"Come, lads," cried Panton at last, "we must be getting on. You see now
how it is there is so much clear water trickling down below. What a
magnificent reservoir!"

"It seems almost too beautiful," sighed Oliver, rising unwillingly.
"Who could expect a place like this with a burning mountain only a few
miles to the north?"

"And think," added Panton, "that this is the crater of an old volcano
that once belched out these stones and poured fire and fluid lava down
the slope we have just climbed."

"It almost seems impossible," said Drew. "The place is so luxuriantly
fertile. Are you sure you are right?"

"Sure," said Panton, "as that we stand here. Look for yourselves at the
perfectly formed crater filled with water now as it was once filled with
seething molten matter. Look yonder, straight across there where the
wall is broken down as it was perhaps thousands of years ago by the
weight of the boiling rock which flowed out. Look, you can see for
yourselves, even at this distance, the head of the river of stone. Chip
any of these blocks, and you have lava and tufa. That block you sat on
is a weather-worn mass of silvery pumice inside, I'm sure, though
outside it is all black and crumbling where it is not covered with
moss."

"But for such luxuriance of growth here all must have been barren
stone."

"Barren till it disintegrated in the course of time, and, by the action
of the sun, rain, and air, became transformed into the most fertile of
soil. Why, Lane, you ought to know these things. Look there, how every
root is at work breaking up the rock to which it clings, and in whose
crevices the plants and trees take root, grow to maturity, die, and add
their decaying matter to the soil, which is ever growing deeper and more
rich."

"Hear, hear," growled Wriggs in a low tone, and Panton frowned, but
smiled directly after as he saw the sailor's intent looks.

"Well, do you understand, Wriggs?" he cried.

"Not quite exactly, sir," said the man. "Some on it, sir; and it makes
me and my mate feel that it's grand like to know as much as you gents
do."

"Ay, ay," cried Smith, taking off his hat and waving it about as he
spoke. "Billy Wriggs is right, sir. It is grand to find you gents with
all your bags o' tricks ready for everything: Mr Drew with his piles o'
blottin'-paper to suck all the joost outer the leaves and flowers, and
Mr Lane here, with his stuff as keeps the skins looking as good as if
they