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