George Washington's birthday
The Country Parson's Formula
The cycles of the sky
Stonehenge and Sothis (third millennium B.C.)
Meton (432 B.C.), Callippus (330 B.C.), and Hipparchus (130 B.C.)
Julius Caesar (46 B.C.)
Constantine the Great (A.D. 321)
Dionysius Exiguus (A.D. 525)
The Synod of Whitby (A.D. 664)
The Venerable Bede (A.D. 725)
Lady Day
Retrospective dating
Pope Gregory XIII (A.D. 1582)
The perfect Christian calendar and God's longitude
Archbishop Ussher and the age of the earth (A.D. 1650)
Lord Chesterfield's Act (A.D. 1751)
Poor Richard's Almanack
President Arthur requests (A.D. 1884)
Marching to the same drummer?
Calendar reform
The Comet of Bethlehem
How many days in a dinosaur year?
Should 2100 be a double leap year?
Appendix A: How long is a day?
Appendix B: How long is a year?
Appendix C: How long is a second?
Appendix D: How long is a month?