Listed only by Audsley, who says: The name given by its introducer, George W. Till, of Philadelphia, Pa. to a labial dual stop, formed of a metal Harmonic Flute, 8 ft., having the compass of CC to C5, and a metal Tierce, 3-1/5 ft., of the same compass, yielding pure organ-tone, and belonging to the 16 ft. harmonic series. In this instance, however, the Tierce is a timbre-creating rather than a harmonic-corroborating stop or rank. In combination with the Harmonic Flute it produces a compound solo voice of an absolutely new and remarkable tone-color, impossible to be produced from a single-ranked Flute, however made and voiced. This dual stop is inserted in the Choir of the Organ in the Wanamaker Store, in Philadelphia, where it speaks on wind of 15 inches. The stop is unique; and it is safe to say that such a dual stop has never been even contemplated in the preparation of the tonal scheme for any other organ hitherto constructed. We know of no Organ in which the component parts of the stop exist in any single manual division. The tone of the Tierce Flute must be heard, it cannot be described. It is especially a solo stop. This stop should not be confused with Terzflöte. Other compound stops designed by George W. Till include Duophone, Nasard Flûte, Nasard Gamba, and Quint Flute.