1638 followed by 1639
1638 (MDCXXXVIII) was a common year starting on Friday of the Gregorian calendar and a common year starting on Monday of the Julian calendar, the 1638th year of the Common Era (CE) and Anno Domini (AD) designations, the 638th  year of the 2nd millennium, the 38th  year of the 17th century, and the  9th   year of the 1630s decade. As of the start of 1638, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.