Over the past century, scholars have identified examples of liturgical chant belonging to more than one Western liturgical tradition, including Franco-Roman, Old Hispanic, Old Beneventan and Milanese. In a seminal study, Kenneth Levy identified a set of offertories that circulate in the Franco-Roman, Old Hispanic and Milanese traditions, arguing that all existing versions derive from an earlier, Gallican tradition. This article expands the evidence for connections between the Franco-Roman and Old Hispanic traditions, identifying nearly two dozen Franco-Roman responsories that are shared with the Old Hispanic rite and may be of Gallican or Iberian origin. The diversity of their liturgical assignments and circulation patterns suggests that the exchange of repertory took place at different times and through different routes. Many of these responsories are assigned to the later layers of the Roman liturgy. Others were added to the Old Hispanic liturgy between the eighth and tenth centuries.

Just over half of these responsories show enough melodic connections between the Franco-Roman and Old Hispanic versions, in contour and melismatic density, to imply a shared melodic ancestor. Each version, however, uses the formulas associated with its own tradition, indicating that the melodies have been assimilated to the style and formulaic content of the receiving tradition. Despite the resulting melodic differences, we identify certain commonalities between Franco-Roman and Old Hispanic chant, such as text-setting strategies and common cadential contours, that facilitated the exchange of repertory.

It is known that the seventh book of Jacobus's Speculum musicae contains, alongside other quotations from Ars Nova treatises, the earliest extant transmission of the salient passage of Johannes de Muris's Musica speculativa, Conclusio XVIII, where Muris questions the nature of the fourth as a perfect consonance. However, the relevant passages of Musica speculativa cited and discussed by Jacobus have not yet been analysed in the context of the rich manuscript tradition of the Musica speculativa, which served the needs of musical education throughout Latin Europe for at least two hundred years. In order to position Jacobus's citations of Muris within the framework of the Musica speculativa tradition, I examine several significant variant readings contained in Speculum musicae, comparing them to two French, most probably Parisian, manuscripts transmitting versions A (A-SPL Cod. 264/4) and B (BnF lat. 7378A) of Musica speculativa. Both A and B versions are provided with colophons dated 1323 and 1325, respectively. Establishing which version of Musica speculativa was the source of Jacobus's citations provides a new basis for the dating of two other treatises by Muris to which Jacobus refers, namely Notitia artis musicae and Compendium musicae practicae, and, more generally, for the date of the seventh book of Speculum musicae.

The earliest known treatise on Boethian proportions in Middle English is attributed to ‘Chilston’ in London, British Library, Lansdowne 763. Nothing is known of Chilston's biography, although his treatise also survives anonymously in two related sources (New York, Morgan Library, B.12 and Dublin, Trinity College, 516). In 1927, Irish musicologist William Henry Grattan Flood suggested an identification between the author of the proportion treatise and the scribe of British Library, Royal 5 A VI, a priest's handbook dated to 1446. English lexicographer Jeffrey Pulver was quick to dismiss Flood's identification, which apparently discouraged any further assessment of it. This article reconsiders Flood's suggestion, taking into account 1920s political and cultural biases that might explain Pulver's swift rejection. A contextual exploration of the evidence supports the connection of the proportion treatise to Royal 5 A VI and sheds light on the milieu in which Chilston may have worked. Long recognised for his significance in the vernacular history of music theory and music pedagogy, the proposed contextual framework has significant implications for understanding the multiple functions of music theory in fifteenth-century England. Most notably, it documents the use of speculative music theory among readers and audiences with limited knowledge of Latin. A variety of uses for music theory reveal themselves within the emerging vernacular pedagogical practices of late medieval England. These reflect the broader production of technical texts in Middle English and the increased vernacularisation of English society at a pivotal moment of ecclesiastic and musical history.