Decorative wall map of America, showing a massive Bay of the West, published by Desnos in Paris.
Desnos' wall map of America was one of a small group of decorative wall maps of America published in France in the second half of the 18th Century, which were intended to be both objects of beauty and cartographic importance. The fashion of decorating private aristocratic libraries, salons and places of business with wall maps became fashionable in the 17th Century and flourished with the masterpieces published by the great mapmakers of Amsterdam, Paris and Rome in the 17th and 18th Centuries. At the height of this design trend, artists such as Johannes Vermeer frequently depicted such wall maps in important paintings of the period, depicting the home lives of Europe's elite and learned classes.
Desno's map is surrounded by allegorical scenes depicting the early discovery and history of America, along with scenes or early commerce, trade and subjugation of the ingenous peoples. In the Atlantic and Pacific Oceans, the routes of major explorers and circumnavigators are shown, with an array of early sailing ships.
Cartographically, the most notable feature of the map is the large depiction of the Sea of the West (also called the Bay of the West), one of the later remnants of the search for the northwest passage. The source of the modern myth of the Sea (or Bay) of the West are manuscript maps by Guillaume De L'Isle, the Royal Geographer to the King of France at the end of the 17th Century and beginning of the 18th Century. There is a map in Yale's map collection, which depicts a 16th century Thames school map of North America with a large "Branch of the South Sea", which closely resembles De L'Isle's Mer de L'Ouest and may well be the source of De L'isle's idea. There are De L'Isle manuscripts in the Bibliotheque Nationale as early as 1696 (dated), that depict this cartographic myth. Interestingly, De L'Isle never depicted this sea on any of his printed maps.
While De L'Isle never printed a map showing the Sea of the West, his rivals Nolin and Covens & Mortier each published such a map shortly after 1700, however, the myth languished until the 1740s, when French, Russian and English intererst and explorations in the region intensified. From 1750 until about 1780, most maps depicted some form of the Sea of the West.