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R Coronae Borealis stars (RCBs) are cool supergiants that displaynon-periodic deep dips in brightness. Recently, a group of `Hot RCB stars` hasbeen discovered to be fast evolving across the HR diagram, as these stars leavethe RCB region, with brightness changes at the rate of $\sim$1 mag/century.Perhaps cool RCB stars can also be seen evolving, either increasing intemperature as they evolve to become Hot RCB stars, or perhaps increasing inluminosity as the stars arrive at the RCB region. To seek these changes, theonly possible method is to extract archival data going back more than acentury, looking for the brightness changes associated with the evolution. Ihave measured and extracted 323,464 magnitudes (mostly from the Harvard platesand from the AAVSO) for ten cool RCB stars, all with over a century for thelight curves, all consistently calibrated to a modern magnitude system. Fortimes away from any dips, these light curves are flat to within the typicaluncertainty of $\pm$0.10 mag/century. That is, I see no significant evolution.I also have collected a large database of light curve dips and theirproperties. From this, the light curves for all the well-observed isolated dipshave the same shape, featuring a flat slope for the few days immediately afterthe minima. Further, I derive a general model for the shape of the light curvefor all isolated RCB dips, with a simple equation accurately describing theobserved recovery to maximum light.

Light Curves For Ten R Coronae Borealis Stars For Longer Than a Century:  Secular Evolution, Dip Statistics, and a General Model for the Shape of  Isolated Light Curve Dips