PORTOLAN/ˈpɔːtələn/

A book containing charts and sailing directions.

Before the days of accurate surveying and printed charts, ships’ captains often maintained vellum manuscript books containing hand-drawn charts and details of routes between ports together with descriptions of harbours and sea coasts. The earliest of those that survive, of Italian, Genoese or Catalan origin and dating from the fourteenth century, are for the western Mediterranean, but others were prepared for trading routes world-wide in the two centuries they remained in use before engraving and improved mapmaking made them obsolete. The name is a version of the original Italian portolano, derived from porto, “port”, and meaning “pilot book”. Portolano sometimes appears as a variant spelling in English.

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