Dates: The Roman Calendar System

The most popular dating system we use today lists the days of the month consecutively from 1 to 30 or 31. Many calendars in the Middle Ages did not show dates of the month in this way, and instead used a dating system inherited from the Romans. 

The video below made by the Getty Museum explains what the Roman calendar system is and how it works. 

 

 

The Roman calendar system on the Zeno Wheel

The Wheel includes both the system of dates we use today (written in Arabic numerals) and the Roman calendar system (in Roman numerals). The table below shows them side-by-side as they are written on part of the Wheel: between the two blue 'KL' that mark the beginnings of April and May. The Roman numerals count down the days between Kalends to Nones, Nones to Ides, and Ides to the end of the month. 

Dates of April on the Zeno wheel: