Remarkable map of the Southern Hemisphere, most notable for its its depiction of Buache's conjectural Antarctic lands and interior sea and its depiction of New Zealand as a part of Terres Antarctiques.
This map was reflects Buache's attempts to reconcile known information with his conjecture and speculation on the unknown southern continent. The map includes information from Abel Tasman and other Dutch Voyages which touched on New Zealand and Australia. While a serious work in Hydrography and comparative cartography, Buache's work is one part speculative fantasy fantasy, incorporating the New Zealand coastline into one of two immense southern landmasses, which were separated by Mer Glaciale (the Glacial Sea).
In the interior of the imagined southern continent, Buache postualates a large Antarctic Sea, larger than that found in the northern polar regions. Buache further believed that a massive chains of mountains like those in America were present in the southern continent, with massive inland rivers.
The map reflects the report from the 1738-9 expedition of Bouvet de Lozier, which mentions the discovery of icebergs between two and three hundred feet high and half a league to two or three leagues in circumference. Buache made Cap de la Circoncision at 54° south, below Africa, a northern promontory of the smaller of his two land masses, next to one of the openings of his polar sea, where Bouvet had recorded his many great icebergs. Buache also shows the route of the voyage of Abel Tasman (1603-1659) in 1642-3 as a source for information about the southern lands. The other opening into the inland sea, to the southwest of South America, was placed where Sharpe and Davis had reported icebergs in 1687. Buache believed that the icebergs must have derived from a floating ice sheet, as in the Arctic, rather than from the newly discovered land. This led him to conclude that the southern continent was not a single landmass but two islands separated by a frozen inland sea, from which icebergs detached themselves to float northwards.
The sea shown in the center of Antarctica was based upon a hypothesis Buache had developed over a number of years. His paper ' Geographical and physical observations, including a theory of the Antarctic regions and the frozen sea which they are supposed to contain' was published by The Gentleman's Magazine in 1763. In it, he hypothesised that the southern pole must contain a frozen sea, fed by mountain ranges and huge rivers, in order to produce icebergs of the size reported by Bouvet; the large sea (Mer Glacial, 'Glacial Sea') depicted on the 1739 map is an early version of this hypothesis. On the map, this sea is described as a Bassin terrestre ('Land-locked basin'), connected to the Southern Ocean by two débouquements ('outlets'); he believed that Antarctica must possess rivers "as considerable as those of Siberia, which create the icebergs of the North". The map states that the sea is conjecturée.
There is also an extensive discusssion of Cap de la Circoncision, which would later become Bouvet Island. The island was discovered on January 1, 1739 by Jean-Baptiste Charles Bouvet de Lozier, commander of the French ships Aigle and Marie. This was the first time land had been spotted south of the 50th parallel south. Bouvet, who was searching for a presumed large southern continent, spotted the island through the fog and named the cape he saw Cap de la Circoncision. He was not able to land and did not circumnavigate his discovery, thus not clarifying if it was an island or part of a continent. but his plotting of its position was inaccurate forcing several expeditions to fail to find the island again.
Buache was an academic geographer who researched his material thoroughly, relying on the most up-to-date information from voyages of discovery. He was the first geographer to recognize the important concept of the watershed and it was this that led him to make a number of deductions, some correct, some not. A correct deduction was the existence of Alaska and the Bering Strait, years before they were officially discovered, while an incorrect deduction was the existence of a central Antarctic sea, which he conjectured to be the source of the icebergs observed by Bouvet in 1738-39.
There are those, including Hapgood, who see Buache's map as a tie in to the Piri Reiss map in the argument that these maps depict a subglacial land mass that is the Antaractic.
Philippe Buache (1700-1773) was one of the most famous French geographers of the eighteenth century. Buache was married to the daughter of the eminent Guillaume Delisle and worked with his father-in-law, carrying on the business after Guillaume died. Buache gained the title geographe du roi in 1729 and was elected to the Academie des Sciences in the same year. Buache was a pioneering theoretical geographer, especially as regards contour lines and watersheds. He is best known for his works such as Considérations géographiques et physiques sur les découvertes nouvelles dans la grande mer (Paris, 1754).