Rules of Navigation...

This work, by Andrés García de Céspedes, was commissioned by Council of the Indies - the highest administrative body of the Spanish Empire for the Americas and the Philippines with legislative, executive and judicial functions. Its purpose was to correct the Royal Patron (the Padrón Real - the official, secret Spanish master map used as a model for all other maps). The 184-sheet work, entitled "Regimiento de navegación [que] mando hazer el rei nuestro señor por orden de su conseio real Real de las Indias a Andres Garcia de Cespedes su cosmógrafo maior siendo Presidente en el dicho consejor el conde de Lemos", was printed by Juan de la Cuesta.

It is one of the most important nautical studies of its time. His work gave rise to a new method for observing the pole star, and provided more accurate direction, allowing for compass needle variation. He also established new navigation rules and modified nautical instruments. One of the most important aspects of García de Céspedes' work was that it corrected studies by Juan Bautista Labaña, Pedro Núñez and Rodrigo Zamorano and as a result, it was highly influential.