 He obtained daily records of the spectrum of the corona, which furnished us with a valuable index of solar activity.At Climax, Walter Roberts quickly proved observationally what most astronomers had previously suspected, that the corona itself rotated with the same period as the solar surface, in something over twenty-five days.He initiated a study of the fine structure of the solar atmosphere, determining the behavior of what he called “spicules,” a phenomenon that I had myself briefly discussed while at Lick Observatory.