The most important of them occurred in August and September, 1863. It was led by Walter W. DeLacy, an engineer and surveyor of some distinction in the early history of Montana. The party at one time numbered forty-two men, although this number did not continue constant throughout the expedition. Its sole object was to "prospect" the country. Evidently nothing in the line of topographical reconnaissance was thought of, for Captain DeLacy says "there was not a telescope, and hardly a watch, in the whole party." The expedition left Virginia City, August 3d; passed south into Idaho until it struck the Snake River, and then ascended that stream to the region about Jackson Lake. Near the mouth of Buffalo Fork a halt was made, a corral was built to hold the stock, and a miners' meeting held at which rules were adopted to govern the miners in the contemplated examination of the country. The party then broke up into small groups and set out in different directions so as to cover as much ground as possible. The last four days of August were spent in this search, but with failure in every direction. This discouragement led to the abandonment of the expedition. Fifteen men set out for home by the way they had come, while DeLacy and twenty-seven men resolved to reach the Madison River and the settlements by going north. A day later this party entered the territory which is now the Yellowstone Park. The route lay up the Snake River to its junction with Lewis River where the hot springs of that locality were discovered. Here another separation occurred. About half the party went back down the river to re-examine a locality where they thought they had found some fair prospects. They soon returned, however, unsuccessful. The main party under DeLacy ascended the hills to the west of the river to seek a more practicable route. They soon reached the summit of the plateau where they discovered what are now Hering and Beula lakes, and noted their divergent drainage. Thence they passed north over Pitchstone Plateau until they struck the valley of Moose Creek. They descended this stream for a few miles and came to a large lake, which they supposed to be tributary to either the Madison or the Yellowstone Rivers. To their great surprise they found, upon rounding its southern point, that it drained _south_ into the Snake. This is what is now called Shoshone Lake.