Forbes' Ghost:
An Archival Study of Environmental Change in the Glaciers of the Mer de Glace and La Meije Using Historical Cartography and Photographic Surveys

The masses do not see the Sirens, they do not hear the songs in the air. Blind, deaf, stooping, they pull at their oars in the hold of the earth. But the more select, harken to a Siren within them...and royally squander their lives with her.
---Nikos Kazantzakis

During my visits to the Alps over the last 15 years I have noticed a change. Instead of snow capped and glacier topped mountains, one has begun to see bare, dark rock, where white snow and ice once stood. For anyone who has spent time anywhere in the Alps this fact is a stark reminder of the current effects of global warming on these fragile mountain environments. A glance through the many scientific journals in the field of glaciology shows how many studies have recently been produced that are concerned with attempts to quantify the extent of this melting by calculating the negative change in the mass balances of glaciers in mountain ranges al of the world. There are few studies however, that have looked at this melting using archival and historic sources. An exception to this can be found in the work of Daniel Steiner, Heinz J. Zumbuhl and Anderas Bauder. Their article, "Two Alpine Glaciers over the Past Two Centuries: A Scientific View Based on Pictorial Sources", (in Darkening Peaks: Glacier Retreat, Science and Society, edited by Ben Orlove (2008)) details the use of historical maps and both early panoramic and stereo photography to study the historical flow of Unterer Grindelwald and Unteraar glaciers in Switzerland. The Unteraar glacier of course being the site where Louis Agassiz did his famous experiments on glacial motion. Others, such as H. Holzhauser, have examined glacier fluctuations in the western Swiss and French Alps using historical sources dating back into the early 16th century. (see his article in Climate Change 43: 223-37 (1999)). Their results show that it is possible to create DEMs (digital elevation models) using various types of historical data and to calculate changes in glacier volume, area, and length over long periods of recent history.

This study looks at the change in the glaciers of the Mer de Glace, a large glacier system around Mount Blanc and the glaciers around La Meije, France's second highest mountain through the use of historic cartography, photographs, and drawings made from 1768-1930 in much the same way as Steiner et.al., 2008.




















Author at the glacial lake around the Arsine Glacier near La Meije in the Parc Nationale des Ecrins (click on images to enlarge)

The geographic region around both of these glacier systems was well traveled, photographed and mapped through the 19th century, with some studies surviving from earlier times. The historical record for the glaciers in the Mont Blanc region being especially rich. The first quantifiable map of the region around Mont Blanc and the Mer de Glace was made by the Scottish scientist James Forbes in 1842, and the triangulations found in his field notebooks (shown on the map below) provide a baseline to compare later cartography of the region and to map the extent of glacial retreat. The map below is found in Tydall's collection of Forbes letters shows the location of the triangulation points on the Mer de Glace that Forbes used in the creation of his map and in the measuring of glacier flows. Forbes tells us in his Travels through the Alps of Savoy that, "Topographical literature, more than almost any other, is diffused over bulky and unindexed compilations, or more irrevocably lost in fugitive pamphlets." It is this very information that we seek to use in this project.

James David Forbes, author of Travels Through the Alps of Savoy which contains one of the first accurate surveys of the Mer de Glace from 1842

This study will make use of these archival sources, thought difficult to find by Forbes, along with modern GIS (geographic information systems) models, to show how historical materials can be used to document environmental change in small glacial systems. Our methodology is derived from the work of A. Kaab and M. Funk whose articles on deriving mass balance and kinematic ice flows from photgrammetric data at the Griesgletscher glaciers in the Swiss Alps have been especially helpful. (Kaab, A. and M. Funk, "Modeling Mass Balance using photogrammetric and geophysical data: A pilot study at Griesgletscher, Swiss Alps," Journal of Glaciology 45: 575-83.

Terminal Moraine of the Arsine Glacier

Author approaching the calving front of the Arsine glacier

Map based on Forbes survey found in Alps glacier systems, published in 1854

Photograph from 1878 taken from Le Jardin, a large rock outcrop found in the middle of the Glacier Talefre

In the coming months there will be more posts and photographs on this subject as I work out the georectification of many of the early glacial maps of these areas and travel to the Mont Blanc and La Meije to record and photograph the conditions as they exist today. Steiner et. al. note, in regards to the type of sources used in this study, "with methods based on historical records a temporal resolution of decades or, in some cases, even individual years can be achieved in the reconstruction of glacier time series."

Thoreau’s Cartographic Explorations:
Imagining Nature through Maps

New York Times/Mattson Lecture
October 16th
Osher Map Library
University of Southern Maine

The human organism has rarely been subjected to a severer test than the study of scientific problems, nor is there a truer hero than an investigator who never loses heart in a life-long grapple with the powers of the universe. It requires courage of the highest order to stand for years face to face with one of the enigmas of nature; to interrogate patiently, and hear no answers....
---Clarence King

Synopsis of the text of my lecture at the re-opening of the Osher Map Library and the "New Directions in the Study of Early American Cartographies" Conference...

In April of 1858, Ralph Waldo Emerson, in a letter to his friend H.S. Randall, wrote that, “Thoreau’s study seems at present to be equally shared between natural and civil history,” and that “he reads both with a keen and original eye.”

The civil history that Emerson refers to here is the history of the early exploration and discovery of the North American continent, especially the northeastern coast of New England and Canada. During the last 12 years of his life, from about 1850 thru 1862, Henry David Thoreau dedicated himself to historical and scientific studies that have either been ignored by or have puzzled generations of his commentators. What was the author of Walden and other works of transcendental literature doing out “in all weathers” as Emerson would say, counting tree rings, measuring the differences in the magnetic variation of compass needles, mapping the depths of streams or listing the blooming of plant species. Why was he borrowing the earliest exploration narratives of the New World from the Harvard Library, taking detailed notes on the names of places and the plants and animals mentioned, and making scaled copies of some of the earliest maps of North America?

During these last, but extremely productive, years of Thoreau’s life his interests turned sharply toward these types of more empirical and less transcendental studies—Thoreau being less influenced in his work at this time by Emerson than by the geographically oriented science of Humboldt and Darwin. Thoreau believed that the secrets of nature, and of humanities place within it, were ultimately revealed by identifying what was significant in the everyday world and that this in turn depended on meticulous attention to and an accounting of, the commonplace.

In this spirit Thoreau’s writings such as the Maine Woods, Cape Cod, Walden, A Yankee in Canada, his natural history essays, and of course his journals have occasionally been probed by humanist geographers and linked with the beginnings of modern environmental thought…this linkage stems mostly from Thoreau’s intense concern with the concept of place and his ability to see deep connections between historical process and environmental change.

Tonight I am going to talk to you about this linkage in a slightly different way than those geographers and historians who have probed Thoreau’s writings…for tonight rather than concentrate on his published works…I am going to speak with you about his cartography and how Thoreau’s cartographic explorations provided a link in his mind between natural and civil history… a link that led him to a very modern sense of man’s place in nature. To do this I am going to discuss, in more detail than perhaps has been done before, several important aspects of Thoreau’s mostly unknown and certainly understudied cartographic works
The first aspect, and perhaps the most important for his technical understanding of cartography and the process of mapmaking, was his work as a land surveyor. This work gave Thoreau the ability to look at maps critically and to understand not only their mathematical limits but also their broader cultural meaning. It also allowed him to wander the fields and woodlots of Concord and to observe nature closely in all seasons…in a way that his fellow transcendentalists certainly never would have.

The second aspect, and for the most part the driving reason for his engagement with early American cartography, was his interest in the history of the indigenous peoples of the north east. Thoreau would take nearly 4000 pages of notes on this subject…none of which has yet to be published and all of which are mostly unknown even to Thoreau specialists. In the course of this note taking Thoreau would copy and comment on many of the early maps of the northeastern United States and Canada by such seminal figures as Champlain, Ortelius, Smith, Verrazano and Wytfliet.

Finally, I am going to present to you two new maps that have recently been attributed by me to Thoreau and discuss my search for some of the other missing maps that he copied and annotated.

Some of what I am about to say might sound to some of you slightly academic, but really my talk tonight it is about something quite humble and speaks to the very heart and reason of why we are all here this evening. What am speaking about in the end is a story about a man in a Library, much like the one we celebrate this weekend, with a notebook, some old maps and his imagination on fire…

I am going to begin with one of those notebooks, namely Thoreau’s field notebook in which he kept the rough notes from his surveying activity. Even though we are talking tonight about Thoreau’s maps, it is with a pencil and a notebook that he truly found his way in the world…and we will have reason this evening to look at many of Thoreau’s notebooks.

The field notebook appears on the surface uninteresting as it is filled for the most part with measurements and locations…places around Concord, MA that Thoreau surveyed. But it provides a detailed record not only of how Thoreau worked but also how he approached the more technical aspects of cartography and we shall return to this notebook many times this evening. Thoreau surveyed many places around Concord and the list of his clients reads like a library of early American authors. Places like Bronson Alcott’s farm shown here.

Thoreau set himself up as a surveyor in late 1849 and by the end of 1851 was recognized as one of best and most accurate operating in the region. The question of exactly how Thoreau learned to survey is for the most part an open one but it does appear that he was mostly self taught. In early April of 1850 Thoreau would borrow from the Harvard Library a copy of Davies’ Elements of Surveying and navigation , [we will see a great deal of Library use by Thoreau this evening.] A copy of the 1847 edition of Davies was also owned by Thoreau. Davies was one of the most widely used books on surveying during the middle of the 19th century and with Galbraith’s mathematical tables, also borrowed from Harvard, represents a solid introduction to the principles of land measurement. Thoreau annotated his copy of Davies with notes from Galbraith on particular mathematical problems…this is Galbraith’s instructions on how to calculate the sine of an angle.

Thoreau took much more from Galbraith than mere mathematical instruction. In a journal entry dated June 9th of 1850 Thoreau lists nine books recommended by Galbraith’s text regarding the esoteric subject of the magnetic variation of compass needles. I am going to spend some time with this subject because I believe it shows how Thoreau thought through and imagined the complexities of mapmaking and his engagement with the subject can be used as a model for us to think through his transition from an Emersonian transcendentalist…to the more empirical view of the world that informed his readings and use of early American cartography

Thoreau’s interest in magnetic variation is first indicated on his advertising broadside where he explains the variation of the compass is noted so that the survey can be repeated.
Throughout the early 1850’s one finds references throughout his journals and field notebooks made to the books and articles Thoreau read on the subject and to the observations of compass needle variations that he made in and around Concord.

Magnetic declination for those of you who do not know is the variation that we see between magnetic north, or the north that a compass needle points to, and true north, the direction of the pole. The variation in the compass needle is caused by the earth’s magnetic field and was the subject of a great deal of scientific research in the mid-19th century. The exact direction that a compass needle points to is not constant even for a specific location, and although few people would notice these small changes, Thoreau, noted them quite explicitly…for example…in November of 1850, he made an entry in his journal that marks the beginning of what would be almost an obsession with the subject…

Thoreau writes,

“When I am considering the way which I walk, my needle is slow to settle, my compass varies by a few degrees and does not always point due southwest; and there is good authority for these variations in the heavens…”

Thoreau’s interest is more than just passing and he delves into the science of magnetic declination in a way that would become representative of his work not only in natural history but also in the way he approached cartography as well. In his field notebook he explains how he established the True meridian so he could continually check his surveys against the variation of his compass needle

True meridian slide

• Found the direction of the pole star at its western elongation (1,58-1/2) at 9h 26m PM (Feb 7th 1851).
• N coincides with a line drawn from the SE course of the stone post on the E side of our western small front gate, to the S side of the first door on the W side of the depot.

Thoreau has measured a reference line for the direction of true north… from the west gate of his home in Concord to the depot across the street.
By establishing a sight line for the True Meridian from his family’s house to the depot, Thoreau could easily check the declination of his compass before or after surveying. Thoreau would begin to include this information on his surveys even though it makes little difference to the purpose of the survey itself. For example we can see on his survey of Hosmer’s farm that Thoreau has added compass headings to each of the boundaries.

Thoreau would continue for some time to make detailed observations of magnetic declination and write them into in his field notebooks…
He would also go as far as to contact and correspond with William Cranch Bond, the director of the Harvard Observatory. Bond was conducting experiments in magnetic variation in Cambridge, and took thousands of measurements on magnetic declination in order to try to predict the changes that he and Thoreau saw in compass needles, a phenomenon that we now know to be chaotic. One can see just how chaotic by looking at one of the many graphs of Bond’s published measurements that Thoreau certainly read.

Thoreau soon found that Bond’s results were not applicable to Concord, even though it was just a few miles away.

One of the most amazing and important things about all this material is how it shows a change in Thoreau’s thought process and his turn away from the transcendentalist mode of thought that drove his early works. Among transcendentalists' core beliefs, at least as it was realized by Emerson, was an ideal spiritualstate that 'transcends' the physical and empirical and is only realized through the individual's intuition. In other words a real mind over matter philosophy. Emerson found little of higher worth in the empirical and downgraded most of science as “mere facts”. Thoreau would begin by the early 1850’s to leave these idealist tendencies behind and turn toward more realist studies of nature and history…to the point that by late 1852 he could write in his journal seemingly against Emerson, that “Mere facts & names & dates communicate to us much more than we suspect…”

This empirical turn toward a more scientific world view… would influence all of Thoreau’s thought from around 1852 onwards. Although we can never really call Thoreau a thinker who fully embraced the pure empiricism of late 19th century science, there is a change in his thought that effects all of his reading and observations even his interpretation of the early exploration narratives and the history of cartography… it is to his cartographic explorations that we will now turn…

In order to talk about Thoreau’s interactions with and interest in early American exploration and cartography we must look to what has become known as the “Canadian Notebook”. The notebook was begun shortly after Thoreau’s return from a trip to Canada and those few scholars who have actually read it….it remains unpublished… differ in their opinions of why it was composed. The notebook is divided into three parts… the second part is certainly the most intense interaction with cartography and cartographic literature that one will find in the entire Thoreau corpus.

This second part of the notebook contains notes from Thoreau’s reading of early exploration narratives and maps by such figures as Champlain, Lescarbot, John Smith, Ortelius and Wytfliet. Thoreau takes note of specific subjects like the changing of place names, the plants and animals that the explorers encountered, the size and flow of rivers, temperatures, snowfall, and the changing shape of the lakes and rivers shown on their maps. In other words facts, empirical data that describes the landscape and the conditions of place. This type of description is paralleled in his journal entries at the time where he is noting things like stream depths, tree ring counts, snowfall, and the blooming times of plants that he observed during his surveying of woodlots and farms around the Concord countryside.

Even as Thoreau was taking detailed notes on the maps and information found in these early exploration narratives he expressed his frustration with the study of human versus natural history. In his journal, on October 19, 1860, he writes,

“It is easier far to recover the history of the trees which stood here a century or more ago than it is to recover the history of the men who walked beneath them, How much do we know---how little more can we know—of these centuries of Concord life?”

It was to answer this question that Thoreau turned to early cartography and the texts that accompanied them. In the back of the Canadian notebook written in Thoreau’s hand, but in pencil, and in the wrong direction if one is reading from the front, Thoreau composes the following list of maps that he has copied…

On the back fly leaf written upside down in Thoreau’s hand:
“I have copied maps made ac. to…”
1.Verarzani’s plot in Hacklyts divers voyage 1582
2. Map made in forme sent from Seville in 1527 by Thorne
3. Map of Nova Francia etc. in Ramurio 3rd volume (1556) ac to discourse of a great sea captiane
4. Of America in Ortelius (1570 &e) who used Cabot and others
5. Of Norumbega and Virginia 1597 Wytfliet Lovanni
6. Nouvelle France Champlain 1612, 1632

The list, although there are 6 numbers, actually describes seven maps there being two by Champlain listed on the same line. I first encountered this list many years ago and became interested in determining if copies of the maps that Thoreau listed still survive, if he in fact drew them, and what they might have looked like.

Two of the maps on the list were quite easy to locate and are part of the Collection of Thoreau surveys and papers in the Concord Free Public Library. The one shown here was copied by Thoreau from Abraham Ortelius’ world atlas, the Theatrum Orbis Terrarum, published in 1570. Ortelius was the royal geographer to King Phillip II of Spain and a prolific atlas maker. Thoreau borrowed several different editions of the atlas from the Harvard Library over a period of years and I have not been able to determine when he made the sketch. Thoreau’s notes on Ortelius in the Canadian notebook are principally devoted to a commentary on this map…”a new description of America”…and they are very much concerned with place names…as is typical of these notebook entries that deal with maps Thoreau brings other sources in and makes comparisons…in the case of Ortelius Thoreau will ask about the antiquity of some of the place names the cartographer uses.

The second map found in the Concord Library is that of Cornelius Wytfleit. Wytfliet was a Flemish geographer who published an atlas called Descriptionis Ptolemaicae Augmentum in 1597. This sketch, which is cruder than the Ortelius, was made in 1855 again from a book borrowed many times from Harvard Library.

The other five maps have been more difficult to find and to identify. Three of them are very small and are found folded in the misc papers of Thoreau that are in the Morgan Library…they are unidentified and therefore do not appear in their catalog lists or finding aids.

Of all of the notes in the Canadian notebook about cartography, by far the most extensive are associated with the narrative of Champlain’s voyages…time and time again Thoreau will borrow the 1613 and 1632 editions of this book from the Harvard Library…
Champlain made several voyages to the New World and explored the St. Lawerence River, along with most of the New England coast, at least as far south as Cape Cod. The narrative of his voyages is filled with maps and his reflections on the explorations.
Thoreau’s notes on Champlain’s texts are full of details on plants, animals, place names and especially the differences in the various editions of the maps Champlain made.…Thoreau writes praising Champlain’s accuracy as a geographer and he quotes in detail Champlain’s own commentary on the methods of his mapmaking.

But what about the two Champlain maps on Thoreau’s list of the maps he copied???…they appear in no inventory of any library, they are talked about in no scholarly articles and appeared to me to be lost.

Then one day, when I first came to the Library of Congress, almost ten years ago I happened to be doing some research on Thoreau and the depth of Walden Pond when Ron Grim…now of the Boston Public Library, mentioned to me that there were several maps in the Geography and Map Division thought to be by Thoreau but with no real attributions. Curious about this but not expecting much…for how could maps by Thoreau be sitting in the Library of Congress without firm attributions…I opened the folder and saw a manuscript…

Immediately I knew that I was looking at the missing Champlain maps. The manuscript that you see here is one of four pages that describes the two Champlain maps that Thoreau listed on the flyleaf of the Canadian notebook and copied, one from 1632,

This map was easy to identify as Thoreau’s because it is in his hand and fits the general form of his other map sketches. The second map however from 1612 was more difficult as it is a tracing and contains almost nothing that would directly link it with Thoreau. Thoreau does say in the manuscripts that accompany the maps that he annotated the 1612 map in red with later places names. This feature can be seen on the 1612 copy below.

While the finding of the two Champlain maps completes the list of the known cartographic copies that Thoreau made… it has opened up the question of how to understand Thoreau’s geographic explorations in relation to some of his larger projects and published works. For Thoreau’s relationship to cartography is a complicated one and has suffered from a lack of scholarly attention. In general Thoreau seems to have remained skeptical of maps even as he made constant use of them…in his journals he wrote,

How little there is on an ordinary map! ...between those lines indicating roads is a plain blank space in the form of a square or triangle or polygon or segment of a circle, and there is naught to distinguish this from another area…for on it are no moral lessons…

And in the Maine Woods he tells us that maps are “labyrinths of error.”

Thoreau’s true attitude toward cartography is not difficult to assess, if one takes the time to read through his extensive notes on the subject closely. The notes express an immediacy of experience that occurs when one is reading and observing directly…Thoreau did not think of historic maps from the past as obsolete, but rather as graphic and ideological documents that could help him understand what had been in a particular place before…In many ways we can consider Thoreau the first "modern" historian of cartography.
To conclude, I want to return to one of Thoreau’s surveys.

It is a simple drawing of a woodlot but I think it sums up Thoreau’s relationship to cartography and its influence on his work. The surveying of woodlots was very much part of Thoreau’s daily routine and it took him into areas of Concord seldom seen by his fellow citizens…surveying a woodlot generally meant the lumber it contained was up for sale and it was going to be cut down. Thoreau would return to the lots after they had been cut and in his journals noted in detail the succession of plants and trees that would follow…these notes would result in Thoreau’s most important work of natural history, “The Dispersion of Seeds”, which he composed shortly after reading Darwin in 1860…

Unfortunately, Thoreau did not live long enough to complete the great work on geography and the indigenous peoples of North America that his extensive notes in the Canadian and Indian notebooks would lead us to believe he was working on…all we have are the notes…more than 4000 pages of them unpublished

I have said that in what Thoreau wrote in these notebooks, as dry and factual as they are, we get a sense of a transition, an empirical turn, that not only occurs in his thought, but that would begin to lay the foundations of modern geography and environmental history…

Besides this however, we may also sense something more important…something deeper that you can all take pride in tonight… Thoreau used many books, articles and maps in these notes, most of which were read in libraries just like the one we celebrate this weekend. In his life and work we can see how something as humble and as common, as book or a map in a library…can spark the imagination and inspire great thoughts…without a library there would be no Henry David Thoreau, there would be no notes and drawings for us to wonder and marvel at this evening… like Thoreau’s notes, libraries, through their collections of books, manuscripts and maps teach us that…

“Mere facts & names & dates communicate to us more than we suspect…”

Thank you all for listening….

The Henchir Mettich Inscription from Central Tunisia:
Further Use of Epigraphy for the Study of Early Surveying and Cartography

The sociologist Max Weber, shown in the photograph below, wrote in his dissertation, Die Römische Agrargeschichte in ihrer Bedeutung für das Staats- und Privatrecht (Roman Agrarian History and its Significance for Public and Private Law), that Roman Surveyors distingushed three categories of land:

1. ager divisus et assignatus, land surveyed and assigned to owners which is further subdivided into two categories
a. ager limitatus, that is land surveyed by centuriae and assigned to owners.
b. ager per scamna et striges land surveyed by scamna and striges and assigned to owners.
2. ager per extremitatem, land surveyed by boundaries.
3. ager arcifinius, land not surveyed.

Weber completed the dissertation in 1891 and was greatly influenced by the work of great Roman historian, Theodor Mommsen, shown below.




















Weber in the dissertation makes a case that the two broad categories of surveyed land, that of centuriae and that of scamna et striges are different systems of mapping based on land ownership laws. The centuriae surveys are more general and do not reflect the actual ownership boundaries of the land, while the scamna surveys follow actual property lines. Centuriation, the process of dividing the land into centuries, formed very regular patterns and, as is shown in the schematic below, had fixed sizes associated with it. Scamna and striges are different, in that the bounaries of the surveyed land form irregular rectangles of various sizes and extents.























Weber makes the case that this distinction has more than just structural meaning and cites the writings of the surveyor Hyginus from the Corpus Agrimensorum. Hyginus says that land surveyed per scamna et strigas was "subject to taxation" and for this reason "permanent property lines" had to be well defined.

The question of the relationship of private property, taxation, and the role of surveying and cartography in the establishment of colonial tax and ownership rights in the Roman Empire is a very complex one and much more historical work needs to be accomplished in this area. One sourse of information regarding the interplay of these various bureacratic entities comes from epigraphic inscriptions.

One important inscription regarding the role of ownership, rents and taxation that survives was found at Henchir Mettich near the village of Testour, Tunisa, west of Carthage. The inscription was originally part of the administrative documents associated with the estate or fundus of Villa Magna Variana. The section of the map below from the Barrington atlas shows the region to have been only lightly centuriated, yet the inscription, as I will show below implies that it was surveyed.














The inscription is currently part of the collections of the Bardo Museum in Tunis and is shown in the photograph below.






















The text found on the momument was published several times after its discovery in 1896. The area around Henchir Mettich is currently an arid district of mostly barren hills, some of which are currently cultivated with olive trees.











Click figure to enlarge









While in Tunisia last year I took detailed photographs of the Henchir Mettich inscription at the Bardo (one of the series is shown in the above figure). The stone on which the inscription is written was in all probability moved from its original location to Henchir Mettich and is dedicated "to the safety of the Emperor Trajan" suggesting a date of around 115-117 AD.

The inscription itself is quite long and is found on all four sides of the momument. It is addressed to the group of landowners and renters who are associated with the fundus. The actual boundaries of the fundus are not given in the inscription but it does tell us that the estate was large enough to have a wide variety of agricultural production. There are fields of wheat, barely and beans, along with orchards of olives and figs. This list is very much in line with the current agricultural output of the region. The inscription also mentions vineyards and pastures and home sites for workers.

One of the most interesting parts of the inscription takes about the fact that some of the land is uncultivated and that a part of the land is leased to cultivators and also contains portions that are given over to the lessors for their own farms. Those who worked the fields are described as coloni, of which the inscriptions defines two types:
1. those who lived on the fundus in their own homes (specifically homes they themselves built)
2. those who lived on the fundus but rented their buildings.

The inscription, whose entire contents I will translate in a future post, divides up in precise terms the rules associated with the various types of land associated with the fundus and talks about land renting and ownership rules and the terms under which things like unalloted farm lands may be occupied and cultivated. Much of the discussion of these rules implies a deep concern with boundary issues and surveying. For example the inscription states:

"To those coloni dwelling on the fundus of Villa Magna Variana, that is, of Mappalia Siga, who wish to cultivate the fields, permission is given to cultivate those fields which have not been alloted, under the terms of the Lex Manciana; namely that he who cultivates shall have personal use of the land. Of the crops which are raised on said land, the cultivators shall give to the owners, or lessors, or stewards of this fundus shares as fixed..."

The unalloted portions that are referred to resulted from the division of land for the purposes of distribution to private individuals. From this one can infer that the fundus was originally surveyed and distributed and therefore became ager privatus. If one believes the methodologies for such distribution as outlined in the Corpus Agrimensorum this implies the creation of a map at some time before 116-117 AD.

There are other instances of this type of example. Mommsen in Volume X of CIL (pp 386) records an inscription from the ager Campanus, which settlers had begun to occupy without permission. The inscription says:

"He divided that territory into small farms (fundi) and leased them out at fixed rents. While in office he recovered more land than was expected, and he had the whole territory recorded on a surveyor's map (forma). This was then engraved on a bronze tablet..."

The inscription's language is complex in a number of areas, especially in those referring to subseciva, or uncultivated, unalloted land. With the little evidence that survives however, regarding Roman surveying and cartography, epigraphy is just one more group of texts that need to be studied in a closer and more a critical way than historians of cartography have generally done...more on this inscription in later posts...




The author practicing his skills in the ruins of Carthage...just
outside of Tunis...

Epigraphic Evidence for Large-Scale Roman Mapping

What survives of their treatises [of the Roman surveyors] can appeal to few readers now, but so diverse are the manuscripts that preserve it, so many the names associated with its preservation, that no text opens the window wider on the transmission of Latin literature from Antiquity to print…
--L.D. Reynolds
Texts and Transmission

Besides the epigraphic cadastres from the colony of Orange in the South of France, a small fragment of which is shown in the figure below, there is other epigraphic evidence that the Romans actually made detailed maps of their territories. Although extremely rare, there are several examples of epigraphic inscriptions where explicit mention is made of the word "map'.

















In the Corpus Agrimensorum, a compilation of Roman Surveying manuals from the 6th century, there are several words used for map. Writing in the text the surveyor Siculus Flaccus says,

“The maps are given various names: some are set up on wooden tablets, others on bronze, still others on skins, although ‘map’ is their generic term, they are sometimes called ‘territory’, ‘centuriation,’ ‘demarcation,’ ‘limitation,’ ‘grid-pattern,’ figures…”

Hence Latin words such as Forma, tabula, pertica, typon, and metatio all appear to mean map.

Epigraphic evidence from Tunisia shows other examples of the word Forma being used in this fashion. In the Corpus Inscriptorum Latinarum we find two examples in which maps are mentioned as having been made or that are being referred to. The figure below shows CIL 22788, an inscription from Henchir Chenah, that is carved on four sides of stone.

CIL 22788

The part of the inscription that we are interested in reads:

sec]undu(m) [f]orma(m) missa(m) sibi ab posu[it]

and records a boundary settlement made "in accordance with the map".

A second inscription from Henchir ez Zoubia, CIL 23910, shown below records a longer inscription referring to a boundary stone set up between the land of two communities.

The inscription reads:

positum sic [secum] dum for[man]um [mar]

This refers to the fact that the settlement was set up once again "according to the map". From the remainder of the inscription we might imply that this was done by a soldier (perhaps a surveyor) attached to the XII Urban cohort based in Carthage.

CIL 23910

Geometrical Problems from the Corpus Agrimensorum :
Mollweide meets Mommsen

A representation is made with a purpose or goal in mind, governed by criteria of adequacy pertaining to that goal, which guide its means, medium and selectivity.
--Bas Van Fraassen

The group of Roman surveying texts known as the Corpus Agrimensorum have provided a great deal of information regarding the actual practices of Roman surveyors in the field and given scholars insight into how the Romans allocated and measured land. My current project in locating and mapping the surviving remains of Roman surveying in North Africa takes its starting point from this 6th century compilation of surveying manuals. The texts themselves and the illustrations attached to them have attracted the attention of many scholars in past including historians of Roman law and agrarian practices such as Theodor Mommsen and Max Weber. In this sence the historiography associated with the texts is almost as interesting as the texts themselves.

What is less known about this historiography is the attraction the texts have held for more mathematically inclined historians of cartography such as C.B. Mollweide. Mollweide is best known as map projectionist, but also did fundamental research into some of the unsolved geometrical problems found in the Corpus.

One of the most interesting of these problems concerns the method for finding south. In the Corpus there are several methods given for this, but the one that interests us here is that given by the writer, Hyginus.

There is also another method of obtaining South, by marking three shadows. On level ground we shall set up a gnomon AB, and note any three of its shadows, CDE. These shadows we shall mark with the set square, to see their distances from each other. If we set them up before noon, the first shadow will be the longest; if after noon, the last. We shall then draw these shadows in proportion by a footrule... Let AB be a gnomon, B the ground. Let us take the longest shadow and mark it [i.e. its end opposite to B] on the ground as C; the second likewise D, the third E... Let us project hypotenuses from C on to A and from D on to A. Now with centre A and radius E let us draw a circle. Then let us project lines parallel to the base, i.e. ground, on to the perpendicular [AB] from the intersections of the hypotenuses and the circumference, from F on to G and from I on to K. Then we shall apply the longest line, GF, to the largest shadow, and from B we shall mark out [the length of] GF ; the second line to the second shadow, and we shall mark out [the length of] KI. Then from F and I we shall project a straight line, and likewise from C and D, the shadow ends. These two lines will meet at T. Join TE; this will be east-west.

The above text by Hyginus is accompanied in the Codex Arcerianus A by the figure shown below.

The figure as drawn by the scribe is however totally inadequate to explain the complexities of the method outlined by Hyginus and one has to question its purpose in the manuscript and whether it was in fact added to the text by a later copiest with less understanding of the method. Mollweide analyzes the text in an article 'Erlduterung einer in der Scriptoribus rei agrariae. . . gegebenen Vorschrift..' published in Zach's Monatliche Correspon-denz zur Beforderung der Erd- und Himmelkunde (Volume 28, 1813. p. 396-425).








Click on Figures to enlarge

The method that is being described in the text by Hyginus is extremely complicated and there are open questions concerning the level of mathematics and solid geometry involved.




















Mollweide's solution is a complex affair and according to Dilke the method as described by Hyginus probably goes back to Alexandrian mathematical scholarship that has been lost but that must have been dependent on Apollonius' Conics.

The modern solution that Dilke adapted from Mollweide can be condensed to the following along with the figure below:

ABC, ABD, ABE are right-angled triangles. The lines CA, DA, EA go towards the centre of the sun. The arc EIF is part of a circle forming the base of a regular cone, parallel to the sun's daily round and so to the equator, and FI is a chord of this circle. Since GF is equal and parallel to BL, FL will be equal and parallel to GB; similarly IM to KB. As FL and IM are parallel to AB and so to each other, they lie in a plane in which FI and LM lie. But FI is also in the plane ACD, and LM is in the horizontal plane BCD; so FI is the intersection of the plane FIML with the plane ACD, and LM the intersection of the plane FIML with the horizontal plane BCD. As the plane ACD is cut by the horizontal plane at CD, which when produced meets LM produced at T, it follows that T is in the plane ACD and also in the plane FIML, and so is a point on the common intersection of both planes, i.e. of FI produced. Since the latter lies entirely on the plane of the circle through FIE, T is also in this plane, but likewise in the horizontal plane BCD, and so is a point on the common intersection of both planes. Since E is also such a point, it follows that ET is the intersection of a plane parallel to the equator plane with the horizontal plane, and so parallel to the east-west line.
One can see how different the figure which displays the actual construction as it described by Hyginus is from the original manuscript illustration.

Using Edge Detection Algorithms to Search for the
Physical Remains of Roman Centuriation and Surveying

But the land surveyor is like a judge; the deserted fields become his forum,
crowded with eager spectators. You would fancy him a madman when you see
him walking along the most devious paths.
----Cassiodorus

It is well known that the remains of Roman Surveying throughout Northern Tunisia are the best preserved in the world, but the difficulties in geographically locating these areas has led to a serious lack of research and scholarship on these remains. The Romans, in the regions around Carthage, Dougga and Enfida, surveyed extensive areas, and left behind physical remains in the form of limites and field boundaries. I have recently begun studying these regions using both fieldwork and computer methods in an attempt to locate and map these important remnants of Roman colonization. In the figure below I have used an edge detection algorithm on a satellite photograph (Landsat) of the area around Carthage that allows for the enhancement of linear field boundary features and whose results can be statistically compared to the known forms of Roman cadastral surveys found in texts such as the Corpus Agrimensorum.





















[click on figures to enlarge]

Once the extent and size of these 'survey areas' has been determined a grid can be fitted and overlaid on a satellite photograph of the region in question. The figure below shows the area around the modern town of Enfida, Tunisia. The calculated grid lines up quite well with the current local path system around the fields and with the intersection known to have been the kardo and decumanus in Roman times.

Below one can see a GIS map that I produced showing several of the areas studied so far using these methods along with a grid over the approximate extent of the physical remains. More complicated algorithms using both Fourier and Radon transforms have also been used to locate and orient the regions shown. I have presented detailed results of this research at the International Conference on the History of Cartography held in Copenhagen in July of 2009, and will provide more on the mathematical details of this in a future post and publication.

Exploring Waldseemuller's World :

An International Symposium at the Library of Congress

For those of you who where unable to make it to the Library for our Waldseemuller Conference last month we have posted the complete conference on-line in four 2.5 hour parts... you can find the video webcasts at...

Part 1: Scholars and Scientists

http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=4568

Part 2: Exploring the Known and Unknown

http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=4567

Part 3: Sources and Texts

http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=4569

Part 4: Changes and Revolutions

http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=4566

Hope you all enjoy...