_Prismatic Lake_ is the most perfect spring of its kind in the world. It rests on the summit of a self-built mound, sloping very gently in all directions. Down this slope the overflow from the spring descends in tiny rivulets, every-where interlaced with each other. A map of the mound resembles a spider web, with the spider (the spring) in the center. The pool is 250 by 300 feet in size. Over the lake hangs an ever-present cloud of steam, which itself often bears a crimson tinge, reflected from the waters below. The steam unfortunately obscures the surface of the lake, and one involuntarily wishes for a row-boat, in which to explore its unseen portions. Wherever visible, there is a varied and wonderful play of colors, which fully justifies the name. _Turquoise Spring_ is another large pool, 100 feet in diameter, and rivals Prismatic Lake in the beauty of its coloring. The Midway Geyser Basin contains hundreds of other springs, some of them very beautiful, but the Basin is mainly noted for the three features just described. CHAPTER XVI. A TOUR OF THE PARK. _Lower Geyser Basin to Upper Geyser Basin._ Distance, nine miles. Road follows the Firehole River. Midway Geyser Basin, already described, is passed four miles out. No other object of interest is met until the visitor actually arrives at the _Upper Basin_. This locality is probably the most popular with the tourist of any in the Park. Its two rivals, the Grand Cañon and the Yellowstone Lake, are so unlike it as not to admit of any comparison. It is the home of the genus _geyser_, as seen in its highest development. There are fifteen examples of the first magnitude and scores of less important ones.[BC] The quiescent pools and springs are also numerous and of great beauty. [BC] For list of names of geysers, with heights of eruptions, see Appendix A, VII. The first important feature _en route_ is the _Biscuit Basin_, which is reached by a side road leading to the west bank of the Firehole River. It contains a fine geyser and several beautiful springs. The most interesting are the _Jewell Geyser_ and the _Sapphire Pool_. Near this locality is the _Mystic Falls_, a fine cascade, on the Little Firehole River. _Artemesia Geyser_ comes next to the attention of the tourist. It has been known as a geyser only since 1886. It is on the right of the roadway, at a considerably lower level. [Illustration: SKETCH MAP OF THE UPPER GEYSER BASIN _Opp. page 228._ ] The _Morning Glory_ is a little further up stream. In this beautiful object the quiescent pool is at its best. Its exquisite bordering and the deep cerulean hue of its transparent waters make it, and others like it, objects of ceaseless admiration.