Dauphin or Harleian world map, c.1547.

Dauphin or Harleian world map, c.1547.

Produced in the northern French port of Dieppe, the Harleian or Dauphin map was prepared during the reign of Francois I of France (1515-1547) for his son, the Dauphin. Along with the Rotz atlas, presented to Henry VIII and also exhibited in Mapping Our World, it was one of several maps that have fuelled speculation about a continent resembling Australia, apparently charted by the Portuguese in the early 1500s and recorded by the map-makers of Dieppe. The Harleian map's most outstanding feature, a huge landmass south of Indonesia, is named ''Iave (Jave) la Grande''.

The map enticingly depicts a new world that awaited maritime enterprise at a moment when Normandy had become the European centre of trade with Brazil and the East Indies. The Norman ports developed a flourishing trade in brazilwood to supply the cloth-dyers of Rouen, and Norman seafarers under Jean Parmentier had ventured as far as Sumatra. Beyond it to the south-east, Java had for centuries enjoyed the reputation of being the largest and most magnificent island in the world, but the geography of the region was not well understood by Europeans until Portuguese voyages there.

Further south of Java, Marco Polo had thought, was ''an extensive and rich province that forms a part of the mainland''. And Ludovico di Varthema had brought home stories of people who navigated by the Southern Cross, who lived in lands so far south that the day did not last more than four hours and where it was colder than in any other part of the world. To the Norman cartographers who were aware that the Portuguese had actually visited Java, it may have appeared that Polo and Varthema had spoken of a continent south of Java, the greatest island in the world.

The rediscovery of Jave la Grande on the Harleian and other Dieppe maps may be attributed to the hydrographer Alexander Dalrymple. In 1786, after examining the Harleian map in the manuscript collection of Edward Harley, second earl of Oxford, Dalrymple noted: ''The East Coast of New Holland as we name it, is expressed with some curious circumstances of correspondence to Captain Cook's MS.'' Dalrymple drew the conclusion that Cook had apparently not been the first to chart the east coast of Australia. Dr Daniel Solander, the botanist on Cook's first voyage and keeper of the Natural History Department of the British Museum, lent the map to Dalrymple, who saw an opportunity to challenge Cook's priority of discovery of the east coast of Australia. The London newspaper The Argus of February 4, 1790, said that the map ''lays down the coasts of New Holland as described by Cooke and Bougainville'' and ''most probably it has been translated from the work of some Spanish Navigator, whose discovery being forgotten, left room for the new discoveries of the English and French navigators''.

What exactly is depicted on the Harleian map remains contested. There have been attempts since to match the coastal features and place name inscriptions on its east and west coasts with already discovered lands such as western Java and Sumatra or Java's south coast, Vietnam and Papua New Guinea, and Australia. But it must be remembered that in the absence of reliable reports of actual discovery by navigators, 16th-century cartographers trying to locate remote lands on their maps often did so in accordance with existing theories and were reluctant to erase the mapping of their predecessors without good reason. Some, driven by ''a horror of the void'' depicted not only lands known, but also those remaining to be discovered.

Martin Woods is Curator of Maps at the National Library of Australia. Mapping Our World: Terra Incognita to Australia runs until March 10, 2014. Entry is free but bookings essential at nla.gov.au. For a map-by-map guide to the exhibition go to canberratimes.com.au/exhibitions.