Shedding (More) Light on Sixteenth-century Mapping Practices. Pieter Pourbus’s Application of Gemma Frisius’s Triangulation Methods

Le résumé fourni par la source

Pieter Pourbus (c. 1523–1584), a renowned sixteenth-century Bruges painter, was not only celebrated for his artistic skills but also for his exceptional proficiency in cartography until the late eighteenth century. Although his cartographic talents have been praised for centuries, the details of his cartographic knowledge and how he acquired and applied it have remained ill-studied topics of scholarly debate. Recent findings have shed new light on Pourbus’s mapmaking practices. Notably, the writings of Gemma Frisius (1508–1555), a physician and mathematician at Louvain’s Collegium Trilingue, played a crucial role in understanding the methods employed by Pourbus. However, traditional photography fell short in capturing the full extent of these cartographic techniques on Pourbus’s manuscript maps, as it appeared he incised preparatory lines and circles as underdrawing, rather than applying them with coloring agents. Additionally, the application of paint further concealed these incised underdrawings. To delve deeper into these barely perceptible traces of production, we employed Multi-Light Reflectance Imaging (MLRI) in a pioneering investigation of historic maps. Our study focused on two remarkable maps from the City Archives of Bruges: Pieter Pourbus’s map of Cadzand (dated around 1578) and Lancelot Blondeel’s (1498–1561) conceptual map of the waterways north of Bruges (1546). The results of our analysis were revelatory for both cases. For Pourbus’s map of Cadzand, our MLRI examination not only confirmed the previously observed lines and systems but also unveiled additional lines in areas where standard photography had failed to provide results. Furthermore, we gained new insights into Pourbus’s cartographic production process, including the use of writing lines and perforations for pricking and pouncing. In the case of Blondeel’s map of the waterways north of Bruges, our findings corroborated the assumption that a similar survey-related set of lines might have been on the map of Pourbus’s father-in-law and artistic mentor. While the lines and circles in this map were not as abundant or systematic, their presence strongly indicated that Blondeel’s workshop in the mid-1540s had at least experimented with Frisius’s triangulation techniques. This research contributes to a deeper understanding of the cartographic practices of Pieter Pourbus and his contemporaries, shedding light on their innovative approaches to map-making in the mid-sixteenth century.

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