Solar radius variations over the past 265 years

Analysis of five different data sets including meridian circle observations, timings of transits of Mercury, and durations of total solar eclipses consistently suggests the presence of a 76 year modulation of the solar radius. The last solar radius maximum occurred in about A. D. 1911, and the half-amplitude of variation is approx.0''.2 (0.02%). The 76 year radius variation is negatively correlated with the Gleissberg cycle of the mean sunspot numbers at the 2 sigma level of significance. A more significant 3 sigma correlation between the solar radius and sunspot cycle is found at 11 years from examination of several independent data sets. Again the correlation is negative, with maximum sunspot number corresponding to minimum solar radius. The half-amplitude of the 11 year variation is approx.0''.1. A secular decrease of approx.0''.1 per century over the last 265 years is also likely from an objective analysis of available data