r away to see clearly what had happened,
but it seemed as if a piece of rock had fallen away on the side
toward us, leaving a jaggedy opening as black as a hat and high
enough for a person to stand upright in.

"The entrance to a subaground tunnel!" Greg shouted, leaping up and
down in the edge of a wave.

He _will_ say "subaground," and it really is quite as sensible as
some words.

"The entrance to a real pirate cave, you mean!" said Jerry. "Glory,
Chris, I really shouldn't wonder if it were. Captain Kidd was up and
down the coast here. What if they buried stuff in there and then
propped a big chunk of rock up against the hole?"

"I wish we had a telescope," I said, "though I don't suppose we
could see into the blackness with it. Mercy, I wish we _could_ get
out there! It's more worth exploring than ever."

"Let's tell Mother and Aunt!" said Greg, and started running back
down the beach, shouting something all the way.

Mother said, "Nonsense!" and, "Of course it's a natural cave in the
rock. You probably only noticed it today."

But she and Aunt Ailsa shut up the H.G. Wells book and came to
look. They did think, when they saw it, that it was something new.
Aunt Ailsa thought it looked very exciting and mysterious, but she
agreed with Mother that it was no sort of place to go to in a boat.

"Just look at the white foam flinging around those rocks," she said;
"and there's practically no surf on today."

We had to admit that it wasn't a nice-looking place to land on from
a rowboat, but we did wish that we were hardy adventuring men, bold
of heart and undeterred by grown-ups. We knew, too, that Captain
Moss would say, "Pshaw!" if we told him there might be treasure on
the Sea Monster, and he certainly wouldn't risk the _Jolly Nancy_ on
those rocks in her nice new green paint.

We were so much excited about the Sea Monster suddenly having a big
black hole in it that we almost forgot to take the bottle when we
went home. We did forget Aunt Ailsa's hatpin, and Greg had to run
back for it, because he can run faster than any of the rest of us,
and Captain Lewis held the ferry for him. Everybody leaned out from
the rail and peered up the landing, because they thought it must be
a fire or the President or something. They all looked awfully
disappointed when it was only Greg, with the black necktie still
around his head and Aunt's hatpin held very far away from him so
that it wouldn't hurt him if he fell down. He tu