This is how they found their way on the high seas mid 16th century.
L'Art de Naviguer. Facsimile of the 1554 French edition of Pedro de Medina's 'Arte de Navegar'.
Published about 1980 by De Boer Maritieme Handboeken, Netherlands, limited to 1000 copies, printed on antique laid paper. ISBN 9782852310087
From Wikipedia:
Arte de navegar ("The Art of Navigation", 1545) was the first work published in Spain dealing exclusively with
navigational techniques (
Martín Fernández de Enciso's
Suma de Geographia, 1519, which gave ample geographical information already contained solar declination tables with explanations and the corrections for finding the latitude by measuring the height of Polaris).
The book was internationally disseminated and quickly translated into several European languages: it was translated into French fifteen times between 1554 and 1663, five times into Dutch (1580-1598), three times into Italian (1554-1609) and twice into English. This work contributed considerably to the development of navigation on the high seas.
