A chart of this kind was called a Portulano, as giving information of the best routes from port to port, and Baron Nordenskiold has recently shown how all these _portulani_ are derived from a single Catalan map which has been lost, but must have been compiled between 1266 and 1291.

And yet there were some of the learned who were not above taking instruction from the practical knowledge of the seamen.
In 1339, one Angelico Dulcert, of Majorca, made an elaborate map of the world on the principle of the portulano, giving the coast line--at least of the Mediterranean--with remarkable accuracy.

A little later, in 1375, a Jew of the same island, named Cresquez, made an improvement on this by introducing into the eastern parts of the map the recently acquired knowledge of Cathay, or China, due to the great traveller Marco Polo.

His map (generally known as the Catalan Map, from the language of the inscriptions plentifully scattered over it) is divided into eight horizontal strips, and on the preceding page will be found a reduced reproduction, showing how very accurately the coast line of the Mediterranean was reproduced in these portulanos.
With the portulanos, geographical knowledge once more came back to the lines of progress, by reverting to the representation of fact, and, by giving an accurate representation of the coast line, enabled mariners to adventure more fearlessly and to return more safely, while they gave the means for recording any further knowledge.

As we shall see, they aided Prince Henry the Navigator to start that series of geographical investigation which led to the discoveries that close the Middle Ages.