Tractatus De Sphaera
About 1230, his best known work, Tractatus de Sphaera (On the Sphere of the World) was published. In this book, Sacrobosco gives a readable account of the Ptolemaic universe. It was required reading by students in all Western European universities for the next four centuries. Though principally about the heavens it contains a clear description of the Earth as a sphere and its popularity shows the nineteenth-century opinion that medieval scholars after this date thought the Earth was flat as a fabrication (See: Flat Earth).
Read more about this topic: Johannes De Sacrobosco