The concept of a great southern continent surrounding the South Pole derived from the ancient Greek view that the landmass of Europe and Asia and North Africa (their known world) must be balanced by a large continent in the southern hemisphere in order to provide the required equilibrium and so prevent the Earth hurtling into space. This theory was consolidated by Ptolemy in his treatise Geographica, a manuscript copy of which came to light in early-15th-century Italy. Subsequent maps, based on the Geographica, depicted the southern tip of Africa stretching as far as latitude 20º South where it joined a west-to-east coastline extending to the Asian continent, thus enclosing the Indian Ocean. Across the bottom of the map, behind this long coastline, was a vast continent known to contemporary cartographers as Terra Incognita (the unknown land).
The Portuguese maritime expansion at the turn of the 15th and 16th centuries, during which they pioneered a route round the Cape of Good Hope into the Indian Ocean in 1488, dispelled the Ptolemaic theory of a landlocked ocean, but the concept of a southern continent was to remain for almost 300 years. Speculation that it extended to the South Atlantic region was seemingly given substance by Amerigo Vespucci’s claim to have reached 52º South latitude and to have sighted an unknown land on his 1501–1502 voyage down the coast of South America. When Ferdinand Magellan penetrated even further south to pass through the strait that now bears his name and reported seeing campfires on a land to the south, which he appropriately named Tierra del Fuego, a vast southern continent became even more imprinted on the minds and maps of European cartographers.
Following Magellan’s voyage across the Pacific, the southern continent’s configuration was amended to an irregular and roughly circular landmass, surrounded by a continuous southern ocean, which appears on the 1531 map drawn by Oronce Finé, Nova Et Integra Universi Orbis Descriptio (A New and Complete Description of the World) on which the continent is designated “Terra Australis Recenter inventa sed nondum plene cognita” (The South Land recently discovered but not yet well known).
Gerard Mercator’s famous 1569 world map outlined Terra Australis’s coastline running continuously and diagonally from Tierra del Fuego to New Guinea. On the promontory closest to New Guinea is the legend “Haec continentem Australem nonnulli Magellanicum regionem ab eius inventore non cupant” (this southern continent some call Magellanica after its discoverer). The name Magellanica continued to appear on maps in tandem with Terra Australis until the 17th century when Terra Australis Incognita (The Unknown Southern Land) was favored by the leading Dutch cartographers.
Mercator’s continental coastline descended into a wide gulf (Gulf of Carpentaria?) containing two islands (Groote Eylandt?) whose western shore was formed by another promontory reaching almost to Java. This was the furthest extent of the imaginary continent in the Pacific region; the coastline now dropped away to the southwest until it completed the circle back to Tierra del Fuego. Abraham Ortelius’s 1571 atlas Theatrum Orbis Terrarum (Theater of the Lands of the World) included a map showing a southern continent similar to Mercator’s.
By the beginning of the 17th century, not only was Terra Australis believed to be a geographical certainty just waiting to be discovered but also, because of its location in the tropics, a vast, untapped source of gold, precious stones, grain, and spices. It was even linked to the distant biblical land of Ophir, which had sent its riches to King Solomon. Not for nothing were the islands discovered by Alvaro de Mendaña and Pedro Fernandez de Quirós named after the Old Testament king.
Brief details of Terra Australis occur in Cornelis Wytfliet’s Descriptionis Ptolemaicae Augmentum (Supplement to Ptolemy’s Descriptions) published in an English-language edition in Louvain in 1598: “The terra Australis is therefore the southernmost of all other lands, directly beneath the Antarctic circle; extending beyond the tropic of Capricorn to the West, it ends almost at the equator itself, and separated by a narrow strait lies on the East opposite to New Guinea, only known so far by a few shores because after one voyage and another that route has been given up and unless sailors are forced and driven by stress of winds it is seldom visited. The terra Australis begins at two or three degrees below the equator and it is said by some to be of such magnitude that if at any time it is fully discovered they think it will be the fifth part of the world.” Vague though this description might be, the passage possesses an intrinsic interest insofar as it mentions a narrow strait separating New Guinea from Terra Australis, eight years before Luis Vaez de Torres sailed through it, giving rise to further speculation regarding a prior discovery by the Portuguese.
Terra Australis continued to bewitch and bewilder cartographers until the latter half of the 18th century when men like Charles de Brosses and Alexander Dalrymple still urged its merits as a source of immense wealth, as a colony, and as a strategic base dominating the Indian and Pacific Ocean sea routes. For a time Abel Tasman’s discovery of New Zealand seemed to confirm Mercator’s northwest-tending Pacific shoreline but, eventually, the voyages of Louis-Antoine, Comte de Bougainville and James Cook crisscrossed the ocean, finding deep waters where Terra Australis was to be found. Eventually this rich and mythical continent shrank into the reality that was Australia, but the one bore virtually no relation to the other.