Archimedes, astronomy, and the planetarium

Abstract

I present, in the form of a working model, a reconstruction of the planetarium instrument that Cicero ascribes to Archimedes. I argue for the adoption in its design of toothed gearing and of mechanism furnishing retrograde episodes for the planets, while accepting that the instrument described may in reality not have been devised by Archimedes. In my reconstruction I adopt mechanism similar to that recently suggested for the restoration of the Antikythera Mechanism, thereby demonstrating that it is practicable. The exercise provides a focus for the discussion of precursors to the Antikythera Mechanism and raises new questions about certain of its features.