Synchronising the hours: a fifteenth-century wooden volvelle from the Basilica of San Zeno, Verona

The San Zeno Wheel of Verona is an exceptional, virtually unstudied fifteenth-century horological device, the only one of its type to have survived. Yet certain features of the Wheel correspond to contemporary manuscript volvelles and to the liturgical calendars of larger horological devices. The interpretation of the object presented here has two main objectives: first, to elucidate the Wheel itself; and second, to consider its role in relation to the ecclesiastical routines of the San Zeno complex. By investigating the relationship of the Wheel to fourteenthand fifteenth-century time-reckoning instruments, notably astronomical clocks, the article shows that it is the oldest liturgical calendar disk to survive and, therefore, an invaluable testament to the original appearance of the earliest astronomical clocks. This is followed by a reconstruction of the way in which the Wheel was used in its original setting. An interpretation of its content in relation to the other horologia at San Zeno suggests that it was made to complement another time-reckoning device in the basilica. San Zeno therefore provides a unique case study regarding the ways in which multiple time systems were synchronised in the reckoning of the liturgy following the invention of the mechanical clock. The analysis of the Wheel has potentially far-reaching implications for our understanding of the ways in which the dispensation of mechanical horologia in monastic settings affected the perception of time. Such an analysis is, therefore, significant not only for the study of historical horology, but of medieval temporality more generally.