Portolan Chart

Date: c. 1565
Owner: Library of Congress
Source Type: Maps


Like many charts of the period, this map was drawn on vellum, a special type of parchment made from the skin of stillborn sheep. It includes several Spanish cities marked by red and white striped flags, including Quito, as well as the Galapagos islands in the Pacific. As on most portolans, the 'mother' compass rose (usually located in the middle, but on the lower right of this damaged map) is surrounded by several other interconnecting roses, all of which are aligned with magnetic north. Another common convention is that each rose has thirty two rhumb lines, or loxodromes, running from its center, to form a grid across the chart. The eight principle compass directions, or "winds," are drawn in bold red, the eight lines for half directions (that bisect principle lines) are done in green, and the thirty two quarter lines are done in lighter red. Using a straight line and a bisector, a navigator would use these lines to plot their ship's position at sea. There is a faded line along the top of the page that indicates latitude, with north located on the left hand side of the page, but--like most practical sea charts of the sixteenth century--this map does not use a graticule. It is probable that the animals depicted in this map are Darwin's rheas, large flightless birds living throughout western South America that are now close to extinction.

CITATION: Portolan chart of the Pacific coast from Guatemala to northern Peru with the Galapagos Islands. c. 1565. Library of Congress Geography and Map Division: G4802.C6P5 1565 .P6 Vault : Vellum 9.