Gerard Mercator (1512 - 1594) is a seminal figure in the history of cartography. Mercator's calculations and map designs redefined the 16th century concept of cartography and were the first to break away from the Ptolemy model. Many of his systems of measurement, such as the Mercator Projection, are still in use today. Despite his prominence as a cartographer, he started his career as a crafter of scientific instruments. He did not construct his first map until 1540, when he made two maps, one of Flanders and another of Palestine. These two impressive works earned him the patronage of the Emperor Charles V, for whom he construed a globe and several large scale maps. Despite this imperial patronage, Mercator was accused of heresy and in 1552 fled to Duisburg. In Duisburg he set himself up as a cartographer and began work on his revised edition of Ptolemy's Geographia. This three volume work was the first book to be called an "Atlas", after the Titan and King of Mauritania. Following Mercator's death his descendants took over his firm but languished because of heavy competition from the Ortelius firm. It was not until Mercator's plates were purchased and republished ( Mercator / Hondius ) by Henricus Hondius and Jan Jansson that Mercator's position as the preeminent cartographer of the age was re-established.