Cartographic Veracity in Medieval Mapping: Analyzing Geographical Variation in the Gough Map of Great Britain

Abstract

This article explores statistical approaches for assessing the relative accuracy of medieval mapping. It focuses on one particular map, the Gough Map of Great Britain. This is an early and remarkable example of a medieval “national” map covering Plantagenet Britain. Conventionally dated to c. 1360, the map shows the position of places in and coastal outline of Great Britain to a considerable degree of spatial accuracy. In this article, aspects of the map's content are subjected to a systematic analysis to identify geographical variations in the map's veracity, or truthfulness. It thus contributes to debates among historical geographers and cartographic historians on the nature of medieval maps and mapping and, in particular, questions of their distortion of geographic space. Based on a newly developed digital version of the Gough Map, several regression-based approaches are used here to explore the degree and nature of spatial distortion in the Gough Map. This demonstrates that not only are there marked variations in the positional accuracy of places shown on the map between regions (i.e., England, Scotland, and Wales), but there are also fine-scale geographical variations in the spatial accuracy of the map within these regions. The article concludes by suggesting that the map was constructed using a range of sources, and that the Gough Map is a composite of multiscale representations of places in Great Britain. The article details a set of approaches that could be transferred to other contexts and add value to historic maps by enhancing understanding of their contents.

En este artículo se exploran las estrategias estadísticas para evaluar la precisión relativa del mapeo medieval. Se concentra en un mapa en particular, el Mapa de Gough de Gran Bretaña. Éste es un ejemplo temprano y extraordinario de un mapa “nacional” medieval que cubre la Bretaña de Plantagenet. Convencionalmente fechado en aproximadamente 1360, el mapa muestra la posición de lugares y el reborde costero de Gran Bretaña con un considerable grado de precisión espacial. En este artículo, se someten aspectos del contenido del mapa a un análisis sistemático para identificar variaciones geográficas en la veracidad del mapa. De este modo contribuye a los debates entre geógrafos históricos e historiadores cartográficos sobre la naturaleza de los mapas y métodos de mapeo medievales, en particular sobre preguntas de su deformación del espacio geográfico. En base a una versión digital recientemente desarrollada del Mapa de Gough, en este estudio se utilizaron varias estrategias basadas en regresión para explorar el grado y la naturaleza de la deformación espacial en el Mapa de Gough. Esto demuestra que no solo hay variaciones marcadas en la precisión de la posición de los lugares mostrados en el mapa entre regiones (esto es, Inglaterra, Escocia y Gales), sino que también hay variaciones geográficas de escala fina en la precisión espacial del mapa dentro de estas regiones. Este artículo termina sugiriendo que el mapa se construyó usando una variedad de fuentes, y que el Mapa de Gough es un conjunto de representaciones multiescalares de lugares de Gran Bretaña. El artículo detalla un conjunto de estrategias que se pueden transferir a otros contextos y añadir valor a los mapas históricos al mejorar el entendimiento de su contenido.

Key Words:

• bidimensional regression
• Gough Map
• historical cartography
• local regression
• medieval maps

关键词:

• 二维回归
• 高夫地图
• 制图历史学
• 局部回归
• 中世纪地图

Palabras claves:

• regresión bidimensional
• Mapa de Gough
• cartografía histórica
• regresión local
• mapas medievales

Acknowledgments

The research on which this article is based is derived from the “Mapping the Realm” project funded by the British Academy (award number SG-39911) and was carried out in summer 2005. The project was directed by Keith Lilley and codirected by Chris Lloyd and Paul Ell of Queen's University Belfast, with substantive contributions made by Steven Trick (GIS database construction and digitization) and Bruce Campbell (place name and socioeconomic data). The project team was also supported by advice and guidance received from Mark Gardiner, Stephen Kelly, and John Thompson, and their comments on previous versions of this article are gratefully acknowledged. Special thanks go to Nick Millea, curator of the Map Library of the Bodleian Library of the University of Oxford, whose encouragement and access to the Gough Map have been invaluable throughout. We are grateful, too, to Robs Watts of DigiData Technologies for making available to us digital images of the Gough Map and to Waldo Tobler for his advice on analytical procedures used in this article. We also acknowledge the four anonymous referees whose comments greatly improved parts of the article.

Notes

^aCornwall was excluded for this analysis, for the reasons described in the text.

^aCornwall was excluded for this analysis, for the reasons described in the text.

1. See http://research.microsoft.com/mapcruncher/ (last accessed 6 December 2007).

2. The Digital Gough resource is available at http://www.qub.ac.uk/urban_mapping/gough_map/ (last accessed 6 December 2007).

3. See http://www.multimap.com/ (last accessed 6 December 2007).