A very rare mutation stop that speaks approximately an F when played from the C key, two octaves and a fourth above. It is found at 1 5/11' pitch in the manuals, where it sounds the 11th harmonic of the 16' harmonic series. In the pedal it is found at 2 10/11' pitch, part of the 32' harmonic series. This stop is listed only by Irwin, who says: It is not a common harmonic of any series of pitches, and is of use only in a very complete Harmonic Chorus, an ancillary that includes stop-pitches for all regular pitch-positions as well as many of those in between. The manual pitch is between the 1-3/5' and the 1-1/3' stops.
Eighteenth 1 5/11', Choir-Swell; Convention Hall, Atlantic City, New Jersey, Midmer-Losh 1929-32.