A Jacobus is an English
gold coin of the reign of
James I, worth 25
shillings. The name of the coin comes from the Latin inscription surrounding the King's head on the obverse of the coin,
IACOBUS D G MAG BRIT FRA ET HI REX ("James, by the grace of God, of Britain, France and Ireland King").
Isaac Newton refers to the coin in a letter to
John Locke
John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenment, Enlightenment thinkers and commonly known as the "father of liberalism ...
:
'' The Jacobus piece coin'd for 20 shillings is the : part of a pound Troy, and a Carolus 20s piece is of the same weight. But a broad Jacobus (as I find by weighing some of them) is the 38th part of a pound Troy.''Letter of Isaac Newton
dated September 19, 1698, to John Locke
John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenment, Enlightenment thinkers and commonly known as the "father of liberalism ...
, concerning the weight and fineness of various coins.
These correspond to masses of 9.10 and 9.82
grams respectively, making the broad Jacobus slightly heavier.
References
Coins of England
English gold coins
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