An engineer graduated from West Point, Lieutenant George Wheeler wanted to find inland passage for troops from Idaho and Utah southward to Arizona. In 1871 he was commissioned with the fourth U.S. Survey to map the topography of that region in view of strategic transit and future settlement. To his original corps of scientists Wheeler added the son of a prominent Boston family, to publicize the expedition in the Eastern press, and Timothy O'Sullivan, to provide a visual record. As O'Sullivan's experience was unequaled in the field, it is not surprising that Wheeler placed great confidence in him from the outset, providing him with a roving commission and a boat of his own on the Colorado River. Although Wheeler's boats progressed slowly (they had to be rowed, sailed, and hauled upriver against the current), O'Sullivan's was tardier still. Exploring the astonishing photographic possiblities of the canyons from his boat, "Picture," he meandered, tacked, and stopped as he studied how to turn to advantage the sun and shade, the sheer cliffs, and their reflection in the water and profile against the sky. Individually, the Black Canyon photographs have exquisite resolution. In sequence, they constitute the pictorial voyage of a reflective, visionary artist who knew how to orchestrate his experience of place. As one turns the pages of the album the shifting perspectives of river and cliff move in stately progression as, effectively as a diorama, they carry the viewer deep into the very heart of the canyon, where, Wheeler wrote, "a stillness like death creates impressions of awe." This photograph appears in an album of fifty photographs, of which thirty-five are by O'Sullivan and fifteen by William Bell, entitled "Photographs Showing Landscapes, Geological and other Features, of Portions of the Western Territory of the United States. . . Seasons of 1871, 1872, and 1873."