One of the first European mathematicians to apply mathematical techniques to cartography was Pedro Nunes (1502–1578), Royal cosmographer and the leading figure in Portuguese mathematics and nautical science. Nunes wrote extensively on spherical geometry, astronomy, navigation and algebra.
In his 1537 treatise on the sphere he showed how to represent rhumb lines or loxodromes (the path of a ship on a fixed bearing) as straight lines; on the globe these are spirals that converge to the poles. He also constructed nonius scales for accurately measuring fractions of a degree; these were used by navigators when measuring the heights of stars with a quadrant.
[Portugal 1978, 2002]