height for a minute or two, looking like a solid pillar of water.
Then the force which had ejected it seemed to be spent, and the huge
fountain descended slowly lower and lower, with several other
elevations, and finally descended below the surface with a hideous
rushing turmoil, and was gone.

They were about to advance and look down again, but there was a roar,
and the water rushed to the surface just high enough to fill the basin,
and for a portion to run gurgling over where the rim, which seemed to be
formed of a curious deposit, was broken away, and trickle down toward
the valley.

"I say, aren't it hot?" said Billy Widgeon, who had thrust in his hands
before the water ran back. "Why, you might cook in it. I say, bo'sun,
look ye here; why if it aren't just like the stuff as my old mother used
to scrape out of the tea-kettle at home."

Small stooped and broke off a scrap of the deposit, and examined it,
holding it out afterwards to Mark.

"Yes," said the major, who examined it in turn, after Mark had taken it
to him, "the man is quite right. It is a limy deposit from the boiling
water, similar to what is found in kettles and boilers. Shows that the
water is very hard, eh, captain?"

"Yes, I suppose that's it," replied Captain Strong. "But all this is
very interesting for travellers, and does not concern us. We've come to
find out our noisy friend, so let's get on. Some day, when we've
nothing to do, we may come here on a pleasure trip. To-day we must
work."

"Stop a few minutes longer, father," said Mark, as the men went to
another of the geysers a little lower down, one which had just thrown a
column of water up some forty feet, and then subsided--a column not a
third of the size of that which they had just seen.

"Very well," said the captain. "Want to see it spout again?"

"I should like to, once," said Mark; and then, moved by that energetic
spirit which is always inciting boys to do something, he ran to the
other side of the basin, where a good-sized piece of rock lay half
incrusted with the stony deposit of the hot spring. It weighed about
three-quarters of a hundredweight, but of so rounded a shape that it
could be easily moved, and Mark rolled it over and over into the basin
of the geyser while his father was pointing out something to the major
across the little valley, and just as the stone was close to the
rock-like opening the captain turned.

"I wouldn't do that, Mark," he said, as h