Johann Karl Friedrich Zöllner (1834–82)

German astrophysicist. Studied physics and natural sciences in Berlin and Basel; doctorate, Basel, 1859. Worked in a private observatory on his father’s estate, where he developed new instruments for photometry and spectroscopy. Assistant, Leipzig observatory, 1862. Habilitated, 1865; professor of astrophysics, Leipzig, 1872. Became interested in spiritualism after seeing performances by Henry Slade; tried to explain Slade’s abilities in terms of his concept of a fourth spatial dimension.