Deceleration of the Earth's rotation from old solar tables

The solar tables of ibn Yunis and of King Alfonso, those of Kepler, of G. D. and J.-J. Cassini, and of Lalande are compared with Newcomb's theory of the Sun to determine the deceleration of the Earth's rotation. Comparisons of mean motion and of longitude lead to separate determinations. A value for the deceleration, , assumed to be independent of time is obtained for the period — 146 through 1892. This result is based on the assumption that Newcomb's theory converts the Earth's orbital motion into a perfect clock, and the result is independent of lunar and tidal theory. The deceleration seems greater than that obtained from the literature for the tidal deceleration caused by the Moon.