Journal cover Journal topic
History of Geo- and Space Sciences An open-access journal
Journal topic

Journal metrics

Journal metrics

  • IF value: 0.294 IF 0.294
  • IF 5-year value: 0.340 IF 5-year
    0.340
  • CiteScore value: indexed CiteScore
    indexed
  • SNIP value: indexed SNIP
    indexed
  • SJR value: indexed SJR
    indexed
  • IPP value: indexed IPP
    indexed
Volume 7, issue 1
Hist. Geo Space. Sci., 7, 27-52, 2016
https://doi.org/10.5194/hgss-7-27-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Hist. Geo Space. Sci., 7, 27-52, 2016
https://doi.org/10.5194/hgss-7-27-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

  11 Mar 2016

11 Mar 2016

The western coast of Africa in Ptolemy's Geography and the location of his prime meridian

Christian Marx Christian Marx
  • Gropiusstraße 6, 13357 Berlin, Germany

Abstract. A controversial question concerning ancient geography is the location of the prime meridian which underlies the position data in Ptolemy's Geography and runs through the Fortunate Islands. An answer to this question is derived by means of a localisation of the places given by Ptolemy at the African western coast, i.e. in Mauritania Tingitana and Libya Interior, whose modern identifications are often uncertain or unknown. The origination of Ptolemy's positions from the distance data of seafarings is considered. A comparison of his data with distances reported by Pliny yields a satisfactory agreement. The localisation of Ptolemy's places is based on distances derived from Ptolemy's coordinates and partly on further information by ancient authors. Through it previous identifications are confirmed and new identifications are found. It shows that the Fortunate Islands correspond to several eastern islands of the Canary Islands. Explanations are given for the errors of Ptolemy's position data. A likely error by Ptolemy barely considered is his repetition of a part of Mauritania Tingitana in his description of Libya Interior. The existence of this repetition is confirmed by an adjustment of a transformation between the positions of the duplicated places and a statistical test of the arranged model. A comparison of longitudinal distances in different ancient sources reveals that the position of Ptolemy's prime meridian is based on distances given by Marinos and Eratosthenes.

Publications Copernicus
Download
Citation
Share