The first earnest attempt to explore the valley of the upper Yellowstone was made in 1859, by Colonel Raynolds, of the Corps of Engineers. His expedition passed entirely around the Yellowstone basin, but could not penetrate it. Ten years after Colonel Raynolds’s unsuccessful attempt to solve the problem of the Yellowstone, a small party under Messrs. Cook and Folsom ascended the river to the lake, and crossed over the divide into the Geyser Basin of the Madison. The general public were indebted for their first knowledge of the marvels of this region to an expedition organized in the summer of 1870 by some of the officials and leading citizens of Montana. In the meantime, a large and thoroughly-organized scientific party, under Dr. F. V. Hayden, U. S. geologist, were making a systematic survey of the region traversed by Colonel Barlow. It is safe to say that no exploring expedition ever had a more interesting field of investigation, or ever studied so many grand, curious and wonderful aspects of nature in so short a time.