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This scarce map of the Southern Hemisphere, published circa 1753 by Leonhard von Euler, a renowned mathematician based in Berlin, offers intricate depictions of the Northern and Southern Hemispheres. Compiled by Johann Christoph Rhode, these maps are notable for their speculative geographic features, such as the sizable Sea of the West, along with the hypothesis of the existence of a large, hitherto unknown continent to the east of Australia.

In the mid-18th century, the European Enlightenment, with its emphasis on empirical observation and intellectual rigor, paved the way for significant advancements in cartography. Leonhard von Euler, a prominent figure in this movement, applied his mathematical expertise to the field, resulting in these maps. He included unverified geographic details, like the supposed discovery of the Straits of Juan de Fuca in 1592 and the claimed discoveries of Martin D'Augilar in 1603, reflecting the ongoing quest for exploration and discovery during the era.

The "Tabula Geographica Hemisphaerii Australis," depicting the Southern Hemisphere, presents an intriguingly speculative continent east of Australia. This hypothetical landmass combines elements of known New Zealand with conjectured coastlines farther east and north, along with initial inklings of what would later be recognized as Antarctica. The presence of this speculative continent represents the synthesis of observable data with scientific conjecture, marking an era of exploration and curiosity about the world's uncharted regions. 

The Sea of the West

Many European maps of North America in the eighteenth century depict a large, western inland sea, hundreds of miles in diameter, with a small inlet to the Pacific and even some interior islands. The origins of this myth can be traced to several different sources and are tied to the search for a Northwest Passage. Like many cartographic myths, the Sea of the West persisted for decades, even in the face of strong evidence pointing to its non-existence.

One of the first European navigators to supposedly explore this area was Martin Aguilar. A Spanish captain, he sailed with Sebastian Vizcaino on a reconnaissance expedition up the California coast in 1602-3. Aguilar, commanding the Tres Reyes, was blown off course, to the north. When the seas calmed, Aguilar reported that he had found the mouth of a large river. Eighteenth-century geographers later conjectured that the river was the entrance to the Sea of the West.

Other maps placed the entrance to the Sea of the West via the Juan de Fuca Strait. Juan de la Fuca is the Castilianized name of Greek navigator Ioánnis Fokás (Phokás). Little archival evidence survives of Fuca’s career, but a chance meeting with an English financier, Michael Lok, in Venice in 1596 gave birth to rumors of Fuca’s voyages in the Pacific. Fuca reported that he had been sent north from New Spain twice in 1592 in search of the Strait of Anian. The Spanish Crown failed to reward Fuca’s discovery of an opening in the coast at roughly 47° N latitude and Fuca left the Spanish service embittered. His story lived on in Lok’s letters and eventually was published in Samuel Purchas’ travel collection of 1625. On many eighteenth-century maps, Fuca’s Strait is linked with a River or Sea of the West. In 1787, the present-day Juan de Fuca Strait was named by the wife of naval explorer Charles William Barkley, making permanent a label that had previously just been hopeful guesswork.

The source of the modern (18th Century) myth of the Sea or Bay of the West (Baye ou Mer de L'Ouest in French), are manuscript maps by Guillaume De L'Isle, who served as the Royal Geographer to the King of France at the end of the 17th Century and beginning of the 18th Century and is widely regarded as the most important map maker of his time. 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.

At the end of the 17th Century, Guillaume De L'Isle had access to the best available maps of the interior of North America, which were being provided from a number of missionary sources, as the French Missionaries pushed west of the Great Lakes and the Mississippi River and obtained information from the indigenous Indian tribes. De L'Isle was regularly producing and updating his manuscript maps in an attempt to integrate new and often conflicting information and improve upon the existing maps of North America. Many of his maps can be viewed as drafts, which were discarded in favor of other and considerably different models.

There are several De L'Isle manuscripts in the Bibliotheque Nationale de France, prepared as early as 1696 (dated), that depict this cartographic myth. Interestingly, while De L'Isle was a prolific publisher of printed maps, he never depicted the Sea or Bay of the West on any of his printed maps, which strongly suggests that he was not able to reconcile this information with the best available source information from America. During this same period, Jean Baptiste Nolin, who had in the prior decade collaborated with Vincenzo Maria Coronelli on his monumental globe for Louis XIV and produced a series of highly important maps of North America and its regions, would have also had access to many of the same reports and maps as De L'Isle. Nolin apparently gave greater credence to the concept than De L'Isle.

The earliest printed map to show the Bay of the West is Jean Baptiste Nolin's rare wall map of the world, published in about 1700.  Nolin plagiarized the idea from Guillaume De L'Isle, as he testified when suing Nolin for plagiarism. He said, the Sea of the West “was one of my discoveries. But since it is not always appropriate to publish what one knows or what one thinks one knows, I have not had this sea engraved on the works that I made public, not wanting foreigners to profit from this discovery” (as quoted in Pedley, The Commerce of Cartography, 109). The court sided with De L'Isle and issued an order requiring Nolin to destroy the copper plates for the map (see Shirley 605).  Nolin's map was in turn copied by the Mortier family, who issued 3 world maps shortly thereafter, showing Nolin's version of the Sea of the West, but the myth ignored for nearly half a century.

While the myth of the Sea or Bay of the West temporarily languished, the proliferation of Russian exploration off the Northwest Coast of America after 1740, as reported by Guillaume's younger brother Joseph Nicholas De L'Isle, reinvigorated interest in the region and forced the most prominent map makers of the period to re-examine existing knowledge. Joseph Nicolas served as a geographer to the Russian Academy and returned with this information to Paris.  The re-introduction of the sea in the mid-eighteenth century was the result of Guillaume De L’Isle’s son-in-law, Philippe Buache’s review of his father-in-law’s papers. Although Guilluame De L’Isle never published a printed map showing the sea, he had postulated that it could exist, and that it might connect to a Northwest Passage through New France, not through English territory farther north.

The sea was a major part of Buache and Joseph-Nicholas Delisle’s maps of the North Pacific, published in the 1750s. While controversial, the features of those maps were quickly copied by other mapmakers, including the Sea of the West. The inland body of water lingered on maps until the later-eighteenth century.

During a period between 1750 and 1770, the most prominent French and British map makers advanced multiple and widely varying theories on the Northwest Coast of America. Denis Diderot dedicates several of the 10 maps in his monumental Encylopedie (1779 and after), to a comprehensive survey of the maps proffered by Joseph Nicholas De L'Isle (Guillaume's brother), Philippe Buache, Thomas Jefferys and others. The debate ended with Captain James Cook's and later George Vancouver and Comte Jean de la Perouse's explorations in the late 18th Century.

Leonhard Euler Biography

Leonhard Euler, born on April 15, 1707, in Basel, Switzerland, stands as a towering figure in the history of mathematics and science. His prolific contributions span a wide range of fields including mathematics, physics, astronomy, and engineering. Recognized for his work in areas such as graph theory, topology, mechanics, fluid dynamics, and optics, Euler's influence is immeasurable, making him one of the greatest mathematicians of the 18th century and indeed, in history.

Euler's early life was steeped in academic and religious influence, with his father serving as a pastor and his mother coming from a line of scholars. His intellectual journey began under the guidance of his father and later, under the renowned mathematician Johann Bernoulli at the University of Basel. Despite his initial aspirations in theology, Euler's fascination with mathematics took precedence, leading to a lifelong dedication to the field.

His professional career was marked by significant periods in Saint Petersburg, Russia, and Berlin, Prussia. In Saint Petersburg, under the auspices of the Russian Academy of Sciences, Euler embarked on extensive scientific endeavors, contributing significantly to the academy's prestige. Despite political upheavals and personal challenges, including a near-fatal fever and deteriorating eyesight, Euler's productivity remained unparalleled. His tenure in Berlin, invited by Frederick the Great, was equally fruitful, yielding numerous works and fostering advancements in various disciplines, including map related projects.

Euler's contributions to mathematics are vast and diverse. He popularized and standardized many mathematical notations, such as the concept of a function and the symbols π, e (Euler's number), and i (the imaginary unit). His works in graph theory emerged from practical problems like the Seven Bridges of Königsberg, laying the foundation for this new field of mathematics. Euler also made groundbreaking contributions to the fields of number theory, calculus, and algebra, influencing countless areas of research and application.

In physics and engineering, Euler's insights transformed understanding and methodologies. His formulation of the Euler–Bernoulli beam equation marked a significant advancement in engineering, while his work in fluid dynamics and optics influenced subsequent theories and practices. Euler's contributions extended to astronomy, where his calculations improved celestial navigation and the understanding of cometary orbits.

Euler's personal life was characterized by his devout faith, simplicity, and resilience in the face of adversity. Despite suffering significant loss of eyesight, he continued his mathematical endeavors with the aid of assistants, demonstrating remarkable adaptability and perseverance. His return to Saint Petersburg in his later years saw continued scientific output until his death on September 18, 1783.

Euler's legacy is enduring, with his extensive body of work influencing countless fields and continuing to inspire future generations. His publications, which include more than 800 articles and numerous books, remain critical resources in mathematics and physics. Leonhard Euler's intellectual legacy is a testament to his unparalleled contribution to science and his enduring impact on the advancement of human knowledge.