World Map in two Hemispheres (Bonne Projection), 1566


This world map in two hemispheres using the Bonne projection is by the Norman hydrographer Guillaume Le Testu (1509−72). Bonne maps used a modified conical map projection from circa 1500; the parallels appeared as equally spaced concentric arcs of a circle and the maps had a straight vertical central meridian. The Norman school of hydrographers was active in the French maritime province of Normandy, chiefly in the city of Dieppe, from the early 16th century to the middle of the 17th century. Its cartographers were all skilled in mathematics and exhibited great mastery of the different cartographic projections in use at that time. They were for the most part also pilots and sailors with extensive experience at sea. Le Testu is reported to have made many voyages to the Americas and Africa. His familiarity with the Grand Banks off the coast of Newfoundland is indicated by the phrase Banc ou ce fait la pesche des morues (Bank where cod fishing is done). Certain regions on the map are still undetermined, for example northern Europe, Labrador, California, and the region of Siberia, Alaska, and the North Pacific. The inscription states: “This map was drawn in total perfection, in both latitude and longitude, by myself, Guillaume Le Testu, royal pilot, native of the French city of Grace... and completed on May 23, 1566."

Last updated: August 19, 2015