixture of equal parts seawater, standing, and flowing water. If we take that to have a density of 

So the boll weighed 123 pounds. So this new boll weighs more than the old boll by forty-one pounds, which makes two and a half gallons. And a chopin of the old measure and the new measure now ordained, nine pints and three mutchkins.

 After this assize the gallon ceases to appear in definitions of liquid measures in the Scottish legal record. In Scotland, the pint played the role the gallon did in England. The gallon does appear in definitions of special units like the salmon barrel.


1. For the argument that the Scottish and English Troy ounces were identical at this date, see Connor and Simpson, page . 



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