see what you said!" cried Mike, ready enough to laugh
now that his companion was out of danger.

"Oh, don't be stupid at a time like this!" grumbled Vince excitedly.
"Once water begins to eat away, it goes on eating a channel for itself,
like it does at the waterfall over the other side of the island. Well,
this must have cut itself a way along. It's quite a big, sloping
passage, and it must go down to the shore. Can't you see now?"

"I don't know. Do you mean that hole leads down to the shore?"

"Yes, or into some cavern like the great holes where the stream runs out
into the sea."

"Then it would be a way down into the Black Scraw?" cried Mike
excitedly.

"Of course it would. Why, Mikey, we've found out what we were looking
for!"

"You mean you tumbled upon it," said Mike, laughing.

"Tumbled into it," cried Vince, whose face was flushed with eagerness.
"Come on down, and let's have a look if I'm not right."

"What, down there?"

"Yes, of course."

"But isn't it dark?"

"Black enough lower down; but you can see the top part, because the
light shines through all these brambles and thorns."

"But hadn't we better wait till I've got a lanthorn and the rope?"

"Why, of course, before we try to explore it; but we might go and look a
little way. You're not afraid?"

"No, I don't think I'm afraid," said Mike.

"Then come on."

Without a moment's hesitation Vince began to lower himself down where he
had so lately emerged, and Mike followed; but in a few minutes they had
decided that they could do nothing without a light. All they could make
out was that there was a rugged slope, very steep and winding, going
right away in the direction of the sea. They picked up the loose stones
beneath their feet, and threw them into the darkness, and listened to
hear them go bounding down, striking the sides and floor; but there
seemed to be no precipitous fall, and at last, thoroughly satisfied with
their discovery, they climbed back into daylight, and sat down on the
stones to rest and think.

"I've got it!" said Mike suddenly. "It isn't what you think."

"What is it, then?"

"An old mine, where they bored for lead in the old, old days."

"No," said Vince stubbornly, "it's what I say--the channel of an old
stream; and you'll see."

"So will you, my lad, when we bring a lanthorn. I say you'll find the
walls sparkling with what-you-may-call-it--you know--that glittering
lead ore, same as we've got spec