This text was copied from Wikipedia on 18 February 2024 at 3:10AM.

A Jacobus is an English gold coin of the reign of James I, worth 25 shillings.[1] 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:

The Jacobus piece coin'd for 20 shillings is the 41st: 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.[2]

These correspond to masses of 9.10 and 9.82 grams respectively, making the broad Jacobus slightly heavier.


  1. ^ A Discourse of Coin and Coinage
  2. ^ Letter of Isaac Newton dated September 19, 1698, to John Locke, concerning the weight and fineness of various coins.

1893 text

A jacobus was a gold coin of the value of twenty-five shillings, called after James I, in whose reign it was first coined.

This text comes from a footnote on a diary entry in the 1893 edition edited by Henry B. Wheatley.

4 Annotations

First Reading

Terry F  •  Link

from L&M Large Glossary
gold sovereign coined under James I.

language hat  •  Link

The current (but not official) name of an English gold coin, struck in the reign of James I.
Originally issued in 1603, under the name of the Sovereign, and current for 20s. In 1604 there was a second issue known as the Unite, which being lighter, the value of the Sovereign rose to 22s. In 1612 the current value of the Unite was raised by statute to 22s., and the earlier piece rose to 24s.

1612 in Crt. & Times Jas. I (1849) I. 197 The prince having entreated him to provide him £1000, in so many Jacobus pieces. a1618 RALEIGH Obs. in Rem. (1661) 200 The English Iacobus goeth for three and twenty shillings in Merchandizing. [...]

language hat  •  Link

(The stress is on the second syllable: ja-CO-bus.)

Second Reading

San Diego Sarah  •  Link

Cosmo, the future Grand Duke of Turin, visited The Tower of London in April, 1669.

I've standardized the spelling of names I know, corrected scanning errors I could figure out, and increased the number of paragraphs. I apologize if they are wrong:

In the lower inclosure of the castle [TOWER OF LONDON], besides the many houses built there for the dwellings of the officers and soldiers of the garrison, and of other artificers, is the mint, in which the gold and silver money is coined.

Those of gold are the Jacobus, introduced by King James, of inferior value to the pound sterling, which is an imaginary coin, of 20 shillings value, a shilling being equal, in Florentine money, to two quilo;
those of silver, are the ducat, value 5 shillings, the half-shilling, and the third of the shilling, called groat; which coins may in truth be said to be better made and executed than any that are current elsewhere, so that they are with difficulty adulterated or diminished in weight.

The inferior coin, called farthings, are, for the most part, of brass and copper, and these are not struck by the public, but by the heads of the wards of the city, who have the privilege of doing it, and therefore they can only be circulated in the district of their respective wards.



His highness, Cosmo, must be considered only as a traveler. Under his direction, the narrator of the records was Count Lorenzo Magalotti, afterwards Secretary to the Academy del Cimento, and one of the most learned and eminent characters of the court of Ferdinand II.

Log in to post an annotation.

If you don't have an account, then register here.


Chart showing the number of references in each month of the diary’s entries.