In this article, we publish the critical edition of Andalò di Negro’s De compositione astrolabii, with English translation and commentary. The mathematician and astronomer Andalò di Negro presumably redacted this treatise on the astrolabe in the 1330s, while residing at the court of King Robert of Naples. The present edition has three purposes: first, to make available a text missing from the previous compilations of works by Andalò di Negro; second, to revise a privately circulated edition of the text; and (...) third, to help disseminating one of the rare Latin texts presenting the principles of the stereographic projection which underlie the construction of the astrolabe. (shrink)

ArgumentA Catoptrica attributed to Euclid appears in manuscripts amongst treatises dealing with elementary astronomy. Despite this textual background, the treatise has always been read literally as a theory of mirrors, and its astronomical significance has gone unnoticed. However, optics, catoptrics, and astronomy appear strongly intermingled in sources such as, amongst others, Geminus, Theon of Smyrna, Plutarch and Cleomedes. If one compares the optical reasoning put forward in these sources to account for the formation of moonlight with arguments of Catoptrica, one (...) is able to shed new light on several principles and propositions of Catoptrica, some of which had been deemed corrupt, meaningless, and obscure. Moreover, the present analysis offers a glimpse at the context of a specific stage in the evolution of ancient catoptrics: Whether literally or by analogy, several of its results appear to have been set against a wider astronomical background, which explains the inclusion of Catoptrica in the group of texts loosely defined as “little astronomy.”. (shrink)