"Perpetual masses here intone, Uncounted censers swing, A psalm on every breeze is blown; The echoing peaks from throne to throne Greet the indwelling King; The Lord, the Lord is everywhere, And seraph-tongued are earth and air." THE YELLOWSTONE PARK GEYSERS THEIR ESSENTIAL FACTS AND CAUSES I have been to school. Dame Nature is a most kind and skillful teacher. She first put me into the ABC class, and advanced me through conic sections. The first thing in the geyser line she showed me was a mound of rock, large as a small cock of hay, with a projection on top large as a shallow pint bowl turned upside down. In the center of this was a half-inch hole, and from it every two seconds, with a musical chuckle of steam, a handful of diamond drops of water was ejected to a height of from two to five feet. I sat down with it half an hour, compelled to continuous laughter by its own musical cachinnations. There were all the essentials of a geyser. There was a mound, not always existent, built up by deposits from the water supersaturated with mineral. It might be three feet high; it might be thirty. There was the jet of water ejected by subterranean forces. It might be half an inch in diameter; it might be three hundred feet, as in the case of the Excelsior geyser. It might rise six inches; it might rise two hundred and fifty feet. There was the interval between the jets. It might be two seconds; it might be weeks or years. [Illustration: Formation of the Grotto Geyser.] A subsequent lesson in my Progressive Geyser Reader was the "Economic." Here was a round basin ten feet in diameter, very shallow, with a hole in the middle about one foot across. The water was perfectly calm. But every six minutes a sudden spurt of water and steam would rise about thirty feet, for thirty seconds, and then settle economically, without waste of water, into the pool, sinking with pulsations as on an elastic cushion a foot below the bottom of the pool. One could stride the opening like a colossus for five and one half minutes without fear. He might be using the calm depth for a mirror. But stay a moment too long and he is scalded to death by the sudden outburst. The next lesson required more patience and gave more abundant reward. I found a great raised platform on which stood a castellated rock, more than twenty feet square, that had been built up particle by particle into a perfect solid by deposits from the fiery flood. In the center was a brilliant orange-colored throat that went down into the bowels of the earth. That was not the geyser--it was only the trump through which the archangel was to blow. I had heard the preliminary tuning of the instrument.