33. Seconds count
The effort to match modern calculations to ancient records reaches across time and space. A recent comprehensive study analyzes Babylonian, Chinese, ancient Greek and Arab timings of solar and lunar eclipses. Still, all too often the computed characteristics of an eclipse do not match the ancient report.
A determination of the upper and lower bounds on delta-T
A determination of delta-T from Ptolemy's Babylonian data (9 pages)
The effect of changes in the length of the day in graphic form (7 pages)