Carte des Nouvelles découvertes au Nord de la Mer du Sud

Rare the map of the Northwest Passage by Joseph Nicolas De L'Isle.

In 1752 Philippe Buache reproduced the information gathered by his son-in-law Joseph-Nicolas Delisle, younger brother of Guillaume, during his 20 years of service as a cartographer to the Russian court. The map shows the Russian discoveries in 1723, 1732 and 1741, the traces of the first and second voyages of Bering, the voyages of De l'Isle de la Croyère with Captain Tchirikow (1741); and the voyage of Frondat in 1709 and the Galleon route in 1743. The west coast of the United States is entirely fantasized, the map represents an imaginary large inland sea to the northwest called the Mer or Baie de l'Ouest, Lake Valasco and the island of Bermuda. It also includes information about a northwest passage from the Pacific to the Atlantic, derived from the apocryphal voyages of Admirals Bartholomew de Fonte and Juan de Fuca.

According to legend, Bartholomew de Fonte, traveling north from the Pacific coast of South America in 1640, discovered a vast network of bays and rivers in the northwest region of North America. It is reported that while sailing inland, he encountered a ship that had traveled west from Boston. In 1592, Juan de Fuca claimed to have discovered a large inland sea in the same part of the American Northwest, indicating that it was connected to the North Sea by a strait. Both accounts were eventually dismissed as overly imaginative speculation.