He became an observer at the AOP in 1898, and the following year he collaborated with Julius Scheiner in an unsuccessful attempt to measure the radio emission from the Sun.
Johannes Vermeer | Johannes Kepler | Johannes Gutenberg | Johannes Peter Müller | Johannes Ockeghem | Johannes Rau | Johannes Müller | Johannes Heesters | Johannes Zukertort | Johannes Meursius | Cornelis Johannes van Houten | Johannes Meyer | Johannes Itten | Johannes Blaskowitz | Johannes von Lahnstein | Johannes Mötsch | Johannes Hevelius | Johannes Ciconia | Johannes von Trapp | Johannes von Müller | Johannes Ullrich | Johannes Trithemius | Johannes Theodor Reinhardt | Johannes Magnus | Johannes Leimena | Johannes Ghiselin | Johannes Gad | Johannes Ewald | Johannes Diderik van der Waals | List of paintings by Johannes Vermeer |