As well as their chief conductor, the orchestra had assistant conductor positions called “first conductor” and “second conductor”. During Mengelberg’s time the “first conductors” included Karl Muck (1921-1925), Pierre Monteux (1924-1934), Bruno Walter (1934-1939), and Eugen Jochum (1941-1943), and the second conductors included the composer Cornelis Dopper, Evert Cornelis and Eduard van Beinum.