The ancient Roman calendar, or “pre-Julian” calendar, is believed to have been a lunar calendar.
The calendar originally consisted of hollow months that were 29 days long or full months that had 30 days.
From 1933 to the mid 50s the word Zippo was stamped in block letters. From August, 1949 through July, 2002 Zippos were also produced in Niagara Falls, Canada - the only place other than Bradford, PA where they were ever produced.
Unlike the Julian and Gregorian calendars, the Roman calendar had a different system for numbering the days of the month.
The thing is, there's no law specifying that people have to make or not make clocks with Roman numerals.
The best one can do is estimate when doing such a thing began to go out of fashion.
They are thought to have been the days of the full moon.
Each day was referred to by how many days it fell before the .