Historical Events
- Pierre de Fermat writes to Marin Mersenne about Fermat's church thesis
1640 Highlights
About December 25, 1640
Calendar: Julian 
Day of the Week: Friday
Calendar: Gregorian 
Day of the Week: Tuesday
How Long Ago? 383 years, 6 months and 13 days
Leap Year: Yes
Star Sign: Capricorn
American
British
Canadian
French
German
Russian