TECHNICAL ARTICLES

A POSSIBLE SOLUTION TO A LONG STANDING CARTOGRAPHIC MYSTERY – PART 1
A time-line from Henges through wayfaring stars and charts-in-the-sky to portolans and the advent of modern charting

S R Lusby, R Hannah and P Knight
University of Otago, New Zealand

Abstract
This paper sets out to establish the possible origin of the Renaissance portolan charts of the Mediterranean and Black Sea. A hypothesis is produced in which the perimeter circle, of an ancient henge or similar, represented the outer disc of the earth, and was used to start what became the process of mapping and charting. Methods of determining latitude and longitude without the need for complex instruments or mathematics are outlined, and a hypothetical method of determining a wayfaring star for travel between remote circles/henges is illustrated. A further hypothesis is then developed concerning the need for cartographers to have a very large circle inscribed in a wooden table or floor to simulate the earth disc perimeter so that survey control points can be processed in a simple analogue graphical manner similar to the postulated henge theory. This evolutionary step is seen as necessary to facilitate control for the detailed and accurate coastlines shown on the portolans and to also overcome the difficulties of multiple chart production using materials such as vellum. An attempt to define the basic projection used in the portolans is made through an initial analysis of a NASA image of the earth as seen in simulation from outer space. This is then followed by a detailed analysis of the Albino de Canepa portolan now held in the James Ford Bell Library of the University of Minnesota. A historical timeline is developed in an attempt to identify the civilisation that first undertook the hydrographic surveys and charting in the Mediterranean and Black Sea region. The paper ends with a short analysis of the world maps that extended out of portolans and the reasons for their failure as modern methods, attributed to the earlier theories of the 2nd Century AD philosopher Claudius Ptolemy, took over their role.
 

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