[Map of Virginia] / discovered and discribed [sic] by Captain John Smith 1606 [?] William Hole.
1606 map of Virginia as described by John Smith showing the Chesapeake Bay, Potomac River, other geographic features, and a vignette of the Native leader, Powhatan, in council.
Illus. in: The generall historie of Virginia, New-England, and the Summer Isles; with the names of the adventurers, planters, and governours from their first beginning, ano: 1584 to this present 1624 / John Smith. London : Printed by I.D, and I.H. for Michael Sparkes, 1624.
Published in: Many nations: A Library of Congress resource guide for the study of Indian and Alaska native peoples of the United States / edited by Patrick Frazier and the Publishing Office. Washington : Library of Congress, 1996, p. 58.
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.