On February 15, the Law Library of Congress in cooperation with the John W. Kluge Center hosted John Hessler, Senior Cartographic Librarian in the Geography and Map Division of the Library of Congress, and a Kluge Staff Fellow, as a guest speaker for the Law Library’s Power Lunch series. Mr. Hessler’s lecture, “Written in Stone: Roman Land Law, Legal Epigraphy and the Search for the Origins of Roman Cartography, 100-350 AD” was a preview of his current research into the extent of Roman land surveying in North Africa and the Mediterranean Basin. Following a variety of methods – including advanced mathematical modeling, GIS and image analysis – Hessler presented a fascinating new way to gather and interpret archeological information.
As a point of departure, Hessler discussed a group of 6th Century legal manuscripts known as the Corpus Agrimensorum, a collection of Roman treatises on land law and surveying practices that offer a rare window into the way Roman land was administered. The Corpus Agrimensorum describes the Roman legal standards for dividing land into individual plots; Hessler began his discussion by focusing on centuriation – the process used for measuring individual plots of land. He showed how Roman surveyors projected grids onto the landscape surrounding their towns, an expanse of enormous squares of land delineated by a series of major avenues and minor access roads. A centuriated field would typically consist of smaller parcels of land that were 20 actus x 20 actus long (approx. 700m x 700m), sitting in rows of five by five, so that the major roads were at a distance of 100 actus from one another.
Through fieldwork in North Africa, specifically in the Bagradas valley, which is a region in Tunisia located about 70 km from the Mediterranean coast to the North, Hessler has identified remains of Roman surveying stretching over a wide area. Evidence usually takes the form of monuments with Roman inscriptions marking property boundaries and the remains of limites, which are manmade boundaries that separate individual plots of land in a centuriated field.
The question that Hessler then set out to determine was how extensive was Roman surveying in the area? To answer that question he turned to GIS and image analysis which he applied to historical aerial photography of the region and remote sensing imagery. The limites are the most visible remains of Roman surveying and can often be identified through these methods, but they are fragmentary, and centuries of deterioration can make them difficult to recognize. To filter out the noise from images of archeological sites, Hessler has begun applying edge detection algorithms. This allowed him to generate a prediction of where the original limites might be found. He has also been working in this connection with Fourier Series and transforms. Because the limites show up as a periodic phenomenon across an expanse of land (that is to say, the grid pattern of a centuriated field is regular and repeats itself), a two dimensional Fourier transform can be used to describe the grid that once existed over a landscape with some precision. Armed with these methods, Hessler hopes to identify previously overlooked evidence of Roman surveying across large areas of the old Roman world.
Hessler will publish his findings about the extent of Roman surveying in the Mediterranean basin and its relation to Roman Land Law in 2014. In the short term, however, stay tuned for his upcoming lecture, “Chasing Krüger’s Dream: Reconstructing the Medieval Transmission of Justinian’s Codex Using Binary Galois Lattices,” to be presented by the John W. Kluge Center at the Library of Congress this Fall. Based on Hessler’s research on the Paul Krüger archive at the Law Library of Congress, this lecture will present an analysis of German classicist Paul Krüger’s collation of medieval manuscripts of Justinian’s Codex and a new computational method for reconstructing the recension of classical and medieval texts.
Great piece, Nathan!
I look forward to more on Hessler’s work on the Paul Kruger Archive. I went to a paper he gave several months ago on using Lattice Theory to look at Medieval Manuscript Transmission and the whole enterprise, while complicated, looked promising. Nathan, keep up the good work on this blog, your posts are always interesting.
I enjoy looking at your websites. Thanks for your time!