On Sat 2019-07-27T01:59:14-0600 Brian Inglis hath writ:
https://en.wikipedia.org/wiki/ΔT#References has an interesting comment: Stephenson, F. R. & Morrison, L.V. "Long-term fluctuations in the Earth's rotation: 700 BC to AD 1990". Philosophical Transactions of the Royal Society of London, Series A 351 (1995) 165-202. https://www.jstor.org/stable/54464. "Includes evidence that the 'growth' in Delta-T is being modified by an oscillation with a wavelength around 1500 years; if that is true, then during the next few centuries Delta-T values will increase more slowly than is envisaged."
P.J. Huber, 2006, Journal of Geodesy, 80, 283-303 points out that the poor sampling of the ancient data and the magnitude of the stochastic terms means that the appearance of a 1500 year term could be due only to statistical fluctuation. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m