In its eruption this geyser is equally fascinating. It always gives ample warning, and visitors have time to station themselves where the view will be most perfect. The graceful column rises, at first with apparent effort, but later with evident ease, to a height of 150 feet. The noise is simply that of a jet of water from an ordinary hose, only in intensity corresponding to the greater flow. The steam, when carried laterally by a gentle breeze, unfurls itself like an enormous flag from its watery standard. The water is of crystal clearness and the myriad drops float in the air with all manner of brilliant effects. To quote Lieutenant Doane again: "Rainbows play around the tremendous fountain, the waters of which fall about the basin in showers of brilliants, and then rush steaming down the slopes to the river." The uniform periodicity of this geyser is its most wonderful and most useful characteristic. It never fails the tourist. With an average interval of sixty-five minutes, it varies but little either way. Night and day, winter and summer, seen or unseen, this "tremendous fountain" has been playing for untold ages. Only in thousands of years can its lifetime be reckoned; for the visible work it has wrought, and its present infinitely slow rate of progress, fairly appall the inquirer who seeks to learn its real age. It is worth while, however, to note the enormous work which this geyser daily performs. A conservative estimate, based upon an extended series of observations made in 1878 by the United States Geological Survey, shows that the outpour for an average eruption is not less 1,500,000 gallons, which gives 33,225,000 gallons per day. This would supply a city of 300,000 inhabitants. The combination of conditions by which the supply of heat and water, and the form of tube, are so perfectly adapted to their work, that even a chronometer is scarcely more regular in its action, is one of the miracles of nature. [Illustration: _Terry Engr. Co._ _U. S. Geological Survey of the Territories._ Kepler Cascade.] CHAPTER XVII. A TOUR OF THE PARK. _Upper Geyser Basin to the Yellowstone Lake._ Distance, nineteen miles. The route ascends the Firehole River to the mouth of Spring Creek, which stream it follows to the Continental Divide. For seven miles it then lies on the Pacific slope, after which it descends the mountains to the Yellowstone Lake. The drive is one of the most pleasant in the Park, and the scenery is unconventional and wild. _Kepler Cascade_ (1.25 miles) is a fascinating water-fall. Lieutenant Doane, who first wrote of it, says:[BH] "These pretty little falls, if located on an eastern stream, would be celebrated in history and song; here, amid objects so grand as to strain conception and stagger belief, they were passed without a halt." [BH] Page 27, "Yellowstone Expedition of 1870." See Appendix E. We counsel the tourist not to so pass them.