I’ll be giving a paper on Ptolemy at the ICA annual workshop on Digital Approaches to Cartographic Heritage at the Hague and it’s been a great excuse to finally put some ideas (old and new) down on paper. Comments welcome!
The Madaba map overlaid with divisions at 1/2, 1/3, 1/4 & 1/6th of a degree. This creates gaps in the coverage which may cause increased assignment to the exact and half degrees (0' and 30'). If assignment is based on labels overlapping the division of highest denominator the clustering will be exaggerated for longitude because of the left-right orientation of writing. This is precisely the effect we actually observe (see below).
Distribution of locations in Germania to minutes of a degree. (Black = longitude, White = latitude)
