Euler organ, after Fokker

The physicist Adriaan Daniël Fokker (1887-1972) succeeded in 1928 H.A. Lorentz as curator of the Physical Laboratory of Teylers Museum and as professor in Leiden. In the Second World War, when the university was closed by the Germans, he started studying music theory.

Fokker assumed that music should be based, melodically as well as harmonically, on intervals with simple frequency relationships. Following Huygens and Euler he argued in favour of replacing the usual division of an octave into twelve equal parts by a division into 31 parts. In 1943 he had this miniature organ built according to these principles and this organ was shown in the auditorium of the museum for years. In 1950 a large 31-tone organ followed, which was shown in Teylers Museum until 2000.