The Mixture voice of a typical Waldkirch-built instrument was
described thus:

  A mixture consists of a number of ranks of open principal pipes
  at different pitches which sound together for each note.  A typical
  "three-rank mixture" in a fairground organ comprises of a 4', the
  quint 2-2/3' above it, and the 2' super octave.  Where the melody
  section is predominantly at 8' pitch, the mixture is added to this
  foundation to achieve a forte effect in the music.  The accompaniment
  is also so strengthened during forte passages; in this case higher
  harmonics are especially favoured, for example 2-2/3' + 2' + l-3/5'
  (thereby forming a "cornet mixture"), or 2-2/3' + 2'.

Ref. page 67, "Waldkirch Street and Fairground Organs", by Herbert
Jüttemann, translation and revision by Andrew Pilmer, publ. (C) 2002 by
A. C. Pilmer Automatic Music (Leasing) Ltd., Rufforth, York YO23 3QW

Robbie Rhodes