Beginning in the early
fifteenth century, the Portuguese explorations of the Atlantic and
of the arts of navigation went hand-in-hand, and most other European
states learned to navigate the oceans from the manuals that the
Portuguese and the Spanish eventually published as a product of
their experiences. In 1519, for instance, Martín Fernández
de Enciso published the first geographical treatise that included
the Old and New Worlds together, the Suma de Geografia que trata
de todas las partidas del mundo. In 1535, Francisco Faleiro,
a Portuguese cosmographer, published the Tratado del Esphera
y del arte de marear con el regimiento de las alturas, con algunas
reglas nuevamente escritas muy necesarias. In 1545, Pedro de
Medina published the Arte de navegar, which was translated
into Italian (three editions in 1554, 1555, 1609), French (15 editions
between 1554 and 1633), Dutch (five editions between 1580 to 1598),
and English (two editions in 1581 and 1595).
The Spanish royal
cosmographer Martín Cortés de Albacar belongs to that
first generation of cosmographers and pilots who sought to establish
an instrumental method of transatlantic navigation and to make that
method available to other pilots. In 1551, Cortés—who
had been teaching cosmography and the art of navigation to pilots
in Cádiz since 1530—published his Breve compendio
de la sphera y de la arte de navegar, con nuevos instrumentos y
reglas, exemplificado com muy subtiles demostraciones. In this
practical book, Cortés clearly discussed matters of navigation
and cosmography and included illustrations and models for making
instruments. His became the standard navigational textbook.
In his letter of dedication
to Charles V, Cortés claims to have been the first person
to "condense the navigational art into a small manual: establishing
infallible principles and evident demonstrations; writing the practice
and theory of the art; providing true rules to sailors; showing
the paths to the pilots, making instruments to take the solar altitude;
. . . discovering the secret property of the magnet; . . . [With
this treatise], those who are alive and those who will succeed us
will see and understand that the world owes more to V.M [Charles
V] than the Egyptians to Isis, for she gave them letters to read
their charts, but V.M gave [the world] rules and method to navigate
the oceans. The benefits of Isis was for only one province; the
benefits of Charles are for the whole universe, for all provinces,
for all oceans, to go to places already discovered and to go to
places not yet discovered" (author's translation; folios IIIv.-IIIIr.).
The treatise was not
only very popular with Spanish sailors but also for mariners from
other countries. It became, for instance, the foundational text
for England's long tradition of sea-dominance and colonization.
Stephen Borough, the chief pilot of the English Muscovy Company,
brought back to England a copy of the Breve Compendio from
his visit to the navigational school in Seville, where it was a
textbook. Borough had his copy translated by Richard Eden and published
as the Art of Navigation in 1561. In the sixteenth century
alone, there were seven English editions. The pirates Martin Frobisher
and Francis Drake were among the Englishmen who enjoyed and used
Corté's book. Robert Norman in his The Newe Atractive
(1581) and William Gilbert in his De magnete (1600) discussed
Cortés's magnetic theories.
Cortés's manual is filled with practical
instructions. Even the illustrations in the book are
meant to be used by the reader, as they not only accompany precise
instructions for the making of nautical instruments but also demonstrate
their working in simplified form. The text contains several volvelles,
for instance, a term derived from the Latin "to turn."
These are devices, such as the one here, that contain several layers
of movable paper parts affixed to a central point with thread (as
here) or perhaps a pin or some other mechanism that will allow the
parts to rotate around a central turning point. The instrument illustrated
here helps a navigator find the declination of the sun as well as
the place of the moon-important in the determination of latitude.
Breve compendio also provided the earliest descriptions
of the method of making, graduating, and using the astrolabe. An
astrolabe is a two-dimensional model of the celestial sphere in
relation to the earth. The instrument had many applications, but
for a navigator was most useful in finding the sun's altitude. If
a pilot knew the altitude of the sun at, say, noon in Seville, once
he found the altitude of the sun at noon in the middle of the ocean
he could find the ship's position in the Atlantic relative to Seville.
Such calculations were critical if explorers were to be able to
ascertain their location when out of sight of land and to mark a
landfall in a distant place so as to be able to return to it.
Piñero, J. M. López. Ciencia
y Técnica en la Sociedad Española de los Siglos
XVI y XVII. Barcelona: Editorial Labor, S. A., 1979.
Waters, David. The Art of Navigation
in England in Elizabethan and Early Stuart Times. London:
Hollis and Carter, 1958.