of a certain Oberto Foglieto of Genoa, where an entry reads unum martelogium....item carta una pro navegando. The first clear appearance and explanation is the 1436 atlas of Venetian captain Andrea Bianco. Other early manuscripts have since been found relating the rule of marteloio, include: an anonymous 15th-century Venetian codex, post-1428, once part of the collection of Doge Marco Foscarini, now lost. the Liber of Venetian mariner Michael of Rhodes (c. 1434–36) (Ms. in private collection) the Adriatic portolano of Grazioso Benincasa of Ancona, compiled 1435–45 (Ms. at Biblioteca comunale Luciano Benincasa in Ancona, Italy). the Venetian portolano manuscript Alcune raxion de marineri by Pietro di Versi, c. 1444 (Ms.It.IV. 170 at Biblioteca Nazionale Marciana in Venice, Italy) The Libro of Venetian naval trumpeter known as Zorzi Trombetta of Modone, dated c. 1444–49 (Cotton MS. Titus A.XXVI at the British Library in London, UK) Anonymous Venetian manuscript known as Arte Veneziana del Navigare, c. 1444–45 (Ms. C.M.17 at the Biblioteca del Museo Civico de Padova in Padua, Italy). Ragioni antique spettanti dall'arte del mare et fabriche de vasselli (Ms. NVT 19, at the National Maritime Museum in Greenwich, UK). Cornaro Atlas, a c. 1489 copy of an earlier manuscript, (Ms.Egerton 73 at the British Library in London) 15th-century anonymous Venetian portolano (Ms. 3345* (Fosc.307) at the Österreichische Nationalbibliothek (ÖNB) in Vienna, Austria) Notes External Resources Altante Bianco, 1436 at Internetculturale.it; Higher resolution at Geoweb.sbn.venezia.it. McGee, D. et al. (2003 onwards) Michael of Rhodes: A medieval mariner and his manuscript website (accessed July 20, 2011). (originally hosted by Dibner Institute for the History of Science and Technology at M.I.T., now hosted by Museo Galileo Institute and Museum of the History of Science in Florence, Italy) References Aczel, A.D. (2001) The Riddle of the Compass: the invention that changed the world New York: Harcourt. Albertis, E.A. (1893) Le construzioni navale e l'arte della navigazione al tempo di Cristoforo Colombo, Pat IV, vol. 1 of Raccolta di Documenti e Studi pubblicati dalla Reale Commissione Colombiana pel quarto Centenario della scoperta dell'America. Rome: Ministero della Pubblica Istruzione. Albuquerque, L. de (1970) "A navegação astronômica", in A. Cortesão, editor, 1969–70, História da cartografia portuguesa, vol. 2. Lisbon: Junta de Investigações do Ultramar, p. (as reprinted in 1975, Estudos de História, Vol. 3. Coimbra: UC Biblioteca Geral online) Albuquerque, Luís de (1973) "O Tratado de Tordesilhas e dificuldades técnicas da sua aplicação rigorosa" in El Tratado