Quinta pars or terra incognita? Verisimilitude in the cartographic representation of the unknown

by Carla Lois

Starting in the early sixteenth century and continuing for more than two hundred years, European world maps showed a huge terra incognita southern landmass, mostly known as Magellanica (after Ferdinand Magellan) or Quinta Pars (the “fifth part” of the world).

As no material demonstration explained its cartographic depiction (because the Quinta Pars simply did not exist), this case allows us to analyze the philosophical conceptions, epistemological bases, and intellectual methods involved in imagining and representing unknown geographies, avoiding the temptation to compare them with “reality” by measuring errors or inaccuracies. This perspective implies a reflection not on how the unknown became known, but rather on how the unknown was conceived and represented while unknown.

It was the European discovery of the New World, also known as the Quarta Pars, that made the existence of an austral continent plausible. By the end of the 16th century, cosmographers and savants accepted that the continents or parts of the world were separated by significant rivers or oceans. In the same way that the Atlantic Ocean divided Europe from America, the Strait of Magellan was thought of as the body of water that conceptually justified ascribing continental status to the barely explored Tierra del Fuego (imagined as part of an as-yet-unknown though expected fifth continent).

Some of the aesthetic components involved in the cartographic representation of the unknown—including graphic patterns (colors, lines, shapes) as well as iconography (symbols, allegories, mirabilia)—were borrowed from early maps of America. These links are symptomatic of how the Quarta Pars worked as the condition of verisimilitude for the imaginary Quinta Pars. Another element shared between New World maps and Quinta Pars cartography was the interrupted coast- lines that, at the same time, acknowledged a lack of empirical knowledge about certain zones and expressed the idea that large land masses could appear after further explorations.

Fragment du planisphère envoyé de Lisbonne à Hercule d'Este duc de Ferrare avant le 19 novembre 1502

Fragment du planisphère envoyé de Lisbonne à Hercule d'Este duc de Ferrare avant le 19 novembre 1502. Alberto Cantino. Paris: [1883]. Image courtesy of the University of Wisconsin, Milwaukee Library.

This chart serves as a counterpoint for Rotz’s world map (below) to compare the (open) cartographic writing of partially explored coastlines. The original manuscript is attributed to the Portuguese cosmographer Pedro Reinel. The map became famous, however, by the name of the man who brought it to the Duke of Ferrara in 1502, Alberto Cantino. The inscription on the map reads: “Carta da navigar per le Isole nouam tr [ovate] in le parte de l'India: dono Alberto Cantino al S. Duca Hercole” (Navigation map for the island not found in the part of India: donated by Alberto Cantino to S. Duca Hercole). The western coast of the New World remains open, awaiting new data to be collected in future explorations.

The Map of the World

Map of the World in Boke of Idrography (The 'Rotz Atlas'). Jean Rotz. 1542. Image courtesy of the British Library.

In this illuminated manuscript, the incomplete trace of the southern continent replicates a well-known graphic strategy used in manuscript maps of the New World by the cosmographers and pilots of the Casa de Contratación in Seville. It indicates the state of exploration and demarcates the limit of empirical knowledge at the time. Up until the 16th century, the region known today as Tierra del Fuego had only been explored in its northern section. Navigators did not know that Tierra del Fuego was an island until the Dutch explorer Jacob Le Maire y Cornelius Willem Schouten circumnavigated it in 1616. By naming this unknown land “Terra,” the cartographers implied that they expected to find not an island but a continent. In the same way, by drawing Tierra del Fuego with an open line, they left room to add a new continent on the map in the near future, as further explorations brought new information about the austral lands. The shape of this part of Quinta Pars suggests the tip of an iceberg, which might also be taken as a metaphor for the state of geographical knowledge: the small part visible at the top is assumed to be hiding a huge mass below that is as-yet unseen.

Chica sive Patagonica et Australis Terra

This composite image pairs two separate maps, each affirming in different ways that the Quinta Pars or Terra Australis was a continent. Along the top are displayed the southern section of the already accepted New World (labeled here Patagonum Regio) and the northern rim of the conjectured southern continent (Terra Australis Pars). The two are separated by the Strait of Magellan, at a time when bodies of waters were considered the key element to distinguish the main parts of the world. (As the French cosmographer Jacques Focard affirmed in 1546: "Here it should be noted that several authors have put the Nile for dividing Asia and Africa. Those who repeat Ptolemy say that it is better to divide land masses by sea when possible, or if not, by rivers.”)

At the bottom of the image, Terra Australis is represented again, this time as a huge and independent landmass. A perfect circle has been drawn inside it and labeled “terra incognita.” Pure geometric shapes like this are a typical type of trace for hypothetical geographies. Unsurprisingly, the acknowledged unknown is located deep in the inaccessible heart of the conjectured continent, where it does not invalidate the existence of the continent itself. By contrast, the clearly rendered and detailed coastlines seem to prove the existence of the landmass itself, independently of the degree of knowledge of its interior.