Portolan Chart of Europe Showing the British Isles f. 8
Cartographer: Martines, Joan
Medium: Ink and pigments on vellum
This is a portolan chart from a bound atlas containing seven charts. It includes an image of the British Isles in the top left corner. It dates from 1567 and was drawn by Joan Martines, of Messina, Italy, as recorded in the margin of the chart. 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. The image of the British Isles that is presented here is interesting in that illustrates that cartographers knowledge of the coast line of Britain is developing. Unlike charts 20 years before this, this chart shows an indentation on the coast of Wales, the Bay of Cardigan, this only begins to appear on maps after c.1550. This chart is drawn in the decorative Catalan style which features representations of cities and flags.