8vo (229 x 139 mm). Large map folding in pocket at rear (discrete repairs along folds verso); 4 lithographed maps (2 folding); 22 lithographed plates. Original brown blind-stamped cloth, gilt-lettered on spine (recased, light rubbing to covers). Provenance: George Clinton Swallow (1817-1899), Missouri's first state geology (bookplate); Intermountain Union College (embossed stamp on title-page); inked numerals in upper margin on title.

FIRST EDITION, the Senate issue, with the astronomical and meteorological observations omitted from the House issue and subsequent editions. The two reports, written with the help of Fremont's wife Jessie Benton, "caught the public imagination: images of Fremont's guide, the then little-known Christopher 'Kit' Carson, riding bareback across the prairie, and Fremont himself, raising a flag on a Rocky Mountain peak, entered the national mythology" (Pamela Herr, ANB). Graff 1436; Howes F-370; Sabin 25845; Streeter VI:3131; Wagner-Camp 115:1.