João Faras, better known simply as Mestre João ("Master John"), was an astrologer, astronomer, physician and surgeon of King Manuel I of Portugal who accompanied Pedro Álvares Cabral in the discovery of Brazil in 1500, and wrote a famous letter identifying the Southern Cross constellation.
Background The celebrated 1500 letter of Mestre João Faras was discovered in the Portuguese royal archives by the historian Francisco Adolfo de Varnhagen, and published for the first time in 1843. Despite extensive research, the figure of Mestre João Faras remains elusive. In his 1500 letter, Mestre João identifies himself simply as a bacherel of arts and medicine ('bachelor' was a general term for someone with formal learning) and a personal physician and surgeon of the King Manuel I of Portugal. Besides the 1500 letter, the only other concrete clue about Mestre João's existence is an (unpublished) manuscript translation of Pomponius Mela's De Situ Orbis from Latin into imperfect Castilian. He may also have gone by the name 'Johannes Emeneslau'. On account of his poor command of Portuguese and preference for Spanish (Castilian), Mestre João Faras is generally believed to have been originally one of the existing nationalities in what would become Spain (whether he was Castilian, Galician or Aragonese has been alternatively proposed). He was almost certainly a Sephardi Jew. He probably fled Spain for Portugal after the 1492 Alhambra decrees, but ended up converting after 1496, to enter the service of King Manuel I of Portugal. Recent research has traced at least two originally Spanish Jews who could plausibly fit his profile: one, a certain Juan Faraz, a native of Seville, another, a "Mestre Joam" (original surname and town not given), who settled in northern Portugal and took up the name João da Paz.
Voyage and mission Mestre João Faras joined the 2nd Portuguese India Armada of thirteen ships, commanded by Pedro Álvares Cabral, which left Lisbon in March 1500, destined for Calicut, India. It is unknown on which ship he sailed, although it has been conjectured (on account of his complaint about it being "small" with insufficient space) to be either the Anunciada commanded by Nuno Leitão da Cunha or the São Pedro commanded by Pero de Ataíde. The purpose of his joining the expedition seemed to have been purely scientific, that is, to assist the future development of navigational science. His predecessor, Mestre José Vizinho, was sent to Guinea back in 1485 to test measurements of solar altitudes. Mestre João Faras was probably sent by the king with a similar intent, to test out new astronomical instruments and tables. It is known that Mestre João Faras brought along a new nautical astrolabe and what he characterised as new Arab astronomical nautical staves (cross-staff?) for experimentation. He was almost certainly furnished with Abraham Zacuto's new tables as well. Mestre João Faras was probably specifically charged to find a way of determining the position of the ship by the stars in the Southern Hemisphere, a difficulty which had not yet been overcome. Since the time of Prince Henry the Navigator, "compass error" (the exact deviation of the magnetic north from the true north) could be corrected in the northern hemisphere by recourse to the position of northern Pole Star (observed on board via the quadrant), thus allowing navigators to determine the correct position of the ship. But the Pole Star disappeared below the horizon as the equator was crossed, rendering this method useless in the southern hemisphere. It was hoped that an equivalent South Pole Star might be found. An alternative method was to take recourse to the position of the Sun at noon. This had been suggested since at least the 1470s, but only became a reality with the publication of the Almanach perpetuum of Abraham Zacuto in 1496, with its tables of solar declination. As the Sun could not be observed directly by the quadrant, Portuguese navigators brought on board their ships land-based astrolabes (which allows the measuring of the Sun's height without looking directly at it). Unfortunately, astrolabe readings required stability which is not possible at sea, so new small hand-held nautical astrolabes were being introduced at this time. This method had still not been perfected. In 1497, Vasco da Gama took Zacuto's tables and the astrolabe with him on his maiden trip to India, but was dissatisfied with the results. Upon his arrival at the Bay of St. Helena in November 1497, da Gama disembarked to take readings on land because he did not trust the readings of the new nautical astrolabe at sea. Master João Faras made much the same complaint about his on-board readings in his letter, claiming that the rocking of the ship put his readings off by a whole four or five degrees. (In his letter, Mestre João hints the pilots on board had engaged him in a friendly charting competition, the pilots betting they could find the Cape of Good Hope more accurately by compass and chart alone than Mestre João could with his astrolabe.)
In Brazil On 22 April 1500, Cabral's armada sighted the land coast of Brazil, and anchored a couple of days later at Cabrália Bay (just north of Porto Seguro, Bahia), where they were met by local Tupiniquim Indians.
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