Listed only by Irwin, who says:

A rank of Foundation pipes that speaks at 4/7' on the manuals, and 1-1/7' on the pedals. These pitches sound at the notes three octaves and a flatted seventh above the keys struck, which is at Bb4 from middle C, and Bb1 from low pedal CCC. It is best identified as the octave of the well-known Septième. It is a mixture rank in a few cases, speaking in the lower octaves where the Septième might be too low in pitch. It is never a separate stop knob.

This rank reinforces the 14th harmonic. In an equally tempered instrument, that harmonic will only approximate a Bb in pitch. See Mutations.

Examples

Twenty Eighth 1-1/7', Pedal; Convention Hall, Atlantic City, New Jersey; Midmer-Losh 1929-32.

Bibliography