We had a skilful driver, who called out the names of the places in a clear voice. This kept the passengers from being under a strain of uncertainty and tense listening. OBSIDIAN CLIFF, formed as the result of volcanic action in ages past, is twelve miles south of Mammoth Hot Springs. It rises two hundred fifty feet above the road and is composed of jet-black, volcanic glass, usually opaque, streaked with red, yellow, and green. When the roadway was constructed, great fires were built around blocks of this glass, which, when heated, were cooled by dashing water upon them resulting in their being shattered into fragments. This is said to be the only stretch of glass road in existence. The cliff was "neutral ground" to the different tribes of Indians. Chips of obsidian and partly finished obsidian arrow-heads are found throughout the Park, usually at places where the Indians had their camps. When the cliff is illuminated by the rays of the sun, it has the appearance of a glistening mirror, and is of much interest to the tourists. Four and one-half miles from Norris is ROARING MOUNTAIN with steam escaping through countless apertures from its rugged side. The sound of the steam struggling to escape is not so audible now as in the past, but the whole picture reminds one of the inferno about ready to blow off its cap. [Illustration: OBSIDIAN CLIFF © _Haynes, St. Paul_] In close proximity to the mountain are greenish, milky pools fed by rivers of sulphur water from the springs. It was not our privilege to tarry here, from the fact that the weather was uncomfortably cold, but the mountain stands out before me as one of the most interesting places to be seen on the tour. The wind was blowing fiercely when we came to TWIN LAKES, four miles from Norris Geyser Basin, but I removed my heavy veil in order to get a better glimpse of them. They are beautiful, and although in such close proximity, their hues are entirely different. How often two objects are found so closely allied to each other as to be inseparable, each one depending upon the other for its existence! This cannot be a freak of nature or the result of chance. The only sensible conclusion is that it was so designed by the Creator to teach a most important spiritual lesson,--that of the two works of grace, which constitute the panoply of the soul. There is no way to discard either without serious results. There is something about clear, pure water, whether it is seen in the placid lake or the gushing, mountain torrent, that inspires and lifts a person above the toils and cares of this life, where he is able to breathe a pure and holy atmosphere. Hence we see why, as shown in the Scriptures, Jesus so often used water to illustrate the plan of salvation. Water is the symbol of life, and in the boiling springs, the pools, the lakes, the chasms, and the great, spouting geysers, a book is written in the Yellowstone that every one should learn to read.