Hot and cold springs, boiling springs, and quiet springs lie within a few feet of each other. They differ also in color, smell, and taste. Some are clear and transparent, others white, yellow, or red with ochre, and still others are of an inky blackness. Some are sulphurous and fetid in odor, and some are charged with alum and salt. The "Steampipe" is an orifice in the hillside, about 8 in. in diameter, from which a volume of steam rises with a continuous roar to a height varying from 50 to 200 ft. In a cavity called the "Witches' Caldron" amass of black fetid mud is ever bubbling with heat, the vapor from it depositing black flowers of sulphur on the rocks around. The surface of the ground about the springs, which is too hot to walk upon with thin shoes, is covered with the minerals deposited by the waters, among which are sulphur, sulphate of magnesia, sulphate of aluminum, and various salts of iron. These springs, none of which are properly geysers, are about 1,700 ft. above the sea.-The geysers at the head waters of the Yellowstone and Missouri rivers are probably the most wonderful on the globe, even those in Iceland and New Zealand sinking into insignificance when compared with them.

The country lying between lat. 43° and 47° N., and Ion. 110° and 114° W., comprising portions of the territories of Idaho, Wyoming, and Montana, is dotted with groups of hot springs, the remains of most remarkable volcanic manifestations, which began probably in the tertiary period. Earthquake shocks are still common throughout this region, and at some seasons of the year are very severe. The most of these springs are not geysers, but simply boiling mineral springs and mud volcanoes. The geysers proper are in the N. W. corner of Wyoming territory, on the Fire-Hole river, the middle fork of the Madison, which is one of the three principal sources of the Missouri. The basin in which they are situated was visited first by a party under Cook and Folsom in 1869. In 1870 Gen. Washburne, surveyor general of Montana, explored it with a party, among whom were Lieut. G. C. Doane and N. P. Langford; and in 1871 it was surveyed by Dr. F. V. Hay-den, United States geologist, and by Col. J. W. Barlow and Capt. D. P. Heap, of the United States engineer corps. Dr. R. W. Raymond, United States commissioner of mining statistics, also visited and described the region in the same year. The geysers lie in two large groups, in what are called the upper and lower geyser basins.

The lower basin, beginning near the junction of the East and Middle forks of the Madison, comprises an area of about 30 sq. m. The springs are divisible into three classes: 1, those which are constantly boiling; 2, those which are agitated only at particular periods; 3, those which are always tranquil. In the geysers proper the water is usually quiet until a short time before an eruption. Dr. Peale, who examined them in 1871, in connection with Prof. Hayden, divides the springs into seven principal groups. In the first group, at the N. end of the basin, the temperature of G7 springs, occupying a space of about a quarter of a mile wide by two miles long, was recorded. The lowest was 106° F., the highest 198°. The temperature of the air was 50°. Some of these are geysers, projecting the water from 2 to 5 ft., but most of them are simply silicious springs, a few being chalybeate. The second group, which lies 2 1/2 m. further S., nearer the centre of the basin, occupies an area of about three fourths of a mile. Sixteen springs here ranged in temperature from 140° to 196°. The temperature of the air was from 55° to 66°. This group is composed principally of geysers, many of them throwing water from 5 to 10 ft. high.

The principal one, on the slope of a hill, is about 20 ft. in diameter, with a rim 5 ft. wide and 5 ft. high. The column of water thrown from it is very wide, and reaches the height of 50 ft. Another is named the Thud geyser, from the dull suppressed sound given off as the water rises and recedes. It has a beautiful scalloped rim, with small basins around it. This group of geysers is said to resemble a factory village, the steam rising in jets from more than 100 orifices. The third group lies three fourths of a mile S. E. of the second, at the base of a spur of the mountains, and extending up a ravine about 1,000 yards. They cover a space 500 yards in width. The temperature of 20 springs ranged from 130° to 196°. Near the centre of the group is a small lake, 600 ft. long by 150 wide, on the E. shore of which is a geyser spouting to the height of from 15 to 20 ft. There are three sulphur springs here, the only ones in the region, and S. E. of the lake is an iron spring. About 1,000 yards further S. is the fourth, group, in a ravine about 1 1/2 m. long and 300 yards wide. It contains many springs and geysers, the temperature of 42 of which ranged from 112° to 198°, the temperature of the air being about 60°. The principal geyser is at the mouth of the ravine.

Its basin is circular and about 60 ft. in diameter, and its spring, in the centre, from 15 to 20 ft. The water is blue, and is constantly agitated. When in eruption the column is projected 100 ft. high, and is accompanied by immense clouds of steam. Near the upper end of the ravine is a spring around which the deposit is black, instead of the usual white. The fifth group, on the banks of the Fire-Hole river, is the largest of all, covering nearly a square mile and comprising a great number of springs and geysers. The temperature of 95 examined ranged from 112° to 196°, the air at the time being 70°. None of them are of much importance. One, from its resemblance to a shell, is named the Conch spring; its basin is triangular, from 8 to 10 ft. in diameter. A little below it, on the bank of the river, there is a fine geyser, with a crater 3 ft. high. The Horn geyser has a crater like a horn, about a foot in diameter at the top and 6 ft. at the base; it is in constant ebullition. The Bath spring has a square basin 30 ft. across, of unknown depth.