Listed only by Irwin, who says: A rank of Foundation pipes that speaks at 6-2/5' on the manuals (32' series), and 12 4/5' on the pedals (64' series). The function of these unusual pitches is to corroborate the fifth harmonic of the sub-sub-unison series of pitches on both the manuals and pedals. These pitches are one octave below those of the Tenth. When drawn with other pitches without their own series, they create resultant tones that are unusually grave and sometimes unpleasant. Their use is limited to a few combinations in even the very large organs. They are necessary to provide the organist with a complete set of pitches in these low series. Middle C would sound at E1 (three notes above the key depressed), and the low pedal CCC at EEE. Terz is also a synonym for Tenth, and most commonly a synonym for Tierce. Third is also used, though rarely, as a numeric prefix; see First.
Third 6-2/5, ; Convention Hall, Atlantic City, New Jersey, USA; Midmer-Losh 1929-32.