y, this path is made of stone!" he cried. He dropped on his knees
and examined more closely. When he rose to his feet his face was grave.

"It's lava!" he stated.

"Then the island must be volcanic!" exclaimed Drew, startled by the
thought.

"Nothing very surprising about that when you come to think of it," Tyke
declared. "We're right down here in the earthquake zone, where the
earth's liable to throw a fit any time. Like enough this old whaleback
is a sleeping volcano. She may blow up again some time."

"Just as it did at Martinique," confirmed the captain. "Perhaps that
may explain the absence of people hereabouts. They may have all been
wiped out by some eruption, or they may have been so scared that they
left the island for safer quarters."

"I don't think we have much to worry about," remarked Tyke. "There
ain't any doubt but this hill we're heading for has been at some time a
volcano. But likely it's been quiet for hundreds of years. An' it's
not likely that it's going to git busy now jest for our special
benefit. Let's hike along."

"There's one good thing about it, anyway," remarked Drew, as they
resumed their march. "It's burned out these paths and made the walking
easier. And it's pointed out just the way we want to go. All we have
to do is to follow this path and it can't help but lead us right up to
the whale's hump."

"That's the point we want to head for," replied the captain, consulting
the map. "You'll notice that these circles seem to be on the slope of
the hill not so very far from the top. Besides, that pirate fellow
would be likely to go quite a way in from the shore to bury his loot."

Half a mile further on, a little stream ran through the forest. The
party went over to it, and Drew, bending down and making a cup of his
hands, bore some of the water to his lips. He made a wry face and
almost choked.

"Sulphur!" he exclaimed. "It's full of it."

Captain Hamilton, too, tasted.

"Another proof, if we needed it, that the island is volcanic," he
observed. Then, in a tone that only Drew heard, he added: "What I
don't like about it is that it shows there's brimstone in the old
whale's hump yet. If there wasn't, the water would have sweetened long
ago."

Tyke and Ruth each took a few drops of the water, and then the party
went on a little more soberly than before. The trees soon became more
scattered, though the undergrowth was dense. Before long they emerged
on a sor