Mutation stop · 1 3/5 ft

The Tierce

The mutation stop that sounds the major third of the note played, two octaves higher: the most distinctively French colour of the classical organ.

Mutation stop

What it is

The tierce is an open mutation stop of wide scale, usually made of étoffe, sometimes of tin, running the full compass. It speaks a third above the doublette, or an octave above the grosse tierce; today it is written 1 3/5 feet. On a C it sounds an E, two octaves and a third higher. There is one on the positive, of slightly narrower scale, and sometimes one in the pedal.

It is never used alone: it is added to the foundation stops and the other mutations to form the jeu de tierce. Builders, Dom Bedos reminds us, never put a tierce in the plein jeu, which contains only fifths and octaves. It is, however, one of the five ranks of the cornet.

L'Art du facteur d'orgues

What Dom Bedos says

La Tierce est un Jeu ouvert & de mutation, de grosse taille, qu’on fait ordinairement en étoffe, quelquefois en étain, & de toute l’étendue du Clavier. Il parle à la Tierce de la Doublette, ou à l’octave de la grosse Tierce. [...] La Tierce est en usage dans toutes les Orgues.

TranslationThe Tierce is an open mutation stop of wide scale, usually made of étoffe, sometimes of tin, running the whole compass of the keyboard. It speaks at the third of the Doublette, or at the octave of the grosse Tierce. [...] The Tierce is in use in all Organs.

Dom Bedos de Celles, L’Art du facteur d’orgues, Part I (1766), ch. IV, sect. I, § 171, p. 47.

In practice

In the music of the Couperins and their contemporaries

The tierce gives its name to a whole repertoire: the jeu de tierce, pieces “on the tierces”, the tierce en taille. Boyvin plays the duo “on the two Tierces”, those of the positive and of the great organ, and places the tierce of the positive at the heart of the tierce en taille.

Dom Bedos describes two combinations: the grand jeu de tierce of the great organ, with all the foundation stops, the two nazards, the two tierces and the quarte, and the jeu de tierce of the positive. He bans any tierce, on the other hand, from the plein jeu, whose edge it would blunt, and from the grand jeu, where it would rob the reeds of their grace.

The works