Portolan chart

From Freepedia

A portolan is an early modern European navigation chart, dating from the fourteenth century or later, in manuscript, usually with rhumb lines, shorelines and place names.

The portolan combined the exact notations of the periplus with the decorative illustrations of the conceptual T and O map but on the whole it offered a realistic depiction of the shore and was meant for practical use by a mariner of the period. The portolan did not take into account the curvature of the Earth, so it was a misleading document for crossing an Ocean. It was useful for navigation in smaller bodies of water such as the Mediterranean or the Red sea.

The oldest portolan which has survived to our era dates from 1296. The cartographer Angelino Dulcert produced a portolan in 1339.