The Sphere of Sacrobosco
An early 13th century treatise on astronomy, by Iohannes de Sacrobosco. Translated by Lynn Thorndike, 1949. PROEMIUMCONTENTS OF THE FOUR CHAPTERS. — The treatise on the sphere we divide into four chapters, telling, first, what a sphere is, what its center is, what the axis of a sphere is, what the pole of the world is, how many spheres there are, and what the shape of the world is.In the second we give information concerning the circles of which this material sphere is composed and that supercelestial one, of which this is the image, is understood to be composed.In the … Continue