A rare and curious “planisphere”

S[amuel] Dunn & W[illiam] Owen, THE EARTH'S WESTERN PLANISPHERE, London, December 1st, 1757 / 1759.
Engraving on wove paper, approx. 22 ¼"h x 22 ½"w at sheet edge, outline color
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A rare and curious map of the Western Hemisphere, originally accompanying a geographical primer by Samuel Dunn.

This complicated image depicts the Western Hemisphere on what Dunn called a “stereographic” projection. He intended this to mimic the visual and mathematical properties of globes, and their utility as teaching tools, without the expense. The map features a fairly basic presentation of North and South America, with the Northwest more or less following Buache and Joseph de L’Isle (more on which below). Superimposed on the whole are a coordinate grid, lines of magnetic variation, and numerous geographical and astronomical notes, making in all for a very busy engraving.

The map first appeared, along with a companion map of the Eastern Hemisphere and maps of the celestial hemispheres, in a small geographical pamphlet published by Dunn in 1757 (The OCLC entry leaves the title unclear, and this writer has been unable to inspect an example of this very rare item.) The pamphlet was expanded and reissued in 1759-again, with the maps-as The Description, and Use, of the Universal Planispheres. In both works the maps were accompanied by a tissue overlay described by Dunn as “a transparent Slider, Index, or Projector, capable of forming instantaneously, of Arches circular, all Kinds of spherical Triangles, such as are usually drawn by Scale and Compasses, in the Science of spherical Geometry.”

Our example of the map retains the Dec. 1, 1757 imprint, but the title has been re-engraved in a more ornate manner, indicating it is from the 1759 second edition of the pamphlet.

The map is also unusual for its treatment of the Pacific Northwest, which largely follows that on de L’Isle and Buache’s 1752 Carte des Nouvelles Decouvertes au Nord de la Mer du Sud. Whereas de L’Isle and Buache depicted a vast “Mer de L’Ouest,” however, Dunn shows only a large opening in the coast north of California with the note “A large Bay within these streights as reported by the natives.” It is possible that Dunn may have been puzzled by the varied depictions of said “Bay” on the maps in de L’Isle’s 1753 Nouvelles cartes des decouvertes de l`Amiral de Fonte and simply elected to hedge his bets.

While Dunn’s 1759 pamphlet is held by a number of institutions, the maps are extremely rare on the market, with Antique Map Price Record listing no examples of any of the Planisphere’s offered for sale in more than a quarter century.


References
OCLC #48747054 (this sheet only, but with the overlay, held in the NYPL Slaughter Collection). OCLC #7690265 records the 1757 pamphlet at Oxford only, though another may reside at the Yale Map Collection (Sterling Library). Not in McGuirk, 1st ed. Thanks to Don McGuirk for the interpretation of Dunn’s treatment of the Bay of the West.

Condition

Minor soiling, creasing and chipping at edges, but about excellent for such a fragile item