And Astrophysics, xii.
From 1872 he held the chair of astrophysics at Leipzig University.
Descriptions of spectroheliographs by Hale, Deslandres, Newall and others, may be found in various papers in Astronomy and Astrophysics, Astrophysical Journal, Comptes rendus, Bulletin astronomique, and other periodicals.
Clerke's The System of the Stars (2nd ed., 1905), which contains full references to original papers; Problems in Astrophysics, by the same author,, may also be consulted.
From 1892 to 1905 he was at the university of Chicago as associate professor of astrophysics, as professor (from 1897), and as director of the Yerkes Observatory (after 1895).
From 1892 to 1895 he was an editor of Astronomy and Astrophysics and thereafter of The Astrophysical Journal.