Astronumicum Caesareum (Astronomy of the Caesars) (Peter Apian, 1540)
Peter Apian’s Astronomicum Caesareum is a masterpiece of printing. With the aid of simple tools, he thought, it should be possible to plot the paths of planets and the movements of the stars, and calculate the occurrence of eclipses and comets. The Astronomicum endeavoured to supply these tools in the form of highly intricate moving discs, or volvelles, from which information could be obtained through combinations of circles and angles.
Photo credit: Bodleian Libraries, University of Oxford