José Vizinho, at the end of the 15th century, had already managed to develop the science of determining latitude. However, there were still important navigation problems that needed to be solved.
One of these was the search for a method to determine longitude to complement the known methods of determining latitude, and hence locate ships on the surface of the Earth's seas.
A famous cosmographer, Francisco Faleiro left us his written work Tratado del Esphera y del arte del marear: com el regimieto de las alturas; cõ algûas reglas nuevamête escritas muy necessarias (Treaty on the Globe and the art of navigation: with the rule of heights and with some very necessary newly written rules). This work was printed in Seville in 1535 and represents a nautical guide in which the most innovative idea is the explanation of three methods for obtaining magnetic declination by solar observation (a fourth method is incorrect). The treatise of Pedro Nunes was only published two years later.
In 1517 he reached Seville together with Rui Faleiro, and began his collaboration with the King of Spain, helping his brother in the scientific planning of the great voyage of circumnavigation.
Like his brother, he did not accompany Magellan on the great voyage, even though he had been asked by King Carlos I to join an expedition which followed behind Magellan's fleet.
From Frei Heitor Pinto
One of the most famous Portuguese writers, Frei Heitor Pinto, was also born in the Serra da Estrela mountains. In his Diálogo da Justiça (Dialogue of Justice) he highlighted the clash between the innovative vision of a ‘mathematician’ on the one hand, the character who argued in defence of the new discipline, and the traditional reservations of a 'jurist' on the other, his interlocutor.
Frei Heitor Pinto continued along the same lines as his contemporaries described above, and understood better than anyone the audacity of nautical science and the power of wisdom and knowledge.
“On that authority, said the mathematician, it is proved that Philosophy, and especially Mathematics, is a necessity for princes and all governors, so that they may know their place in the world, the movements of the heavens, navigation, weather, and constellations, and so that they may locate a city, lead an army and guide a fleet, and other such things of this nature befitting a genuine prince."
