Portolan Charts from the Late Thirteenth Century to 1500
By Tony Campbell
The History of Cartography, Volume One: Cartography in Prehistoric, Ancient, and Medieval Europe and the Mediterranean, edited by J. B. Harley and David Woodward (University of Chicago Press, 1987)
Introduction: To the historian of late medieval and early modern European cartographyl the portolan charts are fundamental documents, if mysterious in their origin and precocious in their precision. Their importance has long been acknowledged, and “The First True Maps” was the enthusiastic title of an article by Charles Raymond Beazley in 1904. More recently, Armando Cortesao considered the “advent of the portolan chart … one of the most important turning points in the whole history of cartography.”
Alberto Magnaghi went further, describing them as a unique achievement not only in the history of navigation but in the history of civilization itself. For Monique de La Ronciere the work of the first named practitioner, Pietro Vesconte, was so exact that the Mediterranean outlines would not be improved until the eighteenth century. In terms of the economic history of cartography, Vesconte and his contemporaries may have been the first, in the plausible opinion of a recent writer, “to pursue mapmaking as a full-time commercial craft.”
From the earliest extant copies, probably a little before 1300, the outline they gave for the Mediterranean was amazingly accurate. In addition, their wealth of placenames constitutes a major historical source. Their improvement over the Ptolemaic maps relating to the same area is obvious at a glance, and the North African coast with its clearly defined Syrtes is the most striking advance. Moreover, the Ptolemaic maps began to circulate widely through Europe only in the fifteenth century, by which time the portolan charts were well established. Though a linear scale was implied on Ptolemy’s maps by their grid of longitude and latitude, the medieval sea charts were the first cartographic documents to regularly display one.
Top Image: Portolan chart by Jorge de Aguiar (1492)