From 45 B.C. to 1582 A.D., the Julian calendar, named for Julius Caesar, was used by nations of the Western World. The Julian calendar established a 12-month solar year consisting of a cycle of 3 years of 365 days, and 1-year of 366 days. However, the Julian calendar imprecisely calculated the length of the solar year and added an extra day every 128 years. This led to seasonal equinoxes falling at the wrong time of the year, and Easter not always occurring in the right season.
To fix this problem, Pope Gregory the XIII established a new calendar in 1582 A.D. to replace the Julian calendar. The “Gregorian Calendar” skipped 10 days in October of 1582 in order to make up for the extra days which had been accrued under the Julian calendar, and established a more accurate accounting for leap years to avoid the accrual of extra days in the future.
Before the adoption of the Gregorian calendar, many Christian nations observed the start of the new year as March 25, coinciding with “Annunciation Day,” the Catholic Feast day that celebrates the angel Gabriel’s announcement to Mary that she would conceive and give birth to Jesus Christ. The Gregorian calendar officially moved the start of the new year to January 1, eliminating March 25 as the legal new year.
Since Britain did not adopt the Gregorian calendar until 1752, early records from colonial Pennsylvania before 1752 that refer to the “first month” actually refer to March, not January. In this book, the authors have accounted for this fact and made every effort to accurately reflect dates in the Gregorian calendar.