Listed only by Irwin, who says: A Foundation stop at the Twelfth's pitch of 2-2/3' on the manuals, and 5-1/3' on the pedals, sounding from Gemshorn pipes. It is a moderately soft Twelfth in most examples, since it is of smaller scale than either the Octave or unison Gemshorns. It has all of the function of the Twelfth, and makes a useful Twelfth with the Strings, Diapasons, and all flues of light tone. It cannot be substituted for the regular Twelfth. It sometimes functions like the Copula.
Gemshorn Twelfth 2-2/3', Choir-Swell; Convention Hall, Atlantic City, New Jersey; USA; Midmer-Losh 1929-32.