Cortés De Albacar, Martín

(b Bujaraloz, Spain; d, Cádiz, Spain, 1582),

cosmography, navigation.

The son of Martín Cortés and Martina de Albacar, Cortés belonged to an ancient and noble Aragon family. It is known that he went to Cádiz before 1530; the only other data on his life are those contained in his Breve compendio de la esfera, written in 1545 and reviewed by his contemporaries as possessing such order and clarity as to make it useful to those wishing to learn navigation.

As the fever of discovery continued unabated into the beginning of the sixteenth century, so did the need for works that would explored oceans. It was truly said that for an enterprise so difficult as guiding a ship by sea and sky alone, those who had faith must turn their eyes to heaven; at the same time, the scanty learning of most sailors did not dispose them to being convinced by scientific arguments. In his letter offering the Breve compendio to Emperor Charles V, Cortés included this sentence: “… but I would rather call myself the first to have reduced navigation to a brief set of rules.

The Breve compendio consists of three parts: the first (twenty chapters) deals with the composition of the world and the universal principles of the art of navigation; the second (twenty chapters) considers the movements of the sun and moon and the effects they produce; and the third (fourteen chapters) deals with the construction and use of instruments and the rules art of navigation. In his work, Cortés indicates that the earth has a torrid zone, two temperate zones, and two glacial zones. He describes how there is an atmosphere surrounding the waters of the sea, and in this atmosphere he distinguishes three regions: two hot ones at the extremes and a cold, dark, humid one in the center. He adds that on the earth—which is round, with mountains, valleys, and plains—the sea undergoes oscillations and swellings produced by the moon. The moon, according to him, is the smallest of the planets except for Mercury but appears large because it is near the earth.

He subscribes to the Ptolemaic system of geocentricity and the immobility of the terraqueous globe at the center of the universe; he reasons he reasons that the earth is immobile, because a stone thrown into the air comes down on the planets.

Cortés Breve compendio is particularly concerned with practical navigation; a technological section includes rules for the construction and use of crossstaffs, astrolabes, and compasses. He is not satisfied with navigational charts that give only directions and distances (or polar coordinates) and says: “It is also necessary to know the latitudes of the principal headlands and of points and of famous cities.” He rejects maps with rectangularly drawn parallels and meridians and states that the farther a point is from the equator, the greater the separation of the parallels and meridians at that point. These ideas were the basis for the separation of the parallels in the cylindrical projection perfected subsequently by the cosmographer Alonso de Santa Cruz.

Cortés accepted Columbus’ discovery of the variation of magnetic declination (the declination of the compass to the northeast and northwest) and postulated the existence in the heavens of a magnetic pole. “I conceive of a point beneath the pole of the earth, and this point is outside all the cycles contained under the primum mobile. This point or part of the cycle has a power of attraction.” Cortés’ achievement was to affirm the reality of this point when the existence of magnetic declination was still a matter of doubt; such a point explains precisely and clearly the declination of the compass to the northeast and northwest. Cortés drew upon these theories to account for the variation of magnetic declination at various places on the globe, attributed in other works of that period to the poor quality of magnets and lodestones.

BIBLIOGRAPHY

Cortés’ only writing is Breve compendio de la esfera y de la arte de navegar (Seville, 1551; repr. Seville, 1556; facs. ed., Zaragoza, 1945). Nine English eds. appeared between 1561 and 1630.

On Cortés or his work, see Diccionario enciclopédico hispano-americano, V (Barcelona, 1890), 1172 ff.; M. Fernádez de Navarrete, Disertación sobre la historia de la naútica y de las matemáticas (Madrid, 1846); and José Gavira Martín, “La ciéncia geográfica espanola del siglo XVI,” in Boletin. Real. Sociedad geográfica, 71 (1931), 401–424.

J. M. LÓpez de Azcona