Abstract

In 1922, Aleksander Birkenmajer presented an unknown work of Albert of Saxony, Quaestiones de sphaera, in a manuscript at the Dominicans in Vienna. In 1989, Jürgen Sarnowsky found a second manuscript in Rome. This paper presents a third complete manuscript (BNE Madrid) and an incomplete one (Amploniana Erfurt) of this work. Furthermore, it is argued that an anonymous expositio of Sacrobosco’s treatise can be ascribed to Albert of Saxony. Finally, an anonymous commentary on Albert’s questions in two manuscripts (Munich, Salzburg) is presented. The possibility that this commentary stems from the famous Viennese master John of Gmunden (d. 1442) is considered, but no decisive result could be achieved yet. In an appendix, a complete list of the titles of Albert’s questions is added.