Did the Portuguese

             The maps themselves have been highly debated as to their authenticity and origin. It has been argued that during the first half of the 19th Century, "say from 1786 - 1859" the Dieppe Maps were known in England and France, and that.
             "In those countries, in those years, they were openly accepted by the greatest geographers of the day as undoubted evidence of a Portuguese discovery of Australia.".
             However, from 1850 onwards, acceptance of this stance began to wane in England. McIntyre argues that it was "never really accepted in Australia" at all, giving the explanation that.
             "there were underlying reasons for this - national prejudices, personal jealousies, official ignorance.".
             As for the Dauphin Map's authenticity, in exactly how probable it is that this Portuguese map of the 16th Century portrays the real shape of Australia has itself been highly debated. It has been suggested that once cartographical errors of the sixteenth century are accounted for and corrected, it becomes possible to redraw the Dauphin Map and it is then that it can be seen to "significantly resemble the real shape of Australia." McIntyre explains that.
             "they had no instrumental means of establishing longitude. As a result the east-west distances on all 16th Century maps are miscalculated, usually exaggerated.With proper understanding of the projections, these apparent distortions can be explained, so that they are no longer distortions at all.".
             The Portuguese discovered the offshore islands of Timor and Solor in 1516, however the official sighting of the mainland was much later. It can be argued that though this is true, "certain maps disclose a knowledge of the mainland that was never publicly admitted.".
             Assuming that the Portuguese did discover Australia in the 1520's, there is much debate as to why the discovery was shrouded in secrecy. Collinridge notes that.
             "you must remember that in those days, maps were power. A great deal of secrecy surrounded hem - cartographic crime was huge in Portugal, the penalty was death for anyone caught leaking details - so that is why those maps were never disclosed at the time.