Both the written and the material documentation is poor, although the "Diversarum artium schedula", compiled by the German monk Theophilus, *23 does provide some indications about manufacturing procedures in Byzantine glassmaking in the eleventh and twelfth centuries. The “Miracles of Saint Photeine” (9th–10th centuries) mentions a fire that started in a glass workshop situated on a road leading from Strategion to Hagia Sophia. *24 This is the only known reference to glass production in Constantinople during the Byzantine Middle Ages
*23 Theophilus, Essai sur divers arts, trans. A. Blanc and J. J. Bourasse (Paris, 1980). *24 F. Halkin, ed.,Hagiographica inedita decem, 21 (Turnhout, 1989), chap. 9, pp. 111–25 (cf. 122–24). See Henderson and Mango, “Glass at Constantinople,” 346, and R. B. Mason, “Glazed ‘Tiles of Nicomedia’ in Bithynia, Constantinople and Elsewhere,” in Mango and Dagron, Constantinople and Its Hinterland (as above, note 1), 317, fig. 5.