The origin of distance and bearing navigational data contained in portolani for the Adriatic Sea basin
In: International journal of cartography. Taylor & Francis: Abingdon. ISSN 2372-9333, more
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| Keywords |
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| Author keywords |
Portolani; portolan chart geometry; portolan mile; navigational data; Adriatic Sea |
| Abstract |
Distance and bearing navigational data for the Adriatic Sea basin, extracted from five portolani written between about 1200 and 1490, is examined and compared to the geometry of their renderings, plotted both on a modern map projected in selected map projections, and on a sample of selected georeferenced portolan charts. The primary conclusion is that the textual data on distances (expressed in portolan miles) and bearings (expressed in wind directions) contained in selected portolani do not represent the aggregated body of genuinely acquired measurements performed during late-medieval navigations, but that they were, most likely, extracted directly from portolan charts already in existence at the time. The secondary conclusion yielded by the methodology applied in the research is that the length of the portolan mile, which is still enigmatic to some extent, might be about 1.29 kilometers. |
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