Amerus’
Practica artis musicae(1271) is among the most significant witnesses to the practice of early mensural music before Franco of Cologne’s
Ars cantus mensurabilis(c.1280) diffused. While most contemporaneous thirteenth-century writings on mensural theory refer to both
tempus/
tempora and rhythmic modes, notably Amerus employs neither. Presumably in order to compensate for Amerus’ text, an anonymous short treatise appended to
Practica(hereafter, the
Appendix) —comprising three paragraphs—describes
tempus/
tempora and the six rhythmic modes.
Intriguingly, the entire content of the
Appendix is considerably inconsistent in terms of its repetitive descriptions of
modus and a three-
tempora long. This incoherency arguably arises from the fact that the
Appendix is a miscellany of major mensural rules from several influential treatises circa 1280. Its first paragraph on the six rhythmic modes in motets appears identical to the principles provided by Anonymous’s
Discantus positio vulgaris(mid-thirteenth century). The second paragraph on the six rhythmic modes in
organum is based on Johannes de Garlandia’s
De musica mensurabili(c.1260). Moreover, the explanation of
proprietas of ligatures in the third paragraph accords with Franco’s doctrine—which contradicts Amerus’ rule of ligatures. This article explicates the ascriptions and networks of each sentence in the
Appendix to other thirteenth-century writings.
In addition, the notational examples in the
Appendix show idiosyncratic ascending three-note ligatures
cum proprietate with a downward stem on the left, which cannot be found in any other sources. This results from the lacuna in the definition of ascending ligatures within the text, and it is conceivable that the author or the scribe(s) attempted to reproduce ascending ligatures on the basis of the textual explanation of descending ligatures
cum proprietate that have a downward stem on the left. These ligatures might reflect the perplexity surrounding multitudinous mensural rules circa 1280, when pre-Franconian and post-Franconian theories coexisted.
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