By THL Máirghréad Stíobhard inghean uí Choinne
The Rochester Institute of Technology Center for Imaging Science hosted a lecture on January 23, 2019 by Dr. David Messinger, Director of the Center, and his PhD students, Di Bai and Morteza Maali Amiri, on the Gough Map, the oldest-known surviving map of Great Britain (dated to approximately 1410 C.B.E., completion date).
The lecture discussed recent work performed to learn more about the origins, materials, tools, and uses of the map. The work has been a collaboration between the R.I.T. team and David Howell of the Bodleian Library at Oxford University where the map is housed, Andy Beebe of the University of Durham, and Catherine Delano-Smith and Damien Bove of the University of London (a group composed of physicists/image scientists, a chemist, a material scientist, and two map historians, respectively).
The Gough Map shows all of England and Scotland and part of Ireland. Robert Gough bequeathed it in 1809 to Oxford after acquiring it from the estate of Thomas “Honest Tom” Martin. The map measures about 115 x 56 cm (45 x 22 inches), which is very large for a manuscript of this era. The parchment is about two-thirds sheepskin and one-third lambskin. The seam joining the two can be seen running across Scotland.
The R.I.T. team’s role was to use a nondestructive technique called hyperspectral imaging spectroscopy (which entails hundreds of colors of light as opposed to the red/blue/green light that digital or phone cameras employ) and a lot of sophisticated mathematics while consulting with the greater team to determine what the materials of the pigments and inks were composed of and which areas of the map contained what materials. To achieve this end, the R.I.T. team traveled to Oxford in 2016 and will continue studies there this summer focusing in more detail on the inks.
Henry IV was king at the time of the map’s creation. It includes 654 place names shown as text in boxes or cartouches. What originally appeared to be roads on the map has proven to be distances between these places. However, the reason for gathering this distance data and how it was used remains a mystery.
There are various characters on the map including fish, sea monsters, and boats, and text such as “where King Arthur landed.” These objects and text can be seen in detail at the interactive, searchable version at www.TheGoughMap.
All of the churches and buildings on the map are identical and are illuminated over four pin holes. It is surmised that a template, as was then common in monastic illumination, was used to draw them and held in place by the holes.
The map was extensively revised after about 100 years of use. Further phases of study will be aimed at determining what materials appear to be different due to aging of the original materials or because they were added during later revisions and/or are indeed different pigments or inks.
During the 1600s, there was some damage to the map. The owner was told the text would be restored if he applied red wine on a sponge to those areas. This actually worked for a few weeks and then, due to chemical reactions, completely destroyed the text and images on those areas of the map. This hyperspectral technique was used to reveal the text and illumination that was removed from the map manuscript.
The map has also been featured in Imago Mundi, a cartography magazine whose editor is Dr. Delano Smith , one of the scientists. They are sponsoring a conference this summer and panel on the map seating Dr. Messinger.
The hyperspectral analysis revealed that the Hadrian’s Wall on the map was not composed of the same material as the red text writing. Analysis initially showed there were two different pigments. Further analysis showed that they were both vermillion pigment, however the text was done with no binder and a quill pen whereas the wall was done with a brush and a binder (such as egg white) had been added to the vermillion. Five unique red pigments were identified in use on the map.
Not only do the pigments appear different depending on how they were mixed, they appear different on the various substrates such as sheepskin versus. lambskin parchment.
The R.I.T. team identified five unique green pigments for the open waterways. Were they used to denote tides? Crossing spots? River depths?
They also identified five unique green pigments for the for inland waterways. Were they used for labels? Town signs? Distance markers?
The answers to these questions remain unknown at this time.
The map was created in three phases starting in 1360 C.B.E: first, the outline of Great Britain and Scotland, second, the other towns, and lastly, London.
Regarding the green pigments, one is a mixture of indigo (also known as woad) and a yellow pigment, but hyperspectral analysis showed the yellow is not orpiment. It is an organic yellow. However, it is not believed to be saffron due to the expense. Another possibility is buckthorn yellow and studies in this area will continue. Further analysis discovered verdigris or copper-based green pigment. This discovery was due to the R.I.T team’s work and a new algorithm they developed. The same technique will be used to separate which areas of the map employ iron gall and carbon inks.
There are years of additional analysis and discovery planned for the map and other historical documents including minimizing light exposure from the imaging analysis to avoid possible long term damage, how to analyze pigments by “unmixing” them spectrally, using hyperspectral fluorescence to recover text and damaged areas, automating the process to identify pigments, and creating an affordable imaging system (the two systems at R.I.T. cost about $50,000 each; the goal is $2,000 per unit).
Rochester, N.Y., located in the Barony of Thescorre in AEthelmearc, is establishing itself as the world center for recovery of historical documents, whether they have been damaged by age, smoke, or water or are palimpsests (which are documents where the original text was scraped off from the parchment or other substrate and new text and or illumination applied). The Rochester Cultural Heritage Imaging, Visualization and Education (R-CHIVE) group meets alternately at R.I.T. and the University of Rochester and is a collaboration of university researchers and students from across the globe. They have held conferences for the past two years in Rochester. You can read the full text of Dr. Messinger’s paper (published in SPIE) through a link at the R-CHIVE website.
See more on the Gough Map here.
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