Portolan Chart of Western Europe Showing the British Isles f. 10
Cartographer: Martines, Joan
Medium: Ink and pigments on vellum
This is a portolan chart from a bound atlas dating from 1550. It is the work of Joan Martines, a chart maker from Messina. Invented by mariners, portolan charts take their name from the Italian ‘Portolano’, meaning a written description of Catalan and Italian ports along a coastline. The first portolan Charts date from the late 13th century and represent an important change in the use of maps and charts. Until this point, most maps had held a religious significance and purpose, such as the medieval mappa mundi which was based on theological beliefs. The portolan chart contrasts with this tradition as they are based on direct observation and first hand experience and have a practical purpose. Reflecting their use by sailors they note only coastal locations, omitting most of the internal detail of the land. Place names are written at right angels to the coast, the more important ports in red ink. The lines which cover this and all other portolan charts are lines of constant bearing known as rhumb lines. These radiate from compass roses and allow the sailor to plot a course from harbour to harbour using dividers and straight edge. Here England, Ireland and Scotland are outlined in different colours and coats of arms denote the independent rule of Scotland. Scotland is joined to England at a central point by a mountain range. The Thames is the only river marked in the whole of the British Isles. Crosses around south east coast denote outcrops of rocks that were a danger to sailors. The chart is presented in the elaborate Catalan style with images of rulers, flags and settlements.