ppointed. But, even as I spoke,
I saw to my astonishment the boiling water in this reservoir sink and
disappear from view.

"Where has it gone?" I eagerly inquired.

"Stand back!" shouted the guide, "she's coming."

[Illustration: "A CLOUD-BURST OF JEWELS."]

I ran back a few steps, then turned and caught my breath; for at that
very instant, up from the pool which I had just beheld so beautiful
and tranquil, there rose in one great outburst of sublimity such a
stupendous mass of water as I had never imagined possible in a
vertical form. I knew that it was boiling, and that a deluge of those
scalding drops would probably mean death, but I was powerless to
move. Amazement and delight enchained me spellbound. Talk of a
fountain! This was a cloud-burst of the rarest jewels which, till
that moment, had been held in solution in a subterranean cavern, but
which had suddenly crystallized into a million radiant forms on thus
emerging into light and air. The sun was shining through the
glittering mass; and myriads of diamonds, moonstones, pearls, and
opals mingled in splendid rivalry two hundred feet above our heads.

[Illustration: THE OBLONG GEYSER.]

We soon approached another of the many geysers in the basin. They are
all different. Around one, a number of colored blocks, exquisitely
decorated by the geyser's waves, appeared to have been placed
artistically in an oblong frame. When I first beheld them, they
looked like huge sea-monsters which, startled by our footsteps, were
about to plunge into the depths.

What is there in the natural world so fascinating and mysterious as a
geyser? What, for example, is the depth of its intensely-colored pool
of boiling water? No one can tell. One thing, however, is certain;
the surface of the pool is but the summit of a liquid column. Its
base is in a subterranean reservoir. Into that reservoir there flows
a volume of cold water, furnished by the rain or snow, or by
infiltration from some lake, or river. Meantime, the walls of the
deep reservoir are heated by volcanic fire. Accordingly the water, in
contact with these walls, soon begins to boil, and a great mass of
steam collects above it. There must, of course, be some escape for
this, and, finally, it makes its exit, hurling the boiling water to a
height of one or two hundred feet, according to the force of the
explosion. Imagine, then, the amount of water that even one such
reservoir contains; for some of these volcanic founta