Editing Grain (unit) (section)

== History ==
{|class="wikitable plainrowheaders" align=right style="text-align: center;"
|+ Approximate weights of grains used for trading in antiquity
|-
! scope="col" | Grain
! scope="col" | {{abbr|Approx.|approximate}} SI mass
|-
! scope="row" |carob seed
| 200&nbsp;mg
|-
! scope="row" |barley grain
| 65&nbsp;mg
|-
! scope="row" |wheat grain
| 50&nbsp;mg
|}
At least since [[classical antiquity|antiquity]], grains of [[wheat]] or [[barley]] were used by [[History of the Mediterranean region|Mediterranean traders]] to define units of mass; along with other seeds, especially those of the [[carob]] tree. According to a longstanding tradition, one [[Carat (unit)|carat]] (the mass of a carob seed) was equivalent to the weight of four wheat grains or three barleycorns.<ref name="Ridgeway1889">{{cite journal |last= Ridgeway |first= William |author-link= William Ridgeway |date= 1889 |title= Metrological Notes: III.- Had the People of Pre-historic Mycenae a Weight Standard? |journal= [[The Journal of Hellenic Studies]] |volume= 10 |pages= 90–97 |publisher= The Council for the [[Society for the Promotion of Hellenic Studies]] |location= London |issn= 0075-4269 |oclc= 51205085 |doi= 10.2307/623588 |jstor= 623588 |s2cid= 164030519 |url= https://zenodo.org/record/1449896 }}</ref>{{rp|95}} Since the weights of these seeds are highly variable, especially that of the cereals as a function of moisture, this is a convention more than an absolute law.<ref name="wms">{{cite book |last1= Connor |first1= R. D. |last2= Simpson |first2= A. D. C. |date= 2004 |title= Weights and Measures in Scotland: A European Perspective |editor-last= Morrison-Low |editor-first= A. D. |location= East Linton}}</ref>{{rp|120–1}}

The history of the modern British grain can be traced back to a royal decree in thirteenth century England, re-iterating decrees that go back as far as [[Offa of Mercia|King Offa]] (eighth century).<ref>{{cite book |last= Zupko |first= Ronald Edward |date= 1977 |title= British Weights and Measures |publisher= University of Wisconsin |location= Madison, Wisconsin |isbn= 0-299-07340-8 |pages= 11}}</ref> The [[Tower pound]] was one of many monetary pounds of 240 [[Silver penny|silver pennies]].{{Citation needed|date=January 2021}}

{{Blockquote|By consent of the whole Realm the King's Measure was made, so that an [[Silver penny|English Penny]], which is called the Sterling, round without clipping, shall weigh Thirty-two Grains of Wheat dry in the midst of the Ear; Twenty pennies make an Ounce; and Twelve Ounces make a Pound.|[[Weights and Measures Acts (UK)#Acts of Parliament|Tractatus de Ponderibus et Mensuris]]<ref name="wms" />{{rp|119}}}}

The pound in question is the [[Tower pound]]. The Tower pound, abolished in 1527, consisted of 12 [[ounce]]s like the troy pound, but was {{frac|16}} (≈6%) lighter. The weight of the original sterling pennies was 22½ troy grains, or 32 "Tower grains".<ref name="wms" />{{rp|116}}

Physical grain weights were made and sold commercially at least as late as the early 1900s, and took various forms, from squares of sheet metal to manufactured wire shapes and coin-like weights.<ref>{{cite web |title= The Grains of History |url= http://www.apothecariesweights.com/articles/the-grains-of-history/ |access-date= 2016-09-21}}</ref>

The troy pound was only "the pound of Pence, Spices, Confections, as of Electuaries", as such goods might be measured by a ''troi'' or small balance. The old troy standard was set by King Offa's [[Silver penny|currency reform]], and was in full use in 1284 (Assize of Weights and Measures, King Edward I), but was restricted to currency (the pound of pennies) until it was abolished in 1527. This pound was progressively replaced by a new pound, based on the weight of 120 silver [[dirhem]]s of 48 grains. The new pound used a barley-corn grain, rather than a wheat grain.<ref name=watson1910>{{cite book |last= Watson |first= C. M. |year= 1910 |author-link= Charles Moore Watson |title= British Weights and Measures as described in the laws of England from Anglo-Saxon times |publisher= John Murray |location= London |pages= 32–34 |url= https://archive.org/details/britishweightsme00watsuoft}}</ref>

Avoirdupois (goods of weight) refers to those things measured by the lesser but quicker balances: the bismar or auncel, the Roman balance, and the [[steelyard balance|steelyard]]. The original mercantile pound of 25 shillings or 15 (Tower) ounces was displaced by, variously, the pound of the Hanseatic League (16 tower ounces) and by the pound of the then-important wool trade (16 ounces of 437 grains). A new pound of {{val|7680|fmt=commas}} grains was inadvertently created as 16 troy ounces, referring to the new troy rather than the old troy. Eventually, the wool pound won out.<ref name="watson1910"/>

The [[avoirdupois pound]] was defined in prototype, rated as {{val|6992|fmt=commas}} to {{val|7004|fmt=commas}} grains. In the Imperial [[Weights and Measures Act 1824]] ([[5 Geo. 4]]. c. 74), the avoirdupois pound was defined as {{val|7000|fmt=commas}} grains exactly. The [[Weights and Measures Act 1855]] authorised Miller's new standards to replace those lost in the fire that destroyed the [[Burning of Parliament|Houses of Parliament]]. The standard was an avoirdupois pound, the grain being defined as {{sfrac|{{val|7000}}}} of it.<ref>{{Cite web |url= http://www.global-converter.com/unit-to-unit/pound-avoirdupois-pound-mass-to-grain-avoirdupois-mass-converter/ |title= Pound (Avoirdupois, pound-mass) to grain (Avoirdupois) conversion &#124; Units of Mass}}</ref>

The division of the carat into four grains survives in both senses well into the early twentieth century. For pearls and diamonds, weight is quoted in carats, divided into four grains. The carat was eventually set to 205 milligrams (1877), and later 200 milligrams. For touch or fineness of gold, the fraction of gold was given as a weight, the total being a solidus of 24 carats or 96 grains.<ref name=Woolhouse>{{cite book |last= Woolhouse |first= W. S. B. |date= 1890 |title= Measures, Weights and Measures of all Nations |publisher= Crosby Lockwood and Son |location= London |page= 33 |url= https://archive.org/details/measuresweights00woolgoog/page/n6/mode/2up |author-link= Wesley S. B. Woolhouse}}</ref>