These names denote a mutation stop of 1-3/5' on the manuals, supporting the 8' harmonic series, and 3-1/5' on the pedals, supporting the 16' harmonic series. It supports the fifth harmonic, sounding approximately an E when played from a C key, seventeen scale steps higher (hence the name Seventeenth). It is therefore known as a “third-sounding” rank.

According to Grove, third-sounding ranks have been known in the organ at least as early as c1450. It was apparently first used extensively in the classical French organ, where it was a wide-scaled flute stop, usually open but sometimes (according to Williams) stopped.

While Grove and Williams state that the Seventeenth was found outside France only in French-influenced organs, Adlung (writing in the mid-1700's) calls it “a familiar stop in the organ”, and describes it as a principal rather than a flute. On organs of the 20th century, the Tierce is often found as part of the Great principal chorus. This rank also often appears as part of a Sesquialtera.

On the theatre organ, Strony tells us that the Tierce was originally borrowed from the Concert Flute, but in modern instruments is usually taken from the Tibia.

It should be noted that in classical instruments this pitch should never be borrowed from an octave-sounding rank. The harmonic it is supposed to support is too far in pitch from the nearest note in the equally-tempered scale; it can never sound properly in tune.

The terms Decem and Decima are also, and more properly, used as synonyms for the Tenth. There are alternate meanings for the word Corneta. Terz is also a synonym for Third and Tenth. Regarding the name Sesquioctava, Adlung writes that it appears “at Sandomir”, and he does not understand why it is used, as the name indicates a ratio of 9/8.

Variants

Examples

The most common of these names is Tierce, with over 450 examples found in Osiris. The name Terz occurs somewhat more than half as frequently. Only a few dozen examples are known for each of Seventeenth, Terts and Tertia. The earliest known examples are given below. Osiris contains nearly a hundred examples of Corneta, but none are known to be single 3rd-sounding ranks. No examples are known of Decem, Detzehm, Detzem, Diatonus, Ditonus, Septadecima, Septuadecima, Sesquioctava, or Sixtil. Contributions welcome.

Tierce 1-3/5', Rugpositief; St. Jacobs, Antwerpen, Belgium; de Lanoy 1654.

Terz 1-3/5', Hauptwerk; Abbey, Muri, Switzerland; Schott 1630.

Seventeenth 1-3/5', manual; Essex Institute, Salem, Massachusetts, USA; Hook 1827.

Terts 1-3/5', manual; Karmelieten Ten Troost, Vilvoorde, Belgium; Marcquet 1633.

Tertia 1-3/5', Brustwerk; St. Cosmae, Stade, Germany; Schnitger 1772.

Decima 3-1/5', Gran Organo; Auditorio Nacional, Mexico City, Mexico; Tamburini 1958. This is the only known example of this name.

Tertie 1-3/5', Oberwerk; Brandenburger Dom (Liebfrauenkirche), Brandenburg, Germany; Wagner 1733. This is the only known example of this name.

Decimasettima [1-3/5'], manual; Chiesa di San Filippo, Castelfranco di Sopra, Italy; Bruschi 1652. This is the only known example of this name.

Sound Clips

See the Sound Files appendix for general information.

Bibliography