Editing Pound (mass) (section)

=== In Britain ===
A number of different definitions of the pound have historically been used in Britain. Among these are the [[#Avoirdupois pound|avoirdupois pound]], which is the common pound used for weights, and the obsolete [[#Tower pound|tower]], [[#Merchants' pound|merchants']] and [[#London pound|London]] pounds.<ref>{{cite web| url = http://home.clara.net/brianp/weights.html| title = Grains and drams, ounces and pounds, stones and tons. Personal notes.}}</ref> The [[Troy weight|troy pound and ounce]] remain in use only for the weight of [[precious metal]]s, 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, the [[troy system]] is assumed.

The [[pound sterling]] money system, which was introduced during the reign of [[King Offa]] of [[Mercia]] (757–96), was based originally on a Saxon pound of silver. After the [[Norman Conquest|Norman conquest]] the Saxon pound was known as the tower pound or moneyer's pound.<ref name="Zupko 1977 11">{{Cite book |last=Zupko |first=Ronald Edward |url=http://archive.org/details/britishweightsme0000zupk |title=British weights & measures : a history from antiquity to the seventeenth century |date=1977 |publisher=Madison : University of Wisconsin Press |others=Internet Archive |isbn=978-0-299-07340-4 |pages=11}}</ref> In 1528, during the reign of [[Henry VIII]], the coinage standard was changed by parliament from the tower pound to the [[#Troy pound|troy pound]].<ref>{{Cite book |last=Zupko |first=Ronald Edward |url=http://archive.org/details/britishweightsme0000zupk |title=British weights & measures : a history from antiquity to the seventeenth century |date=1977 |publisher=Madison : University of Wisconsin Press |others=Internet Archive |isbn=978-0-299-07340-4 |pages=78}}</ref>

==== Avoirdupois pound ====
{{broader|Avoirdupois system}}
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 of [[Elizabeth I|Queen Elizabeth I]], the avoirdupois pound was redefined as 7,000 troy grains. Since then, the [[Grain (measure)|grain]] 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.<ref>{{cite journal| last=Skinner | first=F.G. | journal=Bulletin of the British Society for the History of Science | title=The English Yard and Pound Weight | year=1952 | doi=10.1017/S0950563600000646 | volume=1 | pages=184–6| issue=7 }}</ref><ref name="Standards">{{cite book|author=United States. National Bureau of Standards|author-link=National Institute of Standards and Technology|title=weights and measures|url=https://books.google.com/books?id=ycgOAAAAQAAJ&pg=PA22|access-date=26 December 2011|year=1962|publisher=Taylor & Francis|pages=22–24|id=GGKEY:4KXNZ63BNUF}}</ref>{{efn|A difference of just 194.39673 milligrams}}

===== Imperial Standard Pound =====
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.

The [[Weights 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". Paragraph 13 states that the weight {{lang|la|in 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 {{convert|1.35|in|mm}} high, and {{convert|1.15|in|mm}} diameter, and the edges are carefully rounded off. It has a groove about {{convert|0.34|in|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&nbsp;lb" (P.S. stands for "Parliamentary Standard").

{{English pounds}}

{{See also|English units}}

===== Redefinition in terms of the kilogram =====
The British [[Weights 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&nbsp;lb = {{val|453.59265|u=g}} or 0.45359&nbsp;kg, which made the kilogram equivalent to about {{val|2.2046213|u=lb}}.

In 1883, it was determined jointly by the standards department of the British Board of Trade and the Bureau International that {{val|0.4535924277|u=kg}} was a better approximation, and this figure, rounded to {{val|0.45359243|u=kg}} was given legal status by an [[Order in Council]] in May 1898.<ref name=nbs447>{{cite book | title=Weights and measures standards of the United States&nbsp;– A brief history | year=1976 | url=http://physics.nist.gov/Pubs/SP447/contents.html | first=L.E. | last=Barbrow | author2=Judson, L.V. | url-status=dead | archive-url=https://web.archive.org/web/20080511153143/http://physics.nist.gov/Pubs/SP447/contents.html | archive-date=11 May 2008 | df=dmy-all }}</ref>

In 1959, based on further measurements and international coordination, the [[International Yard and Pound Agreement]] defined an "international pound" as being equivalent to exactly {{val|0.45359237|u=kg}}.<ref name=nbs447/> This meant that the existing legal definition of the UK pound differed from the international standard pound by {{val|0.06|u=milligrams}}. To remedy this, the pound was again redefined in the United Kingdom by the [[Weights and Measures Act 1963]] to match the international pound, stating: "the pound shall be 0.453 592 37 kilogramme exactly",<ref name="vlex 1963" /> a definition which remains valid to the present day.

The [[2019 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.

==== Troy pound ====
{{main|Troy weight}}

A troy pound (abbreviated lb t<ref>Capotosto, R. (1983). 200 Original Shop Aids and Jigs for Woodworkers. Sterling Publishing Company, Inc.</ref>) is equal to 12 [[troy ounce]]s and to 5,760 grains, that is exactly {{val|373.2417216}} grams.<ref>{{cite web| url=https://www.nist.gov/pml/wmd/pubs/upload/AppC-12-hb44-final.pdf| author=United States National Bureau of Standards | title=Appendix C of NIST Handbook 44, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, General Tables of Units of Measurement| page=C-14}}</ref><!--Source uses U+002D Hyphen-Minus in page number and it should not be changed to n-dash. --> Troy weights were used in England by jewellers. Apothecaries also used the troy pound and ounce, but added the drachms and scruples unit in the [[apothecaries' system]] of weights.

[[Troy weight]] may take its name from the French market town of [[Troyes]] in France where English merchants traded at least as early as the early 9th century.<ref name="zupko" /> 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 the [[Weights and Measures Act 1878]]), but the troy ounce, {{frac|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.<ref>[https://www.fiscal.treasury.gov/fsreports/rpt/goldRpt/current_report.htm "Status Report of U.S. Government Gold Reserve"] {{Webarchive|url=https://web.archive.org/web/20151003044818/https://www.fiscal.treasury.gov/fsreports/rpt/goldRpt/current_report.htm |date=3 October 2015 }}, Bureau of the Fiscal Service</ref>

==== Tower pound ====
[[File:The Pound.jpg|thumb|The tower pound displayed as the weight of a [[pound sterling]] of 240 early [[Penny (English coin)|silver pennies]] (original [[pennyweight]])]]
A tower pound is equal to 12 tower ounces and to 5,400 [[troy grains]], which equals around 350 grams.<ref>{{Cite book |last=Ross |first=Lester A. |url=https://sha.org/assets/documents/Metrology.pdf |title=Archaeological Metrology: English, French, American, and Canadian Systems of Weights and Measures for North American Historical Archaeology |date=1983 |publisher=National Historic Parks and Sites Branch, Parks Canada, Environment Canada |isbn=978-0-660-11336-4 |pages=20 |language=en}}</ref> The tower pound is the historical weight standard that was used for England's coinage.<ref>{{Cite book |last=Kampmann |first=Ursula |url=https://books.google.com/books?id=uVDIEAAAQBAJ&pg=PA56 |title=Drachm, Dirham, Thaler, Pound: Money and currencies in history from earliest times to the euro |date=2013-04-29 |publisher=Conzett Verlag |isbn=978-3-03760-029-0 |pages=56 |language=en}}</ref> Before the [[Norman Conquest|Norman conquest]] in 1066, the tower pound was known as the Saxon pound. During the reign of [[King Offa]] (757–96) of [[Mercia]], a Saxon pound of silver was used to set the original weight of a [[pound sterling]].<ref name="Zupko 1977 11"/> From one Saxon pound of silver (that is a tower pound) the king had 240 [[Penny (English coin)|silver pennies]] minted.<ref>{{Cite book |url=https://books.google.com/books?id=ctLECjLTakcC&pg=PA115 |title=The Encyclopædia Britannica: Payn-Polka |date=1911 |publisher=At the University Press |pages=115 |language=en}}</ref>{{efn|"Anglo-Saxon [[Offa of Mercia|King 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{{snd}}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{{snd}} pounds and [[shilling]]s were merely useful units of account".<ref>{{cite web |title=A short history of the pound |publisher=BBC |first=Ed |last=Lowther |date=14 February 2014 |work=BBC News |url=https://www.bbc.co.uk/news/uk-politics-26169070 |quote= |access-date=22 July 2021 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721233848/https://www.bbc.co.uk/news/uk-politics-26169070 |url-status=live }}</ref>{{snd}} Ed Lowther, BBC}} In the pound sterling monetary system, twelve pennies equaled a [[shilling]] and twenty shillings equaled a pound sterling.<ref>{{Cite book |last=Geva |first=Benjamin |url=https://books.google.com/books?id=4yHcBAAAQBAJ&pg=PA88 |title=The Payment Order of Antiquity and the Middle Ages: A Legal History |date=2011-11-01 |publisher=Bloomsbury Publishing |isbn=978-1-84731-843-5 |pages=88 |language=en}}</ref>

The tower pound was referenced to a standard prototype found in the [[Tower of London]]. The tower system ran concurrently with the avoirdupois and troy systems until the reign of [[Henry VIII]], when a royal proclamation dated 1526 required that the troy pound be used for mint purposes instead of the tower pound.<ref>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.[http://www.sizes.com/units/pound_tower.htm] {{Webarchive|url=https://web.archive.org/web/20140222154017/http://www.sizes.com/units/pound_tower.htm|date=22 February 2014}}</ref> No standards of the tower pound are known to have survived.<ref>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.[http://www.sizes.com/units/pound_tower.htm] {{Webarchive|url=https://web.archive.org/web/20140222154017/http://www.sizes.com/units/pound_tower.htm|date=22 February 2014}}</ref>

The tower pound was also called the '''moneyers' pound''' (referring to the Saxon [[moneyer]]s before the Norman conquest);<ref>{{cite web |title=Tower pound |url=https://sizes.com/units/pound_tower.htm |access-date=17 September 2016 |website=Sizes.com}}</ref> the '''easterling pound''', which may refer to traders of eastern Germany, or to traders on the shore of the eastern [[Baltic Sea|Baltic sea]], or dealers of Asiatic goods who settled at the [[Steelyard|London Steelyard wharf]];<ref>{{cite book |url=https://books.google.com/books?id=uQI_AQAAMAAJ&pg=PP33 |title=Facsimile of First Volume of Ms. Archives of the Worshipful Company of Grocers of the City of London A.D. 1345–1463. |date=1886}}</ref> and the '''Rochelle pound''' by French writers, because it was also in use at [[La Rochelle]].<ref>{{cite book |url=https://books.google.com/books?id=2oUBAAAAQAAJ&pg=PA191 |title=The English manual of banking |year=1877 |access-date=17 September 2016}}</ref> 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 25 [[shilling]]-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|date=February 2013}}<ref>{{cite web |title=Weights used for gold |url=http://www.taxfreegold.co.uk/weights.html |access-date=14 January 2011 |publisher=Tax Free Gold}}</ref><ref>{{cite web |title=A brief history of the pound |url=http://www.dozenalsociety.org.uk/history/poundhist.html |access-date=14 January 2011 |publisher=The Dozenal Society of Great Britain}}</ref>
{|
|-
|1 mercantile pound (15&nbsp;oz)
|= 
|align=right|9,600 Tower grains
|= 
|align=right|6,750 troy grains
|-
|1 Tower pound (12&nbsp;oz)
|= 
|align=right|7,680 Tower grains
|= 
|align=right|5,400 troy grains
|-
|1 Tower ounce (20 dwt)
|=
|align=right|640 Tower grains
|=
|align=right|450 troy grains
|-
|1 Tower pennyweight (dwt)
|=
|align=right|32 Tower grains
|=
|align=right|{{frac|22|1|2}} troy grains
|}

==== Merchants' pound ====
The merchants' pound (''mercantile pound'', {{lang|la|libra mercantoria}}, or ''commercial pound'') was considered to be composed of 25 rather than 20 [[Tower pound|Tower shillings]] of 12 [[pennyweight|pence]].<ref name=tract>{{Citation |editor-last=Ruffhead |editor-first=Owen |editor-link=Owen Ruffhead |title=The Statutes at Large |url=https://books.google.com/books?id=tKZFAAAAcAAJ |volume=&nbsp;I: From Magna Charta<!--sic--> 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 |location=London |publisher=Mark Basket for the Crown |date=1763a |pages=[https://books.google.com/books?id=tKZFAAAAcAAJ&pg=PA148 148–149] }}. {{in lang|en}}&nbsp;& {{in lang|la}}&nbsp;& {{in lang|nrf}}</ref> It was equal to 9,600 wheat grains (15 tower ounces or 6,750 grains)<ref name="zupko">{{cite book|last=Zupko|first=Ronald Edward|author-link=Ronald Edward Zupko|title=Dictionary of Weights and Measures for the British Isles: The Middle Ages to the 20th Century|publisher=DIANE Publishing|isbn=0-87169-168-X|date=1 December 1985}}</ref> and was used in England until the 14th century<ref name="zupko"/> for goods other than [[#Tower pound|money]] and [[#Apothecary's pound|medicine]] ("[[electuaries]]").<ref name=tract/>

==== London pound ====
{{disputed section|London pound|date=January 2021}}
The London pound is that of the [[Hanseatic League|Hansa]], 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).

{|
|-
|1 London pound (16&nbsp;oz)
|= 
|align=right|{{frac|1|1|3}} tower pounds (1.25 Troy pounds)
|= 
|align=right|10,240 tower grains
|= 
|align=right|7,200 troy grains
|-
|1 London ounce (20 dwt)
|=
|align=right|1 tower (or troy) ounce
|=
|align=right|640 tower grains
|=
|align=right|450 troy grains
|-
|1 London pennyweight
|=
|align=right|1 tower (or troy) pennyweight
|=
|align=right|32 tower grains
|=
|align=right|{{frac|22|1|2}} troy grains
|}