Stone (unit)

The stone or stone weight (abbreviation: st.) is an English and imperial unit of mass now equal to 14 pounds (6.35029318 kg).

England and other Germanic-speaking countries of northern Europe formerly used various standardised "stones" for trade, with their values ranging from about 5 to 40 local pounds (roughly 3 to 15 kg) depending on the location and objects weighed. The United Kingdom's imperial system adopted the wool stone of 14 pounds in 1835. With the advent of metrication, Europe's various "stones" were superseded by or adapted to the kilogram from the mid-19th century on. The stone continues in customary use in Britain and Ireland used for measuring body weight, but was prohibited for commercial use in the UK by the Weights and Measures Act of 1985.

The name "stone" derives from the use of stones for weights, a practice that dates back into antiquity. The Biblical law against the carrying of "diverse weights, a large and a small" is more literally translated as "you shall not carry a stone and a stone (אבן ואבן), a large and a small". There was no standardised "stone" in the ancient Jewish world, but in Roman times stone weights were crafted to multiples of the Roman pound. Such weights varied in quality: the Yale Medical Library holds 10 and 50-pound examples of polished serpentine, while a 40-pound example at the Eschborn Museum is made of sandstone.

The English stone under law varied by commodity and in practice varied according to local standards. The Assize of Weights and Measures, a statute of uncertain date from c. 1300, describes stones of 5 merchants' pounds used for glass; stones of 8 lb. used for beeswax, sugar, pepper, alum, cumin, almonds, cinnamon, and nutmegs; stones of 12 lb. used for lead; and the London stone of ​12 12 lb. used for wool. In 1350, Edward III issued a new statute defining the stone weight, to be used for wool and "other Merchandizes", at 14 pounds, reaffirmed by Henry VII in 1495.

In England, merchants traditionally sold potatoes in half-stone increments of 7 pounds. Live animals were weighed in stones of 14 lb; but, once slaughtered, their carcasses were weighed in stones of 8 lb. Thus, if the animal's carcass accounted for ​814 of the animal's weight, the butcher could return the dressed carcasses to the animal's owner stone for stone, keeping the offal, blood and hide as his due for slaughtering and dressing the animal. Smithfield market continued to use the 8 lb stone for meat until shortly before the Second World War. The Oxford English Dictionary also lists:

The Scottish stone was equal to 16 Scottish pounds (17 lb 8 oz avoirdupois or 7.936 kg). In 1661, the Royal Commission of Scotland recommended that the Troy stone be used as a standard of weight and that it be kept in the custody of the burgh of Lanark. The tron (or local) stone of Edinburgh, also standardised in 1661, was 16 tron pounds (24 lb 1 oz avoirdupois or 9.996 kg). In 1789, an encyclopedic enumeration of measurements was printed for the use of "his Majesty's Sheriffs and Stewards Depute, and Justices of Peace, ... and to the Magistrates of the Royal Boroughs of Scotland" and provided a county-by-county and commodity-by-commodity breakdown of values and conversions for the stone and other measures. The Scots stone ceased to be used for trade when the Act of 1824 established a uniform system of measure across the whole of the United Kingdom, which at that time included all of Ireland.

This page was last edited on 23 May 2018, at 16:20.
Reference: under CC BY-SA license.

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