Photography in the field was an arduous affair one hundred years ago. On the Yellowstone Expedition, Jackson had to pack by mule both his large, cumbersome cameras and his darkroom—for exposed negatives had to be developed immediately. Hayden was well aware of the artistic and practical worth of Jackson’s photographs. A series of Jackson photos served to illustrate his report on the Yellowstone Country which sparked the interest of government officials and the Public. The two men continued their association for many years, covering many expeditions. Perhaps the most fitting testimonial of Jackson’s contributions to the 1871 Yellowstone Expedition was offered by a former Director of the National Park Service, who said: “It was a singular stroke of fortune that the Hayden Expedition took with it to the Yellowstone land of miracles, the miracle of photography. The camera, in the hands of William H. Jackson, recorded for the first time the phenomena of the Yellowstone in a form that the most skeptical human eye could not dispute. These photographs helped as much as anything to convince Congress that the Yellowstone region should be set aside as a National Park.” [Illustration: Title page for “Photographs of the Yellowstone National Park, etc.” by W. H. Jackson.] PHOTOGRAPHS OF THE YELLOWSTONE NATIONAL PARK AND Views in Montana and Wyoming Territories. DEPARTMENT OF THE INTERIOR. United States Geological Survey of the Territories. F V Hayden, United States Geologist-in-charge W. H. JACKSON, PHOTOGRAPHER. Washington: Government Printing Office 1873. [Illustration: William H. Jackson and an assistant photographing in high places—Tetons.] [Illustration: Camp of U. S. Geological Survey, Ogden, Utah. The camp is located on one of the remarkable lake-terraces which form an interesting feature of the scenery on the Salt Lake Basin. The Wasatch Mountains, in the background, are about five thousand feet above the camp, and nine thousand five hundred and thirty feet above sea level.] [Illustration: Meeting of the U. S. Geological Survey in the Lower Firehole Basin. The two divisions of the Survey met at this locality on the same day, July 17, 1872, starting from this point several hundred miles distant from each other. The locality is near the source of the Madison River, and is within the limits of the National Park, Latitude 44° 34′6″: Longitude 110° 55′15″.]