Gerardus Mercator (5 March 1512 in Rupelmonde in the Hapsburg County of Flanders, Holy Roman Empire, 2 December 1594 in Duisburg, United Duchies of Julich-Cleves-Berg, Holy Roman Empire) was a cartographer, He is remembered for the Mercator projection world map, which is named after him, This proved very useful to many later navigators who could (using his map) sail across the entire ocean on approximately straight paths (called rhumb lines)