A troy pound and a regular avoirdupois pound are two different units of mass measurement that have similar names but are distinctly different from each other. Understanding the key differences between these two pounds is important for accuracy in weighing precious metals, gems, and in historical contexts involving the British Imperial measurement system.
Quick Answers
– A troy pound is used for weighing precious metals while an avoirdupois pound is used for most general purposes.
– A troy pound equals 373.2417216 grams while an avoirdupois pound equals 453.59237 grams.
– A troy pound is divided into 12 troy ounces while an avoirdupois pound contains 16 avoirdupois ounces.
– The troy system was traditionally used by pharmacists, jewelers, and assay offices to weigh metals while the avoirdupois system was used for weighing food and other everyday commodities.
– The origin of the troy pound traces back to the French market town of Troyes while the avoirdupois system has roots in the County of Avoirdupois in France.
– Although the troy pound was previously the official system of units in the apothecaries’ system and a basis for currency in England, the avoirdupois pound has been the primary mass unit used in the UK and US since the 19th century.
The Troy Pound System
The troy pound is a unit of mass that dates back to medieval times in Europe. Up until the 1800s, it was the official system of units used for weighing precious metals such as gold, silver, platinum, and in pharmacy for preparing medicines.
One troy pound is equivalent to 373.2417216 grams. This pound was further divided into 12 troy ounces, with each ounce equaling 31.1034768 grams.
Some key aspects of the troy system are:
– Used for weighing precious metals, gems, and in pharmacy
– 1 troy pound = 12 troy ounces
– 1 troy ounce = 31.1034768 grams
– Originated in the Middle Ages at the annual Champagne fairs held in Troyes, France
– Also called the apothecaries’ pound or pharmaceutical pound
The troy system was traditionally used to weigh gold, silver, platinum, and other high-value metals. Assay offices adopted this system to test and guarantee the purity of precious metals. Pharmacists and apothecaries also used troy weights when preparing pharmaceuticals and medicinal compounds.
The pound in this system was eventually formalized as the troy pound based on the town markets of Troyes in France where this unit became standardized in medieval times.
Origins of the Troy System
The troy system has its origins in the town of Troyes in northern France in the Middle Ages. As an important European trade hub, merchants would gather at Troyes several times a year for large fairs to buy and sell commodities. Gold, silver, and other precious metals were critical trade items at these fairs. By the 14th century, the unit of mass used at the Troyes fairs had become mostly standardized and adopted elsewhere across Europe’s trade routes.
This unit of mass measurement eventually became known as the “troy weight” after the town of Troyes where it originated. The troy markets helped establish the pound and ounce as trusted units for weighing and assaying precious metals. Although troy weights were used for coins and metals across Europe, it wasn’t until 1532 that England formally defined the troy pound as 5,760 grains.
Use in Coinage and Currency
For centuries until 1971, the troy system also served as an important basis for minting British coins and defining the British currency. The origins of the British monetary pound sterling traces back to a troy pound of silver during the Anglo-Saxon era.
Under the troy system, one troy pound was equivalent to 240 silver pennyweights. This formed the basis of the British pound sterling currency, fixed at one pound sterling corresponding to a troy pound of silver. The troy system and decimalization also enabled easier conversion between pounds sterling and its subunit pence in the pre-metric era.
Decline and Current Use
After the adoption of the avoirdupois pound in Britain and the United States in the 19th century, the use of the troy system began declining, especially for commercial and industrial purposes. It remained in use for some special applications such as pharmaceuticals and precious metals.
Today, troy weights are still used for trading precious metals such as gold, silver, and platinum. For example, gold is most often measured in troy ounces internationally, with prices quoted per troy ounce. However, in retail jewelry sales, the troy system has been largely replaced by metric grams and kilograms. The troy pound and ounce also remain as traditional units of mass in some fields today.
The Avoirdupois Pound System
The avoirdupois system is the everyday system of weights now used widely for measuring mass in pounds and ounces across Britain, America and many English-speaking countries. It diverged from the older troy system as a system better suited for weighing day-to-day goods outside of preciious metals and pharmacy.
The avoirdupois pound today equals 0.45359237 kilograms or 453.59237 grams. Key aspects of this system are:
– Used for most everyday weighing including retail and commercial trade
– 1 avoirdupois pound = 16 avoirdupois ounces
– 1 avoirdupois ounce = 28.349523125 grams
– Originated from French towns of Avoir de Peis roughly meaning “goods of weight”
– Gradually replaced troy system in UK and US by 19th century
This pound is divided into 16 avoirdupois ounces with each ounce equal to 28.349523125 grams. The avoirdupois pound diverged from the troy pound as a more suitable unit for general weighing and commerce rather than precious commodities that the troy system catered for.
Origins of Avoirdupois Weights
The avoirdupois system evolved in France in the 13th century based on weight units of the Paris grain, which was smaller than the troy grain. It gets its name from French towns called Avoir de Peis that specialized in weighing heavier goods.
These weights were likely developed to address trade and measurement needs for everyday goods like grain, meat, cheese, wool, and other commodities, as opposed to the troy system tailored for coins, bullion, and pharmacy.
The avoirdupois pound and ounces became established in England by the 14th century for most commercial weighing but was not formally recognized until 1496. Over the next few centuries, it gradually became the primary weight system over troy weights in Britain and subsequently the United States.
Adoption in Britain and America
While attempts to reform British weights and measures had been ongoing since the Middle Ages, the troy system remained integral to British currency and commerce for centuries. But after the troy pound was decoupled from British currency in the early 1800s, reforms could fully shift focus towards the avoirdupois pound.
In 1824, Britain mandated the avoirdupois pound as the official and only legal pound for weights and measures. Troy units were retained only for precious metals and pharmaceuticals. This enabled industry, commerce, and trade to converge on a unified, standardized system.
America independently adopted the avoirdupois pound just before the Revolutionary War in 1776. And in the 19th century, the avoirdupois weights became the customary system across the British Empire and American colonies facilitating global commerce.
Current Status
Today, the avoirdupois pound and ounce are predominantly used for commercial transactions and everyday weighing in the United States, Britain, and several other countries interfaced with Imperial units. Certain fields such as jewelry still tend to use troy ounces for trading convention. The avoirdupois pound also remains the international standard definition of the pound mass unit outside metric systems.
Detailed Differences
Despite their similar names, there are several key differences between the troy and avoirdupois pound systems:
Mass and Size
– A troy pound is lighter at 373.2417216 grams vs. the avoirdupois pound at 453.59237 grams.
– A troy ounce is heavier than a standard avoirdupois ounce with 31.1034768 grams vs. 28.349523125 grams respectively.
Unit Divisions
– A troy pound divides into 12 troy ounces while an avoirdupois pound divides into 16 avoirdupois ounces.
– Both pounds further subdivide into 7000+ grains but troy grains are slightly heavier.
Usage Conventions
– Troy weights became associated with precious metals, pharmacy, currency while avoirdupois weights were everyday commercial and industrial use.
– Certain fields like jewelry still use troy ounces for trading convention though avoirdupois became the legal standard.
| Unit | Troy System | Avoirdupois System |
|---|---|---|
| Pound | 373.2417216 g | 453.59237 g |
| Ounce | 31.1034768 g | 28.349523125 g |
History and Origins
The divergence between the nearly identical troy and avoirdupois pounds traces back to France in the Middle Ages.
Troy Weight Origins
– Emerged at annual fairs in Troyes, France to weigh gold and silver.
– Adopted across Europe’s trade routes by 14th century for coins and metals.
– Formalized in 1496 England as 5,760 grains = 1 troy pound.
Avoirdupois Weight Origins
– Evolved in France in the 13th century based on smaller Paris grain weights.
– Used at French towns called Avoir de Peis for weighing heavy goods.
– Introduced in England by 14th century and formalized in 1496.
Over subsequent centuries, the troy system was ingrained in British currency and commerce but England eventually mandated the avoirdupois pound as the legal standard pound in 1824.
Conclusion
While the troy and avoirdupois pound units bear similar names, they constitute two distinct systems of mass evolved from different origins. The troy pound’s history is tied to precious metals and pharmacy while the avoirdupois pound catered to general commerce. Although the troy system has declined after the 1800s, it remains in use today for weighing precious metals. The avoirdupois pound however is now the predominant pound for legal and commercial purposes across Britain, America, and several countries.
