Contributions to the calculation of latitude in the early seventeenth century spanish navigation contained in the manuscript of Diego Ramírez de Arellano: “Reconocimiento de los estrechos de Magallanes y San Vicente, con algunas cosas curiosas de navegación” (1621)

Abstract

In 1620, was named chief pilot of the Casa de Contratación de Sevilla Diego Ramírez de Arellano, author of a manuscript entitled Reconocimiento de los estrechos de Magallanes y San Vicente, con algunas cosas curiosas de navegación. He had participated in the reconnaissance mission referred by the title of the manuscript, and in that book developed same methods and tools for a nautical understood scientifically, and even used a methodology close to modern science, as in refuting the theory about Figueiredo of the linear relationship between longitude and magnetic variation of the needle navigation. This article is based on some conclusions that can get an analysis of the manuscript. It focuses on the exhibition held at the Diego Ramirez same about a useful procedure for pilots of calculating the latitude of a place by the Sun extrameridianas heights, which meant a breakthrough in navigation methods of the time. It also outlines the motivations and geopolitical interests of the Spanish monarchy to promote scouting expedition that made the manuscript and the innovations it contains.