ins play for
more than half an hour before their contents are discharged! Think,
also, that in this basin there are no less than thirty geysers,
seventeen of which have been observed in action simultaneously.

[Illustration: THE GIANT GEYSER.]

[Illustration: THE CASTLE GEYSER.]

Thus far we had seen merely geysers which arise from pools; but,
presently, we approached one which in the course of ages has built up
for itself a cone, or funnel, for its scalding waves.

"That," said our guide, "is the Castle Geyser."

"That rock a geyser!" I exclaimed incredulously, "it looks like an
old ruin, without a single indication of activity; save, possibly,
the little cloud of steam that hangs above it, as if it were the
breath of some mysterious monster sleeping far below."

"If you doubt it," he replied, "go nearer and examine it."

[Illustration: ON "ITS FLINTY SIDES."]

We did so. I scrambled up its flinty sides, and found an opening in
the summit three feet wide. I touched the rock. It was still warm,
and yet no water was discernible. No sound was audible within its
depths.

[Illustration: THE CASTLE GEYSER'S CONE.]

"If this be really a geyser," I remarked, "it is no doubt a lifeless
one like Liberty Cap."

My comrade smiled, looked at his watch, then at his notebook, and
finally replied: "Wait half an hour and see."

Accordingly, we lingered on the massive ledges of the Castle Geyser,
and learned that it is the largest, probably the oldest, of all the
active geyser cones within the Park. Once its eruptions were no doubt
stupendous; but now its power is waning. The gradual closing up of
its huge throat, and the increasing substitution of steam for water,
prove that the monster has now entered on the final stage of its
career; for here, as on the terraces, we are surrounded by specimens
of life, decay, and death. The young, the middle-aged, the old, the
dead,--they are all here!

The fiery agitation of the pool and the impulsive spurts of water are
indicative of youth. A steady, splendid outburst proves maturity. The
feebler action of the Castle shows the waning powers of old age. Last
of all comes the closed cone, like a sealed sarcophagus, and that is
death.

[Illustration: THE CASTLE AND THE BEEHIVE IN ACTION.]

Meantime, the thirty minutes of expectancy had passed; and, suddenly,
with a tremendous rush of steam, the Castle proved that its resources
were by no means exhausted. At the same instant, half a