A Newly Identified Treatise on the Tables of Marseilles (Twelfth Century) and Its Non-Ptolemaic Planetary Theory

Two Latin manuscripts in Oxford and Florence preserve diverging recensions of a previously unnoticed astronomical treatise beginning Infra signiferi poli regionem (Oxford recension) or Circulorum alius est sub quo (Florence recension). It can be shown that this anonymous text was originally intended to accompany the Tables of Marseilles in Raymond of Marseilles’s twelfth-century Liber cursuum planetarum (ca. 1141). While the core tables for planetary longitudes in this set were founded on Ptolemy’s kinematic models, as known from the Almagest, this new source frequently deviates from the Ptolemaic norm, for instance by explicitly rejecting an epicyclic explanation of planetary stations and retrogradations. In place of the latter, it argues in favour of a heliodynamic theory inspired by Roman sources such as Pliny, which underwent certain developments in the works of twelfth-century Latin writers such as William of Conches. Rather than being wholly exceptional, these features are indicative of a degree of disconnect between planetary theory and computational practice in twelfth-century Latin astronomy, which is also detectable in other sources from this period.