The "quarter of London" mentioned by Magna Carta as the national standard measure for wine, ale, and grain[1] was ¼ ton or tun.
[6] In measures of weight and mass at the time of Magna Carta, the quarter was 1⁄4 ton or (originally 500 pounds).
[citation needed] By the time of the Norman French copies of the c. 1300 Assize of Weights and Measures, the quarter had changed to 512 lbs.
[7] These copies describe the "London quarter" as notionally derived from eight "London bushels" of eight wine gallons of eight pounds of 15 ounces of 20 pennyweights of 32 grains of wheat, taken whole from the middle of an ear;[8][9] the published Latin edition omits the quarter and describes corn gallons instead.
or quartier) came to mean 1⁄4 of a hundredweight: 2 stone or 28 avoirdupois pounds[11] (about 12.7 kg): this is its (only) statutory definition since 1993.
[15][16] The tun was subsequently redefined as 252 gallons, and the quarter was effectively ¼ pipe or butt.