POWELL, John Wesley (1834-1902). Exploration of the Colorado River of the West and Its Tributaries? Washington: Government Printing Office, 1875. 4to. Frontispiece, numerous wood-engraved plates, 2 folding route maps loosely inserted at end. Original brown cloth, gilt-lettered spine (extremities worn, joints cracked, some separation along front joint, ffep starting). FIRST EDITION of Powell?s report which contains a description of the first documented trip down the Colorado River, which covered 1,000 miles in just three months. Graff 3336; Howes P-528. [With:] POWELL. Report on the Lands of the Arid Region of the United States, with a More Detailed Account of the Lands of Utah. Washington: Government Printing Office, 1879. 4to. 3 large folding maps in pocket at rear. Original brown cloth (rubbing at ends). Second edition.