1. Variations in the length of the day: a historical perspective; 2. Tidal friction and the ephemerides of the Sun and Moon; 3. Pre-telescopic eclipse observations and their analysis; 4. Babylonian and Assyrian records of eclipses; 5. Investigation of Babylonian observations of solar eclipses; 6. Timed Babylonian lunar eclipses; 7. Untimed Babylonian observations of lunar eclipses: horizon phenomena; 8. Chinese and other East Asian observations of large solar eclipses; 9. Other East Asian observations of solar and lunar eclipses; 10. Records of eclipses in ancient European history; 11. Eclipse records from medieval Europe; 12. Solar and lunar eclipses recorded in medieval Arabic chronicles; 13. Observations of solar and lunar eclipses made by medieval Arab astronomers; 14. Determination of changes in the length of the day and geophysical interpretation; Appendix A; Appendix B; References.