A new map of Virginia, Maryland, and the improved parts of Pennsylvania & New Jersey.
Relief shown pictorially. Depths shown by soundings.
Date and attribution from On the Map, 1983 (Figure 24).
First state of map published originally in 1685 by Christopher Browne with the imprint in the cartouche under the title. No longitude lines are given.
Available also through the Library of Congress Web site as a raster image.
LC copy annotated with pencil in bottom margin.
Stamped and annotated in blue ink on verso: 24.
LC copy imperfect: Loose binding along bottom margin.
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.