  The Kodaikanal Archive Program (India) is now available to the scientific
community in digital form as daily digitized solar white light pictures, from
1923 to 2011. We present here the solar radius data, obtained after a
painstaking effort to remove all effects that contribute to the error in their
measurements (limb darkening, distortion of the objective lens, refraction,
other instrumental effects, etc.). These data were analyzed to reveal any
significant periodic variations, after applying a multi-taper method with red
noise approximation and the Morlet wavelet transform analysis. After removing
obvious periodic variations (such as solar rotation and Earth annual rotation),
we found a possible cycle variation at 11.4 yr, quasi biennial oscillations at
1.5 and 3.8 yr, and Rieger-type periodicity at ~159, 91, and 63 days. Another
~7.5 yr periodicity (as a mean) resulting from two other main periodicities
detected at 6.3-7.8 yr can be identified as an atmospheric component. The
detrending data show, over a mean radius of 959".7 +/- 0".7, a residual of less
than ~(-)1 mas over the time period of analysis: if not spurious, this estimate
indicates a faint decline, but probably confirms more the constancy of the
solar diameter during the considered ranging time, within instrumental and
methodological limits. The Kodaikanal long quality observations contribute to
international efforts to bring past solar data measurements to the community to
further explore issues, for instance, those of the luminosity/radius properties
that could be used to pinpoint the "seat of the solar cycle."
