Dieppe maps

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First map of Australia: from Nicholas Vallard's atlas, 1547. This map is one of the Dieppe Maps. Copy held by the National Library of Australia.

The Dieppe maps are a set of maps produced in Dieppe, France in the 16th century, thought to provide clues towards the Portuguese exploration of Australia's east coast two hundred years before Captain Cook and even earlier than the first confirmed sighting of Australia by Jansz in his 1606 expedition along the eastern coast of the Gulf of Carpentaria. The maps show part of what might be Queensland, and name the land mass "Java a Grande".

The first historian to put these maps forward as evidence of Portuguese discoveries was George Collingridge, who published The Discovery of Australia in 1895, claiming (unpopularly) that Australia was discovered by other nations than the British long before Cook's 1770 voyage.

Kenneth Gordon McIntyre has described in detail the method by which he believes the Dieppe maps were produced from sailors' charts of the Australian coast.^[1] He believes that despite the secretive nature of the Portuguese naval administration, information was leaked to the mapmaking school at Dieppe, who incorporated this information in their maps between 1536 and 1550. He attributed discrepancies in the Dieppe maps to the difficulties of accurately recording positions without a reliable method of determining longitude, and the techniques used to convert maps to different projections.

In March 2007, Australian science journalist Peter Trickett stated that he believed a simple error had been made by cartographers working on the Vallard Atlas of 1547, and that if part of one map (see image above right) was rotated 90 degrees, it became an accurate map of the eastern and southern Australian coasts, as far west as Kangaroo Island. The map is in Portuguese, which Trickett suggests is evidence that it was based on Cristóvão de Mendonça's explorations in 1522.^[2]

[edit] Notes

^ McIntyre, Gordon (1982). Secret Discovery of Australia: Portuguese Ventures 200 Years Before Captain Cook. Sydney: Pan Books Australia, 236. ISBN 0330270338.
^ [http://www.smh.com.au/news/national/rotated-map-puts-a-twist-in-the-foundation-tale/2007/03/18/1174152882328.html Steve Meacham, "Rotated map puts a twist in the foundation tale", (Sydney Morning Herald, March 19, 2007) Access date: March 21, 2007.