Yellowstone has dozens of geysers of many kinds. They range in size from the little spring that spurts a few inches every minute to the monster that hurls hundreds of tons of water three hundred feet in air every six or eight weeks. Many spout at fairly regular intervals of minutes or hours or days. Others are notably irregular, and these include most of the largest. Old Faithful won its name and reputation by its regularity; it is the only one of the group of monsters which lives up to its time-table. Its period ranges from intervals of about fifty-five minutes in seasons following winters of heavy snow to eighty or eighty-five minutes in seasons following winters of light snow. Its eruptions are announced in the Old Faithful Inn a few minutes in advance of action and the population of the hotel walks out to see the spouting. At night a searchlight is thrown upon the gushing flood. After all, Old Faithful is the most satisfactory of geysers. Several are more imposing. Sometimes enthusiasts remain in the neighborhood for weeks waiting for the Giant to play and dare not venture far away for fear of missing the spectacle; while Old Faithful, which is quite as beautiful and nearly as large, performs hourly for the pleasure of thousands. Even the most hurried visitor to the Upper Basin is sure, between stages, of seeing several geysers in addition to one or more performances of Old Faithful. The greatest of known geysers ceased playing in 1888. I have found no authentic measurements or other stated records concerning the famous Excelsior. It hurled aloft an enormous volume of water, with a fury of action described as appalling. Posterity is fortunate in the existence of a striking photograph of this monster taken at the height of its play by F. Jay Haynes, then official photographer of the park. "The first photographs I made were in the fall of 1881," Mr. Haynes writes me. "The eruptions continued during the winter at increasing intervals from two hours, when the series began, to four hours when it ceased operations before the tourist season of 1882. Not having the modern photographic plates for instantaneous work in 1881, it was impossible to secure instantaneous views then, but in the spring of 1888, I made the view which you write about. It was taken at the fulness of its eruption. "The explosion was preceded by a rapid filling of the crater and a great overflow of water. The column was about fifty feet wide and came from the centre of the crater. Pieces of formation were torn loose and were thrown out during each eruption; large quantities eventually were removed from the crater, thus enlarging it to its present size."