Ioannis de Sacrobusto Libellus de sphaera. : Accessit eiusdem autoris computus ecclesiasticus, & alia quaedam in studiosorum gratiam edita.
Johannes de Sacrobosco's Libellus de sphaera is a 1543 astronomy textbook printed at Wittenberg by Petrus Seitz, prepared for students and including a church computus. Its diagrams show spherical astronomy: horizon and meridian circles, a zodiac wheel with signs and planetary symbols, and paired orbit drawings. A designer might take from them the precise, geometric line work of early modern celestial diagrams, with dense hatching and ringed circles.
