Diderot's famous 2 on 1 map showing the two early mappings of the west coast of North America, the first after Vischer, the second after Plantius' World map. Both show the Straits of Anian, Quivera, Baja and a similarly projected east-west coastline. The larger map inlcudes more detail along the coastline and in the Sierra Nevada Mountains, as well as a truer orientation of Baja California. Diderot's map were one of the first surveys of comparative cartography, tackling a number of the early misconceptions of the west coast of North America and the Northeastern Asian Coastline. The form an excellent baseline for collections of this region, as the maps they illustrate are generally extremely expensive or impossibly rare.
Didier Robert de Vaugondy (ca. 1723-1786) was the son of prominent geographer Gilles Robert de Vaugondy and Didier carried on his father’s impressive work. Together, they published their best-known work, the Atlas Universel (1757). The atlas took fifteen years to create and was released in a folio and ¾ folio edition; both are rare and highly sought-after today. Together and individually, father and son were known for their exactitude and depth of research.
Like his father, Didier served as geographer to King Louis XV. He was especially recognized for his skills in globe making; for example, a pair of his globes made for the Marquise de Pompadour are today in the collection of the Municipal Museum of Chartres. Didier was also the geographer to the Duke of Lorraine. In 1773, he was appointed royal censor in charge of monitoring the information published in geography texts, navigational tracts, and travel accounts.