Hurrying down the Firehole, thinking the wonders of the Yellowstone country had been left behind, and anxious only to reach the settlements of the Madison Valley, the expedition of 1871 was startled and astonished to see at no great distance an immense volume of clear, sparkling water projected into the air to the height of one hundred and twenty-five feet. "Geysers! geysers!" exclaimed one of the company, and, spurring their jaded horses, they were soon gathered around an unexpected phenomenon--a perfect geyser. The aperture through which the column of water was projected was an irregular oval, three feet by seven in diameter. The margin of sinter was curiously piled up, the exterior crust filled with little hollows full of water, in which were globules of sediment, gathered around bits of wood and other nuclei This geyser stands on a mound, thirty feet above the level of the surrounding plain, its crater rising five or six feet higher. It spouted at regular intervals nine times during the explorers' stay, the columns of boiling water being thrown from ninety to one hundred and twenty-five feet at each discharge, which lasted from fifteen to twenty minutes. They gave it the name of "Old Faithful." "Near the crater, and as far as the irruptive waters reach," writes Lieutenant Doane, "the character of the deposit is very peculiar. Close around the opening are built up walls, eight feet in height, of spherical nodules, from six inches to three feet in diameter. These stony spheres, in turn, are covered with minute globules of stalagmite, incrusted with a thin glazing of silica. The rock, at a distance, appears the color of ashes of roses, but near at hand shows a metallic gray, with pink and yellow margins of the utmost delicacy. Being constantly wet, the colors are brilliant beyond description. Sloping gently from this rim of the crater in every direction the rocks are full of cavities in successive terraces, forming little pools, with margins of silica the color of silver, the cavities being of irregular shape, constantly full of hot water, and precipitating delicate, coral-like beads of a bright saffron. These cavities are also fringed with rock around the edges, in meshes as delicate as the finest lace. Diminutive yellow columns rise from their depths, capped with small tablets of rock, and resembling flowers growing in the water. Some of them are filled with oval pebbles of a brilliant white color, and others with a yellow frost-work which builds up gradually in solid stalagmites. Receding still farther from the crater, the cavities become gradually larger, and the water cooler, causing changes in the brilliant colorings, and also in the formations of the deposits. These become calcareous spar, of a white or slate color, and occasionally variegated. The water of the geyser is colorless, tasteless, and without odor. The deposits are apparently as delicate as the down on the butterfly's wing, both in texture and coloring, yet are firm and