Amerigo Vespucci (March 9, 1454 – February 22, 1512) was an Italian explorer, financier, navigator and cartographer who first demonstrated that Brazil and the West Indies did not represent Asia's eastern outskirts as initially conjectured from Columbus' voyages, but instead constituted an entirely separate landmass hitherto unknown to Old Worlders. Colloquially referred to as the New World, this second super continent came to be termed "America", deriving its name from Americus, the Latin version of Vespucci's first name. At the invitation of king Manuel I of Portugal, Vespucci participated as observer in several voyages that explored the east coast of South America between 1499 and 1502. On the first of these voyages he was aboard the ship that discovered that South America extended much further south than previously thought. The expeditions became widely known in Europe after two accounts attributed to Vespucci were published between 1502 and 1504. In 1507, Martin Waldseemüller produced a world map on which he named the new continent America after the feminine Latin version of Vespucci's first name, which is Americus. In an accompanying book, Waldseemüller published one of the Vespucci accounts, which led to criticism that Vespucci was trying to upset Christopher Columbus' glory. However, the rediscovery in the 18th century of other letters by Vespucci has led to the view that the early published accounts, notably the Soderini Letter, could be fabrications, not by Vespucci, but by others. In 1508, the position of chief of navigation of Spain (piloto mayor de Indias) was created for Vespucci, with the responsibility of planning navigation for voyages to the Indies. Two letters attributed to Vespucci were published during his lifetime. Mundus Novus (New World) was a Latin translation of a lost Italian letter sent from Lisbon to Lorenzo di Pierfrancesco de' Medici. It describes a voyage to South America in 1501–1502. Mundus Novus was published in late 1502 or early 1503 and soon reprinted and distributed in numerous European countries. Lettera di Amerigo Vespucci delle isole nuovamente trovate in quattro suoi viaggi (Letter of Amerigo Vespucci concerning the isles newly discovered on his four voyages), known as Lettera al Soderini or just Lettera, was a letter in Italian addressed to Piero Soderini. Printed in 1504 or 1505, it claimed to be an account of four voyages to the Americas made by Vespucci between 1497 and 1504. A Latin translation was published by the German Martin Waldseemüller in 1507 in Cosmographiae Introductio, a book on cosmography and geography, as Quattuor Americi Vespucij navigationes (Four Voyages of Amerigo Vespucci). On March 22, 1508, King Ferdinand made Vespucci chief navigator of Spain at a huge salary and commissioned him to found a school of navigation, in order to standardize and modernize navigation techniques used by Iberian sea captains then exploring the world. Vespucci even developed a rudimentary, but fairly accurate method of determining longitude (which only more accurate chronometers would later improve upon). In the 18th century, three unpublished familiar letters from Vespucci to Lorenzo de' Medici were rediscovered. One describes a voyage made in 1499–1500 which corresponds with the second of the "four voyages". Another was written from Cape Verde in 1501 in the early part of the third of the four voyages, before crossing the Atlantic. The third letter was sent from Lisbon after the completion of that voyage. Some have suggested that Vespucci, in the two letters published in his lifetime, was exaggerating his role and constructed deliberate fabrications. However, many scholars now believe that the two letters were not written by him but were fabrications by others based in part on genuine letters by Vespucci. It was the publication and widespread circulation of the letters that might have led Waldseemüller to name the new continent America on his world map of 1507 in Lorraine. Vespucci used a Latinised form of his name, Americus Vespucius, in his Latin writings, which Waldseemüller used as a base for the new name, taking the feminine form America, according to the prevalent view (for other hypotheses, see the footnote in the introduction). The book accompanying the map stated: "I do not see what right any one would have to object to calling this part, after Americus who discovered it and who is a man of intelligence, Amerige, that is, the Land of Americus, or America: since both Europa and Asia got their names from women". It is possible that Vespucci was not aware that Waldseemüller had named the continent after him. The two disputed letters claim that Vespucci made four voyages to America, while at most two can be verified from other sources.