What this unit was
pennyweight is modelled here as a weight standard of the Troy weight tradition, associated with International during 24 troy grains. The converter represents one dwt as 1.5551738 g; its basis is twenty-four-troy-grains. This is a defined or exact matrix anchor.
Within that setting, the unit belonged to a working system for trade, craft production, taxation, bullion, and sometimes coin accounting. It should be read with its period, locality, and evidential basis attached, not as a universal value shared by every culture using a similar name. Coin mass is not a monetary exchange rate.
Evidence of use and sources
The working value is traceable to NIST SI units: mass. Its record is classified as exact confidence and uses the stated basis rather than an assumed culture-wide constant.
Three directly pertinent excerpts from the supplied library are available.
“the use of grains of corn as a means of expressing small weights is very ancient”
British weights and measures as described in the laws of England from Anglo-Saxon times, PDF p. 22. small-weight practice
“Avoir de poiz weight is to be used for other commodities, for Merchandize, and for Grocers.”
A dictionary of weights and measures for the British Isles, PDF p. 51. commodity trade
“every barrel for ale shall contain xxxii. gallons”
A dictionary of weights and measures for the British Isles, PDF p. 61. regulated cask capacity
Working definition
pennyweight is represented as a Troy weight standard associated with International during 24 troy grains.
The converter uses 1.55517384 g per unit.
How to use it
Basis: twenty-four-troy-grains; confidence: exact. A shared historical name does not make this value portable to another period or polity.
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