From Chapter 40 of the Decline & Fall

Tzetzes describes the artifice of these burning-glasses, which he had read, perhaps, with no learned eyes, in a mathematical treatise of Anthemius. That treatise, has been lately published, translated, and illustrated, by M. Dupuys, a scholar and a mathematician, (Memoires de l'Academie des Inscriptions, tom xlii p. 392 - 451.)