Once more our amateur explorers had recourse to their western vocabulary, and bestowed on this unhappy locality the title, "Hell-broth Springs"--which, says the historian of the expedition, "fully expressed our appreciation of their character." The following season this remarkable group of springs was thoroughly examined by the party under Dr. Hayden. That careful observer says: "They are evidently diminishing in power, but the rims all around reveal the most powerful manifestations far back in the past. Sulphur, copper, alum, and soda cover the surface. There is also precipitated around the borders of some of the mud springs a white efflorescence, probably nitrate of potash. These springs are located on the side of the mountain, nearly 1,000 feet above the margin of the cañon, but extend along into the level portions below.... One of these springs was bubbling quite briskly, but had a temperature of only 100°. Near it is a turbid spring of 170°. In the valley are a large number of turbid, mud, and boiling springs, with temperatures from 175° to 185°. There are a number of springs that issue from the side of the mountain, and the waters, gathering into one channel, flow into the Yellowstone, The number of frying or simmering springs is great. The ground in many places, for several yards in every direction, is perforated like a sieve, and the water bubbles by with a simmering noise. There is one huge boiling spring which deposits fine black mud all around the sides. The depth of the crater of this spring, its dark, gloomy appearance, and the tremendous force which it manifested in its operations, led us to name it the "Devil's Caldron." There are a large number of springs here, but no true geysers. It is plainly the last stages of what was once a most remarkable group. Extending across the cañon on the opposite side of the Yellowstone, interrupted here and there, this group of springs extends for several miles, forming one of the largest deposits of silica, but only here and there are there signs of life. Many of the dead springs are mere basins, with a thick deposit of iron on the sides, lining the channel of the water that flows from them. These vary in temperature from 98° to 120°. The highest temperature was 192°. The steam-vents are very numerous, and the chimneys are lined with sulphur. Where the crust can be removed, we find the under side lined with the most delicate crystals of sulphur, which disappear like frost-work at the touch. Still there is a considerable amount of solid amorphous sulphur. The sulphur and the iron, with the vegetable matter which is always very abundant about the springs, give, through the almost infinite variety of shades, a most pleasing and striking picture. One of the mud springs, with a basin twenty by twenty-five feet, and six feet deep, is covered with large bubbles or puffs constantly bursting with a thud. There are a number of high hills in