The last day of the Julian calendar was 4 October and the following day was 15 October.
It also officially mandated January 1 as the beginning of the New Year -- a practice that had begun earlier among businesses in many western countries.
Even now the Chinese and Islamic calendars are based on the motion of the moon around the earth, rather than the motion of the earth in relation to the sun, and the Jewish calendar links years to the cycle of the sun and months to the cycle of the moon. C., Julius Caesar ordered a calendar consisting of twelve months based on a solar year.
The change in the calendar throughout the western world, during the late 16th to the middle of the 18th century, is often a source of confusion for beginning genealogists.
Even experienced practitioners sometimes have difficulty explaining the matter, an understanding of which is vital to getting genealogical event dates correct.
The first day of the year is 25 March according to the Julian calendar but it is 1 January for the Gregorian calendar.
Calendar reform began in continental Europe and James VI proclaimed that Scotland should adopt the Gregorian calendar on 1 January 1600.
The Julian calendar included an extra day in February every four years.