Portolan Chart of Western Europe Showing the British Isles(001ADD000019927U00007000)
Cartographer: Battista, Agnese
Medium: Ink and pigments on vellum
This is a Portolan Chart, from a bound atlas, showing the British Isles. It is by Baptisa Agnese, a chart maker from Genoa, who prepared many portolan atlases in the 16th century. 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.
This portolan is annotated with the inscription "Baptista Agnesivs Ianvensis fecit Venetijs, 1536, die 13 Octobr[is]". This date also appears on a circular table of the signs of the zodiac prefixed to the charts. It is typical of this period in its representation of the coast line of the British Isles. It shows Scotland as a separate landmass and omits the Bay of Cardigan on the Welsh coast. This later discrepancy is typical of pre c.1550 maps as it is not until the second half of the 16th century that the Bay of Cardigan begins to appear on maps. As charts like this were for 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. Brazil is shown as a circular island off the coast of the west coast of Ireland.