Sumner describes this stop as follows: A mixture stop intended to reinforce the natural harmonics of the diapasons. The composition of the stop varies with different builders, but contains third and flat-seventh sounding ranks as well as octaves and fifths. The ranks are open and of small scale and the thirds and flat sevenths need careful adjusting. The stop is a modern, and usually not very successful, attempt to limit the number of compound stops on a great organ. Irwin describes it thus: This stop-name, like Mixture, is not explicit as to design, pitches, or timbre, but it usually indicates high-pitched ranks of open metal Foundation pipes voiced to augment the Diapasons or Flutes in any division, including the pedals. Irwin goes on to list eight examples of three to four ranks, incomplete as usual, showing only the compositions at middle C, with no mention of breaks. All of his examples contain only octave and fifth sounding ranks. Irwin also lists Harmonics as a synonym for Cornet des Bombardes. Skinner defines it as a V-rank mixture consisting of 15th, 17th, 19th, 21st, and 22nd.