[A portolan chart of the Atlantic Ocean and adjacent continents].
Also shows the southeast Pacific Ocean, the southwest Indian Ocean, as well as the continents of South America, Africa, Europe, and portions of North America and Asia.
Relief shown pictorially.
Title supplied by cataloger.
LC Nautical charts on vellum, 16.
LC Luso-Hispanic World, Vellum Chart 16
Pen-and-ink, watercolors, and colored pencil, matted and mounted between panels of transparent Lucite plexiglass; the panels are riveted on a rigid frame (102 cm. x 118 cm.).
Includes pictures of a fort, circle of compass roses, flags, insignia, coast-of-arms, and religious figures.
Available also through the Library of Congress Web site as a raster image.
Imperfect: Mended horizontal tears across left edge section, some losses along edges, discoloration throughout, with spotting along west side. Blue paint in lower right corner.
Ancient Maps from the Library of Congress. 13th -18th Century Maps.
In the 17th century, maps took a huge leap forward. Mathematical and astronomical knowledge necessary to make accurate measurements had evolved. English mathematicians had perfected triangulation: navigation and surveying by right-angled triangles. Triangulation allowed navigators to set accurate courses and produced accurate land surveys. Seamen learned to correct their compasses for declination and had determined the existence of annual compass variation. Latitude determination was greatly improved with the John Davis quadrant. The measurement of distance sailed at sea was improved by another English invention, the common log. Longitudinal distance between Europe and Québec was determined by solar and lunar eclipses by the Jesuit Bressani in the 1640s and by Jean Deshayes in 1686. With accurate surveys in Europe, the grid of the modern map began to take shape.