Roman Dodecahedron as dioptron: analysis of freely available data

Abstract

Recently I have proposed the Roman Dodecahedra as ancient coincidence rangefinders. Here I discuss several data and references freely available on the Web. After analysis, the common features of these artifacts allow to tell that a Roman Dodecahedron was probably a dioptron. The equation of this optical instrument is given. The paper ends with a discussion on the role of the Web and free information for further studies of these objects.