In their recent translation and commentary, Berggren and Jones have aptly called Ptolemy’s Geography a “map-making kit.”

How should we publish a digital Geography, so that, as Ptolemy intended, it can serve as a “map-making kit”? Certainly we need to be able to read his text, both to follow his discussion of map-making algorithms, and to see his data in context, but we also need to be able to use the tables of data that constitute the bulk of his work as he carefully designed them to serve: that is, as a database with seven properties for each point identified by longitude-latitude coordinates.

In managing the largest scientific dataset to come down to us from antiquity, Ptolemy is constantly concerned with challenges we can appreciate today. These include careful planning to maintain the relational integrity of his data tables, and, as far as his analog medium allowed, to normalize the contents of his tables to avoid repetition of data that could easily lead to errors in copying.

Our own digital map-making kit of Ptolemy therefore should derive both a readable text and a usable geographic database from a single source.

Current status

I have published an initial TEI-compliant text of Ptolemy’s Geography in this Canonical Text Service. The site includes links to OAC annotations of all geographic locations in the Geography. These annotations associate a canonical identifier for each geographic feature in Ptolemy’s database with a canonical reference to a defining passage in the Geography. The feature identifiers can be used to refer to entities in Ptolemy’s geographic database. In the fall of 2011, students in an “Introduction to Classical Archaeology” course at Holy Cross sampled about 10% of the sites in Ptolemy’s and tried to equate them with identifiers in the Pleiades geographic database. I will add further information and links here when we have expanded the comparison to see how Ptolemy’s inventory of the world in the mid-second century compares with the Pleiades’ modern gazetteer.