Algorismus / Tractatus de Sphaera / Computus Lunaris

33 leaves, illuminated manuscript on vellum. 23 cm H. Marginalia throughout. Nine large scientific and astronomical diagrams. Bound manuscript version of Sacro Bosco's Algorismus, on arithmetic, Tractatus de Sphaera, an elementary text on astronomy and the terrestrial globe, and Computus Lunaris, a treatise on the calendar.