Ptolemy's Geography: An Annotated Translation of the Theoretical Chapters (review)

Ptolemy's Cosmographica (Geography), without a doubt, is a landmark in the history of cartography, one of the "Great Books" (if we may still use the term) in the Western canon of science. For over 1,400 years, it constituted the major map of the Western world, yet until now there has been no adequate translation into English. Scholars of ancient history and science are praising this translation, which drew upon several previous editions and five medieval manuscripts.

Written in the second century of our era, Cosmographica is the only ancient work on map-making to survive. It was based on a previous work by Marinos of Tyre, about whom little is known, so that most of the prehistory of Ptolemy's book involves mere speculation. The work (first written as a scroll) was known throughout the Middle Ages. The earliest extant manuscripts date from the thirteenth century. There are about 50 manuscripts, and all seem to descend from one lost prototype.

Ptolemy divided his Geography into eight sections ("Books"). The work contained the first systematic listing of latitude and longitude, the now common terrestrial terms that were first applied to the celestial "globe" of the heavens. The resulting map of about 8,000 locations covered a large part of the surface of the Earth, from Western Europe to Southeast Asia (approximately 180 degrees of longitude) and from Scotland to sub-Sahara Africa (approximately 90 degrees of latitude). The Roman Empire, not surprisingly, was best known. Ptolemy used two projection techniques to create visual maps: for one, the longitudinal lines remained straight, and for the other, both longitude and latitude were curved. In the second, he tried to minimize some of the distortions from the first. In addition to these two "world" maps, there are 26 regional maps. Of course, judging by today's standards, we can see that the distortions of the maps are primarily due not to the methods of projection but to the errors in position of the specific locations, especially as they get further from the Mediterranean region.

In this important edition, the authors have translated only the "theoretical parts" (Books 1, 2, 7 and 8), thus eliminating the lengthy lists of places. They did this to shift attention away from topography to the theory and methodology of map-making. The book begins with a long introductory section of over 50 pages, giving the reader a grounding in fundamental geometrical information and projection techniques required for fully comprehending the maps. The book presents historical background material on the work and the history of the manuscript versions as well as the translations. Following the four translated Books of the Geography (the core of this edition) is a series of plates and maps and eight appendices. Several plates are wonderful color reproductions of the "world" maps, while many of the maps portray sections of Ptolemy's version and juxtapose these with present-day projections of the same sections—a most interesting comparison.

This is an important publication for historians of science (especially of cartography) and classicists. Although the novice reader will enjoy perusing the plates and maps and certainly gain from some of the early introductory material, the rest of this edition is directed primarily to the advanced scholar.