The unit is descended from theRomanlibra (hence the symbollb, descended from thescribal abbreviation,℔). The English wordpound comes from the Romanlibra pondo ('the weight measured inlibra'), and iscognate with, among others,GermanPfund,Dutchpond, andSwedishpund. These units are now designated as historical and are no longer in common usage, being replaced by themetric system.
The word 'pound' and its cognates ultimately derive from a borrowing intoProto-Germanic of the Latin expressionlibra pondo ('the weight measured inlibra'), in which the wordpondo is theablative singular of the Latin nounpondus ('weight').[7]
The yard or themetre shall be the unit of measurement oflength and the pound or thekilogram shall be the unit of measurement of mass by reference to which any measurement involving a measurement of length ormass shall be made in the United Kingdom; and—
(a) the yard shall be 0.9144 metre exactly;
(b) the pound shall be0.45359237 kilogram exactly.
Anavoirdupois pound is equal to 16 avoirdupoisounces and to exactly 7,000grains. The conversion factor between the kilogram and the international pound was therefore chosen to be divisible by 7 with aterminating decimal representation, and an (international) grain is thus equal to exactly64.79891milligrams.
In the United Kingdom, the process ofmetrication andEuropean units of measurement directives were expected to eliminate the use of the pound and ounce, but in 2007 the European Commission abandoned the requirement for metric-only labelling on packaged goods there, and allowed for dualmetric–imperial marking to continue indefinitely.[12][13]
In the United States, theMetric Conversion Act of 1975 declared the metric system to be the "preferred system of weights and measures" but did not suspend use ofUnited States customary units, and the United States is the only industrialised country where commercial activities do not predominantly use the metric system,[14] despitemany efforts to do so, and the pound remains widely used as one of the key customary units.[15][16]
Historically, in different parts of the world, at different points in time, and for different applications, the pound (or its translation) has referred to broadly similar but not identical standards of mass or force.[a]
Comparison of the relative sizes of avoirdupois, troy, Tower, merchant and London pounds
Various historic pounds from a German textbook dated 1848
Thelibra (Latin for 'scale'/'balance') is anancient Roman unit of mass that is now equivalent to 328.9 g (11.60 oz).[17][18][19] It was divided into 12unciae (singular:uncia), or ounces. Thelibra is the origin of the abbreviation for pound, "lb".
A number of different definitions of the pound have historically been used in Britain. Among these are theavoirdupois pound, which is the common pound used for weights, and the obsoletetower,merchants' andLondon pounds.[20] Thetroy pound and ounce remain in use only for the weight ofprecious metals, especially in their trade. The weights of traded precious metals, such as gold and silver, are normally quoted just in ounces (e.g. "500 ounces") and, when the type of ounce is not explicitly stated, thetroy system is assumed.
Thepound sterling money system, which was introduced during the reign ofKing Offa ofMercia (757–96), was based originally on a Saxon pound of silver. After theNorman conquest the Saxon pound was known as the tower pound or moneyer's pound.[21] In 1528, during the reign ofHenry VIII, the coinage standard was changed by parliament from the tower pound to thetroy pound.[22]
The avoirdupois pound, also known as the wool pound, first came into general use c. 1300. It was initially equal to 6,992 troy grains. The pound avoirdupois was divided into 16 ounces. During the reign ofQueen Elizabeth I, the avoirdupois pound was redefined as 7,000 troy grains. Since then, thegrain has often been an integral part of the avoirdupois system. By 1758, two Elizabethan Exchequer standard weights for the avoirdupois pound existed, and when measured in troy grains they were found to be of 7,002 grains and 6,999 grains.[23][24][b]
In the United Kingdom, weights and measures have been defined by a long series of Acts of Parliament, the intention of which has been to regulate the sale of commodities. Materials traded in the marketplace are quantified according to accepted units and standards in order to avoid fraud. The standards themselves are legally defined so as to facilitate the resolution of disputes brought to the courts; only legally defined measures will be recognised by the courts. Quantifying devices used by traders (weights, weighing machines, containers of volumes, measures of length) are subject to official inspection, and penalties apply if they are fraudulent.
TheWeights and Measures Act 1878 (41 & 42 Vict. c. 49) marked a major overhaul of the British system of weights and measures, and the definition of the pound given there remained in force until the 1960s. The pound was defined thus (Section 4): "The ... platinum weight ... deposited in the Standards department of the Board of Trade ... shall continue to be the imperial standard of ... weight ... and the said platinum weight shall continue to be the imperial standard for determining the imperial standard pound for the United Kingdom". Section 13 states that the weightin vacuo of this standard shall be called the imperial standard pound, and that all other weights mentioned in the act and permissible for commerce shall be ascertained from it alone. The first schedule of the act gave more details of the standard pound: it is a platinum cylinder nearly 1.35 inches (34 mm) high, and 1.15 inches (29 mm) diameter, and the edges are carefully rounded off. It has a groove about 0.34 inches (8.6 mm) from the top, to allow the cylinder to be lifted using an ivory fork. It was constructed following the destruction of the Houses of Parliament by fire in 1834, and is stamped "P.S. 1844, 1 lb" (P.S. stands for "Parliamentary Standard").
The BritishWeights and Measures Act 1878 (41 & 42 Vict. c. 49) said that contracts worded in terms of metric units would be deemed by the courts to be made according to the Imperial units defined in the Act, and a table of metric equivalents was supplied so that the Imperial equivalents could be legally calculated. This defined, in UK law, metric units in terms of Imperial ones. The equivalence for the pound was given as 1 lb =453.59265 g or 0.45359 kg, which made the kilogram equivalent to about2.2046213 lb.
In 1883, it was determined jointly by the standards department of the British Board of Trade and the Bureau International that0.4535924277 kg was a better approximation, and this figure, rounded to0.45359243 kg was given legal status by anOrder in Council in May 1898.[25]
In 1959, based on further measurements and international coordination, theInternational Yard and Pound Agreement defined an "international pound" as being equivalent to exactly0.45359237 kg.[25] This meant that the existing legal definition of the UK pound differed from the international standard pound by0.06 milligrams. To remedy this, the pound was again redefined in the United Kingdom by theWeights and Measures Act 1963 to match the international pound, stating: "the pound shall be 0.453 592 37 kilogramme exactly",[11] a definition which remains valid to the present day.
The2019 revision of the SI means that the pound is now defined precisely in terms of fundamental constants, ending the era of its definition in terms of physical prototypes.
A troy pound (abbreviated lb t[26]) is equal to 12troy ounces and to 5,760 grains, that is exactly373.2417216 grams.[27] Troy weights were used in England by jewellers. Apothecaries also used the troy pound and ounce, but added the drachms and scruples unit in theapothecaries' system of weights.
Troy weight may take its name from the French market town ofTroyes in France where English merchants traded at least as early as the early 9th century.[28] The troy pound is no longer in general use or a legal unit for trade (it was abolished in the United Kingdom on 6 January 1879 by theWeights and Measures Act 1878), but the troy ounce,1⁄12 of a troy pound, is still used for measurements of gems such as opals, and precious metals such as silver, platinum and particularly gold.[29]
A tower pound is equal to 12 tower ounces and to 5,400troy grains, which equals around 350 grams.[30] The tower pound is the historical weight standard that was used for England's coinage.[31] Before theNorman conquest in 1066, the tower pound was known as the Saxon pound. During the reign ofKing Offa (757–796) ofMercia, a Saxon pound of silver was used to set the original weight of apound sterling.[21] From one Saxon pound of silver (that is a tower pound) the king had 240silver pennies minted.[32][c] In the pound sterling monetary system, twelve pennies equaled ashilling and twenty shillings equaled a pound sterling.[34]
The tower pound was referenced to a standard prototype found in theTower of London. The tower system ran concurrently with the avoirdupois and troy systems until the reign ofHenry VIII, when a royal proclamation dated 1526 required that the troy pound be used for mint purposes instead of the tower pound.[35] No standards of the tower pound are known to have survived.[36]
The tower pound was also called themoneyers' pound (referring to the Saxonmoneyers before the Norman conquest);[37] theeasterling pound, which may refer to traders of eastern Germany, or to traders on the shore of the easternBaltic sea, or dealers of Asiatic goods who settled at theLondon Steelyard wharf;[38] and theRochelle pound by French writers, because it was also in use atLa Rochelle.[39] An almost identical weight was employed by the Germans for weighing gold and silver.
The mercantile pound (1304) of 6750 troy grains, or 9600 Tower grains, derives from this pound, as 25shilling-weights or 15 Tower ounces, for general commercial use. Multiple pounds based on the same ounce were quite common. In much of Europe, the apothecaries' and commercial pounds were different numbers of the same ounce.[citation needed][40][41]
The merchants' pound (mercantile pound,libra mercantoria, orcommercial pound) was considered to be composed of 25 rather than 20Tower shillings of 12pence.[42] It was equal to 9,600 wheat grains (15 tower ounces or 6,750 grains)[28] and was used in England until the 14th century[28] for goods other thanmoney andmedicine ("electuaries").[42]
The London pound is that of theHansa, as used in their various trading places. The London pound is based on 16 ounces, each ounce divided as the tower ounce. It never became a legal standard in England; the use of this pound waxed and waned with the influence of the Hansa itself.
A London pound was equal to 7,200 troy grains (16 troy ounces) or, equivalently, 10,240 tower grains (16 tower ounces).
In the United States, the avoirdupois pound as a unit of mass has been officially defined in terms of the kilogram since theMendenhall Order of 1893. That order defined the pound to be2.20462 pounds to a kilogram. The following year, this relationship was refined as2.20462234 pounds to a kilogram, following a determination of the British pound.[25]
In 1959, the United States National Bureau of Standards redefined the pound (avoirdupois) to be exactly equal to 0.453 592 37 kilograms, as had been declared by theInternational Yard and Pound Agreement of that year. According to a 1959NIST publication, the United States 1894 pound differed from the international pound by approximately one part in 10 million.[1] The difference is so insignificant that it can be ignored for almost all practical purposes.[43]
The Byzantines used a series of measurements known as pounds (Latin:libra,Ancient Greek:λίτρα,romanized: litra). The most common was thelogarikē litra (λογαρική λίτρα, "pound of account"), established byConstantine the Great in 309/310. It formed the basis of the Byzantinemonetary system, with onelitra of gold equivalent to 72solidi. A hundredlitrai were known as akentēnarion (κεντηνάριον, "hundredweight"). Its weight seems to have decreased gradually from the original 324 g (11.4 oz) to 319 g (11.3 oz). Due to its association with gold, it was also known as thechrysaphikē litra (χρυσαφική λίτρα, "gold pound") orthalassia litra (θαλάσσια λίτρα, "maritime pound"), but it could also be used as a measure of land, equalling a fortieth of thethalassiosmodios.[44]
Thesoualia litra was specifically used for weighing olive oil or wood, and corresponded to 4/5 of thelogarikē or 256 g (9.0 oz). Some outlying regions, especially in later times, adopted various local measures, based on Italian, Arab or Turkish measures. The most important of these was theargyrikē litra (αργυρική λίτρα, "silver pound") of 333 g (11.7 oz), found inTrebizond andCyprus, and probably of Arab origin.[44]
Since the Middle Ages, various pounds (livre) have been used in France. Since the 19th century, alivre has referred to themetric pound, 500 g.
Thelivre esterlin is equivalent to about 367.1 grams (5,665 gr) and was used between the late 9th century and the mid-14th century.[45]
Thelivre poids de marc orlivre de Paris is equivalent to about 489.5 grams (7,554 gr) and was used between the 1350s and the late 18th century.[45] It was introduced by the government ofJohn II.
Thelivre métrique was set equal to the kilogram by the decree of13 Brumaire an IX between 1800 and 1812. This was a form of official metric pound.[45]
Thelivreusuelle (customary unit) was defined as 500 g (18 oz) by the decree of 28 March 1812. It was abolished as a unit of mass effective 1 January 1840 by a decree of 4 July 1837,[45] but is still used informally.[citation needed]
Originally derived from the Roman libra, the definition varied throughout theHoly Roman Empire in the Middle Ages and onward. For example, the measures and weights of theHabsburg monarchy were reformed in 1761 by EmpressMaria Theresa of Austria.[46] The unusually heavy Habsburg (civil) pound of 16 ounces was later defined in terms of 560.012 g (19.7538 oz).Bavarian reforms in 1809 and 1811 adopted essentially the same standard as the Austrian pound. InPrussia, a reform in 1816 defined a uniform civil pound in terms of the Prussian foot and distilled water, resulting in a Prussian pound of 467.711 g (16.4980 oz).
Between 1803 and 1815, all German regions west of theRiver Rhine were under French control, organised in thedepartements:Roer,Sarre,Rhin-et-Moselle, andMont-Tonnerre. As a result of theCongress of Vienna, these regions again became part of various German states. However, many of these regions retained the metric system and adopted a metric pound of precisely 500 g (17.64 oz). In 1854, the pound of 500 g also became the official mass standard of theGerman Customs Union and was renamed theZollpfund, but local pounds continued to co-exist with theZollverein pound for some time in some German states. Nowadays, the termPfund is sometimes still in use and universally refers to a pound of 500 g.[47]
The Russian pound (фунт,funt) is anobsolete Russian unit of measurement of mass. It is equal to 409.51718 g (14.445293 oz).[48] In 1899, thefunt was the basic unit of weight, and all other units of weight were formed from it; in particular, azolotnik was1⁄96 of afunt, and apood was 40funty.
TheSkålpund was a Scandinavian measurement that varied in weight between regions. From the 17th century onward, it was equal to 425.076 g (14.9941 oz) in Sweden but was abandoned in 1889 when Sweden switched to the metric system.
In Norway, the same name was used for a weight of 425.076 g (14.9941 oz). In Denmark, it equaled 471 g (16.6 oz).
In the 19th century, Denmark followed Germany's lead and redefined the pound as 500 g (18 oz).
The Portuguese unit that corresponds to the pounds of different nations is thearrátel, equivalent to 16 ounces ofColonha, a variant of the Cologne standard. Thisarrátel was introduced in 1499 byManuel I,king of Portugal. Based on an evaluation of bronze nesting weight piles distributed by Manuel I to different towns, thearrátel of Manuel I has been estimated to be of 457.8 g (16.15 oz). In the early 19th century, thearrátel was evaluated at 459 g (16.2 oz).[49]
In the 15th century, thearrátel was of 14 ounces ofColonha or 400.6 g (14.13 oz). The Portugueselibra was the same as 2arráteis. There were alsoarráteis of 12.5 and 13 ounces andlibras of 15 and 16 ounces. TheTroyes orTria standard was also used.[50]
A Jersey pound is an obsolete unit of mass used on the island ofJersey from the 14th century to the 19th century. It was equivalent to about 7,561 grains (490 g (17 oz)). It may have been derived from theFrench livre poids de marc.[51]
The trone pound is one of a number ofobsolete Scottish units of measurement. It was equivalent to between 21 and 28 avoirdupois ounces (about 600–800 g (21–28 oz)).
In many countries, upon the introduction of ametric system, the pound (or its translation) became an historic and obsolete term, although some have kept it as an informal term without a specific value. InGerman, the term isPfund, inFrenchlivre, in Dutchpond, inSpanish andPortugueselibra, inItalianlibbra, and inDanish andSwedishpund.
Though not from the same linguistic origin, the Chinesejīn (斤, also known as the "catty") inmainland China has a modern definition of exactly 500 g (18 oz), divided into 10liǎng (两). Traditionally around 600 g (21 oz), thejin has been in use for more than two thousand years varying in exact value from one period to another, serving the same purpose as "pound" for the common-use measure of weight. In Hong Kong, for the purposes of commerce and trade between Britain and Imperial China in the preceding centuries, three Chinese catties were equivalent to four British imperial pounds, defining one catty as 604.78982 g (21.333333 oz) in weight precisely.
Hundreds of older pounds were replaced in this way. Examples of the older pounds are one of around 459–460 g (16.19–16.23 oz) in Spain, Portugal, and Latin America; one of 498.1 g (17.57 oz) in Norway; and several different ones in what is now Germany.
From the introduction of the kilogram scales and measuring devices are denominated only ingrams andkilograms. A pound of product must be determined by weighing the product in grams as the use of thepound is not sanctioned for trade within theEuropean Union.[52]
Smoothbore cannon andcarronades are currently designated by the weight in imperial pounds of round solid iron shot of diameter to fit the barrel. A cannon that fires a six-pound ball, for example, is called asix-pounder. Standard sizes are 6, 12, 18, 24, 32, and 42 pounds; 60-pounders and 68-pounders also exist, along with other nonstandard weapons using the same scheme. Before the introduction of the metric system, countries that produced their own artillery generally used their national pound for these designations. Seecarronade.
^The pound is often described as a unit of "weight", and the word "weight" can refer to either mass or force depending on context. Historically and in common parlance, "weight" refers to mass, butweight as used in modern physics is a force.
^"Anglo-SaxonKing Offa is credited with introducing the system of money to central and southern England in the latter half of the eighth century, overseeing the minting of the earliest English silver pennies – emblazoned with his name. In practice they varied considerably in weight and 240 of them seldom added up to a pound. There were at that time no larger denomination coins – pounds andshillings were merely useful units of account".[33] – Ed Lowther, BBC
^Quoted byLord Justice Laws in the "Metric Martyrs" case:Thoburn v Sunderland City Council, Hunt v London Borough of Hackney, Harman & Dove v Cornwall County Council, Collins v London Borough of Sutton[2002] EWHC 195 (Admin)
^Skinner, F.G. (1952). "The English Yard and Pound Weight".Bulletin of the British Society for the History of Science.1 (7):184–6.doi:10.1017/S0950563600000646.
^abcZupko, Ronald Edward (1 December 1985).Dictionary of Weights and Measures for the British Isles: The Middle Ages to the 20th Century. DIANE Publishing.ISBN0-87169-168-X.
^"A proclamation of Henry VIII". 5 November 1526. Proclamation 112 in Paul L. Hughes and James F. Larkin, editors.Tudor Royal Proclamations. Volume 1. New Haven: Yale University Press,1964.Archived 22 February 2014 at theWayback Machine
^R. D. Connor and A. D. C. Simpson.Weights and Measures in Scotland. A European Perspective. National Museums of Scotland and Tuckwell Press, 2004, page 116, quoting from H. W. Chisholm, Seventh Annual Report of the Warden for the Standards ... for 1872–73 (London, 1873), quoting from 1864 House of Commons Paper.Archived 22 February 2014 at theWayback Machine
^abRuffhead, Owen, ed. (1763a),The Statutes at Large, vol. I: From Magna Charta to the End of the Reign of King Henry the Sixth. To which is prefixed, A Table of the Titles of all the Publick and Private Statutes during that Time, London: Mark Basket for the Crown, pp. 148–149.(in English) &(in Latin) &(in Norman)
^Luís Seabra Lopes,"As Pilhas de Pesos de Dom Manuel I: Contributo para a sua Caracterização, Inventariação e Avaliação", Portugalia: Nova Série, vol. 39, Universidade do Porto, 2018, p. 217-251.
^Luís Seabra Lopes,"Sistemas Legais de Medidas de Peso e Capacidade, do Condado Portucalense ao Século XVI", Portugalia: Nova Série, vol. 24, 2003, p. 113-164.
^Sizes, Inc. (28 July 2003)."Jersey pound". Retrieved12 August 2006.
