Fine example of the first practical treatise on navigation.

Pedro de Medina (1493-1567), was a mathematician, astronomer, and geographer. He started his career as tutor and librarian to the Dukes of Medina. He then began to practice cosmography, and became an examiner of pilots and sailing-masters in Seville in 1539. He was dissatisfied with the level of teaching and quality of the texts and charts he taught with, and wrote his 'Arte del navigare' to remedy the deficiency. This was the first European treatise on navigation, which is why de Medina "may be said to be the founder of the literature of seamanship" (Church). He was subsequently appointed Royal Cosmographer in 1549.

The work was very popular – it was one of the three navigational texts that Sir Francis Drake took on his expedition – and was translated into several languages. His official position as examiner brought him into constant contact with sailors and pilots, and the maps are remarkably up- to-date, incorporating discoveries and reports from Spanish expeditions in the Americas. His map of the Atlantic Ocean and the Americas shows the mouth of the Mississippi, "R. SPT. SAN.", and the St Lawrence River and Gulf. Newfoundland is still shown as a peninsula rather than an island. The river Saguenay is indicated here, a remarkable feature in so early a map. Within the small woodcuts is a map of the world (leaf 26), surrounded by eight windheads. Europe, Asia, and Africa are marked and part of America is shown in simplified form (Shirley).