Dieppe Maps - The Dieppe School of Mapmaking

The Dieppe School of Mapmaking

Because many of the inscriptions on the Dieppe maps are written in French, Portuguese or Gallicised Portuguese, it has often been assumed that the Dieppe school of mapmakers were working from Portuguese sources that no longer exist. It has been assumed that Portuguese cartographers were bribed for information of the latest discoveries, despite the official Portuguese Politica de sigilo (policy of silence). The Cantino map of 1502 (not a Dieppe school map) shows evidence of second hand Portuguese sources, and this has been taken by some as supporting evidence for this assumption.

A common feature of most of the Dieppe world maps (see Vallard 1547, Desceliers 1550) are the compass roses and navigational rhumb lines, suggestive of a sea-chart. However, they are best understood as works of art, clearly intended to be spread out on a table, and containing information on the latest discoveries, side by side with mythological references and illustrations. For example, the Desceliers 1550 map carries descriptions of early French attempts to colonise Canada, the conquests of Peru by the Spanish and the Portuguese sea-trade among the Spice Islands. On the same map can be found descriptions of legendary Cathay, king Prester John in Ethiopia, and the race of Amazons in Russia. Other Dieppe maps also carry fictitious features such as the Marco Polo inspired Zanzibar/Îles des Geanz. (see Vallard 1547, Rotz 1542 and Dauphin c1536-42). As with other maps made before the 17th century, the Dieppe maps show no knowledge of longitude. While latitude could be marked in degrees as observed by astrolabe or quadrant, easting could only be given in distance. Mercator's projection first appeared in 1568-9, a development too late to influence the Dieppe cartographers.

Most of the Dieppe maps depict a large land mass entitled Jave la Grande, between what is now Indonesia and Antarctica. In the English-speaking world particularly, academic and popular interest in the Dieppe maps over the last 150 years has focused largely on this feature of the maps. This is because Jave la Grande is thought by some writers to provide clues of a possible Portuguese exploration of Australia's coasts in the 1520s. However, the most recent academic writings on the Dieppe maps by Carile(1997), Brunelle (2007) and King (2009) have suggested the maps need to be considered in their entirety, and consideration needs to be given to what they reveal about various influences on the mapmakers, as well as French aspirations. This group of writers argue that the maps are not necessarily literal records of voyages of exploration.