Cf. “Quicumque astronomice peritiam discipline” and “Cum volueris facere astrolabium”, in VallicrosaJ. M. Millás, Assaig d'història les idees físiques i matemàtiques a la Catalunya medieval (Barcelona, 1931), 217–27.
2.
Although Borrelli knows well the proceedings of the 1983 conference on Gerbert held at Bobbio and published in Archivum Bobiense studia 2, and the materials in GuyotjeanninO.PoulleE., Autour de Gerbert d'Aurillac (Paris, 1996), she does not seem to have had access to the proceedings of the 2000 and 2004 Gerbert conferences at Bobbio, published as Archivum Bobiense studia 4 and 5, respectively.
3.
The drawing in ms. Avranches 235 is no doubt today diffused around the world, since it has been taken up by the city of Avranches as the emblem illustrative of the “Scriptorial” or museum of the manuscript book that it has opened within its walls, and since it appears on the derivative products on sale at the shop of the Scriptorial.
4.
In the proceedings of the 1983 Bobbio conference. Cf. also “A propos du Scriptorial”, Revue de l'Avranchin et du pays de Granville, lxxxiii (2006), 489–92.
