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The avoirdupois system (; abbreviated avdp.) is a measurement system of weights that uses pounds and ounces as units. It was first commonly used in the 13th century AD and was updated in 1959. In 1959, by international agreement, the definitions of the pound and ounce became standardized in countries which use the pound as a unit of mass. The ''
International Avoirdupois Pound The pound or pound-mass is a unit of mass used in British imperial and United States customary systems of measurement. Various definitions have been used; the most common today is the international avoirdupois pound, which is legally define ...
'' was then created. It is the everyday system of weights used in the United States. It is still used, in varying degrees, in everyday life in the United Kingdom, Canada, New Zealand, Australia, and some other
former British colonies Below are lists of the countries and territories formerly ruled or administered by The United Kingdom or part of the British Empire (including military occupations that did not retain the pre-war central government), with their independence days. ...
, despite their official adoption of the
metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Intern ...
. The avoirdupois weight system's general attributes were originally developed for the international wool trade in the
Late Middle Ages The Late Middle Ages or Late Medieval Period was the period of European history lasting from AD 1300 to 1500. The Late Middle Ages followed the High Middle Ages and preceded the onset of the early modern period (and in much of Europe, the Ren ...
, when trade was in recovery. It was historically based on a physical standardized pound or "prototype weight" that could be divided into 16 ounces. There were a number of competing measures of mass, and the fact that the avoirdupois pound had three even numbers as divisors (half and half and half again) may have been a cause of much of its popularity, so that the system won out over systems with 12 or 10 or 15 subdivisions. The use of this unofficial system gradually stabilized and evolved, with only slight changes in the reference standard or in the prototype's actual mass. Over time, the desire not to use too many different systems of measurement allowed the establishment of "value relationships", with other commodities metered and sold by weight measurements such as bulk goods (grains, ores, flax) and smelted metals; so the avoirdupois system gradually became an accepted standard through much of Europe. In England, Henry VII authorized its use as a standard, and
Queen Elizabeth I Elizabeth I (7 September 153324 March 1603) was Queen of England and Ireland from 17 November 1558 until her death in 1603. Elizabeth was the last of the five House of Tudor monarchs and is sometimes referred to as the "Virgin Queen". Eli ...
acted three times to enforce a common standard, thus establishing what became the Imperial system of weights and measures. Late in the 19th century various governments acted to redefine their base standards on a scientific basis and establish ratios between local avoirdupois measurements and international SI
metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Intern ...
standards. The legal actions of these various governments were independently conceived, and so did not always pick the same ratios to metric units for each avoirdupois unit. The result of this was, after these standardisations, measurements of the same name often had marginally different recognised values in different regions (although the pound generally remained very similar). In the modern day, this is evident in the small difference between United States customary and British Imperial pounds. An alternative system of mass, the troy system, is generally used for precious materials. The modern definition of the avoirdupois pound (1 lb) is exactly kilograms.


Etymology

is from Anglo-Norman French (later ''avoir du pois''), literally "goods of weight" (Old French , as verb meaning "to have" and as noun meaning "property, goods", comes from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
, "to have, to hold, to possess something"; = "from"/"of", cf. Latin; = "weight", from Latin ). This term originally referred to a class of merchandise: , "goods of weight", things that were sold in bulk and were weighed on large steelyards or balances. Only later did the term become identified with a particular ''system of units'' used to weigh such merchandise. Inconsistent
orthography An orthography is a set of conventions for writing a language, including norms of spelling, hyphenation, capitalization, word breaks, emphasis, and punctuation. Most transnational languages in the modern period have a writing system, and ...
throughout history has left many variants of the term, such as and . (The Norman became the Parisian . In the 17th century ''de'' was replaced with ''du''.) The ''avoirdupois'' word is made of three French words (''avoir du pois''). When the word ''avoir'' might both be a verb and a noun, it was used as a noun — meaning a good — in the 16th century to differentiate a good sold by items (''avoir de prix'') from a good sold by its weight (''avoir de pois/poids''). The current orthography of the last word is ''poids'' in the current standard French orthography, but the word ''avoirdupois'' remained as is in the anglosphere.


History

The rise in use of the measurement system corresponds to the regrowth of trade during the
High Middle Ages The High Middle Ages, or High Medieval Period, was the periodization, period of European history that lasted from AD 1000 to 1300. The High Middle Ages were preceded by the Early Middle Ages and were followed by the Late Middle Ages, which ended ...
after the early
crusades The Crusades were a series of religious wars initiated, supported, and sometimes directed by the Latin Church in the medieval period. The best known of these Crusades are those to the Holy Land in the period between 1095 and 1291 that were ...
, when Europe experienced a growth in towns, turned from the chaos of warlordism to long-distance trade, and began annual fairs, tournaments and commerce, by land and sea. There are two major hypotheses regarding the origins of the avoirdupois system. The older hypothesis is that it originated in France. A newer hypothesis is that it is based on the weight system of Florence. The avoirdupois weight system is thought to have come into use in England around 1300. It was originally used for weighing wool. In the early 14th century several other specialized weight systems were used, including the weight system of the
Hanseatic League The Hanseatic League (; gml, Hanse, , ; german: label= Modern German, Deutsche Hanse) was a medieval commercial and defensive confederation of merchant guilds and market towns in Central and Northern Europe. Growing from a few North German to ...
with a 16-ounce pound of grains and an 8-ounce mark. However, the main weight system, used for coinage and for everyday use, was based on the 12-ounce tower pound of grains. From the 14th century until the late 16th century, the system's basis and the prototype for today's international pound, the avoirdupois pound, was also known as the wool pound or the avoirdupois wool pound. The earliest known version of the avoirdupois weight system had the following units: a pound of grains, a stone of 14 pounds, a woolsack of 26 stone, an ounce of pound, and finally, the ounce was divided into 16 "parts". The earliest known occurrence of the word "avoirdupois" (or some variant thereof) in England is from a document entitled ''Tractatus de Ponderibus et Mensuris'' ("Treatise on Weights and Measures"). This document is listed in early statute books under the heading ''31 Edward I'' dated 2 February 1303. More recent statute books list it among statutes of uncertain date. Scholars nowadays believe that it was probably written between 1266 and 1303. Initially a royal memorandum, it eventually took on the force of law and was recognized as a statute by King Henry VIII and Queen Elizabeth I. It was repealed by the Weights and Measures Act 1824. In the ''Tractatus'', the word "avoirdupois" refers not to a weight system, but to a class of goods, specifically heavy goods sold by weight, as opposed to goods sold by volume, count, or some other method. Since it is written in Anglo-Norman French, this document is not the first occurrence of the word in the English language.


Toward a uniformity of measures

Three major developments occurred during the reign of
Edward III Edward III (13 November 1312 – 21 June 1377), also known as Edward of Windsor before his accession, was King of England and Lord of Ireland from January 1327 until his death in 1377. He is noted for his military success and for restoring r ...
(r. 1327–1377). First, a statute known as 14o Edward III. st. 1. Cap. 12 (1340) "Bushels and Weights shall be made and sent into every County." The second major development is the statute 25o Edward III. st. 5. Cap. 9. (1350) "The Auncel Weight shall be put out, and Weighing shall be by equal Balance." The third development is a set of 14th-century bronze weights at the Westgate Museum in Winchester, England. The weights are in denominations of 7 pounds (corresponding to a unit known as the clip or wool-clip), 14 pounds (stone), 56 pounds (4 stone) and 91 pounds ( sack or woolsack). The 91-pound weight is thought to have been commissioned by Edward III in conjunction with the statute of 1350, while the other weights are thought to have been commissioned in conjunction with the statutes of 1340. The 56-pound weight was used as a reference standard as late as 1588.A bronze Edward III standard weight of 56lb (1327-1377)
A statute of Henry VIII (24o Henry VIII. Cap. 3) made avoirdupois weights mandatory. In 1588
Queen Elizabeth Queen Elizabeth, Queen Elisabeth or Elizabeth the Queen may refer to: Queens regnant * Elizabeth I (1533–1603; ), Queen of England and Ireland * Elizabeth II (1926–2022; ), Queen of the United Kingdom and other Commonwealth realms * Queen ...
increased the weight of the avoirdupois pound to grains and added the troy grain to the avoirdupois weight system. Prior to 1588, the "part" () was the smallest unit in the avoirdupois weight system. In the 18th century, the "part" was renamed "drachm".


Original forms

These are the units in their original Anglo-Norman French forms:


Post-Elizabethan units

In the United Kingdom, 14 avoirdupois pounds equal one stone. The quarter, hundredweight, and ton equal respectively, 28 lb, 112 lb, and 2,240 lb in order for
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different ele ...
es to be easily converted between them and stone. The following are the units in the British or
imperial Imperial is that which relates to an empire, emperor, or imperialism. Imperial or The Imperial may also refer to: Places United States * Imperial, California * Imperial, Missouri * Imperial, Nebraska * Imperial, Pennsylvania * Imperial, Texas ...
version of the avoirdupois system: ''Note:'' The plural form of the unit ''stone'' is either ''stone'' or ''stones'', but ''stone'' is most frequently used.


American customary system

The 13 British colonies in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
used the avoirdupois system, but continued to use the British system as it was, without the evolution that was occurring in Britain in the use of the stone unit. In 1824 there was landmark new weights and measures legislation in the United Kingdom that the United States did not adopt. In the United States, quarters, hundredweights, and tons remain defined as 25, 100, and respectively. The quarter is now virtually unused, as is the hundredweight outside of agriculture and commodities. If disambiguation is required, then they are referred to as the smaller "short" units in the United States, as opposed to the larger British "long" units. Grains are used worldwide for measuring
gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
and smokeless powder charges. Historically, the dram ( grains; not to be mixed up with the apothecaries' dram of 60 grains) has also been used worldwide for measuring gunpowder charges, particularly for shotguns and large black-powder rifles.


See also

*
Apothecaries' system The apothecaries' system, or apothecaries' weights and measures, is a historical system of mass and volume units that were used by physicians and apothecaries for medical prescriptions and also sometimes by scientists."Medicinal-Gewicht, Apothek ...
*
Units of measurement in France 200px, Table of the measuring units used in the 17th century at Pernes-les-Fontaines in the covered market at Provence-Alpes-Côte d'Azur Regions of France">region of southeastern France France has a unique history of Unit of measurement, unit ...
* Imperial units * Troy weight * United States customary units * Weighing scales


References


Notes


Citations


Sources

* * * * *


External links

*
A bronze Edward III standard weight of 14lb (1327-1377)

A bronze Edward III standard weight of 91lb (1/4 sack) (1327-1377)
{{United States Customary Units Units of mass Imperial units Customary units of measurement in the United States Customary units of measurement