#251

Portolan Charts

One of the most remarkable and mysterious technical advances in the history of the world is written on the hide of a 13th century calf. Inked into the vellum is a chart of the Mediterranean so accurate that ships today could navigate with it. Most earlier maps that included the region were not intended for navigation and were so imprecise that they are virtually unrecognizable to the modern eye. With this map, it’s as if some medieval mapmaker flew to the heavens and sketched what he saw — though in reality, he could never have traveled higher than a church tower. The person who made this document — the first so-called portolan chart, from the Italian word portolano, meaning “a collection of sailing directions” — spawned a new era of mapmaking and oceanic exploration. For the first time, Europeans could accurately visualize their continent in a way that enabled them to improvise new navigational routes instead of simply going from point to point.

That first portolan mapmaker also created an enormous puzzle for historians to come, because he left behind few hints of his method: no rough drafts, no sketches, no descriptions of his work.


Detail from the 1489 Albino de Canepa Portolan Chart


A typical portolan chart showed coastal contours and the location of harbors and ports, ignoring virtually all inland features. It would be criss-crossed by straight lines, connecting opposite shores by any of the 32 directions of the mariner's compass, thus facilitating navigation. After popping up in Italy, portolans became coveted possessions in the seafaring nations of Spain and Portugal, where they ranked as state secrets.


Little or nothing is known of their origins and production, so the working hypothesis among cartographic historians was that portolans were somehow gathered together from the knowledge of medieval European sailors, possibly enhanced with older knowledge from Byzantine or Arab sources.

        Treatments of medieval mapmaking still occasionally imply that the portolan charts — remarkably accurate charts of the coasts of the Mediterranean and Black seas with part of the Atlantic coast of Europe—were an aberration on the medieval scene. Scott Westrem comments that the “familiarity’ to the modern eye of maps used by navigators . . . may be deceptive, causing us to see them only as ‘precursors’ of the ‘realistic’ cartography of today, thus distracting us from some of their essential medieval qualities”. Even the map historian Tony Campbell refers to portolan charts as “precocious in their precision,” although elsewhere he describes them as “a necessary if specialized element of medieval life”. This view has recently become even less sustainable with the suggestion that the later 13th century date most commonly proposed for their origins be pushed back by a hundred years. Geographically accurate and intended—at least in part— for the purpose of route finding, the portolan charts reflected a different set of assumptions and expectations about the purpose of a map than did contemporary world maps: nevertheless, room must be found in our view of medieval cartography for these fascinating and problematic inventions.

The very earliest evidence that we have of the existence of both portolans and portolan charts stems, not surprisingly, from the intersection between learned culture and the practices of Mediterranean trade and seafaring. In the case of written sailing directions, the first traces appear not in local sources, but in the chronicles of northern European crusaders and pilgrims, for whom Mediterranean navigation was a foreign world and who borrowed from portolans as a helpful framework for writing about unknown coasts and seas. In contrast, the Liber de existencia riveriarum et forma maris nostri Mediterranei, the first known work to be based in part on what may have been a portolan chart, was an entirely Italian undertaking, but, like the works just mentioned, the product of a mixture of information and ideas from both learned and “practical” knowledge spheres. The text we have indicates that the author began by creating a map, which he later supplemented with the text in response to a demand for more historical and learned material by a member of the local clergy.

Both of these examples give early evidence of an interdependence of learned and “practical” cultures and of the cross-fertilization of ideas from cultural communities usually taken as distinct in the Middle Ages. This evidence is corroborated by the available information on the early use and ownership of portolan charts. In addition to pilots and merchants, as we might anticipate, notaries were relatively strongly represented among owners of these charts. Patrick Gautier Dalche suggests that they used them to aid in drawing up contracts involving far-flung trading ventures that required a specific and accurate understanding of Mediterranean, Black Sea, and Atlantic coastal geography. He is also concerned to note the mixed evidence for the actual nature of shipboard usage of these charts. Compare Tony Campbell, “Portolan Charts,” pp. 439 – 444, where the author states that “the evidence that portolan charts were used on board ship is overwhelming,” but who is similarly cautious about the role of the charts in navigation (p. 439). There are also interesting connections between the role of portolan charts as markers of participation in a community of men who gained their livelihood in connection with the sea, an element of display that has something in common with the later importance of maps as prints in the more highly commercialized world of the 16th century. This creative interaction of types of knowledge has been seen as key in Renaissance developments, while, conversely, the separation of medieval knowledge communities has been seen as a limitation on creativity and innovation. Spheres of knowledge did in fact remain quite distinct, but these examples suggest several settings in which contact could occur: the intensely self-conscious world of the nascent Italian communes, heavily influenced by merchant culture and open to any means of expressing civic consciousness; and the Crusades, with their mass movement of northerners out of their habitual intellectual and physical territories into a strange new Mediterranean world. As far as we now know, the interdependence of map, portolan, and learned geographical text that underlies the Liber was not replicated until the late thirteenth or early fourteenth century, al- though new discoveries (like the Liber itself) have been frequent enough in recent years to justify a healthy skepticism about the extent of our knowledge in these areas. Nevertheless, the examples that do exist suggest that in certain circumstances fruitful exchanges could and did occur.


References:

Campbell, T., “Portolan Charts from the Late Thirteenth Century to 1500”, History of Cartography, Volume I, pp. 371-463.

Dalche, P.G., Carte marine et portulan au XIIe siècle: Le Liber de existencia riveriarum et forma maris nostri mediterranei.

Hofmann, Catherine, Helene Richard, Emmanuelle Vagnon, The Golden Age of Maritime Maps: When Europe Discovered the World.

Morse, V., “The Role of Maps in Later Medieval Society: Twelfth to Fourteenth Century”, History of Cartography, Volume IV, pp.25-52.



Portolan Chart of the Mediterranean

Petrus Roselli, 1466, 94 x 54 cm, University of Minnesota

Treatments of medieval mapmaking still occasionally imply that the portolan charts — remarkably accurate charts of the coasts of the Mediterranean and Black seas with part of the Atlantic coast of Europe—were an aberration on the medieval scene. Scott Westrem comments that the “familiarity’ to the modern eye of maps used by navigators . . . may be deceptive, causing us to see them only as ‘precursors’ of the ‘realistic’ cartography of today, thus distracting us from some of their essential medieval qualities”. Even the map historian Tony Campbell refers to portolan charts as “precocious in their precision,” although elsewhere he describes them as “a necessary if specialized element of medieval life”. This view has recently become even less sustainable with the suggestion that the later 13th century date most commonly proposed for their origins be pushed back by a hundred years. Geographically accurate and intended—at least in part— for the purpose of route finding, the portolan charts reflected a different set of assumptions and expectations about the purpose of a map than did contemporary world maps: nevertheless, room must be found in our view of medieval cartography for these fascinating and problematic inventions.

The very earliest evidence that we have of the existence of both portolans and portolan charts stems, not surprisingly, from the intersection between learned culture and the practices of Mediterranean trade and seafaring. In the case of written sailing directions, the first traces appear not in local sources, but in the chronicles of northern European crusaders and pilgrims, for whom Mediterranean navigation was a foreign world and who borrowed from portolans as a helpful framework for writing about unknown coasts and seas. In contrast, the Liber de existencia riveriarum et forma maris nostri Mediterranei, the first known work to be based in part on what may have been a portolan chart, was an entirely Italian undertaking, but, like the works just mentioned, the product of a mixture of information and ideas from both learned and “practical” knowledge spheres. The text we have indicates that the author began by creating a map, which he later supplemented with the text in response to a demand for more historical and learned material by a member of the local clergy.

Both of these examples give early evidence of an interdependence of learned and “practical” cultures and of the cross-fertilization of ideas from cultural communities usually taken as distinct in the Middle Ages. This evidence is corroborated by the available information on the early use and ownership of portolan charts. In addition to pilots and merchants, as we might anticipate, notaries were relatively strongly represented among owners of these charts. Patrick Gautier Dalche suggests that they used them to aid in drawing up contracts involving far-flung trading ventures that required a specific and accurate understanding of Mediterranean, Black Sea, and Atlantic coastal geography. He is also concerned to note the mixed evidence for the actual nature of shipboard usage of these charts. Compare Tony Campbell, “Portolan Charts,” pp. 439 – 444, where the author states that “the evidence that portolan charts were used on board ship is overwhelming,” but who is similarly cautious about the role of the charts in navigation (p. 439). There are also interesting connections between the role of portolan charts as markers of participation in a community of men who gained their livelihood in connection with the sea, an element of display that has something in common with the later importance of maps as prints in the more highly commercialized world of the 16th century. This creative interaction of types of knowledge has been seen as key in Renaissance developments, while, conversely, the separation of medieval knowledge communities has been seen as a limitation on creativity and innovation. Spheres of knowledge did in fact remain quite distinct, but these examples suggest several settings in which contact could occur: the intensely self-conscious world of the nascent Italian communes, heavily influenced by merchant culture and open to any means of expressing civic consciousness; and the Crusades, with their mass movement of northerners out of their habitual intellectual and physical territories into a strange new Mediterranean world. As far as we now know, the interdependence of map, portolan, and learned geographical text that underlies the Liber was not replicated until the late thirteenth or early fourteenth century, al- though new discoveries (like the Liber itself) have been frequent enough in recent years to justify a healthy skepticism about the extent of our knowledge in these areas. Nevertheless, the examples that do exist suggest that in certain circumstances fruitful exchanges could and did occur.


References:

Campbell, T., “Portolan Charts from the Late Thirteenth Century to 1500”, History of Cartography, Volume I, pp. 371-463.

Dalche, P.G., Carte marine et portulan au XIIe siècle: Le Liber de existencia riveriarum et forma maris nostri mediterranei.

Morse, V., “The Role of Maps in Later Medieval Society: Twelfth to Fourteenth Century”, History of Cartography, Volume IV, pp.25-52.




The Petrus Roselli portolan chart is drawn on one skin; the 1466 portolan chart covers the south shore of the Baltic in the north to most of the Red Sea in the south, the Black Sea on the east to the Antilia group of islands on the west. James Ford Bell Library, University of Minnesota