ough the
groves at the broad blue sea, or wonderful landscapes up ravines, with
the mountain towering up behind.

The natural history objects they encountered were plentiful enough. In
fact very few steps were taken without something attracting attention.
Lizards which seemed as they basked on pieces of the heated rock to have
been cut out of glittering metal, till, at the jar of a footstep, or the
shadow of any one cast across them, they darted away. In one place the
doctor pointed out sinuous markings on the sandy ground which looked as
if freshly made.

"Yes, a snake," said Sir John, "and a good-sized one too."

"How large?" said Jack with suppressed excitement.

"Seven or eight feet long, I should say," replied his father.

Jack looked with an expression of mingled dread and longing at the patch
of dense growth into which the track led, and directly after Edward
exchanged glances with him, the man's look seeming to say--

"I've marked down that spot, sir."

Glen after glen was passed, every one full of beauty and interest, and
at last they were brought up short by what looked like some huge pier
running right across their way, down over the sands, and ending suddenly
about a hundred feet out in the beautiful blue lake. At the first sight
it seemed like some great landing-place or wharf, but there was no sign
of handiwork about it, and the lad gazed at it in awe, as the doctor
explained that it was the end where it had cooled and solidified in the
lake of a huge lava-stream which had flowed down from the mountain, high
up on their right.

"But that means it must have run like so much liquid fire for miles."

"Yes, that's exactly what it does mean, Jack," said Sir John; "six or
seven or eight. We shall know some day, when we have explored the
place."

"And that will be like a high-road to the top," said the doctor, "only
I'm afraid it would be a rather rough one."

"We'll try it some day," said Sir John.

"Rather hard for your boots, sir," said the captain. "Look at it: like
glass, and as sharp in places."

"Why, it must be quite fresh," said Jack.

The captain smiled and shook his head.

"But some of these pieces look quite bright," said Jack.

"Yes; and these trees look quite green, and many of them may be a
hundred or two hundred years old."

"What has that got to do with it?" said Jack. "Oh yes, I see now: they
would have been burned up. Of course."

"Yes," said Sir John, as he stood