Affect of leap seconds on the prediction of an eclipse There seem to be irregularities in the motion of the earth, so we add "leap seconds" to adjust our time accordingly. Since 1972 there have been 26 leap seconds I think. If we extrapolate that backwards 0.5 leap seconds per year, it would be 1 leap minute in 120 years and 5 leap minutes in 600 years.

Would this be enough to throw off a prediction of an eclipse? In other words, could someone in 1416 predict an eclipse right now given the unpredictable errors caused by leap seconds?
It has been known that changes in earth rotation affect the location of eclipse paths for over a century.  The most active research in this has been Morrison and Stephenson.  See, for example http://adsabs.harvard.edu/abs/2004JHA....35..327M