TheCarta Pisana orCarte Pisane is a map probably made at the end of the 13th century, about 1275–1300, currently conserved in the Département des cartes et plans at theBibliothèque nationale de France. New research suggests that it was made a century later.[1] It was found inPisa, hence its name. It shows the wholeMediterranean, theBlack Sea and a part of theAtlantic coast, from the north of present-dayMorocco (down to roughly the33rd parallel north, with the town ofAzemmour[2]) to the present-dayNetherlands, but the accuracy of the map is mostly limited to the Mediterranean.[3] It is the oldest survivingnautical chart (that is, not simply a map but a document showing accurate navigational directions).[3][4] It is aportolan chart,[4] showing a detailed survey of the coasts, and many ports, but bears no indication on thetopography ortoponymy of theinland.[5] On the map, North is on the top, in contrast to other maps of the same period such as theHereford Mappa Mundi (ca. 1300), where East is on the top.
Possible places of origin for the map includePisa,[4] where it was found,Venetia, andGenoa,[5] which is the conventionally recognised place of origin.[2] The density of the ports referenced on the map is the highest for the coast of theTyrrhenian Sea, and the lowest for that of theIonian Sea. This is possible evidence that the map is ofGenoese origin, sinceGenoa, at this time, was a major power in theTyrrhenian Sea.[5] Additionally, the first textual reference to the use of such a detailed maritime chart, in 1270, is in relation to a Genoese ship.[2]
The inaccuracy of the Atlantic part of theCarta Pisana, especially when compared to its Mediterranean part, can be exemplified by its depiction ofGreat Britain: an irregular, rectangular shape, lying on an east–west axis. Only six place names are indicated for Great Britain.Civitate Londra (London) is placed in the middle of the southern coast.[2]
As to the date of the map, it is partly indicated by the mention of the town ofManfredonia, which was founded by kingManfred of Sicily in 1256.[5]
The sources used in the making of theCarta Pisana are difficult to determine. The use of several dialects in the place-names indicated on the map would tend to suggest that several regional sources were compiled to make the map. Other possibilities include a hypothetical earlier, no longer extant portolan chart, orAncient Roman cartography. However, there is absolutely no evidence supporting the existence of an earlier portolan chart, and the fact that the map's most glaring error[clarification needed] concerns Italy would undermine the theory of an Ancient Roman influence.[2]
The map encompasses almost all of theMediterranean inside two circles, one for the western Mediterranean, one for the eastern. These circles are divided into sixteen parts, providing the map with sixteen correspondingwind directions. Furthermore, it comprises a two-directionalscale subdivided into several segments corresponding to 200, 50, 10, and 5 miles.[4] The exact value of these "portolan miles" is difficult to calculate in present-day units, given discrepancies between geographical areas on this map and others; but it is conventionally accepted to be around 1.25 kilometers.[2]