The art of making maps. In the development of this art, during the Middle Ages, an epoch is made by the Catalan "portulani"—seamen's charts showing the directions and distances of sailing between different ports, chiefly of the Mediterranean. These differ from the medieval mappœ mundi by having tolerably accurate outlines of the Mediterranean littoral, and are thus, in some measure, the predecessors of modern maps. Baron Nordenskjöld has proved that these are derived from what he calls the normal portulano, compiled in Barcelona about 1280. The best known of the portulani are those drawn up in the island of Majorca, where a school of Jewish chartographers seems to have drawn up sea-charts for the use of seamen. In 1339 Angelico Dulcert drew up a portulano which still exists; and in 1375 this was greatly improved by Cresques lo Juheu, who added to Dulcert's outline the discoveries of Marco Polo in the east of Asia. He thus made the voyage to the Indies westward appear less than it really was, and so helped toward the voyage of Columbus. This map, known as the "Catalan Portulano," was sent by the king of Aragon to the king of France, and is still retained in the Louvre. It formed a model for many globes and later maps, including those which most influenced Columbus, and is perhaps the best known of the portulani. See Cresques; Geographers, Jews as.
- Jacobs, Story of Geographical Discovery, pp. 60-62;
- Nordenskjöld, Periplus, 1897;
- Kayserling, Christopher Columbus, pp. 6-8.